**1. Introduction**

Polymeric-based composites have been frequently used in last decades due to their promising properties and selectable specification. It is widely known that the usage of a polymer and one (or more) type of solid fillers allows us to obtain several advantages. In this case, by using diverse kinds of fillers, we can develop composite structures with selectable mechanical, thermal, electrical, and chemical properties. Among the most common fillers in the composite industry, calcium carbonate, glass fibers, talc, kaolin, mica, wollastonite, silica, graphite, synthetic fillers (e.g., PETor PVA-based fibers), and high-performance fibers (carbon, aramid, etc.) can be mentioned [1]. However, the usage of such additives leads to one of the main limitations of polymer composites; the presence of two different components within the

composite structure makes their recyclability and reuse a bit difficult to the level that it becomes much more economical to dispose them into the dump rather than reusing them [2–8]. Such method is often considered as an unappealing alternative due to its high cost, environmental impacts, and technical limitation/difficulties. Furthermore, it is worsened by the fact that plastic production requires a remarkable consumption of oil-based resources, which are notoriously nonrenewable [9]. Increased pressure from environmental activists, preservation of natural resources, and attended stringency of laws passed by developing countries lead to the invention and development of natural materials with a focus on renewable raw materials [10–12].

In case of chronological order, primary attempts were focused on the fabrication and characterization of polymeric composites based on recyclable polymers (e.g., polyolefin) filled with natural organic fillers, i.e., derived fibers and materials derived from natural plants. Several factors follow this choice. In this regard, the usage of natural organic fillers rather than traditional mineral inorganic additives leads to massive reduction in the usage of nonbiodegradable polymers and nonrenewable resources. Furthermore, these fillers are usually obtained from wastes or abundant plants; thus the final product becomes fairly economical and cheap. Moreover, these additives are less abrasive compared with inorganic mineral counterparts in matter of processing machinery. Likewise, these additives are also less dangerous for employees all of whom working in the production line due to their easy incineration and safe inhalation. The usage of such natural resources for reinforcement of composites can lead to the development of composite structures with lower density (or specific weight), ideal thermal properties, and fine acoustic insulation performance than with their mineral reinforced counterparts. Natural bio-fiber composites are emerging as a viable alternative to glass fiber reinforced plastics, especially in automotive applications. Thermoplastic biocomposites and biopolymer including PP, PE, PS, and PLA all of which were reinforced with natural fibers have attracted great attention toward themselves during the past few years. Such thermoplastic biocomposites, compared with those made using a thermoset matrix, can be processed into different shapes and have the potential to be mechanically recycled [13]. The synthesis of recyclable and degradable polymeric materials with a highly cross-linked three-dimensional network structure like PLA is very important for polymer science and technology for supporting a green sustainable society. PLA offers some advantages over the traditional nonbiodegradable polymers especially when their recycling is quite difficult or not economical. Likewise, there are also many restrictions due to the specification and properties of used materials, while a number of these challenges are expected to be resolved via blending PLA with other polymers, by making micro- and nanocomposites of PLA, coating with high barrier materials, and also through enhancement with practical polymeric materials [13].

The annual disposal of over 10 million tons of plastic wastes in both the EU countries and the USA has raised the demand for management and reuse of these nonbiodegradable waste streams. The synthetic polymeric materials containing displaced glasses, metals, wood, and ceramics have been widely used in many products, especially in the case of packaging. The commodity plastics, the so-called big four including PE, PP, PS, and PVC have been used in variety of forms such as films, rigid containers, and flexible bags which have revolutionized the packaging industry. However, disposal of these kinds of materials within the environment without the possibility of degradation led to rise of multitude environmental and ecological concerns. The important feature of composite materials is that they can be designed and tailored based on selectable properties to meet different requirements. Since biofibers are cheap and biodegradable, biocomposites from biofiber reinforced biodegradable polymers will render a contribution in the twenty-first century due to the serious environmental problem [14].

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**Table 1.**

*Development of Efficient Composites via Renewable, Recyclable, and Degradable Additives*

When traditional nonbiodegradable polymeric matrices are reinforcing with natural fibers (e.g., green fiber and biofibers), the resulting composite structure is becoming partially biodegradable. If the polymeric matrix being selected forms biodegradable resins (i.e., green polymer or biopolymer) and reinforced with natural fibers, the final composite structure is considered as green or fully biodegradable composite. Two or more diverse natural fibers as additives in combination with polymeric matrices (biopolymer or petroleum-based polymer) lead to the development of hybrid green composites. The aim of hybrid composite development is to customize the properties and specifications of resulting green composites. Another subclassification of green composites can be based on the natural fillers and functional behavior of green composites. Depending upon the type of natural fillers, green composites can be classified as unidirectional and bi-directional continuous fiber green composites or discontinuous reinforcement composites (aligned or randomly oriented in the form of particulates, short fibers, and whiskers). According to the functional behavior, they can be classified as functionally graded and smart green composites. At the end of their life cycle, green composites can be easily disposed into the soil without deteriorating the environment by creating pollution sources. Many scientific evaluations have been developed to address the potential and specifications of green and partially biodegradable composites [15]. **Table 1** reviews some of the reported works in case of these kinds of degradable composites. Some processing techniques were widely used for fabrication of composites, while among them extrusion, subsequent injection, and compression molding can be mentioned. It was rarely observed that the overall amount of fillers exceed 50–60 wt%; however, in some cases higher percentages about 70–80 wt% were reported (especially in the USA). Besides, in more excessive situations, the compression molding method is preferred rather than injection molding method. Some common flaws related to the processing of such materials are due to the hygroscopic and hydrophilic nature of these additives along with their low thermal resistance which restrict the production procedure to temperatures lower than 200°C. In fact,

**Fiber Matrix Composition type Ref.**

Banana Polylactic acid Green [17]

Jute Polylactic acid Green [21, 22] Sisal Polylactic acid Green [23]

Flax Starch Green [25] Flax Polylactic acid Green [26, 27] Kenaf Polylactic acid Green [28, 29]

Partially biodegradable

Partially biodegradable

biodegradable

biodegradable

[16]

[18, 19]

[20]

[24]

Epoxy resin (LY556) and hardener

(HY951)

Jute Polypropylene Partially

Sisal Polypropylene Partially

Banana Epoxy resin (LY556) and hardener (HY951)

*List of important partially biodegradable/green composites [15].*

*DOI: http://dx.doi.org/10.5772/intechopen.84560*

**2. Green composites**

Rice husk, wheat, husk, and coconut coir

*Development of Efficient Composites via Renewable, Recyclable, and Degradable Additives DOI: http://dx.doi.org/10.5772/intechopen.84560*
