Fillers for Packaging Applications

*Giovani Otavio Rissi*

### **Abstract**

Packaging in general is frequently overlooked and demonized. The lack of educational programs and efficient waste treatment lead packaging to be treated as an environmental problem. However, packaging is an enabler of our society because it makes feasible the availability of any and every good, regardless of its production location. Furthermore, the packaging business plays a significant role in the global economy, following a continuous trend of growth. The use of fillers in various packaging types can be a valuable resource not only for reducing its cost but also improving its mechanical strength (therefore reducing the number of raw materials required for making that specific package), improving its visual properties to ensure customer attractiveness, creating new possibilities of use, and extending the shelf life of perishable foods. However, the use of fillers in packaging should be made in a way that permits proper recovery and recycling after use.

**Keywords:** packaging, packaging market, paper packaging, plastic packaging, nanofillers, circular economy

#### **1. Introduction**

Before proceeding, it is worthwhile to make a little observation about the environment around you. Take a quick break and behold what surrounds you and the place where you are.

Unless you are reading this in the wild of nature, everything you see was made available through some sort of packaging, even the materials used in the construction of the place where you are were bundled, contained, or packed.

Also, everything you eat—regardless of being an ordinary meal or a gourmet delight—came to you via packaging entrusted to keep high food safety and hygiene standards. Even if one has a backyard or farm that provides a wide variety of fresh produce, at some point in time some packaged foods will be bought and brought home.

Now think about all medicines that are consumed by millions of people every day to keep their well-being and health. Without being noticed, packaging allows for one of the most noble uses: to provide a longer and healthier life. You may now have realized for the first time that life as we know it exists at current standards due to a powerful enabler: packaging. Some studies suggest an association between the quality of life in a certain location and the level of packaging development in the same place [1].

The reason for this is simple: our society has developed in a way that knowledge and experimentation are part of everyday life. We are informed about the latest trends and we want to try new things. At the same time, just a small fraction of the goods we buy is produced in our vicinity. Most goods are produced thousands of

kilometers away from where we live. Some make journeys to our home longer than the longest travel we have ever done.

The definition of the term "packaging" is very broad [2, 3], but it is possible to define it as "a system that consists of different materials, machinery and symbols which are set up in a way to contain, protect, communicate and allow access of its contents to make goods available in a cost-efficient way."

It is not the intention of this chapter to go into detail on marketing aspects of packaging, but references will be made when necessary since most products on shelves rely on their packaging as the sole communication tool with their consumers.

#### **2. Packaging market**

The global market of packaging was estimated to be as of US\$ 851 billion in 2018 as per recent estimates (**Figure 1**) [4, 5].

Considering the market share by material types, cardboard (including corrugated boxes) and plastic packaging in their flexible and rigid forms correspond to almost 80% of the whole market. Fillers are used mainly in these three types of packaging.

Cardboard production has increased due to the rapid growth of e-commerce in recent years. Flexible packaging has proven to be a lightweight and cheaper alternative to glass and metal. The annual growth of the packaging segment is estimated to be between 3.5 and 4.3% and is influenced by the urban shift of populations, the trend of pre-packed products in the food segment, and diversification of retail landscape [6].

It is important to highlight that these estimates were made before the COVID-19 pandemic of 2020, economy was still not precise by the time this chapter was being written. Although exact figures cannot be given, packaging market growth is expected to follow global trade trends, according to previous studies [7].

It is estimated that in 2018 the global plastic production almost reached 359 million tonnes. Even in Europe, where environmental concerns are usually high and public opinion plays a big role, packaging is of key importance since it represents almost 40% of the plastics demand. This share is very expressive since it is more

**31**

improved sales.

**Figure 2.**

*Plastic uses in Europe [8].*

will be further transformed.

in the paper industry [10].

papermaking can be seen in **Table 1** [11].

*Fillers for Packaging Applications*

*DOI: http://dx.doi.org/10.5772/intechopen.93252*

than double the second main use of plastics (building and construction, which

There are two major categories of cellulose-base packaging: corrugated cases the standard brown box using for transporting—and paperboard carton as you may see on supermarket shelves containing cereals, toothpaste, frozen food, etc. There is a wide array of drawing possibilities in both categories and the choice about what should be used depends on product requirements, machinability, and design strategy. These materials are used for "secondary packaging" (because it does not get into contact with the product) in the case of paperboard carton or "transport

The enhancement of visual properties in paper packaging given by fillers makes its use imperative for assuring customer attractiveness. This is not the case for corrugated cases, which have the function of protecting and grouping various units of products during transport. However, for paperboard carton packaging, this feature is crucial for standing out on shelves, grabbing consumer's attention, and providing

Fillers are not added to the process of "converting" cellulosic packaging (printing, cutting, creasing, gluing, etc.) but in the production of the various paper grades that

Fillers used in papermaking are defined as insoluble particles (from 0.1 to 10 μm) added to the slurries of cellulosic fibers before the formation of paper. The uses of fillers vary from zero to 30% [9]. On average, it is estimated that minerals used for wet-end addition and coatings make up 8% (by mass) of the materials used

What defines the amount of fillers used in papermaking is the grade and purpose of that specific paper or paperboard. For instance: an aseptic multilayer packaging like the milk box may have little or no fillers at all, while printing papers

There has been a noted increase in the number of fillers being used, driven by lower cost of fillers themselves compared to the fibers itself, and by meeting market demand for higher opacity and/or brightness. The most common fillers found in

may have 30% (by mass) or more of its content made by fillers.

corresponds to almost 20% of share) (**Figure 2**) [8].

packaging" in the case of corrugated cases for obvious reasons.

**3. Fillers used in paper packaging**

**Figure 1.** *World packaging market (share by material) [4, 5].*

**Figure 2.** *Plastic uses in Europe [8].*

*Fillers*

consumers.

packaging.

**2. Packaging market**

of retail landscape [6].

the longest travel we have ever done.

as per recent estimates (**Figure 1**) [4, 5].

contents to make goods available in a cost-efficient way."

kilometers away from where we live. Some make journeys to our home longer than

The definition of the term "packaging" is very broad [2, 3], but it is possible to define it as "a system that consists of different materials, machinery and symbols which are set up in a way to contain, protect, communicate and allow access of its

It is not the intention of this chapter to go into detail on marketing aspects of packaging, but references will be made when necessary since most products on shelves rely on their packaging as the sole communication tool with their

The global market of packaging was estimated to be as of US\$ 851 billion in 2018

Considering the market share by material types, cardboard (including corrugated boxes) and plastic packaging in their flexible and rigid forms correspond to almost 80% of the whole market. Fillers are used mainly in these three types of

Cardboard production has increased due to the rapid growth of e-commerce in recent years. Flexible packaging has proven to be a lightweight and cheaper alternative to glass and metal. The annual growth of the packaging segment is estimated to be between 3.5 and 4.3% and is influenced by the urban shift of populations, the trend of pre-packed products in the food segment, and diversification

It is important to highlight that these estimates were made before the COVID-19 pandemic of 2020, economy was still not precise by the time this chapter was being written. Although exact figures cannot be given, packaging market growth is

It is estimated that in 2018 the global plastic production almost reached 359 million tonnes. Even in Europe, where environmental concerns are usually high and public opinion plays a big role, packaging is of key importance since it represents almost 40% of the plastics demand. This share is very expressive since it is more

expected to follow global trade trends, according to previous studies [7].

**30**

**Figure 1.**

*World packaging market (share by material) [4, 5].*

than double the second main use of plastics (building and construction, which corresponds to almost 20% of share) (**Figure 2**) [8].

### **3. Fillers used in paper packaging**

There are two major categories of cellulose-base packaging: corrugated cases the standard brown box using for transporting—and paperboard carton as you may see on supermarket shelves containing cereals, toothpaste, frozen food, etc. There is a wide array of drawing possibilities in both categories and the choice about what should be used depends on product requirements, machinability, and design strategy. These materials are used for "secondary packaging" (because it does not get into contact with the product) in the case of paperboard carton or "transport packaging" in the case of corrugated cases for obvious reasons.

The enhancement of visual properties in paper packaging given by fillers makes its use imperative for assuring customer attractiveness. This is not the case for corrugated cases, which have the function of protecting and grouping various units of products during transport. However, for paperboard carton packaging, this feature is crucial for standing out on shelves, grabbing consumer's attention, and providing improved sales.

Fillers are not added to the process of "converting" cellulosic packaging (printing, cutting, creasing, gluing, etc.) but in the production of the various paper grades that will be further transformed.

Fillers used in papermaking are defined as insoluble particles (from 0.1 to 10 μm) added to the slurries of cellulosic fibers before the formation of paper. The uses of fillers vary from zero to 30% [9]. On average, it is estimated that minerals used for wet-end addition and coatings make up 8% (by mass) of the materials used in the paper industry [10].

What defines the amount of fillers used in papermaking is the grade and purpose of that specific paper or paperboard. For instance: an aseptic multilayer packaging like the milk box may have little or no fillers at all, while printing papers may have 30% (by mass) or more of its content made by fillers.

There has been a noted increase in the number of fillers being used, driven by lower cost of fillers themselves compared to the fibers itself, and by meeting market demand for higher opacity and/or brightness. The most common fillers found in papermaking can be seen in **Table 1** [11].


#### **Table 1.**

*Common fillers used in papermaking.*

Fillers from renewable sources can also be used in papermaking [12]. Most common types of natural fillers are:


Although the use of fillers can influence a wide array of attributes in papermaking (coefficient of friction, permeability, burn rate), the two main drivers for their use in cellulose-based packaging are:


Other uses of fillers can lead to the development of nonconventional applications, although commercial use of several novel applications is still strict [13]. Examples are deodorant paper [14], antimicrobial paper [15], flame retardants [16], and magnetic paper [17].

However, fillers reduce the flexibility of paper, posing extra attention to converting operations. Side effects, like creasing, if not done properly the packaging may show small cracks when folded, resulting in reduced mechanical strength and visual defects that can compromise the packaging function of protection and its

**33**

*Fillers for Packaging Applications*

increase abrasion and dusting.

modification among others [13].

**4. Fillers in plastic packaging**

their physical characteristics:

alternatives whenever possible.

packaging materials even at small loads.

used mostly in engineered plastics (**Table 2**).

water vapor, aromas, and oxygen are mandatory [22].

*DOI: http://dx.doi.org/10.5772/intechopen.93252*

attractiveness at the point of sale. Furthermore, and due to its mineral nature, fillers

Plastic packaging is widely used due to its wide range of applications, low cost, relatively high level of safety in terms of migration, and the convenience it can add to packaged products. They have been extensively employed for substituting more

Plastics are commonly used as "primary packaging," meaning it directly contacts the product. Plastics can also be used as secondary packaging to bundle bottles for

Regardless of its use, there are two major groups of plastic packaging, based on

• Flexibles—which include all wraps, bags, and other packaging that can be used

• Rigid—which includes all sorts of tubes, bottles, containers, and drums. This type of packaging is suitable for liquids and products requiring mechanical protection or specific positioning. Due to the higher amount of mass required for achieving rigidity, it is also more expensive and substituted with flexible

Recent developments in the area of material engineering make use of a wide variety of fillers to modify the original properties of plastics. Advances in the production of nanofillers also have shown promising areas of research. These functional fillers can result in unique properties that enhance the performance of

In theory, any material that can be found or transformed into small particles can be used as a filler for plastics in general. Potential combinations are endless but for commercial purposes, fillers for plastics should be readily available, insoluble, and chemically inert; have a low hardness to avoid wear; and be nontoxic, non-flammable,

In general, the most common fillers used in plastics are calcium carbonate, aluminum trihydrate, talc, kaolin, mica, wollastonite, glass fiber, aramid fiber, carbon fiber, and carbon black. However, it is important to highlight that fillers are

The use of fillers affects plastics by modifying original material properties or adding features that did not exist in the original polymer. Specifically for this aim, properties can be changed due to the use of glass fibers, mica flakes, nano-clays, carbon nanotubes/nanofibers, natural fibers, wood flour, talc, and kaolin [21]. Plastic packaging containing nanofillers has been shown to have an enhanced performance especially for food packaging, where high barrier properties against

and finally free from metal impurities, which can degrade plastics [19].

manually or automated through vertical or horizontal machines.

expensive packaging materials like glass, metal, and even wood [18].

instance or to transport packaging in the form of a stretch film.

To overcome these drawbacks, fillers have been modified in several ways to achieve desired properties in an optimized way. Examples of processes that allow filler modification are modification with inorganic substances, modification with natural polymers (or their derivatives), modification with water-soluble synthetic polymers, modification with surfactants, hydrophobic modification, cationic

#### *Fillers for Packaging Applications DOI: http://dx.doi.org/10.5772/intechopen.93252*

*Fillers*

types of natural fillers are:

*Common fillers used in papermaking.*

*Adapted from [11].*

**Table 1.**

capacity.

cellulose.

paper.

customers.

paper [17].

cellulose-based packaging are:

Fillers from renewable sources can also be used in papermaking [12]. Most common

Precipitated calcium carbonate (PCC)

• **Starch or starch derivates**—for increasing fiber bonding and consequently

• **Cellulose derivates (like microcrystalline cellulose)**—for encapsulating fillers and increasing its bonding strength to cellulose fibers, as well as improving heat

• **Chitin or chitosan**—also for improving bonding, since chemically speaking the structure of the molecules of chitin and chitosan are very similar to that of

Although the use of fillers can influence a wide array of attributes in papermaking (coefficient of friction, permeability, burn rate), the two main drivers for their use in

• **Cost reduction**—this can be achieved in two ways: either by partially substituting cellulose content or by reducing the energy demand required for drying

• **Visual properties**—the addition of fillers greatly enhances printing quality on paper packaging by improving opacity, brightness, and smoother surface from calendaring. This is particularly important for products that communicate their brand through their shelf packaging, with the need of attracting

Other uses of fillers can lead to the development of nonconventional applications, although commercial use of several novel applications is still strict [13]. Examples are deodorant paper [14], antimicrobial paper [15], flame retardants [16], and magnetic

However, fillers reduce the flexibility of paper, posing extra attention to converting operations. Side effects, like creasing, if not done properly the packaging may show small cracks when folded, resulting in reduced mechanical strength and visual defects that can compromise the packaging function of protection and its

• **Xantham gum or anionic guar gum**—for improving paper strength.

mechanical properties like tensile, tearing and folding strength.

**Chemical composition Natural source Synthetic source**

TiO2 — Titanium dioxide

Al2O3.2SiO2.2H2O Clay (hydrous kaolinite) Precipitated aluminum silicate

(GCC) Chalk (ground)

Mg3Si4O10(OH)2 Talc — CaSO4.2H2O — Gypsum

CaCO3 Ground limestone

**32**

attractiveness at the point of sale. Furthermore, and due to its mineral nature, fillers increase abrasion and dusting.

To overcome these drawbacks, fillers have been modified in several ways to achieve desired properties in an optimized way. Examples of processes that allow filler modification are modification with inorganic substances, modification with natural polymers (or their derivatives), modification with water-soluble synthetic polymers, modification with surfactants, hydrophobic modification, cationic modification among others [13].

#### **4. Fillers in plastic packaging**

Plastic packaging is widely used due to its wide range of applications, low cost, relatively high level of safety in terms of migration, and the convenience it can add to packaged products. They have been extensively employed for substituting more expensive packaging materials like glass, metal, and even wood [18].

Plastics are commonly used as "primary packaging," meaning it directly contacts the product. Plastics can also be used as secondary packaging to bundle bottles for instance or to transport packaging in the form of a stretch film.

Regardless of its use, there are two major groups of plastic packaging, based on their physical characteristics:


Recent developments in the area of material engineering make use of a wide variety of fillers to modify the original properties of plastics. Advances in the production of nanofillers also have shown promising areas of research. These functional fillers can result in unique properties that enhance the performance of packaging materials even at small loads.

In theory, any material that can be found or transformed into small particles can be used as a filler for plastics in general. Potential combinations are endless but for commercial purposes, fillers for plastics should be readily available, insoluble, and chemically inert; have a low hardness to avoid wear; and be nontoxic, non-flammable, and finally free from metal impurities, which can degrade plastics [19].

In general, the most common fillers used in plastics are calcium carbonate, aluminum trihydrate, talc, kaolin, mica, wollastonite, glass fiber, aramid fiber, carbon fiber, and carbon black. However, it is important to highlight that fillers are used mostly in engineered plastics (**Table 2**).

The use of fillers affects plastics by modifying original material properties or adding features that did not exist in the original polymer. Specifically for this aim, properties can be changed due to the use of glass fibers, mica flakes, nano-clays, carbon nanotubes/nanofibers, natural fibers, wood flour, talc, and kaolin [21].

Plastic packaging containing nanofillers has been shown to have an enhanced performance especially for food packaging, where high barrier properties against water vapor, aromas, and oxygen are mandatory [22].


#### **Table 2.**

*Examples of fillers used in plastics.*

Because the surface area of nano-clays can be more than 750 m2 /g, the use of nanofillers even in loads smaller than 2% (in volume) creates a tortuous path for the diffusion of gases through the polymer matrix, therefore improving its gas barrier. This is of special interest because nanofillers can be an alternative to multilayer coextruded packaging, which are commonly not recyclable. Another advantage of adding nanofillers (like montmorillonite-MMT, kaolinite, carbon nanotubes, and more recently graphene nanosheets) in plastic packaging is the improved mechanical properties that allow downgauging and consequent economic and environmental benefits.

The use of nanofillers can also enable broader use of biopolymers in packaging. This group of materials has been studied for several decades but, usually, their properties are much weaker when compared to petroleum-based polymers. They include natural sources like starch; cellulose; proteins (collagen, soybean protein, zein, etc.); and polylactic acid (PLA). The low-performance properties of these "green" materials and can be compensated by the addition of nanofillers, broadening the possibilities of use at commercial scale [23, 24].

On top of the mechanical reinforcement and improved barrier properties, nanofillers can extend the shelf life of products that may spoil due to the development of pathogenic or spoilage microorganisms. It is known that the use of nanofillers made of silica through the sol-gel method has improved the shelf life of fruits due to their hydrophobic characteristics [25].

Besides the features mentioned above, other beneficial functions of nanofillers in food packaging are the possibility of exploring and developing new technologies in the area of active packaging, where the role of packaging goes beyond traditional purposes. Main groups of research areas can be listed as follows [26, 27]:

a.Oxygen scavenging—oxygen causes food spoilage due to oxidation or due to enabling aerobic bacteria development. Even under proper vacuum, package materials may allow the permeation of O2.

**35**

*Fillers for Packaging Applications*

life of products.

product decay.

polymer nanocomposites.

current analytical methods [28].

**5. Environmental concerns**

chain has detrimentally changed.

impact is called greenwashing.

ingested or been entangled by plastic debris.

*DOI: http://dx.doi.org/10.5772/intechopen.93252*

b.Nanobased sensors—for compensating transport and storage conditions (e.g., temperature variations) and informing about the potential shorter shelf

c.Detection of gases produced by food spoilage—microbial development is commonly followed by gas production, which can be detected by conducting

d.O2 indicators—since the development of aerobic microorganisms happens during the presence of oxygen, the control of this gas is necessary to evaluate

e.Enzyme immobilization at the nanoscale—sometimes the direct uses of enzymes is restricted due to its potential degradation during processing. The absorption of enzymes by nano-clays embedded in a polymer matrix is a

However, the fillers at nanoscale should be only used after a careful study of their toxicology and potential harm to humans and the environment. It is known that migration may happen from food-contact materials through various mechanisms that may not be fully extracted by standardized simulants or quantified by

More than ever, the packaging is under public scrutiny and blamed for environmental problems. Although only approximately 10%, of all solid waste, is plastic, up to 80% of all waste accumulated in land, shorelines, seabed, and ocean surface is plastic due to its long decomposition time. This is a threat to aquatic animals since they can be entangled or ingest plastic fragments. Some researches suggest that over 260 species of animals (invertebrates, mammals, seabirds, fishes, turtles) have

Due to its fragmentation properties, plastic packaging can decompose into microplastics and pose yet another type of hazard. The bodies of all marine species, ranging in size from plankton to the blue whale, contain plastics [29]. The food

While attention has been focused on the number of microplastics in oceans, almost no effort has been made in fighting root causes. The pollution on land, in rivers and the ocean, is not caused by plastic packaging or any other packaging material, but by the lack of educating the public on the consequences of littering. Furthermore, massive marketing is promoting miraculous solutions and materials for the sake of the environment without technical evidence about its effectiveness. Deceiving customers with the promise of mitigating their environmental

Another problem in evaluating the environmental benefit of packaging is to neglect the components of the product itself. It happens for the vast majority of products that the packaging impact is much lower than that of the product itself

The most advanced tool to evaluate the eco-efficiency of packaging is the Life Cycle Assessment (LCA), which has already been used for a wide array of applications with great acceptance from the scientific community. It provides comparative data about the environmental impact of the product under analysis considering

[30] and eventual packaging failure will lead to increased waste.

promising mechanism for efficient release control.

*Fillers*

Natural fibers

*Adapted from [20, 21].*

*Examples of fillers used in plastics.*

**Table 2.**

**Filler source Group Examples**

Inorganic Oxides Glass, SiO2, ZnO, Al2O3, MgO

Hydroxides Mg(OH)2, Al(OH)3

Natural polymers Cellulose, starch

Straw Wheat, corn, and rice Bast Hemp, jute, kenaf, lax Leaf Pineapple leaf, sisal Seed/fruit Cotton, coir

Grass fibers China reed, bamboo, grass Wood fiber Hardwood, softwood

Salts CaCO3, CaSO4, BaSO4, phosphates

flakes

Silicates Talc, kaolin, mica, montmorillonite, wollastonite, feldspar

Metal Steel, boron, (silver for antimicrobial nanofillers) Organics Carbon, graphite Carbon fillers and nanotubes, carbon black, graphite fibers and

Synthetic polymers Polyester, aramid, polyamide and PVOH fibers

Because the surface area of nano-clays can be more than 750 m2

allow downgauging and consequent economic and environmental benefits.

ing the possibilities of use at commercial scale [23, 24].

materials may allow the permeation of O2.

hydrophobic characteristics [25].

fillers even in loads smaller than 2% (in volume) creates a tortuous path for the diffusion of gases through the polymer matrix, therefore improving its gas barrier. This is of special interest because nanofillers can be an alternative to multilayer coextruded packaging, which are commonly not recyclable. Another advantage of adding nanofillers (like montmorillonite-MMT, kaolinite, carbon nanotubes, and more recently graphene nanosheets) in plastic packaging is the improved mechanical properties that

The use of nanofillers can also enable broader use of biopolymers in packaging. This group of materials has been studied for several decades but, usually, their properties are much weaker when compared to petroleum-based polymers. They include natural sources like starch; cellulose; proteins (collagen, soybean protein, zein, etc.); and polylactic acid (PLA). The low-performance properties of these "green" materials and can be compensated by the addition of nanofillers, broaden-

On top of the mechanical reinforcement and improved barrier properties, nanofillers can extend the shelf life of products that may spoil due to the development of pathogenic or spoilage microorganisms. It is known that the use of nanofillers made of silica through the sol-gel method has improved the shelf life of fruits due to their

Besides the features mentioned above, other beneficial functions of nanofillers in food packaging are the possibility of exploring and developing new technologies in the area of active packaging, where the role of packaging goes beyond traditional

a.Oxygen scavenging—oxygen causes food spoilage due to oxidation or due to enabling aerobic bacteria development. Even under proper vacuum, package

purposes. Main groups of research areas can be listed as follows [26, 27]:

/g, the use of nano-

**34**


However, the fillers at nanoscale should be only used after a careful study of their toxicology and potential harm to humans and the environment. It is known that migration may happen from food-contact materials through various mechanisms that may not be fully extracted by standardized simulants or quantified by current analytical methods [28].

#### **5. Environmental concerns**

More than ever, the packaging is under public scrutiny and blamed for environmental problems. Although only approximately 10%, of all solid waste, is plastic, up to 80% of all waste accumulated in land, shorelines, seabed, and ocean surface is plastic due to its long decomposition time. This is a threat to aquatic animals since they can be entangled or ingest plastic fragments. Some researches suggest that over 260 species of animals (invertebrates, mammals, seabirds, fishes, turtles) have ingested or been entangled by plastic debris.

Due to its fragmentation properties, plastic packaging can decompose into microplastics and pose yet another type of hazard. The bodies of all marine species, ranging in size from plankton to the blue whale, contain plastics [29]. The food chain has detrimentally changed.

While attention has been focused on the number of microplastics in oceans, almost no effort has been made in fighting root causes. The pollution on land, in rivers and the ocean, is not caused by plastic packaging or any other packaging material, but by the lack of educating the public on the consequences of littering.

Furthermore, massive marketing is promoting miraculous solutions and materials for the sake of the environment without technical evidence about its effectiveness. Deceiving customers with the promise of mitigating their environmental impact is called greenwashing.

Another problem in evaluating the environmental benefit of packaging is to neglect the components of the product itself. It happens for the vast majority of products that the packaging impact is much lower than that of the product itself [30] and eventual packaging failure will lead to increased waste.

The most advanced tool to evaluate the eco-efficiency of packaging is the Life Cycle Assessment (LCA), which has already been used for a wide array of applications with great acceptance from the scientific community. It provides comparative data about the environmental impact of the product under analysis considering

various aspects like Global Warmth Power (GWP), ozone depletion, toxicity (both cancerous and noncancerous), particulate respiratory effects, ionizing radiation, photochemical ozone creation potential, acidification potential, aquatic eutrophication, freshwater ecotoxicity potential, and nonrenewable resource depletion. Other parameters to be considered are land use, freshwater use, and cumulative energy demand (CED) [31].

It was already mentioned that fillers reduce the drying energy required in papermaking, which will be transformed into cellulosic-based packaging. Although the use of fillers may reduce the carbon footprint of papermaking in some aspects [32], a full LCA analysis should be performed to confirm assumptions. Nevertheless, the environmental impact of mineral fillers in the production of paper or paperboard is expected to be negative according to perspectives below:


**37**

**Figure 3.**

*Fillers for Packaging Applications*

found (e.g., LDPE and talc).

of the system.

*DOI: http://dx.doi.org/10.5772/intechopen.93252*

market to justify production [38, 39].

Fillers of organic origin like wood waste-derived fillers have been studied for several decades and can contribute toward reducing solid waste, even in large-scale commercial activities, although compounders are somehow reluctant to consider this technology because they are not sure how to handle it or are not aware of a

Unfortunately, for the time being, the amount of LCA studies evaluating the environmental impact of fillers added to polymers is likewise small but indicates potential lower GWP comparing to standard plastics. Better eco-performance is achieved using nanofillers, which reduces the amount of petroleum-based raw materials for achieving the same performance although some exceptions can be

The addition of natural fibers to partially substitute polymers may also be an opportunity for reducing the environmental impact especially because they come from renewable sources, but again an LCA analysis is necessary for confirmation due to the production burden of raw materials [40]. It is important to highlight that LCA studies should include not only the resources used to produce that specific type of packaging but also the after-use impact. This broad view limits the boundaries of the analyses "from cradle to grave" and is fundamental for having an overall picture

The process of recovering material by recycling is becoming increasingly important due to environmental and economical concerns. One recent driver toward reduced environmental impact is the concept of circular economy, where the traditional linear model of production is substituted by the concept of keeping

One of the models of circular economy in use was proposed by the Ellen MacArthur Foundation, commonly known as the "butterfly diagram." The smaller the loop, the greater the value of the material in question. The right side of the diagram (in blue) refers to "technical cycles" where goods are designed to stay in use for the longest possible period through sharing, reusing, extended durability,

*The circular economy model with technical (right) and biological (left) cycles proposed by the Ellen* 

goods in use for the longest possible time (**Figure 3**) [41].

repairing, and recycling, the last possible loop.

*MacArthur Foundation. Reproduced with permission.*

#### *Fillers for Packaging Applications DOI: http://dx.doi.org/10.5772/intechopen.93252*

*Fillers*

demand (CED) [31].

of CO2eq.).

various aspects like Global Warmth Power (GWP), ozone depletion, toxicity (both cancerous and noncancerous), particulate respiratory effects, ionizing radiation, photochemical ozone creation potential, acidification potential, aquatic eutrophication, freshwater ecotoxicity potential, and nonrenewable resource depletion. Other parameters to be considered are land use, freshwater use, and cumulative energy

It was already mentioned that fillers reduce the drying energy required in papermaking, which will be transformed into cellulosic-based packaging. Although the use of fillers may reduce the carbon footprint of papermaking in some aspects [32], a full LCA analysis should be performed to confirm assumptions. Nevertheless, the environmental impact of mineral fillers in the production of paper or paperboard is

a.**Substitution of cellulosic fibers**—during plant growth, CO2 from the atmosphere is captured resulting in negative emissions. Although industrial processes have positive emissions for the production of paper, the net absorption of CO2 is much larger. Numbers vary according to countries, paper grades, and technological development, but public data from companies that have an integrated paper facility show that every ton of finished product captures the equivalent of 2.6–3.8 tons of CO2 equivalent (CO2eq.) from the atmosphere [33, 34]. Adding fillers for the sake of sheer cost reduction with no technical benefits increases the environmental impact of the final packaging (in terms

b.**Replacement of a renewable raw material by a nonrenewable one**—although synthetic fillers can be produced, mineral fillers of natural sources are extensively used. They are mined in several parts of the world, which means dependence on the natural availability of that specific resource. On the other hand, cellulose fibers come from trees, which can be planted and harvested repeatedly,

c.**Harder to recycle**—many cellulosic-based packaging may be produced from recycling another packaging due to availability and costs. If the paperboard can not be easily recycled, it is likely to be sent to energy recovery (incineration) or, more commonly, landfilling. During the degradation of cellulose, CH4 is emitted, representing a GWP of about 25 times that of CO2 [35]. Depending on the quality and grade of the recycled paper pursued, fillers have to be removed to provide a higher quality of recycled materials (which also have a higher market value). It is estimated that the removal of fillers along with other contaminants (stickers, inks, fines, etc.) require 30–100% more recovered paper for the same final product, resulting in a higher amount of nonrecyclable waste to deal with [36].

d.**Environmental impact for making fillers**—the process of making fillers comprehends an extensive production chain, which includes removal of impurities, engineering particle shape and size, and finally enhancing its properties through thermal and/or chemical treatments. Also, fillers should be transported to the paper mill facility, which may be located far away, incurring fuel consumption and extra environmental burden. The mining activity alone is very complex: it includes exploration of the deposits, resource development, feasibility and reserve development, mine planning (including permitting and construction), and production. When resources are exhausted and the mine is

closed, further work is necessary for restoring the area [37].

expected to be negative according to perspectives below:

if responsible soil and water handling are provided.

**36**

Fillers of organic origin like wood waste-derived fillers have been studied for several decades and can contribute toward reducing solid waste, even in large-scale commercial activities, although compounders are somehow reluctant to consider this technology because they are not sure how to handle it or are not aware of a market to justify production [38, 39].

Unfortunately, for the time being, the amount of LCA studies evaluating the environmental impact of fillers added to polymers is likewise small but indicates potential lower GWP comparing to standard plastics. Better eco-performance is achieved using nanofillers, which reduces the amount of petroleum-based raw materials for achieving the same performance although some exceptions can be found (e.g., LDPE and talc).

The addition of natural fibers to partially substitute polymers may also be an opportunity for reducing the environmental impact especially because they come from renewable sources, but again an LCA analysis is necessary for confirmation due to the production burden of raw materials [40]. It is important to highlight that LCA studies should include not only the resources used to produce that specific type of packaging but also the after-use impact. This broad view limits the boundaries of the analyses "from cradle to grave" and is fundamental for having an overall picture of the system.

The process of recovering material by recycling is becoming increasingly important due to environmental and economical concerns. One recent driver toward reduced environmental impact is the concept of circular economy, where the traditional linear model of production is substituted by the concept of keeping goods in use for the longest possible time (**Figure 3**) [41].

One of the models of circular economy in use was proposed by the Ellen MacArthur Foundation, commonly known as the "butterfly diagram." The smaller the loop, the greater the value of the material in question. The right side of the diagram (in blue) refers to "technical cycles" where goods are designed to stay in use for the longest possible period through sharing, reusing, extended durability, repairing, and recycling, the last possible loop.

#### **Figure 3.**

*The circular economy model with technical (right) and biological (left) cycles proposed by the Ellen MacArthur Foundation. Reproduced with permission.*

The left part of the diagram (in green) refers to "biological cycles," where components of any goods or packaging may biodegrade. This is a feasible alternative for organic waste or sewage, but it is the least wanted solution for packaging because recycling has a greater value and lower environmental impact than biodegrading.

#### **6. Conclusion**

Packaging plays a fundamental role in our society by providing accessibility to food and any other type of physical goods. Broad multidisciplinary knowledge is necessary for making the definition of a packaging system accurately.

The choice of packaging which is more adequate for a specific product must pass through the definition of suitable materials and its properties for best fulfilling production, distribution, preservation and sales requirements. Most important packaging materials are made of cellulose (cases and folded carton) and polymers (flexible or rigid packaging), which are the types of materials where fillers are mostly used.

No matter what type of packaging system is chosen, the end of life of that specific packaging (reuse, recycling, incineration or composting) should always be considered in the project phase. The selection of the proper filler(s) combined with the optimum amount used to contribute to the success of that package either during its lifespan as well as during the recycling stage.

#### **Acknowledgements**

The author would like to thank Juliano Barbosa and Stefan Viering for sharing their expertise. The author is also grateful to Hessa Tary for her feedback and friendship.

#### **Conflict of interest**

The author declares no conflict of interest.

#### **Author details**

Giovani Otavio Rissi Independent Packaging Consultant, Gavardo, Italy

\*Address all correspondence to: giovani.rissi@gmail.com

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**39**

2020]

*Fillers for Packaging Applications*

[1] Bülent E, Aysel I. Packaging materials and effects on quality of life. In: Proceedings of the 1st International conference on Quality of Life; June 2016. Serbia: Center for Quality, Faculty of Engineering, University of

[2] Emblem A, Emblem H, editors. Packaging Technology: Fundamentals, Materials and Processes. Cambridge: Woodhead Publishing; 2012. p. 579

[3] Hanlon F.J, Kelsey R. J, Forcinio, H, authors. Handbook of Package Engineering, 3rd ed. Boca Raton: CRC

[4] The Future of Global Packaging to 2022. Smithers Pira [Internet]. 2018. Available from: https://www.smithers. com/resources/2018/feb/paper-andboardroles-in-the-future-of-packaging

Kragujevac; 2016

**References**

Press; 1998. 698

[Accessed: 15 April 2020]

[5] Packaging Market Continuous to Grow [Internet]. Available from: https://www.interpack.com/en/ TIGHTLY\_PACKED/SECTORS/ INDUSTRIAL\_GOODS\_PACKAGING/ News/Packaging\_market\_continues\_to\_

grow [Accessed: 15 April 2020]

[6] Packaging and Protective Packaging [Internet]. 2020. Available from: https://www.alliedmarketresearch. com/packaging-and-protectivepackagingmarket [Accessed: 17 April

[7] Packaging and Trade Kofi Manso Essuman [Internet]. 2018. Available from: https://www.worldpackaging.org/ Uploads/2018-11/ResourcePDF27.pdf

[Accessed: 22 April 2020]

[8] Plastics—The facts 2019 [Internet]. 2019. Available from: https://www.plasticseurope.org/ application/files/9715/7129/9584/ FINAL\_web\_version\_Plastics\_the\_

*DOI: http://dx.doi.org/10.5772/intechopen.93252*

facts2019\_14102019.pdf [Accessed: 22

[10] Chamberlain D, Kirwan M. Chapter

1 - Paper and paperboard - Raw materials, processing and properties. In: Handbook of Paper and Paperboard Packaging Technology. 2nd ed. Sussex Willey-Blackwell; 2012. pp. 1-49. DOI:

10.1002/9781118470930.ch1

[11] Gill RA. Applications of wet-end paper chemistry fillers for papermaking. In: Au CO, Thorn I, editors. Applications of Wet-End Paper Chemistry. Dordrech:

Springer; 1995. pp. 54-75. DOI: 10.1007/978-94-017-0756-5\_4

[12] Shen J, Song Z, Qian X, Ni Y. Carbohydrate-based fillers and pigments for papermaking: A review. Carbohydrate Polymers. 2011;**85**:17-22. DOI: 10.1016/j.carbpol.2011.02.026

[13] Shen J, Song Z, Qian X, Ni Y. Modification of papermaking grade fillers: A brief review. BioResources.

[14] European Patent Specification, A functional Paper and Its Use as a Deodorant, Filtering Medium or Adsorbent [Internet]. 1997. Available from: https://patentimages. storage.googleapis.com/ee/5e/5b/ f254362b546ee8/EP0393723B1.pdf

[15] Kim C-H, Cho S-H, Park W-PO. Inhibitory effect of functional

packaging paper containing grapefruit seed extracts and zeolite against microbial growth. Appita Journal.

2009;**4**:1190-1209

[Accessed: 27 April 2020]

2005;**58**:202-207

[9] Hubbe M, Gill R. Fillers for papermaking: A review of their properties, usage practices, and their mechanistic role. BioResources. 2016;**11**:2886-2963. DOI: 10.15376/

biores.11.1.2886-2963

April 2020]

*Fillers for Packaging Applications DOI: http://dx.doi.org/10.5772/intechopen.93252*

#### **References**

*Fillers*

**6. Conclusion**

**38**

**Author details**

Giovani Otavio Rissi

**Acknowledgements**

**Conflict of interest**

friendship.

Independent Packaging Consultant, Gavardo, Italy

provided the original work is properly cited.

The author declares no conflict of interest.

its lifespan as well as during the recycling stage.

\*Address all correspondence to: giovani.rissi@gmail.com

The left part of the diagram (in green) refers to "biological cycles," where components of any goods or packaging may biodegrade. This is a feasible alternative for organic waste or sewage, but it is the least wanted solution for packaging because recycling has a greater value and lower environmental impact than biodegrading.

Packaging plays a fundamental role in our society by providing accessibility to food and any other type of physical goods. Broad multidisciplinary knowledge is

The choice of packaging which is more adequate for a specific product must pass through the definition of suitable materials and its properties for best fulfilling production, distribution, preservation and sales requirements. Most important packaging materials are made of cellulose (cases and folded carton) and polymers (flexible or rigid packaging), which are the types of materials where fillers are mostly used. No matter what type of packaging system is chosen, the end of life of that specific packaging (reuse, recycling, incineration or composting) should always be considered in the project phase. The selection of the proper filler(s) combined with the optimum amount used to contribute to the success of that package either during

The author would like to thank Juliano Barbosa and Stefan Viering for sharing their expertise. The author is also grateful to Hessa Tary for her feedback and

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

necessary for making the definition of a packaging system accurately.

[1] Bülent E, Aysel I. Packaging materials and effects on quality of life. In: Proceedings of the 1st International conference on Quality of Life; June 2016. Serbia: Center for Quality, Faculty of Engineering, University of Kragujevac; 2016

[2] Emblem A, Emblem H, editors. Packaging Technology: Fundamentals, Materials and Processes. Cambridge: Woodhead Publishing; 2012. p. 579

[3] Hanlon F.J, Kelsey R. J, Forcinio, H, authors. Handbook of Package Engineering, 3rd ed. Boca Raton: CRC Press; 1998. 698

[4] The Future of Global Packaging to 2022. Smithers Pira [Internet]. 2018. Available from: https://www.smithers. com/resources/2018/feb/paper-andboardroles-in-the-future-of-packaging [Accessed: 15 April 2020]

[5] Packaging Market Continuous to Grow [Internet]. Available from: https://www.interpack.com/en/ TIGHTLY\_PACKED/SECTORS/ INDUSTRIAL\_GOODS\_PACKAGING/ News/Packaging\_market\_continues\_to\_ grow [Accessed: 15 April 2020]

[6] Packaging and Protective Packaging [Internet]. 2020. Available from: https://www.alliedmarketresearch. com/packaging-and-protectivepackagingmarket [Accessed: 17 April 2020]

[7] Packaging and Trade Kofi Manso Essuman [Internet]. 2018. Available from: https://www.worldpackaging.org/ Uploads/2018-11/ResourcePDF27.pdf [Accessed: 22 April 2020]

[8] Plastics—The facts 2019 [Internet]. 2019. Available from: https://www.plasticseurope.org/ application/files/9715/7129/9584/ FINAL\_web\_version\_Plastics\_the\_ facts2019\_14102019.pdf [Accessed: 22 April 2020]

[9] Hubbe M, Gill R. Fillers for papermaking: A review of their properties, usage practices, and their mechanistic role. BioResources. 2016;**11**:2886-2963. DOI: 10.15376/ biores.11.1.2886-2963

[10] Chamberlain D, Kirwan M. Chapter 1 - Paper and paperboard - Raw materials, processing and properties. In: Handbook of Paper and Paperboard Packaging Technology. 2nd ed. Sussex Willey-Blackwell; 2012. pp. 1-49. DOI: 10.1002/9781118470930.ch1

[11] Gill RA. Applications of wet-end paper chemistry fillers for papermaking. In: Au CO, Thorn I, editors. Applications of Wet-End Paper Chemistry. Dordrech: Springer; 1995. pp. 54-75. DOI: 10.1007/978-94-017-0756-5\_4

[12] Shen J, Song Z, Qian X, Ni Y. Carbohydrate-based fillers and pigments for papermaking: A review. Carbohydrate Polymers. 2011;**85**:17-22. DOI: 10.1016/j.carbpol.2011.02.026

[13] Shen J, Song Z, Qian X, Ni Y. Modification of papermaking grade fillers: A brief review. BioResources. 2009;**4**:1190-1209

[14] European Patent Specification, A functional Paper and Its Use as a Deodorant, Filtering Medium or Adsorbent [Internet]. 1997. Available from: https://patentimages. storage.googleapis.com/ee/5e/5b/ f254362b546ee8/EP0393723B1.pdf [Accessed: 27 April 2020]

[15] Kim C-H, Cho S-H, Park W-PO. Inhibitory effect of functional packaging paper containing grapefruit seed extracts and zeolite against microbial growth. Appita Journal. 2005;**58**:202-207

[16] United States Patent—Fire retardant pigment [Internet]. 1989. Available from: https://patentimages. storage.googleapis.com/17/b2/ a4/456a42fe06b828/US4842772.pdf

[17] Zakaria S, Ong BH, van de Ven T. Lumen loading magnetic paper I: Flocculation. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2004;**251**:1-4. DOI: 10.1016/j. colsurfa.2004.06.020

[18] DeArmitt C. Functional fillers for plastics. In: Kutz M, editor. Applied Plastics Engineering Handbook: Processing and Materials. Oxford: Elsevier; 2011. pp. 455-468. DOI: 10.1016/B978-1-4377-3514-7.10026-1

[19] Filled with Success [Internet]. 2010. Available from: https://phantomplastics. com/wp-content/uploads/2013/08/ Filled-with-Success-Composites-World-July-August-2010.pdf [Accessed: 05 May 2010]

[20] Bos HL. The Potential of Flax Fibres as Reinforcement for Composite Materials. Eindhoven: Technische Universiteit Eindhoven; 2004. DOI: 10.6100/IR575360

[21] Xanthos M, editor. Polymers and polymer composites. In: Functional Fillers for Plastics. Weinheim: WILEY-VCH Verlag GmbH & Co. KGaA; 2011. p. 451. DOI: 10.1002/9783527629848.ch1

[22] Ahmed MR. Polymer nanocomposites as a new trend for packaging applications. Polymer-Plastics Technology and Engineering. 2013;**52**(7):635-660. DOI: 10.1080/03602559.2012.762673

[23] Arora A, Padua GW. Review: Nanocomposites in food packaging. Journal of Food Science. 2010;**75**:R43–R49. DOI: 10.1111/j.1750-3841.2009.01456.x

[24] Chielini E. Environmentally Compatible Food Packaging.

Cambridge: Woodhead Publishing; 2008. p. 592

[25] Arreche R, Blanco M, Vázquez P, Martin-Martinez J. Use of new silica fillers as additives for polymers used in packaging of fruit. Química Nova. 2011;**35**:1907-1911. DOI: 10.1590/ S0100-40422012001000003

[26] Azeredo H. Nanocomposites for food packaging applications. Food Research International. 2009;**42**(9):1240-1253. DOI: 10.1016/j. foodres.2009.03.019

[27] Azeredo H, Otoni C, Assis O, Correa D, Moura M, Mattoso L. Nanoparticles and Antimicrobial Food Packaging. Basel MDPI. 2018. DOI: 10.1016/B978-0-08-1005965.21874-X

[28] Maryam J, Gitte AP, Katrin L. Six open questions about the migration of engineered nano-objects from polymerbased food-contact materials: A review. Food Additives & Contaminants: Part A. 2017;**34**(3):434-450. DOI: 10.1080/19440049.2016.1271462

[29] Wabnitz C, Nichols W. Editorial: Plastic pollution: An ocean emergency. Marine Turtle News Letter. 2010;**129**:1-4

[30] Grant T, Barichello V, Fitzpatrick L. Accounting the impacts of waste product in package design. In: Procedia CIRP; 7-9 April 2015; Sydney, Australia. p. 568572. DOI: 10.1016/j. procir.2015.02.062

[31] Tacker M. Methods for the assessment of environmental sustainability of packaging: A review. IJRDO. 2017;**3**:33

[32] Shen J, Song Z, Qian X. Fillers and the carbon footprint of papermaking. BioResources. 2010;**5**:2026-2028. DOI: 10.15376/biores.5.4.2026-2028

[33] Relatório de sustentabilidade Irani [Internet]. 2018. Available from:

**41**

*Fillers for Packaging Applications*

[Accessed: 16 May 2020]

May 2020]

*DOI: http://dx.doi.org/10.5772/intechopen.93252*

[41] The Circular Economy in Detail [Internet]. 2017. Available from: https:// www.ellenmacarthurfoundation.

explore/the-circular-economy-in-detail

org/explore/the-circulareconomy-indetailhttps://www. ellenmacarthurfoundation.org/

[Accessed: 15 May 2020]

http://www.irani.com.br/wp-content/ uploads/2019/04/Relat%C3%B3riode-Sustentabilidade-Irani-2018.pdf

[34] Inventário Corporativo de Gases de Efeito Estufa [Internet]. 2013. Available from: http://www.irani.com.br/uploads/ mediacenter/9dafb35a11fe587a8b093f2 b76871241f823eda6.pdf [Accessed: 16

[35] Ongmongkolkul A. Life cycle assessment of paperboard packaging produced in Thailand [M.S. thesis]. Thailand: School of Environment, Resource and Development Asian Institute of Technology (AIT); 2001

[36] Ghinea C, Petraru M, Simion I, Sobariu D, Bressers H, Gavrilescu M. Life cycle assessment of waste management

[37] Kogel JE. Mining and processing kaolin. Elements. 2014;**10**(3):189-193. DOI: 10.2113/gselements.10.3.189

[38] English B, Clemons CM, Stark N, Schneider JP. Waste-wood-derived fillers for plastics. In: Gen. Tech. Rep. FPL-GTR-91. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory; 1996. p. 15. DOI: 10.2737/FPL-GTR-91

[39] Clemons CM. Natural fibers. In: Xanthos M, editor. Functional Fillers for Plastics. Weinheim, WILEY-VCH Verlag GmbH & Co. KGaA. 2010. DOI:

[40] Civancik-Uslu D, Ferrer L, Puig R, Fullana-i-Palmer P. Are functional fillers improving environmental behavior of plastics? A review on LCA studies. Science of the Total Environment. 2018;**626**:927-940. DOI: 10.1016/j.

10.1002/9783527629848.ch11

scitotenv.2018.01.149

and recycled paper systems. Environmental Engineering and Management Journal. 2014;**13**:2073- 2085. DOI: 10.30638/eemj.2014.230

*Fillers for Packaging Applications DOI: http://dx.doi.org/10.5772/intechopen.93252*

*Fillers*

[16] United States Patent—Fire retardant pigment [Internet]. 1989. Available from: https://patentimages. storage.googleapis.com/17/b2/ a4/456a42fe06b828/US4842772.pdf

Cambridge: Woodhead Publishing;

[25] Arreche R, Blanco M, Vázquez P, Martin-Martinez J. Use of new silica fillers as additives for polymers used in packaging of fruit. Química Nova. 2011;**35**:1907-1911. DOI: 10.1590/ S0100-40422012001000003

[26] Azeredo H. Nanocomposites for food packaging applications. Food Research International.

[27] Azeredo H, Otoni C, Assis O, Correa D, Moura M, Mattoso L. Nanoparticles and Antimicrobial Food Packaging. Basel MDPI. 2018. DOI: 10.1016/B978-0-08-1005965.21874-X

[28] Maryam J, Gitte AP, Katrin L. Six open questions about the migration of engineered nano-objects from polymerbased food-contact materials: A review. Food Additives & Contaminants: Part A. 2017;**34**(3):434-450. DOI: 10.1080/19440049.2016.1271462

[29] Wabnitz C, Nichols W. Editorial: Plastic pollution: An ocean emergency. Marine Turtle News Letter. 2010;**129**:1-4

[30] Grant T, Barichello V, Fitzpatrick L. Accounting the impacts of waste product in package design. In:

Procedia CIRP; 7-9 April 2015; Sydney, Australia. p. 568572. DOI: 10.1016/j.

sustainability of packaging: A review.

[32] Shen J, Song Z, Qian X. Fillers and the carbon footprint of papermaking. BioResources. 2010;**5**:2026-2028. DOI:

[31] Tacker M. Methods for the assessment of environmental

10.15376/biores.5.4.2026-2028

[33] Relatório de sustentabilidade Irani [Internet]. 2018. Available from:

procir.2015.02.062

IJRDO. 2017;**3**:33

foodres.2009.03.019

2009;**42**(9):1240-1253. DOI: 10.1016/j.

2008. p. 592

[17] Zakaria S, Ong BH, van de

colsurfa.2004.06.020

2010]

10.6100/IR575360

[22] Ahmed MR. Polymer nanocomposites as a new trend for packaging applications. Polymer-Plastics Technology and Engineering. 2013;**52**(7):635-660. DOI:

10.1080/03602559.2012.762673

Review: Nanocomposites in food packaging. Journal of Food Science.

10.1111/j.1750-3841.2009.01456.x

[24] Chielini E. Environmentally Compatible Food Packaging.

[23] Arora A, Padua GW.

2010;**75**:R43–R49. DOI:

Ven T. Lumen loading magnetic paper I: Flocculation. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2004;**251**:1-4. DOI: 10.1016/j.

[18] DeArmitt C. Functional fillers for plastics. In: Kutz M, editor. Applied Plastics Engineering Handbook: Processing and Materials. Oxford: Elsevier; 2011. pp. 455-468. DOI: 10.1016/B978-1-4377-3514-7.10026-1

[19] Filled with Success [Internet]. 2010. Available from: https://phantomplastics. com/wp-content/uploads/2013/08/ Filled-with-Success-Composites-World-July-August-2010.pdf [Accessed: 05 May

[20] Bos HL. The Potential of Flax Fibres as Reinforcement for Composite Materials. Eindhoven: Technische Universiteit Eindhoven; 2004. DOI:

[21] Xanthos M, editor. Polymers and polymer composites. In: Functional Fillers for Plastics. Weinheim: WILEY-VCH Verlag GmbH & Co. KGaA; 2011. p. 451. DOI: 10.1002/9783527629848.ch1

**40**

http://www.irani.com.br/wp-content/ uploads/2019/04/Relat%C3%B3riode-Sustentabilidade-Irani-2018.pdf [Accessed: 16 May 2020]

[34] Inventário Corporativo de Gases de Efeito Estufa [Internet]. 2013. Available from: http://www.irani.com.br/uploads/ mediacenter/9dafb35a11fe587a8b093f2 b76871241f823eda6.pdf [Accessed: 16 May 2020]

[35] Ongmongkolkul A. Life cycle assessment of paperboard packaging produced in Thailand [M.S. thesis]. Thailand: School of Environment, Resource and Development Asian Institute of Technology (AIT); 2001

[36] Ghinea C, Petraru M, Simion I, Sobariu D, Bressers H, Gavrilescu M. Life cycle assessment of waste management and recycled paper systems. Environmental Engineering and Management Journal. 2014;**13**:2073- 2085. DOI: 10.30638/eemj.2014.230

[37] Kogel JE. Mining and processing kaolin. Elements. 2014;**10**(3):189-193. DOI: 10.2113/gselements.10.3.189

[38] English B, Clemons CM, Stark N, Schneider JP. Waste-wood-derived fillers for plastics. In: Gen. Tech. Rep. FPL-GTR-91. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory; 1996. p. 15. DOI: 10.2737/FPL-GTR-91

[39] Clemons CM. Natural fibers. In: Xanthos M, editor. Functional Fillers for Plastics. Weinheim, WILEY-VCH Verlag GmbH & Co. KGaA. 2010. DOI: 10.1002/9783527629848.ch11

[40] Civancik-Uslu D, Ferrer L, Puig R, Fullana-i-Palmer P. Are functional fillers improving environmental behavior of plastics? A review on LCA studies. Science of the Total Environment. 2018;**626**:927-940. DOI: 10.1016/j. scitotenv.2018.01.149

[41] The Circular Economy in Detail [Internet]. 2017. Available from: https:// www.ellenmacarthurfoundation. org/explore/the-circulareconomy-indetailhttps://www. ellenmacarthurfoundation.org/ explore/the-circular-economy-in-detail [Accessed: 15 May 2020]

**43**

**Chapter 4**

Plastic

**Abstract**

reinforced plastics.

**1. Introduction**

*Mattia Bartoli, Mauro Giorcelli,* 

*Pravin Jagdale and Massimo Rovere*

single-layer graphene is still sold at 200 €/cm<sup>2</sup>

Towards Traditional Carbon

Fillers: Biochar-Based Reinforced

The global market of carbon-reinforced plastic represents one of the largest economic platforms. This sector is dominated by carbon black (CB) produced from traditional oil industry. Recently, high technological fillers such as carbon fibres or nanostructured carbon (i.e. carbon nanotubes, graphene, graphene oxide) fillers have tried to exploit their potential but without economic success. So, in this chapter we are going to analyse the use of an unconventional carbon filler called biochar. Biochar is the solid residue of pyrolysis and can be a solid and sustainable replacement for traditional and expensive fillers. In this chapter, we will provide overview of the last advancement in the use of biochar as filler for the production of

**Keywords:** biochar, composites, sustainable production, carbon materials

Carbon-based materials are a very well-established commodity generally used in materials science [1]. Nowadays, many commodities makes use of carbon fibres as they become an unavoidable asset for the global market [2]. Carbon fibres represent the most diffuse high-tech carbon materials, but carbon black played the main role in these materials. Carbon black (CB) harvests a great global carbon revenue due to its use for the production of plenty of composites but mainly for tyres [3]. Over the years, high-cost carbon materials such as carbon nanotubes (CNTs) and graphene-like materials have gained the attention of the scientific community with their amazing conductivity and optic and mechanical properties [4, 5]. Despite the expected revolution, nanosized allotropic carbon form did not have much progress in the research area. In a very optimistic report, Segal [6] dreamed that the world was ready for the industrial-scale production of graphene, but after a decade,

€/kg [7]. On the other hand, CB is sold for around 1 €/kg [8]. New-generation high-tech carbon materials (i.e. CNT, graphene and graphene oxide) have not yet fulfilled the promise for a new carbon era. While the industry waits for large-scale commercialization of high-quality affordable carbon allotropes, new materials have been considered through engineered carbon for profitable business. In recent years, a new material has emerged as the most promising for the integration of carbon

, while graphene oxide costs 100,000

#### **Chapter 4**

## Towards Traditional Carbon Fillers: Biochar-Based Reinforced Plastic

*Mattia Bartoli, Mauro Giorcelli, Pravin Jagdale and Massimo Rovere*

#### **Abstract**

The global market of carbon-reinforced plastic represents one of the largest economic platforms. This sector is dominated by carbon black (CB) produced from traditional oil industry. Recently, high technological fillers such as carbon fibres or nanostructured carbon (i.e. carbon nanotubes, graphene, graphene oxide) fillers have tried to exploit their potential but without economic success. So, in this chapter we are going to analyse the use of an unconventional carbon filler called biochar. Biochar is the solid residue of pyrolysis and can be a solid and sustainable replacement for traditional and expensive fillers. In this chapter, we will provide overview of the last advancement in the use of biochar as filler for the production of reinforced plastics.

**Keywords:** biochar, composites, sustainable production, carbon materials

#### **1. Introduction**

Carbon-based materials are a very well-established commodity generally used in materials science [1]. Nowadays, many commodities makes use of carbon fibres as they become an unavoidable asset for the global market [2]. Carbon fibres represent the most diffuse high-tech carbon materials, but carbon black played the main role in these materials. Carbon black (CB) harvests a great global carbon revenue due to its use for the production of plenty of composites but mainly for tyres [3]. Over the years, high-cost carbon materials such as carbon nanotubes (CNTs) and graphene-like materials have gained the attention of the scientific community with their amazing conductivity and optic and mechanical properties [4, 5]. Despite the expected revolution, nanosized allotropic carbon form did not have much progress in the research area. In a very optimistic report, Segal [6] dreamed that the world was ready for the industrial-scale production of graphene, but after a decade, single-layer graphene is still sold at 200 €/cm<sup>2</sup> , while graphene oxide costs 100,000 €/kg [7]. On the other hand, CB is sold for around 1 €/kg [8]. New-generation high-tech carbon materials (i.e. CNT, graphene and graphene oxide) have not yet fulfilled the promise for a new carbon era. While the industry waits for large-scale commercialization of high-quality affordable carbon allotropes, new materials have been considered through engineered carbon for profitable business. In recent years, a new material has emerged as the most promising for the integration of carbon

production with waste management [9–11]. This material is biochar, the solid residue from pyrolytic conversion of biomass. Biomass waste stream is one of the most abundant worldwide, and it is generally disposed through incineration. This presents both an environmental issue and an economic loss due to the transformation of a high-quality material into heat. Accordingly, a more profitable advantage was found in their thermal conversion for the production of biofuels [12, 13], chemicals [14] and other materials [15]. Conversion of biomass into liquid fuels is challenging due to the high oxygen content compared with traditional oil-derived products (i.e. gasoline, virgin nafta, diesel). On the contrary, biochar production is a process full of opportunities with the emergence of carbonaceous material from both lignocellulosic and non-lignocellulosic biomasses. This bioderived carbon is used in many applications [16] due to its properties and low cost attested at around 1–2 €/kg [17–19]. Actually, biochar has found a large-scale application for soil health improvement [20–22] and as solid fuel with a heating content of around 40 kJ/mol [23]. Nonetheless, these applications are limited and unable to exploit the full potentiality of biochar due to their easy tunability with simple process adjustment [24].

In this book chapter, we report an overview of the composite applications of biochar to prove its feasibility as a replacement for traditional carbon materials and as a solid competitor with high-tech reinforced plastics.

#### **2. Biochar: production ways**

Biochar is produced through thermochemical routes such as torrefaction, pyrolysis and hydrothermal carbonisation and as residue of gasification.

Torrefaction is a low-temperature thermal conversion used to densify the biomasses for energy purposes [25]. The process temperature is in the range from 200–350°C, and the conversion requires long residence and processing times. Torrefaction is characterised by biochar and biochar-like yields [26]. The carbon percentage of solid residue is generally around 50–60 wt.% [27], but it can reach 72–80 wt.% using microwave process with the addition of microwave absorbers as reported in several studies [28–31]. Microwave use leads to the drastic reduction of process timescale from hours to minutes.

Pyrolysis is a high-temperature thermochemical conversion which induces the cracking of polymers with the formation of low-molecular-weight compounds in an oxygen-free or oxygen-poor atmosphere [12, 32]. Pyrolysis is run using different heating technologies [33] and apparatus design [34–37] at a temperature range from 450–700°C [38] with huge variations in product fraction yields. Pyrolysis of biomasses was deeply studied, and the main mechanisms can be rationalised in a few different steps. The first is the release of moisture from the feedstock, increasing the surface area and improving the pore structure, which favours a quick release of volatiles and minimizes char-catalysed secondary cracking. Lignocellulosic biomass behaviour during pyrolysis could be rationalised through the behaviour of the main components as cellulose, hemicellulose and lignin. The pyrolysis of cellulose takes place between 430 and 470°C and hemicellulose between 470 and 600°C while lignin between 600 and 800°C. During this process other reactions such as dehydration of the sample, pyrolysis of the volatiles present, formation of levoglucosan from cellulose [39] and formation of substituted aromatic rings from lignin [40] take place together with the formation of carbon.

Hydrothermal carbonisation is a thermal cracking used to produce crude-like oil and hydrochar under moderate temperature and high pressure [41] using aqueous solvent [42], nonaqueous solvent [43, 44] or subcritical/critical media [45].

**45**

species.

**Figure 1.**

properties.

temperature.

summarised in **Figure 2.**

**3. Biochar-based reinforced plastics**

*Conversion of lignocellulosic biomasses to carbon structures.*

*Towards Traditional Carbon Fillers: Biochar-Based Reinforced Plastic*

Finally, gasification is the conversion of biomass into combustible gas by heating in air [46], pure oxygen or steam [47] at temperatures higher than 800°C with or without a catalyst [48]. Products from gasification are a mixture of carbon monoxide, carbon dioxide, methane, hydrogen and water vapour. Biochar is not the main product of gasification, but it is characterised by a simultaneous high carbon and ash content.

Furthermore, it is relevant to notice that leaves, stems, bark and roots are different lignin/cellulose ratio and mechanical properties. The same is true for different

Some of these differences could be retained into biochar and induce appreciable

Also, the graphitic domains formed during pyrolytic treatment could undergo a stacking rearrangement leading to a graphitization of biochar with the increasing

Nowadays, reinforced plastic materials are one of the largest global markets in the polymer sector with an expected global revenue of up to 130 M\$/year in 2024 as

Carbon-containing reinforced plastic is one of the most relevant materials with an annual production of up to 150 kton/y in 2018 [50]. As clearly reported in **Figure 3**, around 80% of the total carbon-containing reinforced plastic is represented by polymer host materials, 49% of which comes from thermoset resin and 30% from thermoplastic polymers. Among them, carbon fibre-reinforced epoxy polymers are the larger amount. This is due to their numerous applications in allcapital high-tech sectors ranging from aeronautics and aerospace industries [51] to automotive industries [52]. In this global scenario, biochar plays a minor role even if it could be used, and it is going to consolidate itself as a trustworthy commodity

with its production flexibility and property tunability [53].

In summary, **Figure 1** shows the main stage of biomass conversion.

*DOI: http://dx.doi.org/10.5772/intechopen.91962*

#### *Towards Traditional Carbon Fillers: Biochar-Based Reinforced Plastic DOI: http://dx.doi.org/10.5772/intechopen.91962*

*Fillers*

adjustment [24].

**2. Biochar: production ways**

process timescale from hours to minutes.

take place together with the formation of carbon.

production with waste management [9–11]. This material is biochar, the solid residue from pyrolytic conversion of biomass. Biomass waste stream is one of the most abundant worldwide, and it is generally disposed through incineration. This presents both an environmental issue and an economic loss due to the transformation of a high-quality material into heat. Accordingly, a more profitable advantage was found in their thermal conversion for the production of biofuels [12, 13], chemicals [14] and other materials [15]. Conversion of biomass into liquid fuels is challenging due to the high oxygen content compared with traditional oil-derived products (i.e. gasoline, virgin nafta, diesel). On the contrary, biochar production is a process full of opportunities with the emergence of carbonaceous material from both lignocellulosic and non-lignocellulosic biomasses. This bioderived carbon is used in many applications [16] due to its properties and low cost attested at around 1–2 €/kg [17–19]. Actually, biochar has found a large-scale application for soil health improvement [20–22] and as solid fuel with a heating content of around 40 kJ/mol [23]. Nonetheless, these applications are limited and unable to exploit the full potentiality of biochar due to their easy tunability with simple process

In this book chapter, we report an overview of the composite applications of biochar to prove its feasibility as a replacement for traditional carbon materials and

Biochar is produced through thermochemical routes such as torrefaction,

Torrefaction is a low-temperature thermal conversion used to densify the biomasses for energy purposes [25]. The process temperature is in the range from 200–350°C, and the conversion requires long residence and processing times. Torrefaction is characterised by biochar and biochar-like yields [26]. The carbon percentage of solid residue is generally around 50–60 wt.% [27], but it can reach 72–80 wt.% using microwave process with the addition of microwave absorbers as reported in several studies [28–31]. Microwave use leads to the drastic reduction of

Pyrolysis is a high-temperature thermochemical conversion which induces the cracking of polymers with the formation of low-molecular-weight compounds in an oxygen-free or oxygen-poor atmosphere [12, 32]. Pyrolysis is run using different heating technologies [33] and apparatus design [34–37] at a temperature range from 450–700°C [38] with huge variations in product fraction yields. Pyrolysis of biomasses was deeply studied, and the main mechanisms can be rationalised in a few different steps. The first is the release of moisture from the feedstock, increasing the surface area and improving the pore structure, which favours a quick release of volatiles and minimizes char-catalysed secondary cracking. Lignocellulosic biomass behaviour during pyrolysis could be rationalised through the behaviour of the main components as cellulose, hemicellulose and lignin. The pyrolysis of cellulose takes place between 430 and 470°C and hemicellulose between 470 and 600°C while lignin between 600 and 800°C. During this process other reactions such as dehydration of the sample, pyrolysis of the volatiles present, formation of levoglucosan from cellulose [39] and formation of substituted aromatic rings from lignin [40]

Hydrothermal carbonisation is a thermal cracking used to produce crude-like oil and hydrochar under moderate temperature and high pressure [41] using aqueous solvent [42], nonaqueous solvent [43, 44] or subcritical/critical media [45].

pyrolysis and hydrothermal carbonisation and as residue of gasification.

as a solid competitor with high-tech reinforced plastics.

**44**

**Figure 1.** *Conversion of lignocellulosic biomasses to carbon structures.*

Finally, gasification is the conversion of biomass into combustible gas by heating in air [46], pure oxygen or steam [47] at temperatures higher than 800°C with or without a catalyst [48]. Products from gasification are a mixture of carbon monoxide, carbon dioxide, methane, hydrogen and water vapour. Biochar is not the main product of gasification, but it is characterised by a simultaneous high carbon and ash content.

In summary, **Figure 1** shows the main stage of biomass conversion.

Furthermore, it is relevant to notice that leaves, stems, bark and roots are different lignin/cellulose ratio and mechanical properties. The same is true for different species.

Some of these differences could be retained into biochar and induce appreciable properties.

Also, the graphitic domains formed during pyrolytic treatment could undergo a stacking rearrangement leading to a graphitization of biochar with the increasing temperature.

#### **3. Biochar-based reinforced plastics**

Nowadays, reinforced plastic materials are one of the largest global markets in the polymer sector with an expected global revenue of up to 130 M\$/year in 2024 as summarised in **Figure 2.**

Carbon-containing reinforced plastic is one of the most relevant materials with an annual production of up to 150 kton/y in 2018 [50]. As clearly reported in **Figure 3**, around 80% of the total carbon-containing reinforced plastic is represented by polymer host materials, 49% of which comes from thermoset resin and 30% from thermoplastic polymers. Among them, carbon fibre-reinforced epoxy polymers are the larger amount. This is due to their numerous applications in allcapital high-tech sectors ranging from aeronautics and aerospace industries [51] to automotive industries [52]. In this global scenario, biochar plays a minor role even if it could be used, and it is going to consolidate itself as a trustworthy commodity with its production flexibility and property tunability [53].

**Figure 2.** *Reinforced plastic worldwide revenue with a prediction for the year 2024 [49].*

#### **Figure 3.**

*World's carbon-based reinforced plastic production in 2018 [50].*

Therefore, the main uses of biochar in both thermoset and thermoplastic matrices are overviewed.

Carbonaceous-reinforced thermoset resins are the most commonly used materials dispersed in plenty of different polymer hosts [54–56]. Epoxy resins are the most deeply applied and used around the world. Consequently, the replacement of carbon fibres and carbon black, carbon soot and anthracites with biochar has gained a great interest. Khan et al. [57] described the mechanical and dielectric properties of high-temperature-annealed maple-derived biochar dispersed into a two-component epoxy resin. Biochar filler was used in concentration ranging from 0.5 wt.% to 20 wt.%. The authors clearly showed the improvement of mechanical properties using filler loading of up to 4 wt.%. Regarding electric properties, Khan and co-workers found that a low loading of multiwalled CNTs induced the same effects of a 20 wt.% loading of biochar. Recently, Bartoli et al. [58] described the relationship between the biochar morphology and related composite mechanical properties using a biochar loading of 2 wt.%. The authors achieved a 40% increment of maximum elongation using a rhizomatous grass-derived biochar and Young's modulus increment using a wheat straw as a source for biochar production.

**47**

**Figure 4.**

*Towards Traditional Carbon Fillers: Biochar-Based Reinforced Plastic*

The authors suggested that smooth surface could induce an improved mobility inside the epoxy matrix, while highly porous and channelled surfaces do not. Additionally, they suggested that the dispersion methodology adopted based on ultrasonication, summarised in **Figure 4**, reduced the size of biochar particles with

Furthermore, pyrolytic temperature is the main and critical parameter for tuning biochar properties with the goal of improving resin properties. The interactions between epoxy resin and biochar particles. Bartoli et al. [59] studied the effect of the heating rate and maximum pyrolytic temperature on biochar. Furthermore, cellulose templates could be used for the production of biochar fibres and balls using selected precursors. As a matter of fact, biochar produced from wasted cotton fibres could be recovered as carbon fibre shape showing a property enhancement of epoxy resin host matrix [60, 61], while the one produced from cellulose nanocrystals

Authors showed the complex relationship of produced biochar with related containing epoxy composites. Sample prepared at different temperature and using different heating rate increment or the Young's modulus or the toughness of the reinforced plastics. Interestingly, the biochar produced at very high temperature of up to 1000°C generally induced a high increment of elongation probably due to the

Similarly, Giorcelli et al. [63] proved the effectiveness of maple tree-derived biochar produced at 600°C and 1000°C, observing a drastic improvement of maximum

Temperature also affected the electrical properties of biochar and biocharcontaining composites. High thermal annealed biochar could represent a solid choice for the production of conductive epoxy composites. Giorcelli et al. [64] described that highly graphitic biochar induced better performances during DC electrical conductivity measurements. Temperature treatment and related graphitization processes lead to an improved ability of these materials to shield microwave radiation with similar outputs with respect to multiwalled CNTs [65] even under

The other huge field of composite materials is represented by thermoplastic reinforced plastics. In this very same field, polyolefin represents the greater amount of worldwide production. Among them, biochar-containing polyethylene was studied by Arrigo et al. [67] using an exhausting coffee-derived biochar produced at 700°C. The authors described the rheological and thermal properties of biocharrelated composites with a filler loading up to 7.5 wt. %, showing a decrement of the dynamics of polymer chains in the host matrix related to the confinement of the

*Ultrasonication methodology for the effect dispersion of biochar inside the epoxy resin host.*

a direct relation with the original morphology of the very same particles.

could be recovered as micrometrics ball or nanometric needles [62].

*DOI: http://dx.doi.org/10.5772/intechopen.91962*

unpacking of the aromatic ring of epoxy host.

elongation compared with neat resin.

thin-film shape [66].

#### *Towards Traditional Carbon Fillers: Biochar-Based Reinforced Plastic DOI: http://dx.doi.org/10.5772/intechopen.91962*

*Fillers*

**Figure 2.**

**Figure 3.**

**46**

matrices are overviewed.

*World's carbon-based reinforced plastic production in 2018 [50].*

Therefore, the main uses of biochar in both thermoset and thermoplastic

*Reinforced plastic worldwide revenue with a prediction for the year 2024 [49].*

als dispersed in plenty of different polymer hosts [54–56]. Epoxy resins are the most deeply applied and used around the world. Consequently, the replacement of carbon fibres and carbon black, carbon soot and anthracites with biochar has gained a great interest. Khan et al. [57] described the mechanical and dielectric properties of high-temperature-annealed maple-derived biochar dispersed into a two-component epoxy resin. Biochar filler was used in concentration ranging from 0.5 wt.% to 20 wt.%. The authors clearly showed the improvement of mechanical properties using filler loading of up to 4 wt.%. Regarding electric properties, Khan and co-workers found that a low loading of multiwalled CNTs induced the same effects of a 20 wt.% loading of biochar. Recently, Bartoli et al. [58] described the relationship between the biochar morphology and related composite mechanical properties using a biochar loading of 2 wt.%. The authors achieved a 40% increment of maximum elongation using a rhizomatous grass-derived biochar and Young's modulus increment using a wheat straw as a source for biochar production.

Carbonaceous-reinforced thermoset resins are the most commonly used materi-

The authors suggested that smooth surface could induce an improved mobility inside the epoxy matrix, while highly porous and channelled surfaces do not. Additionally, they suggested that the dispersion methodology adopted based on ultrasonication, summarised in **Figure 4**, reduced the size of biochar particles with a direct relation with the original morphology of the very same particles.

Furthermore, pyrolytic temperature is the main and critical parameter for tuning biochar properties with the goal of improving resin properties. The interactions between epoxy resin and biochar particles. Bartoli et al. [59] studied the effect of the heating rate and maximum pyrolytic temperature on biochar. Furthermore, cellulose templates could be used for the production of biochar fibres and balls using selected precursors. As a matter of fact, biochar produced from wasted cotton fibres could be recovered as carbon fibre shape showing a property enhancement of epoxy resin host matrix [60, 61], while the one produced from cellulose nanocrystals could be recovered as micrometrics ball or nanometric needles [62].

Authors showed the complex relationship of produced biochar with related containing epoxy composites. Sample prepared at different temperature and using different heating rate increment or the Young's modulus or the toughness of the reinforced plastics. Interestingly, the biochar produced at very high temperature of up to 1000°C generally induced a high increment of elongation probably due to the unpacking of the aromatic ring of epoxy host.

Similarly, Giorcelli et al. [63] proved the effectiveness of maple tree-derived biochar produced at 600°C and 1000°C, observing a drastic improvement of maximum elongation compared with neat resin.

Temperature also affected the electrical properties of biochar and biocharcontaining composites. High thermal annealed biochar could represent a solid choice for the production of conductive epoxy composites. Giorcelli et al. [64] described that highly graphitic biochar induced better performances during DC electrical conductivity measurements. Temperature treatment and related graphitization processes lead to an improved ability of these materials to shield microwave radiation with similar outputs with respect to multiwalled CNTs [65] even under thin-film shape [66].

The other huge field of composite materials is represented by thermoplastic reinforced plastics. In this very same field, polyolefin represents the greater amount of worldwide production. Among them, biochar-containing polyethylene was studied by Arrigo et al. [67] using an exhausting coffee-derived biochar produced at 700°C. The authors described the rheological and thermal properties of biocharrelated composites with a filler loading up to 7.5 wt. %, showing a decrement of the dynamics of polymer chains in the host matrix related to the confinement of the

polymer chains on the biochar surface. Additionally, the well-embedded biochar particles improved the thermo-oxidative stability of polyethylene composites produced. Zhang et al. [68] studied the temperature influence on biochar production from poplar and its use as filler for high-density polyethylene. Curiously, the microcrystalline structure of the polymer was not affected by the presence of biochar according to the thermal data collected. A different trend was reported for the mechanical properties that were appreciable different in the comparison between neat and biochar-loaded poly(ethylene) with an improvement of flexural strength and a decrement of the impact strength. Zhang et al. [69] valourized agricultural waste streams through pyrolysis, and the resulting biochar was used as filler for ultra-high-density poly(ethylene). The authors observed improvement in their mechanical properties and improvement in the flame retardancy of the high filler loading materials. Similar results were achieved by Sundarakannan et al. [70] using biochar derived from cashew nuts. Also Li et al. [71] investigated the high loads of biochar in ultra-high-molecular-weight poly(ethylene), achieving a remarkable electromagnetic interference shielding properties using an 80 wt.% of bamboo biochar pyrolysed at 1100°C. This material showed a very high conductivity of up to 107.6 S/m. Furthermore, Bajwa et al. [72] described the use of biochar for the production of a composite blend based on high-density poly(ethylene), poly(lactic acid) and wood flour with superior thermal stability.

The other largely used polyolefins is poly(propylene). Poly(propylene) is widely applied for the realisation of biochar-based composites due its workability. The main application of poly(propylene)-related composites is in the automotive sector. Tadele et al. [73] published an interesting comparative study on life cycle assessment of biochar used in automotive, showing the feasibility of its use. Das et al. [74] reached the same conclusions about the economic feasibility of the use of biochar instead of traditional carbonaceous fillers. The authors showed the appreciable cost reduction of a biochar-containing composites achieving the same properties of carbon black-based ones due to the sensible reduction of compatibilizer down to a maximum of 3 wt.%. The affordability of the cost of biochar was the core of the research proposed by Behazin et al. [75]. In this study, a pyrolysed perennial cane was used as filler of a polymer blend based on poly(propylene)/ poly(octene-ethylene). The produced composite contained a filler loading ranging from 10 to 20 wt.% and showed the very strong interactions between polymer matrix and biochar particles. The most detailed and comprehensive set of studies about poly(propylene) and biochar interactions was conducted by Bhattacharyya research group and his co-workers as attested by many papers [76–78]. During this pluri-annual research, the authors investigated the kind and magnitude of interactions between filler and poly(propylene). They conclude that the addition of several types of biochars lead to a general improvement of the mechanical and thermal properties of related poly(propylene) composites together with the induction of flame retardancy properties. Additionally, Elnour et al. [79] studied the relationship between biochar properties and related poly(propylene) composites showing an increment of stiffness together with unaffected tensile strength. In the same period, Poulose et al. [80] mixed date palm-derived biochar with poly(propylene) showing the negligible effect of biochar on the storage modulus in a range of concentration of up to 15 wt.%. Poly(ethylene) and poly(propylene) are not the only polyolefins used for the production of carbon-based composites. Other largely used polyolefin matrices were poly(vinyl alcohol) and its derivatives [81, 82] and poly(acrylonitrile) [83]. Both of those two polymeric hosts are used for the realisation of piezo sensors due to their elastic properties.

Furthermore, polyesters were used for the realisation of carbon-based reinforced materials. As an example, polyamides were impregnated with biochar as

**49**

**Author details**

**4. Conclusions**

Mattia Bartoli\*, Mauro Giorcelli, Pravin Jagdale and Massimo Rovere

\*Address all correspondence to: mattia.bartoli@polito.it

provided the original work is properly cited.

Department of Applied Science and Technology, Polytechnic of Turin, Torino, Italy

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

*Towards Traditional Carbon Fillers: Biochar-Based Reinforced Plastic*

up to 93% was compared with neat polymer matrix.

for spreading its use across the field of materials science.

described by Ogunsona et al. [84]. The authors mixed nylon 6 with the biochar produced from the pyrolysis of *Miscanthus* canes. The biochar used was produced using a process temperature ranging from 500–900°C. The different temperatures used affected the output of the composites with a beneficial effect on only the high-temperature-treated biochar and a detrimental effect on the others. In 2019, Sheng et al. [85] modified bamboo biochar through the addition of silyl groups on the particle surface for the production of poly(lactic acid) composites. Surface functionalization showing an appreciable enhancement of maximum elongation of

Recently, biochar was used for the realisation of biopolymer composites based on polysaccharides such as cellulose [86], starch [87] or gluten [88] under the vision

In this chapter, we provided overview of the most recent applications of biochar

in the field of polymer composite production with a focus on more useful and unusual ones. We also described in detail the possibility of using biochars as a sound replacement for traditional fillers in both thermoset and thermoplastic composite materials. The researches herein described the feasibility of biochar used in different industrial sectors as a solid alternative to traditional and nanostructured materials. The adaptive nature of biochar presents a very strong point of advantage

of blue and green economy for a total bio- and sustainable productive line.

*DOI: http://dx.doi.org/10.5772/intechopen.91962*

*Towards Traditional Carbon Fillers: Biochar-Based Reinforced Plastic DOI: http://dx.doi.org/10.5772/intechopen.91962*

described by Ogunsona et al. [84]. The authors mixed nylon 6 with the biochar produced from the pyrolysis of *Miscanthus* canes. The biochar used was produced using a process temperature ranging from 500–900°C. The different temperatures used affected the output of the composites with a beneficial effect on only the high-temperature-treated biochar and a detrimental effect on the others. In 2019, Sheng et al. [85] modified bamboo biochar through the addition of silyl groups on the particle surface for the production of poly(lactic acid) composites. Surface functionalization showing an appreciable enhancement of maximum elongation of up to 93% was compared with neat polymer matrix.

Recently, biochar was used for the realisation of biopolymer composites based on polysaccharides such as cellulose [86], starch [87] or gluten [88] under the vision of blue and green economy for a total bio- and sustainable productive line.

#### **4. Conclusions**

*Fillers*

polymer chains on the biochar surface. Additionally, the well-embedded biochar particles improved the thermo-oxidative stability of polyethylene composites produced. Zhang et al. [68] studied the temperature influence on biochar production from poplar and its use as filler for high-density polyethylene. Curiously, the microcrystalline structure of the polymer was not affected by the presence of biochar according to the thermal data collected. A different trend was reported for the mechanical properties that were appreciable different in the comparison between neat and biochar-loaded poly(ethylene) with an improvement of flexural strength and a decrement of the impact strength. Zhang et al. [69] valourized agricultural waste streams through pyrolysis, and the resulting biochar was used as filler for ultra-high-density poly(ethylene). The authors observed improvement in their mechanical properties and improvement in the flame retardancy of the high filler loading materials. Similar results were achieved by Sundarakannan et al. [70] using biochar derived from cashew nuts. Also Li et al. [71] investigated the high loads of biochar in ultra-high-molecular-weight poly(ethylene), achieving a remarkable electromagnetic interference shielding properties using an 80 wt.% of bamboo biochar pyrolysed at 1100°C. This material showed a very high conductivity of up to 107.6 S/m. Furthermore, Bajwa et al. [72] described the use of biochar for the production of a composite blend based on high-density poly(ethylene), poly(lactic

The other largely used polyolefins is poly(propylene). Poly(propylene) is widely applied for the realisation of biochar-based composites due its workability. The main application of poly(propylene)-related composites is in the automotive sector. Tadele et al. [73] published an interesting comparative study on life cycle assessment of biochar used in automotive, showing the feasibility of its use. Das et al. [74] reached the same conclusions about the economic feasibility of the use of biochar instead of traditional carbonaceous fillers. The authors showed the appreciable cost reduction of a biochar-containing composites achieving the same properties of carbon black-based ones due to the sensible reduction of compatibilizer down to a maximum of 3 wt.%. The affordability of the cost of biochar was the core of the research proposed by Behazin et al. [75]. In this study, a pyrolysed perennial cane was used as filler of a polymer blend based on poly(propylene)/ poly(octene-ethylene). The produced composite contained a filler loading ranging from 10 to 20 wt.% and showed the very strong interactions between polymer matrix and biochar particles. The most detailed and comprehensive set of studies about poly(propylene) and biochar interactions was conducted by Bhattacharyya research group and his co-workers as attested by many papers [76–78]. During this pluri-annual research, the authors investigated the kind and magnitude of interactions between filler and poly(propylene). They conclude that the addition of several types of biochars lead to a general improvement of the mechanical and thermal properties of related poly(propylene) composites together with the induction of flame retardancy properties. Additionally, Elnour et al. [79] studied the relationship between biochar properties and related poly(propylene) composites showing an increment of stiffness together with unaffected tensile strength. In the same period, Poulose et al. [80] mixed date palm-derived biochar with poly(propylene) showing the negligible effect of biochar on the storage modulus in a range of concentration of up to 15 wt.%. Poly(ethylene) and poly(propylene) are not the only polyolefins used for the production of carbon-based composites. Other largely used polyolefin matrices were poly(vinyl alcohol) and its derivatives [81, 82] and poly(acrylonitrile) [83]. Both of those two polymeric hosts are used for the realisa-

acid) and wood flour with superior thermal stability.

tion of piezo sensors due to their elastic properties.

Furthermore, polyesters were used for the realisation of carbon-based reinforced materials. As an example, polyamides were impregnated with biochar as

**48**

In this chapter, we provided overview of the most recent applications of biochar in the field of polymer composite production with a focus on more useful and unusual ones. We also described in detail the possibility of using biochars as a sound replacement for traditional fillers in both thermoset and thermoplastic composite materials. The researches herein described the feasibility of biochar used in different industrial sectors as a solid alternative to traditional and nanostructured materials. The adaptive nature of biochar presents a very strong point of advantage for spreading its use across the field of materials science.

#### **Author details**

Mattia Bartoli\*, Mauro Giorcelli, Pravin Jagdale and Massimo Rovere Department of Applied Science and Technology, Polytechnic of Turin, Torino, Italy

\*Address all correspondence to: mattia.bartoli@polito.it

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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polyacrylonitrile. Materials Letters.

[84] Ogunsona EO, Misra M, Mohanty AK. Impact of interfacial adhesion on the microstructure and property variations of biocarbons reinforced nylon 6 biocomposites. Composites Part A: Applied Science and

Manufacturing. 2017;**98**:32-44

[85] Sheng K, Zhang S, Qian S,

Fontanillo Lopez CA. High-toughness PLA/bamboo cellulose nanowhiskers bionanocomposite strengthened with silylated ultrafine bamboo-char. Composites Part B: Engineering.

[86] Zhang Q, Lei H, Cai H, Han X, Lin X, Qian M, et al. Improvement on the properties of microcrystalline cellulose/polylactic acid composites by using activated biochar. Journal of Cleaner Production. 2020;**252**:119898

[87] George J, Azad LB, Poulose AM, An Y, Sarmah AK. Nano-mechanical behaviour of biochar-starch polymer composite: Investigation through advanced dynamic atomic force microscopy. Composites Part A: Applied Science and Manufacturing.

[88] Das O, Hedenqvist MS, Johansson E,

Olsson RT, Loho TA, Capezza AJ, et al. An all-gluten biocomposite: Comparisons with carbon black and pine char composites. Composites Part A: Applied Science and Manufacturing.

2017;**205**:206-210

2019;**165**:174-182

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*Fillers*

[70] Sundarakannan R, Arumugaprabu V,

Polymer Degradation and Stability.

[78] Das O, Bhattacharyya D, Hui D, Lau K-T. Mechanical and flammability

characterisations of biochar/ polypropylene biocomposites. Composites Part B: Engineering.

[79] Elnour AY, Alghyamah AA,

Anis A, et al. Effect of pyrolysis

evolution, physicochemical

[80] Poulose AM, Elnour AY, Anis A, Shaikh H, Al-Zahrani SM, George J, et al. Date palm biocharpolymer composites: An investigation of electrical, mechanical, thermal and rheological characteristics. Science of the Total Environment.

2018;**619-620**:311-318

[81] Nan N, DeVallance DB, Xie X, Wang J. The effect of bio-carbon addition on the electrical, mechanical, and thermal properties of polyvinyl alcohol/biochar composites. Journal of Composite Materials. 2016;**50**:1161-1168

[82] Nan N, DeVallance DB.

2017;**52**:8247-8257

Development of poly (vinyl alcohol)/ wood-derived biochar composites for use in pressure sensor applications. Journal of Materials Science.

[83] Nan W, Zhao Y, Ding Y, Shende AR, Fong H, Shende RV. Mechanically flexible electrospun carbon nanofiber mats derived from biochar and

Shaikh HM, Poulose AM, Al-Zahrani SM,

temperature on biochar microstructural

characteristics, and its influence on biochar/polypropylene composites. Applied Sciences. 2019;**9**:1149

2016;**106**:120-128

[77] Das O, Sarmah AK, Bhattacharyya D. Biocomposites from waste derived biochars: Mechanical, thermal, chemical, and morphological properties. Waste Management. 2016;**49**:560-570

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Mechanical property analysis of biochar derived from cashew nut shell waste reinforced polymer matrix. Materials Research Express. 2020;**6**:125349

Manikandan V, Vigneshwaran S.

[71] Li S, Huang A, Chen Y-J, Li D, Turng L-S. Highly filled biochar/ultrahigh molecular weight polyethylene/ linear low density polyethylene composites for high-performance electromagnetic interference shielding. Composites Part B: Engineering.

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[72] Bajwa DS, Adhikari S,

Shojaeiarani J, Bajwa SG, Pandey P, Shanmugam SR. Characterization of bio-carbon and ligno-cellulosic fiber reinforced bio-composites with compatibilizer. Construction and Building Materials. 2019;**204**:193-202

[73] Tadele D, Roy P, Defersha F, Misra M, Mohanty AK. A comparative life-cycle assessment of talc-and biochar-reinforced composites for lightweight automotive parts. Clean Technologies and Environmental Policy.

[74] Das O, Bhattacharyya D, Sarmah AK. Sustainable eco–composites obtained from waste derived biochar: A consideration in performance properties, production costs, and environmental impact. Journal of Cleaner Production. 2016;**129**:159-168

[75] Behazin E, Misra M, Mohanty AK. Sustainable biocarbon from pyrolyzed perennial grasses and their effects on impact modified polypropylene biocomposites. Composites Part B: Engineering. 2017;**118**:116-124

[76] Das O, Kim NK, Kalamkarov AL, Sarmah AK, Bhattacharyya D. Biochar to the rescue: Balancing the fire

performance and mechanical properties

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**54**

[84] Ogunsona EO, Misra M, Mohanty AK. Impact of interfacial adhesion on the microstructure and property variations of biocarbons reinforced nylon 6 biocomposites. Composites Part A: Applied Science and Manufacturing. 2017;**98**:32-44

[85] Sheng K, Zhang S, Qian S, Fontanillo Lopez CA. High-toughness PLA/bamboo cellulose nanowhiskers bionanocomposite strengthened with silylated ultrafine bamboo-char. Composites Part B: Engineering. 2019;**165**:174-182

[86] Zhang Q, Lei H, Cai H, Han X, Lin X, Qian M, et al. Improvement on the properties of microcrystalline cellulose/polylactic acid composites by using activated biochar. Journal of Cleaner Production. 2020;**252**:119898

[87] George J, Azad LB, Poulose AM, An Y, Sarmah AK. Nano-mechanical behaviour of biochar-starch polymer composite: Investigation through advanced dynamic atomic force microscopy. Composites Part A: Applied Science and Manufacturing. 2019;**124**:105486

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**57**

**Chapter 5**

**Abstract**

**1. Introduction**

POSS Fillers as a Factor

*Magdalena Lipińska, Klaudia Toczek* 

*and Magdalena Stefaniak*

Influencing on Viscoelastic

Properties, Crystallization, and

Thermo-Oxidative Degradation

of Poly(Lactic Acid)-Epoxidized

Natural Rubber PLA/ENR Blend

Polyhedral oligomeric silsesquioxanes (POSS) can be considered as the smallest silica particles that contain an inorganic cage-like silicon-oxygen structure surrounded by organic substituents. POSS are known to be reinforcing fillers able to enhance the fire retardancy and to increase the thermo-oxidative stability. The application of POSS with various functional groups and their effect on the properties of poly(lactic acid) (PLA) is analyzed based on the literature review. The influence of POSS with hydroxyl and glycidyl groups on the viscoelastic properties, crystallization, and thermo-oxidative degradation of PLA containing various contents of natural rubber ENR is discussed. The application of POSS with hydroxyl and glycidyl groups as an additive enhancing compatibility of PLA toughened by epoxidized rubber (ENR) is described. It is reported that POSS molecules with hydroxyl groups can enhance the thermo-oxidative stability of PLA melt.

Nowadays polyhedral oligomeric silsesquioxanes (POSS) particles has received growing attentions as a new type of nanofillers used to prepare nanocomposites

POSS has hybrid organic-inorganic structure, and it can be considered as the smallest functionalized silica particle containing a cage-like silicon-oxygen inorganic core surrounded by organic groups. Typical POSS structure has the formula (RSiO1.5)n, where n = 6, 8, 10, and R are organic substituents at the corners of the inorganic cage [3]. The most common POSS structure has n = 8. Many research reports have been devoted to the various aspects of the application of POSS.

**Keywords:** POSS, poly(lactic acid), epoxidized natural rubber ENR,

viscoelastic properties, thermo-oxidative stability

with enhanced thermal or mechanical properties [1, 2].

#### **Chapter 5**

## POSS Fillers as a Factor Influencing on Viscoelastic Properties, Crystallization, and Thermo-Oxidative Degradation of Poly(Lactic Acid)-Epoxidized Natural Rubber PLA/ENR Blend

*Magdalena Lipińska, Klaudia Toczek and Magdalena Stefaniak*

#### **Abstract**

Polyhedral oligomeric silsesquioxanes (POSS) can be considered as the smallest silica particles that contain an inorganic cage-like silicon-oxygen structure surrounded by organic substituents. POSS are known to be reinforcing fillers able to enhance the fire retardancy and to increase the thermo-oxidative stability. The application of POSS with various functional groups and their effect on the properties of poly(lactic acid) (PLA) is analyzed based on the literature review. The influence of POSS with hydroxyl and glycidyl groups on the viscoelastic properties, crystallization, and thermo-oxidative degradation of PLA containing various contents of natural rubber ENR is discussed. The application of POSS with hydroxyl and glycidyl groups as an additive enhancing compatibility of PLA toughened by epoxidized rubber (ENR) is described. It is reported that POSS molecules with hydroxyl groups can enhance the thermo-oxidative stability of PLA melt.

**Keywords:** POSS, poly(lactic acid), epoxidized natural rubber ENR, viscoelastic properties, thermo-oxidative stability

#### **1. Introduction**

Nowadays polyhedral oligomeric silsesquioxanes (POSS) particles has received growing attentions as a new type of nanofillers used to prepare nanocomposites with enhanced thermal or mechanical properties [1, 2].

POSS has hybrid organic-inorganic structure, and it can be considered as the smallest functionalized silica particle containing a cage-like silicon-oxygen inorganic core surrounded by organic groups. Typical POSS structure has the formula (RSiO1.5)n, where n = 6, 8, 10, and R are organic substituents at the corners of the inorganic cage [3]. The most common POSS structure has n = 8. Many research reports have been devoted to the various aspects of the application of POSS.

The inorganic core of POSS may provide molecular reinforcement, while the organic functional groups may increase the compatibility with polymeric matrix or be incorporated into polymeric network via co- and polymerization reactions [4].

POSS nanoparticles due to their flexible chemical and physical hybrid properties can be applied as functional additives able to reinforce, to toughen, and to stabilize various polymeric matrices, among them are polypropylene [5], polystyrene [6], polyamide [7], polyurethanes [8], and polysiloxane elastomer [9]. Herein the incorporation of POSS particles, which provide remarkable reinforcement at low filler loading, is advantageous and beneficial. Additionally POSS can be grafted to the polymer chains via chemical reactions of functional organic groups leading to the formation of chemical bonds [10]. POSS particles offer the possibility for the participation in curing by a reaction between POSS functional groups and the end or functional groups of polymer chains. The radicals generated during peroxide curing were used to initiate the grafting reactions between methacrylisobutyl-POSS and octavinyl-POSS and ethylene-propylene elastomer/hydrogenated acrylonitrile rubber EPM/HNBR blends [11]. The incorporation of octavinyl-POSS particles, which were able to form crosslinks between both rubbers, enhanced the compatibility of EPM/HNBR blend. Glycidyl polyhedral oligomeric silsesquioxane POSS was utilized as a crosslinking additive to prepare an organic-inorganic hybrid material based on the carboxyl-terminated poly(acrylonitrile-*co*-butadiene) [12]. In this work the trisilanolisobutyl-POSS and glycidyl-POSS were incorporated into the epoxidized natural rubber/poly(lactic acid) blend to enhance the mechanical, thermal, and oxidative properties. The influence of both POSS molecules on the thermo-oxidative degradation of polylactide is analyzed.

#### **2. POSS structures as reinforcing additives to poly(lactic acid)**

Thermoplastic material such as poly(lactic acid) usually is processed into fiber and films. Likewise many other aliphatic polyesters are an emerging polymer from renewable sources. In general, PLA is biodegradable and nontoxic for human body and thus is used for implantable composites, controlled drug release, food-packaging materials, and systems for sustained release of pesticides and fertilizers [13]. The high strength, modulus, and biodegradation make PLA a promising material for the production of packaging materials, although the brittleness restricts its largescale application as an environmental friendly plastic product. Due to the chirality of lactic acid, various forms of polylactide exist as poly(L-lactide) PLLA or PLA, poly(D-lactide) PDLA, poly(D,L-lactide) PDLA, and poly(L-lactide-*co*-D,L-lactide) PLDLLA, which vary in properties [14–16]. PLLA is the product of L,L-lactide polymerization. It has a glass transition temperature Tg in a range of 50–65°C, a melting temperature of about 173–178°C, a crystallinity of around 37%, and a tensile modulus between 2.7 and 16 GPa [17, 18]. The blending of PLLA with PDLA allows the increase of the melting temperature and the temperature stability of the blend; additionally PDLA acts as a nucleating agent increasing the crystallization rate [14, 19, 20]. Biodegradation of the polylactide occurs due to a simple hydrolysis as the main degradation mechanism; thus it depends on the chirality of various PLA forms, and it is slower for PDLA because of the higher crystallinity [21].

Various methods were applied to obtain the POSS/poly(lactic acid) composites, among them are the solution casting method [22], the melt blending method [23–27], and injection molding [28].

These reports confirmed that the incorporation of various POSS particles had a reinforcing effect on the polylactide PLA properties. The crucial significance of the chemistry, reactivity, or non-reactivity of the functional POSS groups was

**59**

*DOI: http://dx.doi.org/10.5772/intechopen.92595*

*POSS Fillers as a Factor Influencing on Viscoelastic Properties, Crystallization…*

and poly(lactic acid) leading to the better mechanical performance.

PEG-POSS particles acted as an efficient plasticizing agent.

temperatures of the PLLA matrix to lower values of temperature.

Zhang et al. [31] investigated the mechanical properties of octa(3-chloropropylsilsesquioxane)/PLLA hybrid films containing 3, 5, 10 and 15 wt% of incorporated POSS. The octa(3-chloropropylsilsesquioxane) was dispersed at molecular level at 3 wt%; higher loading led to aggregation and the crystallization of POSS particles. The tensile behavior of the PLLA material changed. More ductile behavior instead of the brittle behavior was observed. Elongation of break increased significantly from 13.5 (neat PLLA) to 91.0% (PLLA), containing 15 wt% of POSS confirming that the PLLA matrix was more plasticized [31]. Furthermore the incorporation of POSS caused the shifting of the glass transition temperature Tg and the melting

PLA composites having various octaisobutyl-POSS content (1, 3, 7, and 10 wt%)

were obtained using a twin-screw micro-compounder [24]. It was showed that the isobutyl groups present in POSS increased compatibility with PLA backbone groups resulting in higher homogeneity and the miscibility between both components. Additionally, Yilmaz et al. [24] demonstrated that the incorporation of the octaisobutyl-POSS affected two components of total fracture work: essential work of fracture (the work spent in the inner fracture process zone) and nonessential work of fracture (the work spent in the plastic deformation zone). The unstable and rapid crack growth occurred suddenly after the maximum load in the neat PLA. The presence of octaisobutyl-POSS in PLA matrix raised the ductility of the composite, resulting in a stable crack growth for all POSS loadings. The greater energy absorption, the enhancement in toughness, and the increased extension to break without a significant loss of Young's modulus were attributed to the plasticization of PLA caused by the presence of octaisobutyl-POSS. The chain mobility of PLA was facilitated, as confirmed by the reduction in the glass transition temperature Tg of composites [24].

observed. These groups can control and enhance the compatibility between POSS

Octaisobutyl-POSS, aminopropylisobutyl-POSS, trisilanolisobutyl-POSS, and glycidylisobutyl-POSS/poly(ethylene-glycol) plasticized PLA composites, having various POSS content (1, 3, 7, and 10 wt%), were prepared [28]. The presence of different functional groups in POSS structure affected the dispersion and hence the mechanical properties of composites. Kodal et al. [28] reported the enhancement of the impact strength. Toughness of the plasticized poly(lactic acid) was significantly affected by the incorporation of POSS particles leading to the increase of the elongation at break. Moreover, it was revealed that regardless of POSS type, the melt viscosity of the composites decreased, in particular for the glycidylisobutyl-POSS. The presence of functional groups and its polarity was a crucial factor influencing the compatibility between POSS and polymer leading to the changes in mechanical performance. With the increasing POSS amount (from 1 to 10 wt%) incorporated into the polymer matrix, the tensile modulus of POSS/PEG/PLA composites decreased due to the worse dispersion of POSS particles at higher loading. Opposite the elongation at break, the energy at break and Izod impact strength meaningfully increased, indicating better toughness of the material after the incorporation of POSS particles. A poly(ethylene glycol)-POSS containing long and flexible PEG segments attached to the inorganic core were prepared and applied to modify the brittleness of PLA [29, 30]. The toughening effect of PEG-POSS was observed [30]. The stress-strain curves of neat PLLA showed the typical brittle polymer tensile behavior, whereas for the PLLA containing 10 wt% of PEG-POSS, the shape of the curve was changed to atypical for ductile polymers. The tensile strength of the PEG-POSS/PLLA was reduced from 41.4 (neat PLLA) to 21.6 MPa; simultaneously the elongation of break increased from 8.7 (neat PLLA) to 21.6% [30]. The effect was attributed to the higher chain mobility of the PEG-POSS/PLLA composites as a

#### *DOI: http://dx.doi.org/10.5772/intechopen.92595 POSS Fillers as a Factor Influencing on Viscoelastic Properties, Crystallization…*

observed. These groups can control and enhance the compatibility between POSS and poly(lactic acid) leading to the better mechanical performance.

Octaisobutyl-POSS, aminopropylisobutyl-POSS, trisilanolisobutyl-POSS, and glycidylisobutyl-POSS/poly(ethylene-glycol) plasticized PLA composites, having various POSS content (1, 3, 7, and 10 wt%), were prepared [28]. The presence of different functional groups in POSS structure affected the dispersion and hence the mechanical properties of composites. Kodal et al. [28] reported the enhancement of the impact strength. Toughness of the plasticized poly(lactic acid) was significantly affected by the incorporation of POSS particles leading to the increase of the elongation at break. Moreover, it was revealed that regardless of POSS type, the melt viscosity of the composites decreased, in particular for the glycidylisobutyl-POSS. The presence of functional groups and its polarity was a crucial factor influencing the compatibility between POSS and polymer leading to the changes in mechanical performance. With the increasing POSS amount (from 1 to 10 wt%) incorporated into the polymer matrix, the tensile modulus of POSS/PEG/PLA composites decreased due to the worse dispersion of POSS particles at higher loading. Opposite the elongation at break, the energy at break and Izod impact strength meaningfully increased, indicating better toughness of the material after the incorporation of POSS particles.

A poly(ethylene glycol)-POSS containing long and flexible PEG segments attached to the inorganic core were prepared and applied to modify the brittleness of PLA [29, 30]. The toughening effect of PEG-POSS was observed [30]. The stress-strain curves of neat PLLA showed the typical brittle polymer tensile behavior, whereas for the PLLA containing 10 wt% of PEG-POSS, the shape of the curve was changed to atypical for ductile polymers. The tensile strength of the PEG-POSS/PLLA was reduced from 41.4 (neat PLLA) to 21.6 MPa; simultaneously the elongation of break increased from 8.7 (neat PLLA) to 21.6% [30]. The effect was attributed to the higher chain mobility of the PEG-POSS/PLLA composites as a PEG-POSS particles acted as an efficient plasticizing agent.

Zhang et al. [31] investigated the mechanical properties of octa(3-chloropropylsilsesquioxane)/PLLA hybrid films containing 3, 5, 10 and 15 wt% of incorporated POSS. The octa(3-chloropropylsilsesquioxane) was dispersed at molecular level at 3 wt%; higher loading led to aggregation and the crystallization of POSS particles. The tensile behavior of the PLLA material changed. More ductile behavior instead of the brittle behavior was observed. Elongation of break increased significantly from 13.5 (neat PLLA) to 91.0% (PLLA), containing 15 wt% of POSS confirming that the PLLA matrix was more plasticized [31]. Furthermore the incorporation of POSS caused the shifting of the glass transition temperature Tg and the melting temperatures of the PLLA matrix to lower values of temperature.

PLA composites having various octaisobutyl-POSS content (1, 3, 7, and 10 wt%) were obtained using a twin-screw micro-compounder [24]. It was showed that the isobutyl groups present in POSS increased compatibility with PLA backbone groups resulting in higher homogeneity and the miscibility between both components. Additionally, Yilmaz et al. [24] demonstrated that the incorporation of the octaisobutyl-POSS affected two components of total fracture work: essential work of fracture (the work spent in the inner fracture process zone) and nonessential work of fracture (the work spent in the plastic deformation zone). The unstable and rapid crack growth occurred suddenly after the maximum load in the neat PLA. The presence of octaisobutyl-POSS in PLA matrix raised the ductility of the composite, resulting in a stable crack growth for all POSS loadings. The greater energy absorption, the enhancement in toughness, and the increased extension to break without a significant loss of Young's modulus were attributed to the plasticization of PLA caused by the presence of octaisobutyl-POSS. The chain mobility of PLA was facilitated, as confirmed by the reduction in the glass transition temperature Tg of composites [24].

*Fillers*

The inorganic core of POSS may provide molecular reinforcement, while the organic functional groups may increase the compatibility with polymeric matrix or be incorporated into polymeric network via co- and polymerization reactions [4]. POSS nanoparticles due to their flexible chemical and physical hybrid properties can be applied as functional additives able to reinforce, to toughen, and to stabilize various polymeric matrices, among them are polypropylene [5], polystyrene [6], polyamide [7], polyurethanes [8], and polysiloxane elastomer [9]. Herein the incorporation of POSS particles, which provide remarkable reinforcement at low filler loading, is advantageous and beneficial. Additionally POSS can be grafted to the polymer chains via chemical reactions of functional organic groups leading to the formation of chemical bonds [10]. POSS particles offer the possibility for the participation in curing by a reaction between POSS functional groups and the end or functional groups of polymer chains. The radicals generated during peroxide curing were used to initiate the grafting reactions between methacrylisobutyl-POSS and octavinyl-POSS and ethylene-propylene elastomer/hydrogenated acrylonitrile rubber EPM/HNBR blends [11]. The incorporation of octavinyl-POSS particles, which were able to form crosslinks between both rubbers, enhanced the compatibility of EPM/HNBR blend. Glycidyl polyhedral oligomeric silsesquioxane POSS was utilized as a crosslinking additive to prepare an organic-inorganic hybrid material based on the carboxyl-terminated poly(acrylonitrile-*co*-butadiene) [12]. In this work the trisilanolisobutyl-POSS and glycidyl-POSS were incorporated into the epoxidized natural rubber/poly(lactic acid) blend to enhance the mechanical, thermal, and oxidative properties. The influence of both POSS molecules on the

thermo-oxidative degradation of polylactide is analyzed.

**2. POSS structures as reinforcing additives to poly(lactic acid)**

and it is slower for PDLA because of the higher crystallinity [21].

[23–27], and injection molding [28].

Thermoplastic material such as poly(lactic acid) usually is processed into fiber and films. Likewise many other aliphatic polyesters are an emerging polymer from renewable sources. In general, PLA is biodegradable and nontoxic for human body and thus is used for implantable composites, controlled drug release, food-packaging materials, and systems for sustained release of pesticides and fertilizers [13]. The high strength, modulus, and biodegradation make PLA a promising material for the production of packaging materials, although the brittleness restricts its largescale application as an environmental friendly plastic product. Due to the chirality of lactic acid, various forms of polylactide exist as poly(L-lactide) PLLA or PLA, poly(D-lactide) PDLA, poly(D,L-lactide) PDLA, and poly(L-lactide-*co*-D,L-lactide) PLDLLA, which vary in properties [14–16]. PLLA is the product of L,L-lactide polymerization. It has a glass transition temperature Tg in a range of 50–65°C, a melting temperature of about 173–178°C, a crystallinity of around 37%, and a tensile modulus between 2.7 and 16 GPa [17, 18]. The blending of PLLA with PDLA allows the increase of the melting temperature and the temperature stability of the blend; additionally PDLA acts as a nucleating agent increasing the crystallization rate [14, 19, 20]. Biodegradation of the polylactide occurs due to a simple hydrolysis as the main degradation mechanism; thus it depends on the chirality of various PLA forms,

Various methods were applied to obtain the POSS/poly(lactic acid) composites,

These reports confirmed that the incorporation of various POSS particles had a reinforcing effect on the polylactide PLA properties. The crucial significance of the chemistry, reactivity, or non-reactivity of the functional POSS groups was

among them are the solution casting method [22], the melt blending method

**58**

It was found also that the addition of octaisobutyl-POSS (5 wt%) led to the enhancement of the storage modulus (E′) below the glass transition temperature Tg; as compared with neat PLLA, the values of E′ increased from 1875 (neat PLLA) to 2485 MPa POSS/PLLA composite at 20°C [22]. The segmental motions of polymer chains in POSS/PLLA composite were not restricted, and no significant shift of the glass transition temperature Tg was observed [22].

Turan et al. [23] observed the plasticizing effect of POSS containing seven isobutyl groups and one functional aminopropyl group on PLA. Aminopropylisobutyl-POSS (1, 3, 10 wt%) reduced the melt viscosity of PLA composites. The power consumption during melt processing lowered as the processing was facilitated. This could be the additional advantage of POSS application. Tensile strength studies showed that the lower 1, 3 wt% content of aminopropylisobutyl-POSS enhanced Young's modulus. As the POSS content increased to 3 wt%, the modulus increased to 40% [23]. On the other hand, the incorporation of aminopropylisobutyl-POSS reduced the strain at break and yield point of PLA composites [23].

The formation of covalent bonds and physical interactions via hydrogen bonds between POSS and PLA chains usually lead to the enhancement of dynamic mechanical properties of POSS/PLA composites. This effect was observed for aminopropylisobutyl-POSS/PLA composites [23] up to 3 wt% of POSS content due to the physical (H-bonding) interactions of PLA chains with—NH2 functional groups [23]. Higher content (10 wt%) of POSS particles caused the deterioration of dynamic mechanical properties resulting from the agglomeration of the filler.

In order to improve the compatibility and lead to better mechanical properties, the hybrid POSS-PLLA nanoparticles with different tail lengths were incorporated to neat PLLA. PLLA/POSS nanocomposites, in which the PLLA chains were grafted onto the POSS molecules, were prepared via microwave-assisted ring-opening polymerization [32]. The interfacial compatibility was strongly affected by the length of grafted PLLA chain and the amount of PLLA-POSS added. The addition of 6 wt% of PLLA-POSS with the longest grafted PLLA tail leading to effective nucleation activity and the improvement of Young's modulus by 57% and the tensile strength by 26.5%. Other authors [33] observed simultaneous enhancement in toughness and strength for polylactide containing octa-armed polyhedral oligomeric silsesquioxanes POSS-(PLLA)8 star hybrid particles.

The ability to increase the compatibility between components of blends is another important factor that the application of POSS offers.

Blends of poly(lactic acid) PLA, triallyl isocyanurate, and octavinyl-POSS were prepared and cured by γ-irradiation [27]. The presence of the unsaturated functional groups in POSS structure provided the possibility of the grafting of POSS moieties to the PLA chains. The crosslinking occurred together with the degradation processes. The chemical bonds were formed between the double bonds of POSS particles and the polymer radical generated during γ-irradiation exposure. Due to the higher crosslink density of octavinyl-POSS/PLA composites the tensile strength, E-modulus, and the heat deflection temperature increased. The glass transition temperatures of POSS/PLA composites were shifted to higher temperature confirming the formation of more cross-linked network in the presence of octavinyl-POSS.

Other authors [25] incorporated 2 and 5 wt% of octavinyl-POSS and epoxycyclohexyl-POSS to blend prepared by mixing of poly(lactic acid) and poly(butylene succinate-co-adipate). PLA/PBSA blend was prepared using a fixed weight ratio of 70:30 of both components [25]. The opposite effects of both POSS on the viscoelastic properties, the storage modulus and complex viscosity, were observed. Octavinyl-POSS acted as a plasticizing additive, reducing the melt elasticity and decreasing the values of the storage modulus and complex viscosity. The epoxycyclohexyl group of POSS reacted with the functional groups present at the end of

**61**

**of poly(lactic acid)**

*DOI: http://dx.doi.org/10.5772/intechopen.92595*

compatibility of the blend.

*POSS Fillers as a Factor Influencing on Viscoelastic Properties, Crystallization…*

Izod impact strength and tensile mechanical properties.

PLA/PBSA chains leading to the enhancement of the storage modulus and higher

Octaisobutyl-POSS and trans-cyclohexanediolisobutyl POSS containing functional hydroxyl groups potentially that are able to interact with both polymer matrices were added at 2 wt% loading to poly(lactide) and poly(ε-caprolactone) blend by melt blending method [34]. Moreover, to enhance the POSS adhesion to the components of the blends, authors [34] grafted the PCL-*b*-PLLA block copolymer onto the aminopropyl heptaisobutyl-POSS molecules via ring-opening polymerization of ε-caprolactone and L-lactide. The functionalized POSS molecules were found to be compatibilizing agent able to stabilize the morphology of PLA/PCL blends [34]. The compatibilizing and stabilizing effect of various particles reported in literature can be attributed to the decrease of the interfacial energy; the localization of the solid particles at the interphase between two polymers, acting as a solid barrier preventing the coalescence; the strong interactions with polymeric chains bringing about the steric hindrance; and the change in the viscosity ratio resulting from the uneven distribution of filler particles in both phases. Monticelli et al. [34] reported that the octaisobutyl-POSS was preferentially located in PCL phase resulting in the increase of polymer viscosity. Higher viscosity reduced the coalescence leading to the reduction of the PCL droplets size. Trans-cyclohexanediolisobutyl POSS because of its higher functionality and affinity to both phases was able to locate at the interphase leading to stronger interfacial adhesion of both components in PLA/PCL composite. Han et al. [35] reported the compatibilizing effect of Janus POSS star hybrid, which contained an inorganic POSS core and three poly(ε-caprolactone) arms and five poly(L-lactide) arms, on the PLLA/PCL (w/w = 70/30) blends. Due to the reduction in interfacial tension, the dispersed PCL domain size decreased from 1 to 0.5 μm. Better compatibility caused by POSS star particles led to the increase of the

The reduced interfacial tension in poly(lactic acid)/starch/poly(ε-caprolactone) blends after the incorporation of the trifluoropropyl-POSS particles (1, 3, 5 wt%) was also the main factor leading to the enhanced compatibility of the system [26]. Summarizing the application of various POSS molecules, it is worth to underline that the reinforcing effect of POSS molecules is strongly dependent on the chemistry of the organic groups present in the filler structure. The compatibility between the POSS and PLA can be enhanced by the presence in POSS backbone aliphatic groups with higher affinity to polymer chains. These groups can facilitate mixing between polymer and filler during processing reducing, uneven dispersion of filler in matrix and leading to higher homogeneity. Thus the better dispersion improves mechanical properties. On the other hand, more polar groups, in particular glycidyl, epoxy, or hydroxyl groups, can form physical interactions or even covalent bonds with the end

groups of PLA, causing the improvement of dynamic mechanical properties.

Herein we decided to apply POSS molecules containing isooctyl, hydroxyl, and glycidyl functionalities as an additive to epoxidized natural rubber PLA blends.

**3. Influence of POSS on crystallinity, thermal stability, and degradation** 

of crystallinity are important factors playing a vital role in various properties, e.g., mechanical, thermal, and degradation properties. A large number of studies are reported in the literature related to the crystallization of poly(lactic acid) [36–39]. The crystallization kinetics [40], the influence of the molecular weight and undercooling on morphology and crystal grow [41], and the isothermal

PLLA is a semicrystalline polymer; thus its crystallization behavior and degree

#### *DOI: http://dx.doi.org/10.5772/intechopen.92595 POSS Fillers as a Factor Influencing on Viscoelastic Properties, Crystallization…*

PLA/PBSA chains leading to the enhancement of the storage modulus and higher compatibility of the blend.

Octaisobutyl-POSS and trans-cyclohexanediolisobutyl POSS containing functional hydroxyl groups potentially that are able to interact with both polymer matrices were added at 2 wt% loading to poly(lactide) and poly(ε-caprolactone) blend by melt blending method [34]. Moreover, to enhance the POSS adhesion to the components of the blends, authors [34] grafted the PCL-*b*-PLLA block copolymer onto the aminopropyl heptaisobutyl-POSS molecules via ring-opening polymerization of ε-caprolactone and L-lactide. The functionalized POSS molecules were found to be compatibilizing agent able to stabilize the morphology of PLA/PCL blends [34].

The compatibilizing and stabilizing effect of various particles reported in literature can be attributed to the decrease of the interfacial energy; the localization of the solid particles at the interphase between two polymers, acting as a solid barrier preventing the coalescence; the strong interactions with polymeric chains bringing about the steric hindrance; and the change in the viscosity ratio resulting from the uneven distribution of filler particles in both phases. Monticelli et al. [34] reported that the octaisobutyl-POSS was preferentially located in PCL phase resulting in the increase of polymer viscosity. Higher viscosity reduced the coalescence leading to the reduction of the PCL droplets size. Trans-cyclohexanediolisobutyl POSS because of its higher functionality and affinity to both phases was able to locate at the interphase leading to stronger interfacial adhesion of both components in PLA/PCL composite.

Han et al. [35] reported the compatibilizing effect of Janus POSS star hybrid, which contained an inorganic POSS core and three poly(ε-caprolactone) arms and five poly(L-lactide) arms, on the PLLA/PCL (w/w = 70/30) blends. Due to the reduction in interfacial tension, the dispersed PCL domain size decreased from 1 to 0.5 μm. Better compatibility caused by POSS star particles led to the increase of the Izod impact strength and tensile mechanical properties.

The reduced interfacial tension in poly(lactic acid)/starch/poly(ε-caprolactone) blends after the incorporation of the trifluoropropyl-POSS particles (1, 3, 5 wt%) was also the main factor leading to the enhanced compatibility of the system [26].

Summarizing the application of various POSS molecules, it is worth to underline that the reinforcing effect of POSS molecules is strongly dependent on the chemistry of the organic groups present in the filler structure. The compatibility between the POSS and PLA can be enhanced by the presence in POSS backbone aliphatic groups with higher affinity to polymer chains. These groups can facilitate mixing between polymer and filler during processing reducing, uneven dispersion of filler in matrix and leading to higher homogeneity. Thus the better dispersion improves mechanical properties. On the other hand, more polar groups, in particular glycidyl, epoxy, or hydroxyl groups, can form physical interactions or even covalent bonds with the end groups of PLA, causing the improvement of dynamic mechanical properties.

Herein we decided to apply POSS molecules containing isooctyl, hydroxyl, and glycidyl functionalities as an additive to epoxidized natural rubber PLA blends.

#### **3. Influence of POSS on crystallinity, thermal stability, and degradation of poly(lactic acid)**

PLLA is a semicrystalline polymer; thus its crystallization behavior and degree of crystallinity are important factors playing a vital role in various properties, e.g., mechanical, thermal, and degradation properties. A large number of studies are reported in the literature related to the crystallization of poly(lactic acid) [36–39]. The crystallization kinetics [40], the influence of the molecular weight and undercooling on morphology and crystal grow [41], and the isothermal

*Fillers*

It was found also that the addition of octaisobutyl-POSS (5 wt%) led to the enhancement of the storage modulus (E′) below the glass transition temperature Tg; as compared with neat PLLA, the values of E′ increased from 1875 (neat PLLA) to 2485 MPa POSS/PLLA composite at 20°C [22]. The segmental motions of polymer chains in POSS/PLLA composite were not restricted, and no significant shift of the

Turan et al. [23] observed the plasticizing effect of POSS containing seven isobutyl groups and one functional aminopropyl group on PLA. Aminopropylisobutyl-POSS (1, 3, 10 wt%) reduced the melt viscosity of PLA composites. The power consumption during melt processing lowered as the processing was facilitated. This could be the additional advantage of POSS application. Tensile strength studies showed that the lower 1, 3 wt% content of aminopropylisobutyl-POSS enhanced Young's modulus. As the POSS content increased to 3 wt%, the modulus increased to 40% [23]. On the other hand, the incorporation of aminopropylisobutyl-POSS

The formation of covalent bonds and physical interactions via hydrogen bonds

In order to improve the compatibility and lead to better mechanical properties, the hybrid POSS-PLLA nanoparticles with different tail lengths were incorporated to neat PLLA. PLLA/POSS nanocomposites, in which the PLLA chains were grafted onto the POSS molecules, were prepared via microwave-assisted ring-opening polymerization [32]. The interfacial compatibility was strongly affected by the length of grafted PLLA chain and the amount of PLLA-POSS added. The addition of 6 wt% of PLLA-POSS with the longest grafted PLLA tail leading to effective nucleation activity and the improvement of Young's modulus by 57% and the tensile strength by 26.5%. Other authors [33] observed simultaneous enhancement in toughness and strength for polylactide containing octa-armed polyhedral oligo-

The ability to increase the compatibility between components of blends is

Blends of poly(lactic acid) PLA, triallyl isocyanurate, and octavinyl-POSS were prepared and cured by γ-irradiation [27]. The presence of the unsaturated functional groups in POSS structure provided the possibility of the grafting of POSS moieties to the PLA chains. The crosslinking occurred together with the degradation processes. The chemical bonds were formed between the double bonds of POSS particles and the polymer radical generated during γ-irradiation exposure. Due to the higher crosslink density of octavinyl-POSS/PLA composites the tensile strength, E-modulus, and the heat deflection temperature increased. The glass transition temperatures of POSS/PLA composites were shifted to higher temperature confirming the formation of more cross-linked network in the presence of octavinyl-POSS. Other authors [25] incorporated 2 and 5 wt% of octavinyl-POSS and epoxycyclohexyl-POSS to blend prepared by mixing of poly(lactic acid) and poly(butylene succinate-co-adipate). PLA/PBSA blend was prepared using a fixed weight ratio of 70:30 of both components [25]. The opposite effects of both POSS on the viscoelastic properties, the storage modulus and complex viscosity, were observed. Octavinyl-POSS acted as a plasticizing additive, reducing the melt elasticity and decreasing the values of the storage modulus and complex viscosity. The epoxycyclohexyl group of POSS reacted with the functional groups present at the end of

between POSS and PLA chains usually lead to the enhancement of dynamic mechanical properties of POSS/PLA composites. This effect was observed for aminopropylisobutyl-POSS/PLA composites [23] up to 3 wt% of POSS content due to the physical (H-bonding) interactions of PLA chains with—NH2 functional groups [23]. Higher content (10 wt%) of POSS particles caused the deterioration of dynamic mechanical properties resulting from the agglomeration of the filler.

reduced the strain at break and yield point of PLA composites [23].

meric silsesquioxanes POSS-(PLLA)8 star hybrid particles.

another important factor that the application of POSS offers.

glass transition temperature Tg was observed [22].

**60**

melting mechanism [42] were investigated. PLA crystallization, even at high L-LA content, is typically too slow; thus, to increase the crystallinity, three main strategies can be considered: the incorporation of a nucleating agent, the addition of a plasticizer, and the adjustment of the molding conditions, in particular molding temperature and cooling time. Talc is usually used as a nucleating agent that lowers the surface-free energy barrier toward nucleation, increasing the crystallization rate [39].

Some authors reported a nucleating influence of aminopropylisobutyl-POSS particles on the crystallization [23]. The effect was confirmed by the enhanced degree of crystallinity and lower cold crystallization temperatures for PLA composites containing 3 and 10 wt% of POSS [23].

Wang et al. [25] showed that octavinyl-POSS, and epoxycyclohexyl-POSS can act as nucleating agents, enhancing the crystallization ability of poly(lactic acid) in PLA/PBSA blends. Additionally both incorporated POSS increased the decomposition temperature retarding the thermal degradation of PLA/PBSA blends.

Qiu et al. [22] investigated poly(L-lactide)/octaisobutyl-POSS nanocomposites prepared via solution casting method. The crystallization studies revealed that 5 wt% of octaisobutyl-POSS increased the degree of crystallinity from around 14.8% for neat PLLA to around 43.2% for the PLLA/octaisobutyl-POSS composites. Octaisobutyl-POSS reduced the half time of crystallization t0.5 defined as the time required to achieve 50% of the final crystallinity for the sample. The nucleation density was enhanced in the PLLA/octaisobutyl-POSS composites compared with that of neat PLLA. Octaisobutyl-POSS increased the values of weight loss with prolonged exposure time, indicating the accelerating effect of the POSS particles on the hydrolytic degradation of PLLA in composite.

Other authors [28] also reported the influence of POSS with octaisobutyl, amine, hydroxyl, and epoxide groups on the crystallization behavior of PEGplasticized PLA. All POSS types reduced the cold crystallization temperature Tcc, leading to much faster nucleation rate of POSS-filled PLA and PEG-plasticized PLA. Furthermore the POSS addition shifted the glass transition temperature of PLA phase to lower value of temperature due to the plasticization of PLA matrix. The strongest plasticizing effect was observed for octaisobutyl-POSS. All utilized POSS particles enhanced the thermal stability acting as a physical barrier which reduced the heat flow to the matrix and increased the decomposition temperatures at 5%, 10%, and maximum weight loss.

Yu and Qiu [43] studied the crystallization behavior, spherulitic morphology, and crystal structure of poly(L-lactide) mixed via solution casting method with two different weight ratios (0.5, 1 wt%) of octavinyl-POSS. Both the nonisothermal melt and cold crystallization of PLLA were enhanced by the presence of octavinyl-POSS presence, to the higher degree of crystallinity χC = 44.4% for 1 wt% of octavinyl-POSS compared to χC = 8.0% for neat PLLA. The overall crystallization rates during isothermal crystallization were faster and improved with increasing octavinyl-POSS content. The time to achieve the 50% progress of crystallization shortened, and the calculated values of t0.5 were lower for octavinyl-POSS/PLLA composites confirming that the crystallization of PLLA was accelerated in the presence of POSS particles. No significant changes in the crystallization mechanism were found, although the number and the size of developed spherulites changed indicating the nucleating effect caused by the POSS particles. The nucleation density of PLLA spherulites increased significantly in the octavinyl-POSS/PLLA in respect to the neat PLLA. The neat PLLA and octavinyl-POSS/PLLA composites showed a similar degradation profile. The degradation temperatures at 5% of weight loss and the decomposition temperatures were reduced slightly after the incorporation of octavinyl-POSS particles [43].

**63**

*DOI: http://dx.doi.org/10.5772/intechopen.92595*

*POSS Fillers as a Factor Influencing on Viscoelastic Properties, Crystallization…*

had an adverse influence on the growth of spherulites [26].

increasing the degree of crystallinity of PLA [32, 33].

formation of degradation products [44].

**4. Materials and characterization**

Guthrie Company) was used.

Similar effect on crystallinity was reported for the PLLA composites containing various octa(3-chloropropylsilsesquioxane) content [31]. Studies indicated that octa(3-chloropropyl)-POSS can be an effective heterogeneous nucleating agent promoting the crystallization of PLLA and increasing the degree of crystallinity. The low concentration of fluorinated POSS particles (0.5 wt%) was found to be a suitable nucleating agent, increasing the crystallinity of PLA in PLA/starch/PCL blend [26]. At a low concentration POSS acted as a lubricating agent that lowered the viscosity of polymer melt which had the positive effect on the nucleation and growth stages. At higher POSS concentration the increased viscosity of the system

As we previously described, silsesquioxanes with reactive functionalities are suitable for polymerization, surface bonding, or grafting. The POSS molecules containing hydroxyl groups could be adopted as initiators of the ring-opening polymerization ROP during the synthesis of PLA from lactide. Organic-inorganic hybrids with various arms' length of poly(lactic acid) tethered with POSS synthetized via ring-opening polymerization of L-lactide were found to be nucleating additives

Similar to other aliphatic polyesters, PLA is able to degrade during processing because of the action of the external factors. Polymer degradation can occur due to the influence of the temperature (thermal degradation), the effect of the presence of oxygen, and the elevated temperature (thermo-oxidative degradation), as a result of the mechanical stress (thermomechanical degradation). During the processing at the elevated temperature (usually in temperature range of 180–200°C), the thermo-oxidative degradation can lead to the random chain scission and the

POSS molecules were found to be the additives which according to the chemical structure can both accelerate or postpone the thermal degradation of PLA composites. The influence of the octaisobutyl-POSS and the accelerating effect of POSS incorporation on the hydrolytic degradation of POSS/PLLA nanocomposite with respect to neat PLLA were reported [22]. Octavinyl-POSS caused the opposite effect leading to the higher thermal stability and the delay in oxidation of PLA [45].

L-polylactide PLA, CAS number 331335-50-1 product of Simagchem

100 g PLA—ENR 75 g, further denoted as 75 ENR/PLA blend 100 g PLA—ENR 50 g, further denoted as 50 ENR/PLA blend 100 g PLA—ENR 25 g, further denoted as 25 ENR/PLA blend

Corporation (China) was applied as a dominant component of the poly(lactic acid)/ epoxidized natural rubber blends, the formulations of the blends were as follows:

In this study the epoxidized natural rubber ENR50 (Epoxyprene 50, Muang Mai

A liquid glycidyl-POSS cage mixture EP0409 (Hybrid, USA), further denoted as Gly-POSS, with an inorganic silsesquioxane core and eight glycidyl groups attached to the corners of the cage; characterized by the properties (e.g., epoxy equivalent weight 167; thermal stability (5 wt% loss) 365°C; and a liquid trisilanolisooctyl-POSS SO1455 (Hybrid, USA)); further marked as HO-POSS, an open cage POSS with seven isooctyl groups attached at the corners of the cage and three active silanol (hydroxyl groups) functionalities; and characterized by thermal stability (5 wt% loss) 363°C was applied as an additive at 3 wt% to the 50 ENR/PLA blend.

#### *DOI: http://dx.doi.org/10.5772/intechopen.92595 POSS Fillers as a Factor Influencing on Viscoelastic Properties, Crystallization…*

Similar effect on crystallinity was reported for the PLLA composites containing various octa(3-chloropropylsilsesquioxane) content [31]. Studies indicated that octa(3-chloropropyl)-POSS can be an effective heterogeneous nucleating agent promoting the crystallization of PLLA and increasing the degree of crystallinity.

The low concentration of fluorinated POSS particles (0.5 wt%) was found to be a suitable nucleating agent, increasing the crystallinity of PLA in PLA/starch/PCL blend [26]. At a low concentration POSS acted as a lubricating agent that lowered the viscosity of polymer melt which had the positive effect on the nucleation and growth stages. At higher POSS concentration the increased viscosity of the system had an adverse influence on the growth of spherulites [26].

As we previously described, silsesquioxanes with reactive functionalities are suitable for polymerization, surface bonding, or grafting. The POSS molecules containing hydroxyl groups could be adopted as initiators of the ring-opening polymerization ROP during the synthesis of PLA from lactide. Organic-inorganic hybrids with various arms' length of poly(lactic acid) tethered with POSS synthetized via ring-opening polymerization of L-lactide were found to be nucleating additives increasing the degree of crystallinity of PLA [32, 33].

Similar to other aliphatic polyesters, PLA is able to degrade during processing because of the action of the external factors. Polymer degradation can occur due to the influence of the temperature (thermal degradation), the effect of the presence of oxygen, and the elevated temperature (thermo-oxidative degradation), as a result of the mechanical stress (thermomechanical degradation). During the processing at the elevated temperature (usually in temperature range of 180–200°C), the thermo-oxidative degradation can lead to the random chain scission and the formation of degradation products [44].

POSS molecules were found to be the additives which according to the chemical structure can both accelerate or postpone the thermal degradation of PLA composites. The influence of the octaisobutyl-POSS and the accelerating effect of POSS incorporation on the hydrolytic degradation of POSS/PLLA nanocomposite with respect to neat PLLA were reported [22]. Octavinyl-POSS caused the opposite effect leading to the higher thermal stability and the delay in oxidation of PLA [45].

#### **4. Materials and characterization**

L-polylactide PLA, CAS number 331335-50-1 product of Simagchem Corporation (China) was applied as a dominant component of the poly(lactic acid)/ epoxidized natural rubber blends, the formulations of the blends were as follows:

100 g PLA—ENR 75 g, further denoted as 75 ENR/PLA blend 100 g PLA—ENR 50 g, further denoted as 50 ENR/PLA blend 100 g PLA—ENR 25 g, further denoted as 25 ENR/PLA blend

In this study the epoxidized natural rubber ENR50 (Epoxyprene 50, Muang Mai Guthrie Company) was used.

A liquid glycidyl-POSS cage mixture EP0409 (Hybrid, USA), further denoted as Gly-POSS, with an inorganic silsesquioxane core and eight glycidyl groups attached to the corners of the cage; characterized by the properties (e.g., epoxy equivalent weight 167; thermal stability (5 wt% loss) 365°C; and a liquid trisilanolisooctyl-POSS SO1455 (Hybrid, USA)); further marked as HO-POSS, an open cage POSS with seven isooctyl groups attached at the corners of the cage and three active silanol (hydroxyl groups) functionalities; and characterized by thermal stability (5 wt% loss) 363°C was applied as an additive at 3 wt% to the 50 ENR/PLA blend.

*Fillers*

crystallization rate [39].

ites containing 3 and 10 wt% of POSS [23].

the hydrolytic degradation of PLLA in composite.

at 5%, 10%, and maximum weight loss.

tion of octavinyl-POSS particles [43].

melting mechanism [42] were investigated. PLA crystallization, even at high L-LA content, is typically too slow; thus, to increase the crystallinity, three main strategies can be considered: the incorporation of a nucleating agent, the addition of a plasticizer, and the adjustment of the molding conditions, in particular molding temperature and cooling time. Talc is usually used as a nucleating agent that lowers the surface-free energy barrier toward nucleation, increasing the

Some authors reported a nucleating influence of aminopropylisobutyl-POSS particles on the crystallization [23]. The effect was confirmed by the enhanced degree of crystallinity and lower cold crystallization temperatures for PLA compos-

Wang et al. [25] showed that octavinyl-POSS, and epoxycyclohexyl-POSS can act as nucleating agents, enhancing the crystallization ability of poly(lactic acid) in PLA/PBSA blends. Additionally both incorporated POSS increased the decomposi-

Qiu et al. [22] investigated poly(L-lactide)/octaisobutyl-POSS nanocomposites prepared via solution casting method. The crystallization studies revealed that 5 wt% of octaisobutyl-POSS increased the degree of crystallinity from around 14.8% for neat PLLA to around 43.2% for the PLLA/octaisobutyl-POSS composites. Octaisobutyl-POSS reduced the half time of crystallization t0.5 defined as the time required to achieve 50% of the final crystallinity for the sample. The nucleation density was enhanced in the PLLA/octaisobutyl-POSS composites compared with that of neat PLLA. Octaisobutyl-POSS increased the values of weight loss with prolonged exposure time, indicating the accelerating effect of the POSS particles on

Other authors [28] also reported the influence of POSS with octaisobutyl, amine, hydroxyl, and epoxide groups on the crystallization behavior of PEGplasticized PLA. All POSS types reduced the cold crystallization temperature Tcc, leading to much faster nucleation rate of POSS-filled PLA and PEG-plasticized PLA. Furthermore the POSS addition shifted the glass transition temperature of PLA phase to lower value of temperature due to the plasticization of PLA matrix. The strongest plasticizing effect was observed for octaisobutyl-POSS. All utilized POSS particles enhanced the thermal stability acting as a physical barrier which reduced the heat flow to the matrix and increased the decomposition temperatures

Yu and Qiu [43] studied the crystallization behavior, spherulitic morphology, and crystal structure of poly(L-lactide) mixed via solution casting method with two different weight ratios (0.5, 1 wt%) of octavinyl-POSS. Both the nonisothermal melt and cold crystallization of PLLA were enhanced by the presence of octavinyl-POSS presence, to the higher degree of crystallinity χC = 44.4% for 1 wt% of octavinyl-POSS compared to χC = 8.0% for neat PLLA. The overall crystallization rates during isothermal crystallization were faster and improved with increasing octavinyl-POSS content. The time to achieve the 50% progress of crystallization shortened, and the calculated values of t0.5 were lower for octavinyl-POSS/PLLA composites confirming that the crystallization of PLLA was accelerated in the presence of POSS particles. No significant changes in the crystallization mechanism were found, although the number and the size of developed spherulites changed indicating the nucleating effect caused by the POSS particles. The nucleation density of PLLA spherulites increased significantly in the octavinyl-POSS/PLLA in respect to the neat PLLA. The neat PLLA and octavinyl-POSS/PLLA composites showed a similar degradation profile. The degradation temperatures at 5% of weight loss and the decomposition temperatures were reduced slightly after the incorpora-

tion temperature retarding the thermal degradation of PLA/PBSA blends.

**62**

Additionally, the PLA formulations containing 3 wt% of Gly-POSS and HO-POSS, with properties described above were prepared.

Before the preparation of the PLA blends, the oven drying at 80°C during 24 h for polymer pellets was done. ENR/PLA blends were prepared by melt mixing in Brabender Lab Station Plasti-Corder, a small laboratory mixer with counterrotating rotors. First the PLA pellets were placed in a mixing chamber and melted at 180°C. After 5 min the appropriate amount of epoxidized rubber was added. In the case of ENR/PLA/POSS blends, the appropriate amount (3 wt%) of Gly-POSS or HO-POSS, respectively, was added to PLA before the epoxidized rubber. The composition was mixed during 5 min at 150 rpm of rotor speed and then removed from mixer. After the mixing blends were again preheated at 180°C for 2 min and transferred to a mold, they are pressed at 200 bar during 10 min to form films. Similar procedure was applied to prepare the samples of PLA containing 3 wt% of various POSS molecules.

The tensile strength TS and the elongation at break of samples were measured according to ISO 37:2005 standard using universal testing machine Zwick Roell 1435 at room temperatures. The films were shaped into specimens by dumbbell-shaped cutter. The width and the length of the gauge region of the specimens were 4 mm and 25 mm, respectively. The speed of crosshead was 100 mm min<sup>−</sup><sup>1</sup> . The average values of six measurements were taken for each sample. The changes in mechanical properties after the degradation in soil during 1 month under controlled aging conditions (temperature 50°C, humidity 90%, pH = 5.5) were determined.

The dynamic viscoelastic properties of PLA/ENR blends at ambient temperatures were investigated using oscillation rheometer Ares G2 (TA Instruments) equipped with parallel-plate geometry (diameter of 25 mm). The oscillation amplitude sweep tests at temperature 25°C and constant angular frequency of 10 rad s<sup>−</sup><sup>1</sup> were conducted in oscillation strain range from 0.001 to 50%. Storage shear modulus G′, loss shear modulus G″, and loss tan δ were analyzed. Studies of thermo-oxidative degradation were done using Ares G2 equipment, the samples were degraded at 180°C during 0, 30, 60, and 120 min under air atmosphere (flow rate 1 L min<sup>−</sup><sup>1</sup> ), and then a frequency sweep tests at low oscillation strain (linear viscoelastic region) from 1 rad s<sup>−</sup><sup>1</sup> to 628 rad s<sup>−</sup><sup>1</sup> were performed.

The fitting of the storage shear modulus G′ and the loss shear modulus G″ values to Maxwell's equations (4) and (5) and the calculation of the discrete relaxation spectrum were done by the TRIOS® Software provided by TA Instruments.

DSC analysis was performed using DSC1 apparatus (Mettler Toledo). All tests were performed under nitrogen atmosphere. The samples were subjected to two heating steps from 20 to 210°C, with a heating rate of 10°C/min. The objective of the first heating step was to eliminate the heat history of the sample.

The analysis of blend morphology was done using SEM microscope (JEOL Sendai Japan) for the fracture surface covered by gold. The ENR phase in 50 ENR/ PLA samples was removed before the test by dissolving in toluene during 72 h.

#### **5. Influence of Gly-POSS and HO-POSS on mechanical properties and crystallization of PLA/ENR blends: changes in mechanical performance of the blends after degradation in soil**

The brittleness of PLA can be improved by elastomeric toughening additives. The polyisoprene rubber (IR), silicone rubber (SI), and acrylic rubber (AR) were used as a second component of the PLA blend to improve the mechanical performance of poly(lactic acid) [46]. Among all these blends, PLA/polyisoprene possessed high-tensile toughness due to its rubbery characteristic but low degree of crystallinity. Opposite the incorporation of acrylic rubber led to higher degree of crystallinity but quite low

**65**

**Figure 1.**

*SEM image of 25 ENR/PLA blend.*

*DOI: http://dx.doi.org/10.5772/intechopen.92595*

to 4.52 kJ m<sup>−</sup><sup>2</sup>

better dispersion of rubber particles in PLA.

of oscillation strain at angular frequency of 10 rad s<sup>−</sup><sup>1</sup>

crystallinity after incorporation of both rubbers was observed.

from 3.35 kJ m<sup>−</sup><sup>2</sup>

*POSS Fillers as a Factor Influencing on Viscoelastic Properties, Crystallization…*

toughness. The toughness of PLA has been improved by the incorporating core-shell rubber particles [47]. It was found that the impact strength and the elongation at break increased without deterioration of thermal properties of final material. A matrix/ dispersed morphology of various acrylonitrile content acrylonitrile-butadiene rubber/ PLA blends was reported [48]. It was concluded that the incorporation of 10 wt% of rubber resulted in the enhancement of toughness and impact strength of neat PLA without any reduction in crystallinity. Desa et al. [49] investigated properties of PLA toughened by the addition of natural rubber (NR) and epoxidized natural rubber (ENR), after the addition of 5 wt% of rubber the impact strength of PLA increased

(NR) and 4.14 kJ m<sup>−</sup><sup>2</sup>

Since mechanical properties of immiscible polymer blends depend strongly on the formed morphology the analysis of SEM images was applied to observe the microstructure of the ENR/PLA. **Figures 1**–**4** display the changes in the microstructure of the blends. The EPM phase was dissolved and removed. The voids indicate the areas where the ENR phase was previously present. All blends showed phase separation confirming immiscibility of both phases. The droplets of ENR were dispersed throughout the PLA matrix. The PLA blend with 25 wt% of rubber characterized the smaller size of the elastomer domains. The increase of rubber loading up to 50 wt% resulted in higher melt strength during blend preparation at 180°C, retarding the rubber particle rupture during mixing consequently increasing the size of the rubber droplets in ENR/PLA blend. The elongated shape of rubber phase droplets was observed for the PLA blend containing 75 wt% of ENR. The addition of HO-POSS with isooctyl groups decreased the interfacial tension between the components of 50 ENR/PLA blend; as a consequence, the melt blending process was facilitated. The breakdown of rubber droplets was favorable leading to the

Dynamic mechanical characterization of obtained polymer blends at ambient temperature is able to give an additional insight onto the changes in mechanical performance after the incorporation of both POSS. Firstly, the attention of studies was focused on the effect of the various formulation of the ENR/PLA blend on the viscoelastic behavior; the changes of the storage shear modulus G′ as a function

For the ENR/PLA composites, the storage shear modulus was found to be independent of strain up to low strain levels comparing to the neat uncured ENR rubber.

(ENR). The decrease of PLA

were estimated (**Figure 5**).

*DOI: http://dx.doi.org/10.5772/intechopen.92595 POSS Fillers as a Factor Influencing on Viscoelastic Properties, Crystallization…*

toughness. The toughness of PLA has been improved by the incorporating core-shell rubber particles [47]. It was found that the impact strength and the elongation at break increased without deterioration of thermal properties of final material. A matrix/ dispersed morphology of various acrylonitrile content acrylonitrile-butadiene rubber/ PLA blends was reported [48]. It was concluded that the incorporation of 10 wt% of rubber resulted in the enhancement of toughness and impact strength of neat PLA without any reduction in crystallinity. Desa et al. [49] investigated properties of PLA toughened by the addition of natural rubber (NR) and epoxidized natural rubber (ENR), after the addition of 5 wt% of rubber the impact strength of PLA increased from 3.35 kJ m<sup>−</sup><sup>2</sup> to 4.52 kJ m<sup>−</sup><sup>2</sup> (NR) and 4.14 kJ m<sup>−</sup><sup>2</sup> (ENR). The decrease of PLA crystallinity after incorporation of both rubbers was observed.

Since mechanical properties of immiscible polymer blends depend strongly on the formed morphology the analysis of SEM images was applied to observe the microstructure of the ENR/PLA. **Figures 1**–**4** display the changes in the microstructure of the blends. The EPM phase was dissolved and removed. The voids indicate the areas where the ENR phase was previously present. All blends showed phase separation confirming immiscibility of both phases. The droplets of ENR were dispersed throughout the PLA matrix. The PLA blend with 25 wt% of rubber characterized the smaller size of the elastomer domains. The increase of rubber loading up to 50 wt% resulted in higher melt strength during blend preparation at 180°C, retarding the rubber particle rupture during mixing consequently increasing the size of the rubber droplets in ENR/PLA blend. The elongated shape of rubber phase droplets was observed for the PLA blend containing 75 wt% of ENR. The addition of HO-POSS with isooctyl groups decreased the interfacial tension between the components of 50 ENR/PLA blend; as a consequence, the melt blending process was facilitated. The breakdown of rubber droplets was favorable leading to the better dispersion of rubber particles in PLA.

Dynamic mechanical characterization of obtained polymer blends at ambient temperature is able to give an additional insight onto the changes in mechanical performance after the incorporation of both POSS. Firstly, the attention of studies was focused on the effect of the various formulation of the ENR/PLA blend on the viscoelastic behavior; the changes of the storage shear modulus G′ as a function of oscillation strain at angular frequency of 10 rad s<sup>−</sup><sup>1</sup> were estimated (**Figure 5**). For the ENR/PLA composites, the storage shear modulus was found to be independent of strain up to low strain levels comparing to the neat uncured ENR rubber.

**Figure 1.** *SEM image of 25 ENR/PLA blend.*

*Fillers*

10 rad s<sup>−</sup><sup>1</sup>

rate 1 L min<sup>−</sup><sup>1</sup>

viscoelastic region) from 1 rad s<sup>−</sup><sup>1</sup>

Additionally, the PLA formulations containing 3 wt% of Gly-POSS and

Before the preparation of the PLA blends, the oven drying at 80°C during 24 h for polymer pellets was done. ENR/PLA blends were prepared by melt mixing in Brabender Lab Station Plasti-Corder, a small laboratory mixer with counterrotating rotors. First the PLA pellets were placed in a mixing chamber and melted at 180°C. After 5 min the appropriate amount of epoxidized rubber was added. In the case of ENR/PLA/POSS blends, the appropriate amount (3 wt%) of Gly-POSS or HO-POSS, respectively, was added to PLA before the epoxidized rubber. The composition was mixed during 5 min at 150 rpm of rotor speed and then removed from mixer. After the mixing blends were again preheated at 180°C for 2 min and transferred to a mold, they are pressed at 200 bar during 10 min to form films. Similar procedure was applied to prepare the samples of PLA containing 3 wt% of various POSS molecules. The tensile strength TS and the elongation at break of samples were measured according to ISO 37:2005 standard using universal testing machine Zwick Roell 1435 at room temperatures. The films were shaped into specimens by dumbbell-shaped cutter. The width and the length of the gauge region of the specimens were 4 mm

HO-POSS, with properties described above were prepared.

and 25 mm, respectively. The speed of crosshead was 100 mm min<sup>−</sup><sup>1</sup>

values of six measurements were taken for each sample. The changes in mechanical properties after the degradation in soil during 1 month under controlled aging

The dynamic viscoelastic properties of PLA/ENR blends at ambient temperatures were investigated using oscillation rheometer Ares G2 (TA Instruments) equipped with parallel-plate geometry (diameter of 25 mm). The oscillation amplitude sweep tests at temperature 25°C and constant angular frequency of

shear modulus G′, loss shear modulus G″, and loss tan δ were analyzed. Studies of thermo-oxidative degradation were done using Ares G2 equipment, the samples were degraded at 180°C during 0, 30, 60, and 120 min under air atmosphere (flow

to 628 rad s<sup>−</sup><sup>1</sup>

to Maxwell's equations (4) and (5) and the calculation of the discrete relaxation spectrum were done by the TRIOS® Software provided by TA Instruments.

the first heating step was to eliminate the heat history of the sample.

**performance of the blends after degradation in soil**

The fitting of the storage shear modulus G′ and the loss shear modulus G″ values

DSC analysis was performed using DSC1 apparatus (Mettler Toledo). All tests were performed under nitrogen atmosphere. The samples were subjected to two heating steps from 20 to 210°C, with a heating rate of 10°C/min. The objective of

The analysis of blend morphology was done using SEM microscope (JEOL Sendai Japan) for the fracture surface covered by gold. The ENR phase in 50 ENR/ PLA samples was removed before the test by dissolving in toluene during 72 h.

The brittleness of PLA can be improved by elastomeric toughening additives. The polyisoprene rubber (IR), silicone rubber (SI), and acrylic rubber (AR) were used as a second component of the PLA blend to improve the mechanical performance of poly(lactic acid) [46]. Among all these blends, PLA/polyisoprene possessed high-tensile toughness due to its rubbery characteristic but low degree of crystallinity. Opposite the incorporation of acrylic rubber led to higher degree of crystallinity but quite low

**5. Influence of Gly-POSS and HO-POSS on mechanical properties and crystallization of PLA/ENR blends: changes in mechanical** 

were conducted in oscillation strain range from 0.001 to 50%. Storage

), and then a frequency sweep tests at low oscillation strain (linear

were performed.

conditions (temperature 50°C, humidity 90%, pH = 5.5) were determined.

. The average

**64**

#### **Figure 2.** *SEM image of 50 ENR/PLA blend.*

#### **Figure 3.**

*SEM image of 50 ENR/PLA blend modified by HO-POSS.*

**67**

**Figure 6.**

*DOI: http://dx.doi.org/10.5772/intechopen.92595*

HO-POSS, on the 50 ENR/PLA blend.

*strain of 0.01%, angular frequency of 10 rad s<sup>−</sup><sup>1</sup>*

**Figure 5.**

*POSS Fillers as a Factor Influencing on Viscoelastic Properties, Crystallization…*

An increase of the oscillation strain above 0.2% caused strong decrease of storage shear modulus G′ for all formulations. As it was expected, the higher ratio of ENR in 75 ENR/PLA blend reduced significantly the values of storage shear modulus G′; at the same time, the loss tan δ increased, indicating stronger energy dissipation and better damping properties. It should be noted that both POSS molecules decreased the storage modulus G′ in comparison with neat 50 ENR/PLA blend. This effect can be attributed to a plasticization effect caused by the liquid Gly-POSS and

*, and temperature of 25°C) (right).*

*Storage shear modulus G' as a function of oscillation strain (%) at 25°C for ENR/PLA blends with various ENR/PLA ratio (left). Damping properties and loss tan δ measured at linear viscoelastic region (oscillation* 

The more significant increase of the values of loss shear modulus as a function of oscillation strain was observed for 25 and 50 ENR/PLA blends (**Figure 6**). The higher applied force caused first the increase of the loss modulus G′ attributed to the higher dissipation of the energy, which resulted from the presence of the rubber phase in the blend, and then the microstructure of the blend collapsed leading to the decrease of both G′ and G″ moduli. Increasing the content of ENR in the blend caused the shift of the obtained maximum value of loss modulus G′ to a higher value of oscillation strain indicating that the formed microstructure was able to

*Loss shear modulus G" as a function of oscillation strain (%) at angular frequency of 10 rad s<sup>−</sup><sup>1</sup>*

*temperature of 25°C for ENR/PLA blends with various ENR/PLA ratio.*

 *and* 

**Figure 4.** *SEM image of 75 ENR/PLA blend.*

*DOI: http://dx.doi.org/10.5772/intechopen.92595 POSS Fillers as a Factor Influencing on Viscoelastic Properties, Crystallization…*

#### **Figure 5.**

*Fillers*

**Figure 2.**

**Figure 3.**

*SEM image of 50 ENR/PLA blend.*

*SEM image of 50 ENR/PLA blend modified by HO-POSS.*

**66**

**Figure 4.**

*SEM image of 75 ENR/PLA blend.*

*Storage shear modulus G' as a function of oscillation strain (%) at 25°C for ENR/PLA blends with various ENR/PLA ratio (left). Damping properties and loss tan δ measured at linear viscoelastic region (oscillation strain of 0.01%, angular frequency of 10 rad s<sup>−</sup><sup>1</sup> , and temperature of 25°C) (right).*

An increase of the oscillation strain above 0.2% caused strong decrease of storage shear modulus G′ for all formulations. As it was expected, the higher ratio of ENR in 75 ENR/PLA blend reduced significantly the values of storage shear modulus G′; at the same time, the loss tan δ increased, indicating stronger energy dissipation and better damping properties. It should be noted that both POSS molecules decreased the storage modulus G′ in comparison with neat 50 ENR/PLA blend. This effect can be attributed to a plasticization effect caused by the liquid Gly-POSS and HO-POSS, on the 50 ENR/PLA blend.

The more significant increase of the values of loss shear modulus as a function of oscillation strain was observed for 25 and 50 ENR/PLA blends (**Figure 6**). The higher applied force caused first the increase of the loss modulus G′ attributed to the higher dissipation of the energy, which resulted from the presence of the rubber phase in the blend, and then the microstructure of the blend collapsed leading to the decrease of both G′ and G″ moduli. Increasing the content of ENR in the blend caused the shift of the obtained maximum value of loss modulus G′ to a higher value of oscillation strain indicating that the formed microstructure was able to

#### **Figure 6.**

*Loss shear modulus G" as a function of oscillation strain (%) at angular frequency of 10 rad s<sup>−</sup><sup>1</sup> and temperature of 25°C for ENR/PLA blends with various ENR/PLA ratio.*

dissipate the energy up to higher level of deformation. For the composition containing POSS molecules, the lower values of loss shear modulus G′ were observed.

The mechanical properties of PLA blended with various content of ENR rubber are shown in **Table 1**. As it can be seen, the increasing ENR content led to the decrease of tensile strength, simultaneously increasing the elongation of break. Comparing all blends containing 50 wt% of ENR rubber, the tensile properties enhanced after the incorporation of both POSS additives. As the tensile properties of a polymer blends are correlated with the micromorphology, the better dispersion of rubber droplets in PLA matrix and the extent of the interfacial adhesion caused by the presence of functional groups in POSS molecules are responsible for the tensile strength increase observed for 50 ENR/PLA blend after the incorporation of both POSS.

In order to be assimilated by the microorganism present in soil, degradable polymer material needs to be fragmented. Even for the biodegradable materials such as poly(lactic acid), the unintentionally disposal of polymeric material could generate problems. It should be taken under consideration that soils can vary from place to place. The soil characteristic (temperature, water content, chemical composition, and pH) strongly influences on the degradation [50]. Degradation of polymer occurs due to the presence of oxygen, water, atmospheric pollutants, and agrochemicals. Activity of water, pH, temperature, and time must be controlled because they are factors promoting the hydrolytic degradation of polymers containing hydrolysable covalent bonds such as ester bonds. Moreover, the ratio of crystallinity affects the oxidative and hydrolytic degradation. The crystalline domains can restrict the diffusion of oxygen and water, limiting the chemical degradation [51]. The presence of rubber particles can be another factor strongly influencing on the degradation of the ENR/PLA blend. It was reported in literature that the degradation of polymers containing unsaturated bonds or backbone groups can occur via processes leading to crosslinking reactions or chain scission [52].

The changes in mechanical properties of the ENR/PLA blends were determined after the degradation of the material in soil during 1 month (**Table 1**). Additionally to estimate the effect of rubber on the degradation of the ENR/PLA blend, the aging coefficient KC was calculated according to Eq. (1):

$$\text{tested according to Eq. (1):}$$

$$\mathbf{K\_C = \frac{\{\text{TS} \ast \mathbf{E\_b}\}\_{\text{aged}}}{\{\text{TS} \ast \mathbf{E\_b}\}\_{\text{before again}}},\tag{1}$$

**69**

*DOI: http://dx.doi.org/10.5772/intechopen.92595*

calculated according to Eq. (2) [48]:

*DSC analysis of ENR/PLA composites.*

**Table 2.**

during the second heating cycle, respectively; ΔHo

crystalline PLA homopolymer (93.7 J g<sup>−</sup><sup>1</sup>

**PLA and ENR/PLA blends**

molecules on melt properties.

*POSS Fillers as a Factor Influencing on Viscoelastic Properties, Crystallization…*

presence of unsaturated >C〓C < bonds, the crosslinking occurred. In comparison with the neat PLA, the incorporation of rubber increased the values of KC parameters, although lower than one values of the Kc parameter indicated that the partial degradation occurred. The changes in the microstructure of the blend caused by the degradation of PLA phase resulted in the deterioration of mechanical properties and in the decrease of the tensile strength TS and the elongation of break Eb of blend. The incorporation of Gly-POSS accelerated significantly the aging process, and lower value of Kc parameter was observed compared with 50 ENR/PLA blend. The decrease of Kc parameter resulted from the plasticizing influence of the liquidlike POSS on the PLA phase and the lower amount of crystalline phase. Both factors improved the diffusion of water and oxygen throughout the material, accelerating the degradation. Observations were confirmed by the degree of crystallinity

**Composition of blend Tg °C Tcc °C Tm °C χ<sup>c</sup>** Neat PLA 55.4 106.1 156.8 2.7 25 ENR/PLA 55.3 124.9 148.5 1.9 50 ENR/PLA 55.3 128.3 147.3 0.8 **50 Gly-POSS** 49.4 — — — **50 HO-POSS** 54.5 125.6 147.1 1.5 75 ENR/PLA 55.9 105.7 146.8 0.1

*C* = \_

where ΔHm and ΔHC are the enthalpies of melting and cold crystallization

PLA component in the blend (**Table 2**). The degree of crystallinity was calculated for the second cycle of heating, after erasing the thermal history of samples. During cooling no crystallization was observed. The crucial factor influencing the ratio of degradation in soil for 50 ENR/PLA blend modified by Gly-POSS in comparison with not modified 50 ENR/PLA blend and modified by HO-POSS was the amorphous structure and absence of crystalline phase. It should be also underlined that significant decrease in degree of crystallinity is observed for each ENR/PLA blend. The higher the amount of rubber, the lower the percentage of crystallization. Similar influence of epoxidized rubber on PLA was reported by Desa et al. [49].

**6. Influence of POSS on the thermo-oxidative degradation of neat** 

It is well known that the dynamic oscillatory measurements are very sensitive and allowed to characterize the changes occurred in the structure of melted polymers. Different POSS were reported to be able to retard the changes of material properties occurring during processing; for this reason, the viscoelastic rheological characterization at 180°C was investigated to estimate the influence of POSS

*Hm* − *Hc wPLA* *Hm* **°** 

, (2)

m is the enthalpy of 100%

) [53]; and wPLA is the weight fraction of


where TS is tensile strength and Eb is the elongation at break. The observed for the neat ENR value of the Kc coefficient (higher than one) and the increase of the tensile strength after aging confirmed that during composting, because of the

#### **Table 1.**

*Mechanical properties, tensile strength TS (MPa), and elongation at break Eb (%) of PLA/ENR blends with various PLA/ENR ratio. Tensile strength TS\* and elongation at break Eb \* after composting. Calculated values of compositing coefficient KC.*


*DOI: http://dx.doi.org/10.5772/intechopen.92595 POSS Fillers as a Factor Influencing on Viscoelastic Properties, Crystallization…*

#### **Table 2.**

*Fillers*

dissipate the energy up to higher level of deformation. For the composition containing POSS molecules, the lower values of loss shear modulus G′ were observed. The mechanical properties of PLA blended with various content of ENR rubber are shown in **Table 1**. As it can be seen, the increasing ENR content led to the decrease of tensile strength, simultaneously increasing the elongation of break. Comparing all blends containing 50 wt% of ENR rubber, the tensile properties enhanced after the incorporation of both POSS additives. As the tensile properties of a polymer blends are correlated with the micromorphology, the better dispersion of rubber droplets in PLA matrix and the extent of the interfacial adhesion caused by the presence of functional groups in POSS molecules are responsible for the tensile strength increase

In order to be assimilated by the microorganism present in soil, degradable polymer material needs to be fragmented. Even for the biodegradable materials such as poly(lactic acid), the unintentionally disposal of polymeric material could generate problems. It should be taken under consideration that soils can vary from place to place. The soil characteristic (temperature, water content, chemical composition, and pH) strongly influences on the degradation [50]. Degradation of polymer occurs due to the presence of oxygen, water, atmospheric pollutants, and agrochemicals. Activity of water, pH, temperature, and time must be controlled because they are factors promoting the hydrolytic degradation of polymers containing hydrolysable covalent bonds such as ester bonds. Moreover, the ratio of crystallinity affects the oxidative and hydrolytic degradation. The crystalline domains can restrict the diffusion of oxygen and water, limiting the chemical degradation [51]. The presence of rubber particles can be another factor strongly influencing on the degradation of the ENR/PLA blend. It was reported in literature that the degradation of polymers containing unsaturated bonds or backbone groups can occur via processes leading to crosslinking reactions or chain scission [52]. The changes in mechanical properties of the ENR/PLA blends were determined after the degradation of the material in soil during 1 month (**Table 1**). Additionally to estimate the effect of rubber on the degradation of the ENR/PLA blend, the

KC = (TS <sup>∗</sup> Eb)aged \_\_\_\_\_\_\_\_\_\_\_\_\_\_ (TS <sup>∗</sup> Eb)befor ageing

Neat ENR 0.50 ± 0.04 399 ± 31 0.68 ± 0.05 369 ± 73 1.26 ± 0.05 Neat PLA 24.7 ± 0.9 2.1 ± 0.5 3.43 ± 1.10 0.4 ± 0.4 0.03 ± 0.01 25 ENR/PLA 20.7 ± 3.6 3.8 ± 0.9 9.21 ± 1.2 2.7 ± 0.6 0.32 ± 0.05 50 ENR/PLA 10.4 ± 0.9 4.4 ± 1.4 6.99 ± 0.82 2.7 ± 0.7 0.41 ± 0.04 **50 Gly-POSS 12.0 ± 0.6 4.7 ± 1.6 3.88 ± 0.53 1.8 ± 0.9 0.12 ± 0.03 50 HO-POSS 11.0 ± 0.9 4.7 ± 1.4 3.60 ± 0.83 3.5 ± 0.7 0.24 ± 0.03** 75 ENR/PLA 6.9 ± 0.9 7.1 ± 2.4 5.68 ± 0.91 4.3 ± 1.1 0.50 ± 0.04

*Mechanical properties, tensile strength TS (MPa), and elongation at break Eb (%) of PLA/ENR blends with* 

 *and elongation at break Eb*

*\**

where TS is tensile strength and Eb is the elongation at break. The observed for the neat ENR value of the Kc coefficient (higher than one) and the increase of the tensile strength after aging confirmed that during composting, because of the

, (1)

**\***

 *after composting. Calculated values* 

 **(%) KC**

 **(MPa) Eb**

observed for 50 ENR/PLA blend after the incorporation of both POSS.

aging coefficient KC was calculated according to Eq. (1):

**Composition of PLA/ENR TS (MPa) Eb (%) TS\***

*Bolded values are for the samples of blend containing POSS*

*various PLA/ENR ratio. Tensile strength TS\**

*of compositing coefficient KC.*

**68**

**Table 1.**

*DSC analysis of ENR/PLA composites.*

presence of unsaturated >C〓C < bonds, the crosslinking occurred. In comparison with the neat PLA, the incorporation of rubber increased the values of KC parameters, although lower than one values of the Kc parameter indicated that the partial degradation occurred. The changes in the microstructure of the blend caused by the degradation of PLA phase resulted in the deterioration of mechanical properties and in the decrease of the tensile strength TS and the elongation of break Eb of blend. The incorporation of Gly-POSS accelerated significantly the aging process, and lower value of Kc parameter was observed compared with 50 ENR/PLA blend. The decrease of Kc parameter resulted from the plasticizing influence of the liquidlike POSS on the PLA phase and the lower amount of crystalline phase. Both factors improved the diffusion of water and oxygen throughout the material, accelerating the degradation. Observations were confirmed by the degree of crystallinity calculated according to Eq. (2) [48]: *C* = \_

$$\mathcal{K}\_C = \frac{\Delta H\_m - \Delta H\_c}{\omega\_{PLA} \Delta H\_m^{"\prime}} \tag{2}$$

where ΔHm and ΔHC are the enthalpies of melting and cold crystallization during the second heating cycle, respectively; ΔHo m is the enthalpy of 100% crystalline PLA homopolymer (93.7 J g<sup>−</sup><sup>1</sup> ) [53]; and wPLA is the weight fraction of PLA component in the blend (**Table 2**). The degree of crystallinity was calculated for the second cycle of heating, after erasing the thermal history of samples. During cooling no crystallization was observed. The crucial factor influencing the ratio of degradation in soil for 50 ENR/PLA blend modified by Gly-POSS in comparison with not modified 50 ENR/PLA blend and modified by HO-POSS was the amorphous structure and absence of crystalline phase. It should be also underlined that significant decrease in degree of crystallinity is observed for each ENR/PLA blend. The higher the amount of rubber, the lower the percentage of crystallization. Similar influence of epoxidized rubber on PLA was reported by Desa et al. [49].

#### **6. Influence of POSS on the thermo-oxidative degradation of neat PLA and ENR/PLA blends**

It is well known that the dynamic oscillatory measurements are very sensitive and allowed to characterize the changes occurred in the structure of melted polymers.

Different POSS were reported to be able to retard the changes of material properties occurring during processing; for this reason, the viscoelastic rheological characterization at 180°C was investigated to estimate the influence of POSS molecules on melt properties.

**Figure 7** displays the evolution of complex viscosity as a function of angular frequency. It can be seen that η\* of the ENR/PLA blends containing higher rubber loading increased. Further, analyzing the influence of POSS incorporation the powerful influence of HO-POSS on η\* is observed for the whole frequency range in comparison with neat 50 ENR/PLA blend. The viscosity of POSS-polymer composite depends on the level of interactions. HO-POSS because of the presence of hydroxyl groups as well as isooctyl groups has higher affinity to both phases of the blend. Higher level of physical interactions between the polymer chains and HO-POSS resulted in increased viscosity of the melt in comparison with neat 50 ENR/PLA. This effect was not observed in case of Gly-POSS. As shown in **Figure 7** the thermo-oxidative degradation during 30 min led to the continuous increase of the complex viscosity of blends containing higher content of ENR rubber. The temperature probably caused the partial curing of the ENR phase. Additionally the formation of covalent bonds between hydroxyl groups present at the end of PLA chains and the epoxy groups of ENR was possible under these conditions of aging. Therefore all these reactions led to the changes in the polymer structure resulting in the formation of more branched structures and in the increase of the molecular weight. Taking into account that all degraded at 180°C samples showed during 30 min the increase of the complex viscosity η\* to quantify the effect of POSS for various degradation times, a relative degradation index RDI (3) was calculated according to the equation: *<sup>R</sup>***.** *D***.** *<sup>I</sup>* = \_

$$R.D.I = \frac{\eta\_{time=0}}{\eta\_{time}}\tag{3}$$

**71**

30 min of degradation.

*DOI: http://dx.doi.org/10.5772/intechopen.92595*

**Figure 8.**

*POSS Fillers as a Factor Influencing on Viscoelastic Properties, Crystallization…*

frequencies can relate to a restriction in chain mobility caused by chain branching or curing of ENR phase. During thermo-oxidative degradation of the melt blend, the total amount of the hydroxyl groups present at the end of the PLA chains increased, causing higher possibility to react with epoxy groups present in ENR. Comparing both POSS molecules, the weaker influence of HO-POSS on the increase of melt viscosity during thermo-oxidative degradation is observed. HO-POSS contains three silanol groups potentially able to react with epoxy functionalities of ENR, but these groups are covered by the isooctyl groups linked to the same silicon atom reducing the probability of the covalent bond formation with polymeric chains due to the steric hindrance. Moreover the higher melt viscosity of HO-POSS 50ENR/PLA blend (**Figure 7**) in comparison with neat 50 ENR/PLA formulation reduced the diffusion

*Values of RDI indexes for the ENR/PLA blend (left) and PLA (right) modified by HO-POSS and Gly-POSS.*

Additionally **Figure 8** displays the evolution of RDI indexes for the neat PLA and PLA modified by 3 wt% of HO-POSS and Gly-POSS. All degraded samples presented similar behavior, which is typical for the thermo-oxidative degradation of PLA. The longer degradation time caused a decrease in melt viscosity, indicating the chain scission that was confirmed by the continuous increase of the RDI indexes after longer period of time. However, as for HO-POSS PLA, it can be indicated from **Figure 8** that the longer time of degradation favored the chain scission and decrease of melt viscosity, but the obtained viscosity reduction was restricted in comparison with neat PLA. Similarly, a reduction in values of RDI index after 120 min of thermo-oxidative degradation after incorporation of Gly-POSS is observed compared with neat PLA. Both POSS molecules enhanced the thermo-oxidative stability of neat PLA, although more significant stabilizing effect occurred for the HO-POSS. To analyze more deeply the influence of POSS molecules on the rheological behavior, the changes of storage modulus G**′** and loss modulus G**″** after thermooxidative aging during various times were determined. As an illustrative example, the evolution of both viscoelastic moduli as a function of frequency for 50 ENR/ PLA blend is showed in **Figure 9**. As can be observed, all degraded samples of 50 ENR/PLA blend during various times of 30, 60, and 120 min showed predominant elastic behavior with storage modulus values G**″** higher than loss modulus values G**″** in whole studied frequency range. The thermo-oxidative degradation led to the increase of both moduli G**′** and G**″**, and the increment of both moduli was dependent on the time of degradation. This fact pointed out that a degradation under this condition showed similar qualitative response, but the quantitative effect varied according to the time of degradation and was more accelerated during the first

of oxygen preventing the degradation of both phases during processing.

where η time = 0 is the complex viscosity value at 1 rad s<sup>−</sup><sup>1</sup> for a sample not degraded and ηtime is a the complex viscosity at 1 rad s<sup>−</sup><sup>1</sup> after 30, 60, and 120 min of thermooxidative degradation at 180°C. Hence, the parameter allows to quantify the increase in the melt viscosity due the crosslinking reactions or the formation of more branched structures with higher molecular weight (values lower than 1) or the drop of melt viscosity resulting from the chain scission (values higher than 1). The calculated values of RDI indexes for ENR/PLA POSS composites are compiled in **Figure 8**. The significantly lower values of RDI indexes observed for neat 50 ENR/PLA and Gly-POSS 50 ENR/PLA indicate that an increase of the melt viscosity occurred in higher extent than the HO-POSS 50 ENR/PLA blend. The increase in η\* at intermediate

#### **Figure 7.**

*Complex viscosity η\* as a function of angular frequency ω at 180°C (left). Complex viscosity as a function of time during 30 min of thermo-oxidative aging at 180°C (right).*

*DOI: http://dx.doi.org/10.5772/intechopen.92595 POSS Fillers as a Factor Influencing on Viscoelastic Properties, Crystallization…*

**Figure 8.**

*Fillers*

frequency. It can be seen that η\*

powerful influence of HO-POSS on η\*

30 min the increase of the complex viscosity η\*

and ηtime is a the complex viscosity at 1 rad s<sup>−</sup><sup>1</sup>

*time during 30 min of thermo-oxidative aging at 180°C (right).*

*<sup>R</sup>***.** *D***.** *<sup>I</sup>* = \_

where η time = 0 is the complex viscosity value at 1 rad s<sup>−</sup><sup>1</sup>

according to the equation:

**Figure 7** displays the evolution of complex viscosity as a function of angular

loading increased. Further, analyzing the influence of POSS incorporation the

in comparison with neat 50 ENR/PLA blend. The viscosity of POSS-polymer composite depends on the level of interactions. HO-POSS because of the presence of hydroxyl groups as well as isooctyl groups has higher affinity to both phases of the blend. Higher level of physical interactions between the polymer chains and HO-POSS resulted in increased viscosity of the melt in comparison with neat 50 ENR/PLA. This effect was not observed in case of Gly-POSS. As shown in **Figure 7** the thermo-oxidative degradation during 30 min led to the continuous increase of the complex viscosity of blends containing higher content of ENR rubber. The temperature probably caused the partial curing of the ENR phase. Additionally the formation of covalent bonds between hydroxyl groups present at the end of PLA chains and the epoxy groups of ENR was possible under these conditions of aging. Therefore all these reactions led to the changes in the polymer structure resulting in the formation of more branched structures and in the increase of the molecular weight. Taking into account that all degraded at 180°C samples showed during

various degradation times, a relative degradation index RDI (3) was calculated

oxidative degradation at 180°C. Hence, the parameter allows to quantify the increase in the melt viscosity due the crosslinking reactions or the formation of more branched structures with higher molecular weight (values lower than 1) or the drop of melt viscosity resulting from the chain scission (values higher than 1). The calculated values of RDI indexes for ENR/PLA POSS composites are compiled in **Figure 8**. The significantly lower values of RDI indexes observed for neat 50 ENR/PLA and Gly-POSS 50 ENR/PLA indicate that an increase of the melt viscosity occurred in higher extent than the HO-POSS 50 ENR/PLA blend. The increase in η\* at intermediate

*Complex viscosity η\* as a function of angular frequency ω at 180°C (left). Complex viscosity as a function of* 

*time*=0

of the ENR/PLA blends containing higher rubber

is observed for the whole frequency range

to quantify the effect of POSS for

*time* , (3)

after 30, 60, and 120 min of thermo-

for a sample not degraded

**70**

**Figure 7.**

*Values of RDI indexes for the ENR/PLA blend (left) and PLA (right) modified by HO-POSS and Gly-POSS.*

frequencies can relate to a restriction in chain mobility caused by chain branching or curing of ENR phase. During thermo-oxidative degradation of the melt blend, the total amount of the hydroxyl groups present at the end of the PLA chains increased, causing higher possibility to react with epoxy groups present in ENR. Comparing both POSS molecules, the weaker influence of HO-POSS on the increase of melt viscosity during thermo-oxidative degradation is observed. HO-POSS contains three silanol groups potentially able to react with epoxy functionalities of ENR, but these groups are covered by the isooctyl groups linked to the same silicon atom reducing the probability of the covalent bond formation with polymeric chains due to the steric hindrance. Moreover the higher melt viscosity of HO-POSS 50ENR/PLA blend (**Figure 7**) in comparison with neat 50 ENR/PLA formulation reduced the diffusion of oxygen preventing the degradation of both phases during processing.

Additionally **Figure 8** displays the evolution of RDI indexes for the neat PLA and PLA modified by 3 wt% of HO-POSS and Gly-POSS. All degraded samples presented similar behavior, which is typical for the thermo-oxidative degradation of PLA. The longer degradation time caused a decrease in melt viscosity, indicating the chain scission that was confirmed by the continuous increase of the RDI indexes after longer period of time. However, as for HO-POSS PLA, it can be indicated from **Figure 8** that the longer time of degradation favored the chain scission and decrease of melt viscosity, but the obtained viscosity reduction was restricted in comparison with neat PLA. Similarly, a reduction in values of RDI index after 120 min of thermo-oxidative degradation after incorporation of Gly-POSS is observed compared with neat PLA. Both POSS molecules enhanced the thermo-oxidative stability of neat PLA, although more significant stabilizing effect occurred for the HO-POSS. To analyze more deeply the influence of POSS molecules on the rheological behavior, the changes of storage modulus G**′** and loss modulus G**″** after thermooxidative aging during various times were determined. As an illustrative example, the evolution of both viscoelastic moduli as a function of frequency for 50 ENR/ PLA blend is showed in **Figure 9**. As can be observed, all degraded samples of 50 ENR/PLA blend during various times of 30, 60, and 120 min showed predominant elastic behavior with storage modulus values G**″** higher than loss modulus values G**″** in whole studied frequency range. The thermo-oxidative degradation led to the increase of both moduli G**′** and G**″**, and the increment of both moduli was dependent on the time of degradation. This fact pointed out that a degradation under this condition showed similar qualitative response, but the quantitative effect varied according to the time of degradation and was more accelerated during the first 30 min of degradation.

#### **Figure 9.**

*Influence of the thermo-oxidative aging (30, 60, 120 min) on the viscoelastic properties (storage modulus G', loss modulus G") as a function of angular frequency at 180°C for 50 ENR/PLA blend.*

For HO-POSS 50 ENR/PLA blend, when increasing degradation time, both moduli increased (**Figure 10**); regarding the increment of the G**′** and G**″** moduli, the presence of POSS molecules slowed the degradation of the blend. Interestingly, the opposite effect was observed for Gly-POSS 50 ENR/PLA; the degradation led to remarkable increase of the G**′** modulus and decrease of the G**″** modulus, indicating that the curing reactions occurred in higher extent. These results confirmed the observation from the analysis of melt viscosity and RMI indexes.

#### **Figure 10.**

*Influence of the thermo-oxidative aging (30, 60, 120 min) on the viscoelastic properties (storage modulus G', loss modulus G") as a function of angular frequency ω for the POSS-modified PLA/ENR blends at 180°C.*

**73**

**Figure 11.**

*DOI: http://dx.doi.org/10.5772/intechopen.92595*

HO-POSS formulation comparing with neat PLA.

loss G″ moduli with high level of correlation (R<sup>2</sup>

ships (4, 5) [54]:

relaxation of the molt.

*POSS Fillers as a Factor Influencing on Viscoelastic Properties, Crystallization…*

The plasticizing effect of Gly-POSS on PLA was confirmed, and the addition of 3 wt% of Gly-POSS caused the decrease of the melt viscosity (not showed here); additionally lower values of storage modulus G′ were observed, indicating the decrease in chain entanglement and more free volume in the melt (**Figure 11**). For the PLA composites containing POSS molecules when increasing the degradation time, both moduli underwent a drop, and the effect was less predominant in the case of HO-POSS; thus, these investigations confirmed better thermal stability of

The linear viscoelasticity data were used to obtain the discrete relaxation spectrum, which provides additional information about possible changes in PLA structure occurring during thermo-oxidative degradation. A discrete relaxation spectra is described by the generalized Maxwell model by the following relation-

*Gi* (ω λ*i*) \_

2 1 + (ω λ*i*)<sup>2</sup>

\_ (ω λ*i*) 1 + (ω λ*i*)<sup>2</sup>

(4)

(5)

= 0.999). **Figure 12** presents

*G*′( ω) = ∑ *i*=1 *N*

> (ω) = ∑ *i*=1 *N Gi*

where Gi and λi are the relaxation strength and relaxation time, respectively. It was found that for the experimental frequency range used in studies, the six Maxwell elements are sufficient for recalculation of the values of storage G′ and

the discrete relaxation spectrum for PLA not aged and degraded during 120 min samples. In **Table 3** calculated values of Gi and λi are compiled. The chain scissions and the decrease in the molecular weight of the polymer after 120 min of thermooxidative degradation were confirmed by the lower relaxation times. Finally, also from this study, the plasticizing effect of Gly-POSS on the behavior of not-aged PLA was observed, the enhanced mobility of PLA chains reflecting in the lower relaxation times as compared with PLA or HO-POSS PLA. The shorter relaxation time observed for neat PLA and Gly-POSS PLA degraded during 120 min, indicating the presence of the larger amount of the short PLA chains facilitating the

*Influence of the thermo-oxidative aging (120 min) on the viscoelastic properties (storage modulus G', loss* 

*modulus G") as a function of angular frequency ω for the POSS-modified PLA at 180°C.*

*G*′′

*DOI: http://dx.doi.org/10.5772/intechopen.92595 POSS Fillers as a Factor Influencing on Viscoelastic Properties, Crystallization…*

The plasticizing effect of Gly-POSS on PLA was confirmed, and the addition of 3 wt% of Gly-POSS caused the decrease of the melt viscosity (not showed here); additionally lower values of storage modulus G′ were observed, indicating the decrease in chain entanglement and more free volume in the melt (**Figure 11**). For the PLA composites containing POSS molecules when increasing the degradation time, both moduli underwent a drop, and the effect was less predominant in the case of HO-POSS; thus, these investigations confirmed better thermal stability of HO-POSS formulation comparing with neat PLA.

The linear viscoelasticity data were used to obtain the discrete relaxation spectrum, which provides additional information about possible changes in PLA structure occurring during thermo-oxidative degradation. A discrete relaxation spectra is described by the generalized Maxwell model by the following relationships (4, 5) [54]: *Gi* (ω λ*i*) \_

$$\mathbf{G}'(\alpha) = \sum\_{i=1}^{N} \mathbf{G}\_i \frac{\left(\alpha \lambda\_i\right)^2}{\mathbf{1} + \left(\alpha \lambda\_i\right)^2} \tag{4}$$

$$\mathbf{G}''(\alpha) = \sum\_{i=1}^{N} \mathbf{G}\_i \frac{\left(\alpha \lambda\_i\right)}{\mathbf{1} + \left(\alpha \lambda\_i\right)^2} \tag{5}$$

$$\text{G}^{\stackrel{\text{\textquotedblleft}}{}}\text{(co)} = \sum\_{i=1}^{N} \text{G}\_{i} \frac{\text{(co}\lambda\_{i}\text{)}}{\mathbf{1} + \text{(co}\lambda\_{i}\text{)}^{2}}\tag{5}$$

where Gi and λi are the relaxation strength and relaxation time, respectively. It was found that for the experimental frequency range used in studies, the six Maxwell elements are sufficient for recalculation of the values of storage G′ and loss G″ moduli with high level of correlation (R<sup>2</sup> = 0.999). **Figure 12** presents the discrete relaxation spectrum for PLA not aged and degraded during 120 min samples. In **Table 3** calculated values of Gi and λi are compiled. The chain scissions and the decrease in the molecular weight of the polymer after 120 min of thermooxidative degradation were confirmed by the lower relaxation times. Finally, also from this study, the plasticizing effect of Gly-POSS on the behavior of not-aged PLA was observed, the enhanced mobility of PLA chains reflecting in the lower relaxation times as compared with PLA or HO-POSS PLA. The shorter relaxation time observed for neat PLA and Gly-POSS PLA degraded during 120 min, indicating the presence of the larger amount of the short PLA chains facilitating the relaxation of the molt.

#### **Figure 11.**

*Influence of the thermo-oxidative aging (120 min) on the viscoelastic properties (storage modulus G', loss modulus G") as a function of angular frequency ω for the POSS-modified PLA at 180°C.*

*Fillers*

**Figure 9.**

**72**

**Figure 10.**

*Influence of the thermo-oxidative aging (30, 60, 120 min) on the viscoelastic properties (storage modulus G', loss modulus G") as a function of angular frequency ω for the POSS-modified PLA/ENR blends at 180°C.*

For HO-POSS 50 ENR/PLA blend, when increasing degradation time, both moduli increased (**Figure 10**); regarding the increment of the G**′** and G**″** moduli, the presence of POSS molecules slowed the degradation of the blend. Interestingly, the opposite effect was observed for Gly-POSS 50 ENR/PLA; the degradation led to remarkable increase of the G**′** modulus and decrease of the G**″** modulus, indicating that the curing reactions occurred in higher extent. These results confirmed the

*Influence of the thermo-oxidative aging (30, 60, 120 min) on the viscoelastic properties (storage modulus G', loss* 

observation from the analysis of melt viscosity and RMI indexes.

*modulus G") as a function of angular frequency at 180°C for 50 ENR/PLA blend.*

#### **Figure 12.**

*Discrete relaxation spectrum for not aged and aged during 120 min PLA samples.*


#### **Table 3.**

*The calculated values of relaxation strength Gi and relaxation time.*

#### **7. Conclusions**

ENR/PLA composites were prepared by melt blending method. All prepared ENR/PLA composites showed immiscible droplet microstructure. The amount of added rubber strongly influenced on the tensile strength and elongation at break of blends. Incorporation of HO-POSS led to more homogenous morphology of

**75**

**Author details**

of Technology, Lodz, Poland

provided the original work is properly cited.

Magdalena Lipińska\*, Klaudia Toczek and Magdalena Stefaniak

\*Address all correspondence to: magdalena.lipinska@p.lodz.pl

Chemistry Department, Institute of Polymer and Dye Technology, Lodz University

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

*POSS Fillers as a Factor Influencing on Viscoelastic Properties, Crystallization…*

the blend resulting in the enhancement of tensile strength as compared with 50 ENR/PLA blend. Both incorporated POSS molecules influenced on the dynamic performance of the 50 ENR/PLA blend, decreasing the values of the storage shear modulus. The effect was attributed to the lubricating influence of the liquid POSS molecules. The amorphous structure of the 50 ENR/PLA blend modified by Gly-POSS accelerated the degradation of the material in soil as compared to neat 50 ENR/PLA blend and HO-POSS-modified blend. The cold crystallization of the blend was affected by the presence of rubber phase, the degree of crystallinity meaningfully decreased after the addition of the higher rubber ratio. Dynamic oscillatory measurements in melt state indicated that an increase of the melt viscosity and the storage shear modulus occurred during thermo-oxidative degradation at various degradation times for ENR/PLA blends resulting from curing reactions. Significant increase of the storage modulus G**′** during thermo-oxidative degradation of the 50 ENR/PLA blend modified by Gly-POSS was observed. The HO-POSS enhanced the thermal stability of blend resulted in lower changes of both modulus and melt viscosity values after thermo-oxidative degradation. Similar stabilizing effect of HO-POSS was observed for virgin PLA; the thermo-oxidative degradation of the melt and chain scissions occurred in the lower extent after the incorporation of HO-POSS. Considering that one of the disadvantages of PLA is its thermo-oxidative and thermomechanical degradation during processing at higher temperature, the enhanced thermo-oxidative stability after incorporation of HO-POSS is promising.

*DOI: http://dx.doi.org/10.5772/intechopen.92595*

*POSS Fillers as a Factor Influencing on Viscoelastic Properties, Crystallization… DOI: http://dx.doi.org/10.5772/intechopen.92595*

the blend resulting in the enhancement of tensile strength as compared with 50 ENR/PLA blend. Both incorporated POSS molecules influenced on the dynamic performance of the 50 ENR/PLA blend, decreasing the values of the storage shear modulus. The effect was attributed to the lubricating influence of the liquid POSS molecules. The amorphous structure of the 50 ENR/PLA blend modified by Gly-POSS accelerated the degradation of the material in soil as compared to neat 50 ENR/PLA blend and HO-POSS-modified blend. The cold crystallization of the blend was affected by the presence of rubber phase, the degree of crystallinity meaningfully decreased after the addition of the higher rubber ratio. Dynamic oscillatory measurements in melt state indicated that an increase of the melt viscosity and the storage shear modulus occurred during thermo-oxidative degradation at various degradation times for ENR/PLA blends resulting from curing reactions. Significant increase of the storage modulus G**′** during thermo-oxidative degradation of the 50 ENR/PLA blend modified by Gly-POSS was observed. The HO-POSS enhanced the thermal stability of blend resulted in lower changes of both modulus and melt viscosity values after thermo-oxidative degradation. Similar stabilizing effect of HO-POSS was observed for virgin PLA; the thermo-oxidative degradation of the melt and chain scissions occurred in the lower extent after the incorporation of HO-POSS. Considering that one of the disadvantages of PLA is its thermo-oxidative and thermomechanical degradation during processing at higher temperature, the enhanced thermo-oxidative stability after incorporation of HO-POSS is promising.

### **Author details**

*Fillers*

**Figure 12.**

**74**

**7. Conclusions**

**Table 3.**

ENR/PLA composites were prepared by melt blending method. All prepared ENR/PLA composites showed immiscible droplet microstructure. The amount of added rubber strongly influenced on the tensile strength and elongation at break of blends. Incorporation of HO-POSS led to more homogenous morphology of

*The calculated values of relaxation strength Gi and relaxation time.*

**R2 = 0.9998 Before aging Time of aging 120 min Sample n GikPa λis GikPa λis** PLA 1 308.888 1.59·10<sup>−</sup><sup>4</sup> 235.202 4.35·10<sup>−</sup><sup>4</sup>

*Discrete relaxation spectrum for not aged and aged during 120 min PLA samples.*

PLA HO-POSS 1 783.398 1.66·10<sup>−</sup><sup>4</sup> 275.002 4.81·10<sup>−</sup><sup>4</sup>

PLA Gly-POSS 1 753.776 1.59·10<sup>−</sup><sup>4</sup> 310.597 3.06·10<sup>−</sup><sup>4</sup>

 153.685 3.06·10<sup>−</sup><sup>3</sup> 98.838 2.23·10<sup>−</sup><sup>3</sup> 67.539 0.01265 40.131 7.53·10<sup>−</sup><sup>3</sup> 24.786 0.04587 13.449 0.02266 5.710 0.17028 2.662 0.07096 0.665 0.76539 0.220 0.28426

 218.508 3.31·10<sup>−</sup><sup>3</sup> 118.889 2.45·10<sup>−</sup><sup>3</sup> 95.374 0.01555 49.410 8.13·10<sup>−</sup><sup>3</sup> 25.367 0.06399 19.076 0.02409 2.440 0.28063 4.138 0.07430 0.090 1.50808 0.438 0.27293

 191.331 2.71·10<sup>−</sup><sup>3</sup> 106.000 1.89·10<sup>−</sup><sup>3</sup> 80.970 9.87·10<sup>−</sup><sup>3</sup> 35.012 6.27·10<sup>−</sup><sup>3</sup> 33.950 0.03092 12.362 0.017141 7.009 0.10387 3.062 0.04833 0.521 0.46087 0.386 0.18548

Magdalena Lipińska\*, Klaudia Toczek and Magdalena Stefaniak Chemistry Department, Institute of Polymer and Dye Technology, Lodz University of Technology, Lodz, Poland

\*Address all correspondence to: magdalena.lipinska@p.lodz.pl

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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polylactide (PLA) research. Bioresource Technology. 2010;**101**(22):8493-8501. DOI: 10.1016/j.biortech.2010.05.092

[14] Tsuji H. Poly(lactide) stereocomplexes: Formation, structure, properties, degradation, and applications. Macromolecular Bioscience. 2005;**5**(7):569-597. DOI: 10.1002/mabi.200500062

[15] Srisa-ard M, Baimark Y. Effects of arm number and arm length on thermal properties of linear and star-shaped poly(D,L-lactide)s. Journal of Applied Science. 2010;**10**(17):1937-1943. DOI: 10.3923/jas.2010.1937.1943

[16] Martino VP, Ruseckaite RA, Jimenez A. Thermal and mechanical characterization of plasticized poly(Llactide-*co-*D, L-lactide) films for packaging. Journal of Thermal Analysis and Calorimetry. 2006;**86**(3):707-712. DOI: 10.1007/s10973-006-7897-3

[17] Sodergard A, Stolt M. Properties of lactic acid based polymers and their correlation with composition. Progress in Polymer Science. 2002;**27**(6):1123-1163. DOI: 10.1016/ S0079-6700(02)00012-6

[18] Middleton JC, Tipton AJ. Synthetic biodegradable polymers as orthopedic devices. Biomaterials. 2000;**21**(23): 2335-2346. DOI: 10.1016/S0142- 9612(00)00101-0

[19] Sun J, Yu H, Zhuang X, Chen X, Jing X. Crystallization behavior of asymmetric PLLA/PDLA blends. The Journal of Physical Chemistry. B. 2011;**115**(12):2864-2869. DOI: 10.1021/ jp111894m

[20] Schmidt SC, Hillmyer MA. Polylactide stereocomplex crystallites as nucleating agents for isotactic polylactide. Journal of Polymer Science Part B: Polymer Physics. 2001;**39**(3):300-313

[21] Pistner H, Bendix DR, Muhling J, Reuther JF. Poly(L-lactide): A longterm degradation study in-vivo. Part III. Analytical characterization. Biomaterials. 1993;**14**(4):291-298. DOI: 10.1016/0142-9612(93)90121-H

[22] Qiu Z, Pan H. Preparation, crystallization and hydrolytic degradation of biodegradable poly(Llactide)/polyhedral oligomeric silsesquioxanes nanocomposite. Composites Science and Technology. 2010;**70**:1089-1094. DOI: 10.1016/j. compscitech.2009.11.001

[23] Turan D, Sirin H, Ozkoc G. Effects of POSS particles on the mechanical, thermal, and morphological properties of PLA and plasticised PLA. Journal of Applied Polymer Science. 2011;**121**(2):1067-1075. DOI: 10.1002/ app.33802

[24] Yilmaz S, Kodal M, Yilmaz T, Ozkoc G. Fracture toughness analysis of O-POSS/PLA composites assessed by essential work of fracture method. Composites Part B Engineering. 2014;**56**:527-535. DOI: 10.1016/j. compositesb.2013.08.081

[25] Wang R, Wang S, Zhang Y. Morphology, rheological behavior, and thermal stability of PLA/PBSA/POSS composites. Journal of Applied Polymer Science. 2009;**113**:3095-3102. DOI: 10.1002/app.30333

[26] Oshani BN, Davachi SM, Hejazi I, Seyfi J, Khonakdar HA, Abbaspourrad A. Enhanced compatibility of starch with poly(lactic acid) and poly(εcaprolactone) by incorporation of POSS nanoparticles: Study on thermal properties. International Journal of Biological Macromolecules. 2019;**141**:578-584. DOI: 10.1016/j. ijbiomac.2019.09.026

[27] Kodal M, Wis AA, Ozkoc G. The mechanical, thermal and morphological properties of γ-irradiated PLA/TAIC

**76**

*Fillers*

**References**

[1] Raftopoulos KN, Pielichowski K. Segmental dynamics in hybrid polymer/ POSS nanomaterials. Progress in Polymer Science. 2016;**52**:136-187. DOI: 10.1016/j.progpolymsci.2015.01.003

dispersion and surface energetics of polymer nanocomposites containing hydrophilic POSS and layered silicates. Journal of Colloid and Interface Science. 2011;**355**(1):222-230. DOI: 10.1016/j.

[8] Lewicki JP, Pielichowski K, Jancia M, Hebda E, Albo RLF, Maxwell RS. Degradative and morphological characterization of POSS modified nanohybrid polyurethane elastomers. Polymer Degradation and Stability. 2014;**104**:50-56. DOI: 10.1016/j. polymdegradstab. 2014.03.025

[9] Lipińska M, Soszka K. Viscoelastic behavior, curing and reinforcement mechanism of various silica and POSS filled methyl-vinyl polysiloxane MVQ rubber. Silicon. 2019;**11**:2293-2305. DOI:

10.1007/ s12633-019-0081-8

[10] Meng Y, Wei Z, Liu L, Liu L, Zhang L, Nishi T, et al. Significantly improving the thermal stability and dispersion morphology of polyhedral oligomeric silsesquioxanes/polysiloxane composites by in-situ grafting reactions. Polymer. 2013;**54**(12):3055-3064. DOI:

10.1016/j.polymer.2013.03.061

[11] Lipińska M, Imiela M. Morphology, rheology and curing of (ethylenepropylene elastomer/hydrogenate acrylonitrile-butadiene rubber) blends reinforced by POSS and organoclay. Polymer Testing. 2019;**75**:26-37. DOI: 10.1016/j.polymertesting.2019.01.020

[12] Konnola R, Nair CPR, Joseph K. Cross-linking of carboxyl-terminated

[13] Madhavan Nampoothiri K, Nair Nimisha R, John RP. And overview of the recent developments in

nitrile rubber with polyhedral oligomeric silsesquioxane. Cure kinetics. Journal of Thermal Analysis and Calorimetry. 2016;**123**(2):1479- 1489. DOI: 10.1007/s10973-015-5019-9

jcis.2010.12.010

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progpolymsci.2016.09.011

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heptaisobutyl POSS. European Polymer Journal. 2009;**45**(2):325-331. DOI: 10.1016/j.eurpolymj.2008.10.025

[4] Goffin A, Duquesne E, Moins S, Alexandre M, Dubois P. New organicinorganic nanohybrids via ring opening polymerization of (di)lactones initiated by functionalized polyhedral oligomeric silsesquioxanes. European Polymer Journal. 2007;**43**(10):4103-4113. DOI: 10.1016/j.eurpolymj.2007.07.041

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development of isotactic polypropylene

polyhedral oligomeric silsesquioxanes

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behavior and morphological

blended with nanostructured

molecules. Journal of Polymer Science Part B: Polymer Physics. 2006;**44**(15):2122-2134. DOI: 10.1002/

561-571. DOI: 10.3144/ expresspolymlett.2012.59

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[34] Monticelli O, Calabrese M, Gardella L, Fina A, Gioffredi E. Silsesquioxanes: Novel compatibilizing agents for tuning the microstructure and properties of PLA/PCL immiscible blends. European Polymer Journal. 2014;**58**:69-78. DOI: 10.1016/j. eurpolymj.2014.06.021

[35] Han D, Wen TJ, Han G, Deng YY, Deng Y, Zhang Q, et al. Synthesis of Janus POSS star polymer and exploring its compatibilization behavior for PLLA/PCL polymer blends. Polymer. 2018;**136**:84-91. DOI: 10.1016/j. polymer.2017.12.050

[36] Nijenhuis AJ, Grijpma DW, Pennings AJ. Highly crystalline as-polymerized poly(L-lactide). Polymer Bulletin. 1991;**26**:71-77. DOI: 10.1007/BF00299350

[37] Kalb B, Pennings AJ. General crystallization behaviour of poly(Llactic acid). Polymer. 1980;**21**:607-612. DOI: 10.1016/0032-3861(80)90315-8

[38] Migliaresi C, de Lollis A, Fambri L, Cohn D. The effect of thermal history on the crystallinity of different molecular weight PLLA biodegradable polymers. Clinical Materials. 1991;**8**:111-118. DOI: 10.1016/0267-6605(91)90018-B

[39] Battegazzore D, Bocchini S, Frache A. Crystallization kinetics of poly(lactic acid)-talc composites. Express Polymer Letters. 2011;**5**(10):849-858. DOI: 10.3144/ expresspolymlett.2011.84

[40] Tábi T, Sajó IE, Luyt AS, Kovács JG. Crystalline structure of annealed polylactic acid and its relation to processing. Express Polymer Letters. 2010;**4**:659-668. DOI: 10.3144/ expresspolymlett.2010.80

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*POSS Fillers as a Factor Influencing on Viscoelastic Properties, Crystallization…*

[49] Desa MM, Hassan A, Arsad A, Mohammad N. Mechanical and thermal

[50] Siracusa V. Microbial degradation of synthetic biopolymers waste. Polymers. 2019;**11**:1-18. DOI: 10.3390/

[51] Lucas N, Bienaime C, Belloy C,

[52] Briassoulis D. The effect of tensile stress and agrochemicals Vapam on the ageing of low density polyethylene (LDPE) agricultural films. Part 1. Mechanical behavior. Polymer Degradation and Stability. 2005;**86**:

[53] Liu H, Song W, Cheng F, Guo L, Zhang J. Interaction of microstructure and interfacial adhesion on impact performance of polylactide (PLA) ternary blends. Macromolecules. 2011;**44**:1513-1522. DOI: 10.1021/

[54] Cuadri AA, Martin-Alfonso JE. Thermal, thermo-oxidative and thermomechanical degradation of PLA: A comparative study based on rheological, chemical and thermal properties. Polymer Degradation and Stability. 2018;**150**:37-45. DOI: 10.1016/j.

polymdegradstab. 2018.02.011

Queneudec M, Silvestre F, Nava-Saucedo JE. Polymer biodegradation: Mechanism and estimation techniques. Chemosphere. 2008;**73**:429-442. DOI: 10.1016/j. chemosphere.2008.06.064

489-503. DOI: 10.1016/j. polymdegradstab. 2004.11.021

ma1026934

properties of rubber toughened poly(lactic acid). Advanced Materials

Research. 2015;**1125**:222-226. DOI: 10.4028/www.scientific.net/

AMR.1125.222

polym11061066

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[43] Yu J, Qiu J. Effect of low octavinylpolyhedral oligomeric silsesquioxanes loadings on the melt crystallization and morphology of biodegradable poly(L-lactide). Thermochimica Acta. 2011;**519**:90-95. DOI: 10.1016/j.

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[45] Zaharescu T, Rapa M,

Lungulescu EM, Butoi N. Filler effect on the degradation of γ-processed PLA/ vinyl POSS hybrid. Radiation Physics and Chemistry. 2018;**153**:188-197. DOI: 10.1016/j.radphyschem.2018.09.025

[46] Phattarateera S, Pattamaprom C. Comparative performance of functional rubbers on toughness and thermal property improvement of polylactic acid. Materials Today Communications.

2019;**19**:374-382. DOI: 10.1016/j.

[48] Maroufkhani M, Katbab A, Liu W, Zhang J. Polylactide (PLA) and acrylonitrile butadiene rubber (NBR) blends: The effect of ACN content on morphology, compatibility and mechanical properties. Polymer. 2017;**115**:37-44. DOI: 10.1016/j.

polymer.2017.03.025

[47] Lee JY, Chin IJ, Choi HJ. Effect of particle size and crosslinking on the toughening of core-shell type rubber modified poly(lactic acid) composites. Polymer Testing. 2018;**65**:440-449. DOI: 10.1016/j.polymertesting.2017.12.028

mtcomm.2019.02.012

*POSS Fillers as a Factor Influencing on Viscoelastic Properties, Crystallization… DOI: http://dx.doi.org/10.5772/intechopen.92595*

[42] Kishore K, Vasanthakumari R, Pennings AJ. Isothermal melting behavior of poly(L-lactic acid). Journal of Polymer Science Polymer Physics Edition. 1984;**22**:537-542. DOI: 10.1002/ pol.1984.180220401

*Fillers*

and PLA/OvPOSS. Radiation Physics and Chemistry. 2018;**153**:214-225. DOI: 10.1016/j.radphyschem.2018.10.018

[34] Monticelli O, Calabrese M, Gardella L, Fina A, Gioffredi E. Silsesquioxanes: Novel compatibilizing agents for tuning the microstructure and properties of PLA/PCL immiscible blends. European Polymer Journal. 2014;**58**:69-78. DOI: 10.1016/j. eurpolymj.2014.06.021

[35] Han D, Wen TJ, Han G, Deng YY, Deng Y, Zhang Q, et al. Synthesis of Janus POSS star polymer and exploring its compatibilization behavior for PLLA/PCL polymer blends. Polymer. 2018;**136**:84-91. DOI: 10.1016/j.

polymer.2017.12.050

10.1007/BF00299350

[36] Nijenhuis AJ, Grijpma DW, Pennings AJ. Highly crystalline as-polymerized poly(L-lactide). Polymer Bulletin. 1991;**26**:71-77. DOI:

[37] Kalb B, Pennings AJ. General crystallization behaviour of poly(Llactic acid). Polymer. 1980;**21**:607-612. DOI: 10.1016/0032-3861(80)90315-8

10.1016/0267-6605(91)90018-B

[39] Battegazzore D, Bocchini S, Frache A. Crystallization kinetics of poly(lactic acid)-talc composites.

2011;**5**(10):849-858. DOI: 10.3144/

relation to processing. Express Polymer Letters. 2010;**4**:659-668. DOI: 10.3144/

[41] Vasanthakumari R, Pennings AJ. Crystallization kinetics of poly(L-lactic acid). Polymer. 1983;**24**:175-178. DOI: 10.1016/0032-3861(83)90129-5

Express Polymer Letters.

expresspolymlett.2011.84

expresspolymlett.2010.80

[40] Tábi T, Sajó IE, Luyt AS, Kovács JG. Crystalline structure of annealed polylactic acid and its

[38] Migliaresi C, de Lollis A, Fambri L, Cohn D. The effect of thermal history on the crystallinity of different molecular weight PLLA biodegradable polymers. Clinical Materials. 1991;**8**:111-118. DOI:

[28] Kodal M, Sirin H, Ozkoc G. Effects of reactive and nonreactive POSS types on the mechanical, thermal, and morphological properties of plasticized poly(lactic acid). Polymer Engineering and Science. 2014;**54**(2):264-275. DOI:

[29] Zubrowska A, Piotrowska E, Kowalewska A, Cichorek M. Novel blends of polylactide with ethyleneglycol derivatives of POSS. Colloid & Polymer Science. 2015;**293**(1):23-33. DOI: 10.1007/s00396-014-3344-3

[30] Tang L, Qiu Z. Effect of poly(ethylene glycol)-polyhedral oligomeric silsesquioxanes on the thermal and mechanical properties of biodegradable poly(L-lactide). Composites Communications. 2017;**3**:11- 12. DOI: 10.1016/j.coco.2016.11.003

[31] Zhang X, Sun J, Fang S, Han X, Li Y, Zhang C. Thermal, crystalline, and mechanical properties of octa(3 chloropropylsilsesquioxane)/poly(Llactic acid) hybrid films. Journal of Applied Polymer Science. 2011;**122**: 296-303. DOI: 10.1002/app.34059

[32] Huang L, Tan J, Li W, Zhou L, Liu Z, Luo B, et al. Functional polyhedral oligomeric silsesquioxane reinforced poly(lactic acid) nanocomposites for biomedical applications. Journal of the Mechanical Behavior of Biomedical Materials. 2019;**90**:604-614. DOI: 10.1016/j.jmbbm.2018.11.002

[33] Liu Z, Hu D, Huang L, Li W, Tian J, Lu L, et al. Simultaneous improvement in toughness, strength and biocompatibility of poly(lactic acid) with polyhedral oligomeric silsesquioxanes. Chemical Engineering Journal. 2018;**346**:649-661. DOI:

10.1016/j.cej.2018.03.077

10.1002/pen.23557

**78**

[43] Yu J, Qiu J. Effect of low octavinylpolyhedral oligomeric silsesquioxanes loadings on the melt crystallization and morphology of biodegradable poly(L-lactide). Thermochimica Acta. 2011;**519**:90-95. DOI: 10.1016/j. tea.2011.03.009

[44] Kopinke FD, Remmler M, Mackenzie K, Moder M, Wachsen O. Thermal decomposition of biodegradable polyesters-II. Poly(lactic acid). Polymer Degradation and Stability. 1996;**53**:329-342

[45] Zaharescu T, Rapa M, Lungulescu EM, Butoi N. Filler effect on the degradation of γ-processed PLA/ vinyl POSS hybrid. Radiation Physics and Chemistry. 2018;**153**:188-197. DOI: 10.1016/j.radphyschem.2018.09.025

[46] Phattarateera S, Pattamaprom C. Comparative performance of functional rubbers on toughness and thermal property improvement of polylactic acid. Materials Today Communications. 2019;**19**:374-382. DOI: 10.1016/j. mtcomm.2019.02.012

[47] Lee JY, Chin IJ, Choi HJ. Effect of particle size and crosslinking on the toughening of core-shell type rubber modified poly(lactic acid) composites. Polymer Testing. 2018;**65**:440-449. DOI: 10.1016/j.polymertesting.2017.12.028

[48] Maroufkhani M, Katbab A, Liu W, Zhang J. Polylactide (PLA) and acrylonitrile butadiene rubber (NBR) blends: The effect of ACN content on morphology, compatibility and mechanical properties. Polymer. 2017;**115**:37-44. DOI: 10.1016/j. polymer.2017.03.025

[49] Desa MM, Hassan A, Arsad A, Mohammad N. Mechanical and thermal properties of rubber toughened poly(lactic acid). Advanced Materials Research. 2015;**1125**:222-226. DOI: 10.4028/www.scientific.net/ AMR.1125.222

[50] Siracusa V. Microbial degradation of synthetic biopolymers waste. Polymers. 2019;**11**:1-18. DOI: 10.3390/ polym11061066

[51] Lucas N, Bienaime C, Belloy C, Queneudec M, Silvestre F, Nava-Saucedo JE. Polymer biodegradation: Mechanism and estimation techniques. Chemosphere. 2008;**73**:429-442. DOI: 10.1016/j. chemosphere.2008.06.064

[52] Briassoulis D. The effect of tensile stress and agrochemicals Vapam on the ageing of low density polyethylene (LDPE) agricultural films. Part 1. Mechanical behavior. Polymer Degradation and Stability. 2005;**86**: 489-503. DOI: 10.1016/j. polymdegradstab. 2004.11.021

[53] Liu H, Song W, Cheng F, Guo L, Zhang J. Interaction of microstructure and interfacial adhesion on impact performance of polylactide (PLA) ternary blends. Macromolecules. 2011;**44**:1513-1522. DOI: 10.1021/ ma1026934

[54] Cuadri AA, Martin-Alfonso JE. Thermal, thermo-oxidative and thermomechanical degradation of PLA: A comparative study based on rheological, chemical and thermal properties. Polymer Degradation and Stability. 2018;**150**:37-45. DOI: 10.1016/j. polymdegradstab. 2018.02.011

### *Edited by Emmanuel Flores Huicochea*

Fillers, in general, are substances that can be added to various polymer systems to reduce the cost or/and improve their physical-chemistry properties. Fillers can be either organic or inorganic, and added into the main matrix in different ways as a solid, liquid, or gas with different dimension scales, including macro, micro, even nanoscale.

The aim of this book is to present the most updated information on the fillers in different application fields, such as wood adhesives, plastic, poly (lactic acid, PLA)/ rubber composite, and packaging fields. In addition, the most recent research achievements of fillers in different fields will also be covered.

Published in London, UK © 2021 IntechOpen © serezniy / iStock

Fillers

Fillers

*Edited by Emmanuel Flores Huicochea*