1. Introduction

Residual biomass is defined as a compound that contains mainly nonedible vegetal material called lignocellulose. Lignocellulose is the most important component found in plant tissues and is composed of three different polymers: cellulose,

hemicellulose, and lignin. Each of these components can be found on different parts of the biological structure of the plant, being the hemicellulose is the matrix that covers the cellulose skeleton and the lignin is the encrusting material or protective layer [1].

On the other hand, a plastic waste is defined as the material recovered by the final users after having complied with the use for which it was produced [2, 3]. This type of waste is classified in two categories: postconsumer plastic and postindustrial. The first one refers to residual plastics that have been previously used by people. In contrast, postindustrial or preconsumer plastics are defined as the industrial reject material (cuts of materials and damaged pieces, among others) that is not returned to the production line. These are recycled to a great extent, due to the high availability that exists and its relative degree of purity.

Around 140 billion tons/year of biomass wastes are generated in the world as a result of agricultural activities [4] and 230 million tons/year of plastic wastes [5] related to the production of these materials. In the case of Colombia, an estimated production of 72 million tons/year of residual biomass is reported [6]. Crops such as coffee, bananas, coconut, corn, and sugar cane contribute a large proportion to this production. Waste generated by the coconut processing industry includes its shell, water, and coir. Shell and coir represent 35% in weight of the entire fruit. In Colombia, about 4100 tons/year of this type of waste are produced that is the reason why some studies are being carried out in the biotechnology and construction fields to give them an adequate use [7]. There are two types of coir, the brown coir which is obtained from mature coconuts and the white coir which is extracted from green coconuts. Generally, this type of fiber has a length of 350 mm, a diameter between 0.12 and 0.25 mm, and a density of 1250 kg/m<sup>3</sup> . It is a material resistant to microbial degradation and salt water. It has a high content of lignin and is defined as a strong material with a high tensile strength [8]. On the other hand, one of the wastes generated in large quantities during the process of the coffee bean transformation is the coffee husk. This material represents 4.5% of the grain composition, and about 33.000 tons/year is produced in Colombia [9]. The proposed uses for this waste are fermentation in order to obtain enzymes, organic acids, or bioethanol. Also, it is used as a substrate for the growth of fungi and other microorganisms [10]. This type of vegetable fiber has an average diameter of 1.2 mm, a high content of holocellulose, as well as a significant proportion of lignin [11].

On the other hand, the national demand for plastic resins is close to 1.2 million ton/ year [12], of which about 27.5% are recovered [13]. The rest of the material is disposed in landfills or inadequately in open dumps. Tables 1 and 2 show the waste generation of the main agricultural crops and plastic resins in Colombia, respectively.

There are different studies from different areas related to the use of biomass waste. A great number of treatments have been proposed to add value to this type of material or simply to change its characteristics and make its final disposition simpler [15]. The main areas for the use of biomass waste are animal and human nutrition, energy generation, biotechnology industry, and the production of biocomposites (natural fiber reinforced polymers or NFRP).

These materials have the potential to be used in different industrial areas, mostly on automotive, industrial, construction, and decoration applications [23]. Due to its renewable nature, research and development of biocomposites have been constantly increasing, and its applications are spreading to multiple areas, being its main attractive is the combination between low price, biodegradability, availability, and their capability to substitute other compounds that use regular reinforcements as glass or carbon fibers [24, 25]. Characteristics as the ones mentioned before contribute to lower the environmental burden of these kinds of materials throughout their life cycle. When compared to traditional plastic products, the substitution of the polymeric material with a natural fiber fraction on the composite can reduce

Crop Production (Ton/

year) [6]

DOI: http://dx.doi.org/10.5772/intechopen.81635

Oil Palm 3.039.637 Coarse

Corn 1.293.975 Leaves and

Generation of lignocellulosic waste in Colombia.

Generation of plastic waste in Colombia.

Table 1.

Table 2.

89

Waste Waste factor (Tonwaste/

Leaves

Recycled Polypropylene-Coffee Husk and Coir Coconut Biocomposites: Morphological…

stems

Sugarcane 24.811.681 Leaves 3.26 10.110.760

Coffee 850.500 Pulp 2.13 1.811.565

Rice 2.243.981 Straw 2.35 5.273.355

Banana 2.026.828 Coir 1 2.026.828

Coconut 129.956 Coir 0.35 [14] 45484.6

Polymer National demand (Ton/year) [12] Waste mass (Ton/year)

PVC 220.000 159.500 PS 78.000 56.550 LDPE 119.000 86.275 HDPE 160.000 116.000 PP 240.000 174.000 PET 163.000 118.175

Tonproduct) [6]

Fiber 0.63 1.148.982 Palm Coir 1.06 1.933.209

Bagasse 2.68 8.311.913

Husk 0.21 178.605 Stem 3.02 2.568.510

Cob 0.27 349.373 Fibers 0.21 271.734

Husk 0.2 448.796

Stem 5 10.134.140 Discard fruit 0.15 304.024 Skin 0.3 608.048

Waste mass (Ton/year)

0.22 401.232

0.93 1.203.396

Since several decades, biocomposites have emerged as an option aimed to solve several issues within the composite materials science. In most of published cases in literature, the use of natural fibers combined with polymers is carried out to achieve some degree of reinforcement from the fibers to the polymer. Many studies report the use of natural fibers such as flax, hemp, jute, sisal, coconut fiber, banana, and fique, among many others [16], using an extensive variety of polymer matrices like polyethylene [17, 18], polypropylene (PP) [19] polystyrene (PS) [20], epoxy resin (EP) [21], natural rubber [22], and recycled polypropylene (r-PP) [2]. Clear effects have been seen in the improvement of mechanical and thermal performance.


Recycled Polypropylene-Coffee Husk and Coir Coconut Biocomposites: Morphological… DOI: http://dx.doi.org/10.5772/intechopen.81635

#### Table 1.

hemicellulose, and lignin. Each of these components can be found on different parts of the biological structure of the plant, being the hemicellulose is the matrix that covers the cellulose skeleton and the lignin is the encrusting material or protective

On the other hand, a plastic waste is defined as the material recovered by the final users after having complied with the use for which it was produced [2, 3]. This type of waste is classified in two categories: postconsumer plastic and postindustrial. The first one refers to residual plastics that have been previously used by people. In contrast, postindustrial or preconsumer plastics are defined as the industrial reject material (cuts of materials and damaged pieces, among others) that is not returned to the production line. These are recycled to a great extent, due to the high avail-

Around 140 billion tons/year of biomass wastes are generated in the world as a result of agricultural activities [4] and 230 million tons/year of plastic wastes [5] related to the production of these materials. In the case of Colombia, an estimated production of 72 million tons/year of residual biomass is reported [6]. Crops such as coffee, bananas, coconut, corn, and sugar cane contribute a large proportion to this production. Waste generated by the coconut processing industry includes its shell, water, and coir. Shell and coir represent 35% in weight of the entire fruit. In Colombia, about 4100 tons/year of this type of waste are produced that is the reason why some studies are being carried out in the biotechnology and construction fields to give them an adequate use [7]. There are two types of coir, the brown coir which is obtained from mature coconuts and the white coir which is extracted from green coconuts. Generally, this type of fiber has a length of 350 mm, a diameter between

degradation and salt water. It has a high content of lignin and is defined as a strong material with a high tensile strength [8]. On the other hand, one of the wastes generated in large quantities during the process of the coffee bean transformation is the coffee husk. This material represents 4.5% of the grain composition, and about 33.000 tons/year is produced in Colombia [9]. The proposed uses for this waste are fermentation in order to obtain enzymes, organic acids, or bioethanol. Also, it is used as a substrate for the growth of fungi and other microorganisms [10]. This type of vegetable fiber has an average diameter of 1.2 mm, a high content of

On the other hand, the national demand for plastic resins is close to 1.2 million ton/ year [12], of which about 27.5% are recovered [13]. The rest of the material is disposed in landfills or inadequately in open dumps. Tables 1 and 2 show the waste generation

There are different studies from different areas related to the use of biomass waste. A great number of treatments have been proposed to add value to this type of material or simply to change its characteristics and make its final disposition simpler [15]. The main areas for the use of biomass waste are animal and human nutrition, energy generation, biotechnology industry, and the production of

Since several decades, biocomposites have emerged as an option aimed to solve several issues within the composite materials science. In most of published cases in literature, the use of natural fibers combined with polymers is carried out to achieve some degree of reinforcement from the fibers to the polymer. Many studies report the use of natural fibers such as flax, hemp, jute, sisal, coconut fiber, banana, and fique, among many others [16], using an extensive variety of polymer matrices like polyethylene [17, 18], polypropylene (PP) [19] polystyrene (PS) [20], epoxy resin (EP) [21], natural rubber [22], and recycled polypropylene (r-PP) [2]. Clear effects have been seen in the improvement of mechanical and thermal performance.

. It is a material resistant to microbial

ability that exists and its relative degree of purity.

0.12 and 0.25 mm, and a density of 1250 kg/m<sup>3</sup>

holocellulose, as well as a significant proportion of lignin [11].

biocomposites (natural fiber reinforced polymers or NFRP).

of the main agricultural crops and plastic resins in Colombia, respectively.

layer [1].

Thermosoftening Plastics

88

Generation of lignocellulosic waste in Colombia.


#### Table 2.

Generation of plastic waste in Colombia.

These materials have the potential to be used in different industrial areas, mostly on automotive, industrial, construction, and decoration applications [23]. Due to its renewable nature, research and development of biocomposites have been constantly increasing, and its applications are spreading to multiple areas, being its main attractive is the combination between low price, biodegradability, availability, and their capability to substitute other compounds that use regular reinforcements as glass or carbon fibers [24, 25]. Characteristics as the ones mentioned before contribute to lower the environmental burden of these kinds of materials throughout their life cycle. When compared to traditional plastic products, the substitution of the polymeric material with a natural fiber fraction on the composite can reduce

environmental impacts derived from raw material acquisition, operation life of the product, and end of life processes. Since natural fibers are in most cases residues from agricultural practices, their incorporation on an industrial processes serves as a waste management alternative where the fibers are recycled as reinforcement for plastic materials, helping to minimize environmental burdens from their primary process in agriculture where they are treated as conventional waste. Also, the reincorporation of these residues contributes to assess environmental impacts of raw material transportation at a local scale. Furthermore, this material fraction substitution reduces the amount of plastic material needed to fabricate one product, and as a consequence, less quantity of polymers are demanded for production, and less extraction of fossil resources has to be made in order to supply this productive sector. Regarding processing, biocomposites offer a wide amount of advantages related to processing techniques. These materials not only can reduce the melting temperatures on the process, contributing to lower the embodied energy of the product and consequently the carbon emissions of the product, but also can be processed with existing tools and procedures, which means that the producer does not have to make major adjustments on his production line to work with them.

Manufacturing techniques should be strongly studied and refined in order to make them mainstream and reduce concerns and impacts regarding their development degree. Therefore, as mentioned before, this is the main reason why every case of composite material has to be reported on a case-based scenario in order to objectively define the sustainable nature of products developed with these kinds of materials. In this book chapter, biocomposites based on recycled polypropylene (r-PP) and two different natural fibers (coffee husk and coconut coir fibers) with maleated polypropylene (MAPP) as a coupling agent were prepared through extrusion and injection molding processes. Morphological, mechanical, and thermal properties of the biocomposites were investigated with the aim to understand the effect of fiber type and MAPP addition on the r-PP matrix properties. Also, the environmental performance of the materials was studied through a carbon footprint

Recycled Polypropylene-Coffee Husk and Coir Coconut Biocomposites: Morphological…

Coconut coir (CCF) was obtained from "Kiero Coco" S.A (Manizales-Colombia), and coffee husk fiber (CHF) was obtained from a local coffee mill located in Tuluá-Colombia. Recycled polypropylene (rPP) was a postindustrial waste collected from extrusion and injection processes carried out in the materials laboratory of the Autónoma de Occidente University (Cali, Colombia). Maleic anhydride grafted polypropylene (Licocene MAPP 6452 by Clariant) was used as

The time between the generation of the different fiber waste and its storage (at 20°C) was less than 8 hours, in order to minimize biochemical changes in the fibers. After separation, the fibers were dried in an oven at 45°C until reaching constant weight. Drying process was carried out at this temperature in order to avoid the elimination of volatile compounds and degradation of the lignocellulosic composition. After drying, the samples were milled (particle size <1 mm) in an impact mill (Retsch SR200). The milling time was 15 minutes for CHF and

30 minutes for CCF. Finally, fibers samples were stored in polyethylene bags with a hermetic seal at room temperature. After the characterization, the fibers were sieved in ASTM sieves, with the purpose of reaching a 60 mesh particle size,

The fibers (CHF and CCF) were characterized by proximate and elemental

performed in triplicate. Through the proximate analysis, the percentage of moisture content (M), volatile matter (VM), ash (A), and fixed carbon (FC) was determined according to ASTM D7582-12 [31]. These analyzes were performed using approximately 1.0 g of sample in a Leco brand thermogravimetric analyzer, TGA-601. Table 3 shows the equations used in the determination of the proximate analysis of CHF and CCF. The calorific value was calculated using 1.0 g of sample in a Leco AC-350 calorimeter pump, following the ASTM 5865-13 standard. The calorific value establishes the amount of energy per unit mass that the waste can deliver when it is completely oxidized. This property was calculated using the equation also

established by the ASTM standards for the analysis of solid samples.

analysis, calorific power, and structural composition. These analyzes were

evaluation on a cradle to gate life cycle assessment.

DOI: http://dx.doi.org/10.5772/intechopen.81635

2. Materials and methods

2.2 Natural fibers characterization

2.1 Materials

coupling agent.

presented in Table 3.

91

Nevertheless, not every composite is easy to process, and so traditional material may have a favored position related to biocomposites due to its advanced and wellstudied processing techniques, and as direct result, fewer residues can be achieved during the fabrication process. Still some experiences with biocomposites have led to significant reduction of Greenhouse Gasses during processing and transformation stages [26]. In the case of thermoformed trays, it was found that by replacing talc fillers with starch fibers, the carbon footprint for this product was reduced around a 20% regarding gas emissions from processing [27].

Other outstanding characteristic of biocomposites compared to their traditional counterparts is the reduction of weight for the final product. For automotive applications, this characteristic could allow savings of carbon emissions by reducing the total weight of the vehicle and thus consuming less fuel without compromising the integrity of the material properties and the security guidelines of the automotive industry. Materials that possess high specific stiffness and specific strength are often very valuable in applications in which weight will be a critical factor [25], which makes biocomposites ideal candidates for automobile design and spare parts production. Different automakers believe that all advanced composite car bodywork could be around 50–67% lighter than current similarly sized steel auto-body, 40–55% lighter than an aluminum auto-body, and 25–30% lighter than a steel autobody. Nevertheless, there are not bio-based materials on commercial use or development that can be fully considered sustainable [28]. It is a fact that products derived from renewable resources tend to be competitive in the market if they prove to be similar or better than other products regarding performance and price. In fact, Reinders et al. [29] said that full bio-based brands usually have stronger purchase intentions than other brands, including those that are partially composed by bio-based products. However, the fact that a product has a renewable origin does not mean that its environmental performance is better when comparing it to traditional products in the market. A case-based evaluation is necessary to define the environmental aspects of a product and thus the sustainable nature of the product [30]. Virtually, biocomposites can be considered sustainable materials compared to traditional composites or fossil-based polymeric materials. The renewable provenance of these materials and the availability of the resource can suggest better environmental performance among its life cycle, easing pressures over the natural systems. However, critical aspects of the elaboration process during the materials life cycle can lead to different types of environmental impacts, which in turn, may be worse than the ones derived from traditional composite elaboration.

Recycled Polypropylene-Coffee Husk and Coir Coconut Biocomposites: Morphological… DOI: http://dx.doi.org/10.5772/intechopen.81635

Manufacturing techniques should be strongly studied and refined in order to make them mainstream and reduce concerns and impacts regarding their development degree. Therefore, as mentioned before, this is the main reason why every case of composite material has to be reported on a case-based scenario in order to objectively define the sustainable nature of products developed with these kinds of materials. In this book chapter, biocomposites based on recycled polypropylene (r-PP) and two different natural fibers (coffee husk and coconut coir fibers) with maleated polypropylene (MAPP) as a coupling agent were prepared through extrusion and injection molding processes. Morphological, mechanical, and thermal properties of the biocomposites were investigated with the aim to understand the effect of fiber type and MAPP addition on the r-PP matrix properties. Also, the environmental performance of the materials was studied through a carbon footprint evaluation on a cradle to gate life cycle assessment.
