**3. Bio-based and biodegradable polymeric composites**

When a biodegradable material (neat polymer, blended product, or composite) is obtained completely from renewable resources, we usually call it a green polymeric material. Biopolymers from renewable resources have attracted much attention in recent years due to their advantages to nature [37]. Renewable resources of polymeric materials offer a solution to maintain sustainable development of economically and ecologically attractive technologies. The innovations in the development of materials from biopolymers, preservation of fossil-based raw materials, complete biological degradability of polymeric materials, reduction in the volume of garbage and composability in the natural cycle, protection of the climate through the reduction of carbon dioxide released, as well as the applications of agricultural resources for the production of bio/green materials are among the reasons that attracted the public attention toward such materials [38–40].

Bio-based and biodegradable polymeric materials have a wide range of applications in diverse fields such as packaging, biomedical, and agricultural fields. The most common application of biodegradable materials is in case of blends for TPS and aliphatic/aromatic polyesters, such as PLA or polylactides, PCL, PBAT, and PHB [41]. Recently, PLA has attracted considerable attention toward itself due to its biodegradability in the composting situation. PLA has turned into an economically plastic material for industries which is commonly used for production of films and

**99**

**Table 2.**

**Type of fiber**

Ramie Kenaf

**Cellulose (wt%)**

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

packaging materials, e.g., trays, bottles, and thin films for food packaging industry [42–44]. This cost affordable polymeric material can meet the requirement of industries for composite materials with ideal mechanical properties along with easy processability. However, PLA has some environmental impacts according to the life cycle assessment (LCA) [45]. PLA is a thermoplastic aliphatic polyester obtained from the ring-opening polymerization of lactide, which may be derived from the fermentation of sugar feedstock at competitive prices [14]. The same as most of thermoplastics, PLA can be molded into bottles, containers, and so on by injection molding, blow molding, etc. or be extruded into fibers, films, and sheets [13]. Polyester-derived by-products are playing an important role in case of biodegradable plastics due to their highly potential hydrolysable ester bonds. Polyesterderived materials are consisted from two main chemical groups, i.e., aliphatic (liner) and aromatic (aromatic rings) polyesters. Recently, various kinds of commercially biodegradable polyester materials were developed; among which we can refer to PHA, PHH, PHB, PHV, PLA, PCL, PBS, PBSA, AAC, PET, PBAT, and PTMAT [46]. The major constituents of biofibers (lignocelluloses) are cellulose, hemicellulose, and lignin. The overall amount of cellulose in lignocellulosic systems can vary based on the type and age of the plants or species that were used. Cellulose is a hydrophilic glucan polymer, while lignin is a phenolic compound, generally resistant to microbial degradation, but the pretreatment of fiber renders it susceptible to the cellulose enzyme [47, 48]. The exact chemical nature of the principal component of biofiber (the lignin) still remains obscure [14, 38]. The chemical compositions and structural parameters of some important biofibers are represented in **Table 2**. As shown in **Table 2**, specifications of natural fiber significantly vary from each other. Such variation may be due to the origin, age, retting (mode of extraction

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

of fiber from the source) process adopted, etc. [14].

**Lignin (wt%)**

**Hemicellulose (wt%)**

**Pectin (wt%)**

Bast 61–71.5 12–13 13.6–20.4 0.2 0.5 8.0 12.6 [49,

Jute 71 2.2 18.6–20.6 2.3 1.7 10.0 10.0 [51,

Flax 70.2–74.4 3.7–5.7 17.9–22.4 1.9 0.8 6.2 10.8 [49] Hemp 68.6–76.2 0.6–0.7 13.1–16.7 1.9 0.3 7.5 8.0 [53]

Leaf 67–78 8–11 10–14.2 10 2 20 11 [55] Sisal 67–78 8–11 10–14.2 10 2 20 11 [55] PALF 70–82 5–12 — — — 14 11 [56] Henequen 77.6 13.1 4–8 — — — 8 [56] Seed 82.7 — 5.7 — 6 — — [57,

Cotton 82.7 — 5.7 — 6 — — [57,

Fruit coir 36–43 41–45 0.15–0.25 3–4 — 41–45 8 [57,

*Chemical composition and structural parameters of some natural fibers [14].*

31–39 15–19 21.5 — — — — [54]

**Wax (wt%)** **Microfibrillar/ spiral angle (deg.)**

**Moisture content (wt%)**

**Ref.**

50]

52]

58]

58]

58]

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

packaging materials, e.g., trays, bottles, and thin films for food packaging industry [42–44]. This cost affordable polymeric material can meet the requirement of industries for composite materials with ideal mechanical properties along with easy processability. However, PLA has some environmental impacts according to the life cycle assessment (LCA) [45]. PLA is a thermoplastic aliphatic polyester obtained from the ring-opening polymerization of lactide, which may be derived from the fermentation of sugar feedstock at competitive prices [14]. The same as most of thermoplastics, PLA can be molded into bottles, containers, and so on by injection molding, blow molding, etc. or be extruded into fibers, films, and sheets [13].

Polyester-derived by-products are playing an important role in case of biodegradable plastics due to their highly potential hydrolysable ester bonds. Polyesterderived materials are consisted from two main chemical groups, i.e., aliphatic (liner) and aromatic (aromatic rings) polyesters. Recently, various kinds of commercially biodegradable polyester materials were developed; among which we can refer to PHA, PHH, PHB, PHV, PLA, PCL, PBS, PBSA, AAC, PET, PBAT, and PTMAT [46].

The major constituents of biofibers (lignocelluloses) are cellulose, hemicellulose, and lignin. The overall amount of cellulose in lignocellulosic systems can vary based on the type and age of the plants or species that were used. Cellulose is a hydrophilic glucan polymer, while lignin is a phenolic compound, generally resistant to microbial degradation, but the pretreatment of fiber renders it susceptible to the cellulose enzyme [47, 48]. The exact chemical nature of the principal component of biofiber (the lignin) still remains obscure [14, 38]. The chemical compositions and structural parameters of some important biofibers are represented in **Table 2**. As shown in **Table 2**, specifications of natural fiber significantly vary from each other. Such variation may be due to the origin, age, retting (mode of extraction of fiber from the source) process adopted, etc. [14].


### **Table 2.**

*Chemical composition and structural parameters of some natural fibers [14].*

*Renewable and Sustainable Composites*

their mechanical properties [9].

among the most highlighted problems of this field, we can refer to hygroscopic and hydrophilic nature of additives. Such features can significantly affect the distribution of fillers within the matrix and the interfacial adhesion between fillers and matrix. Additionally, in case of injection molding and during the processing of composites, the presence of humidity throughout materials leads to the formation of water vapor which can cause several systematic problems in the following molding steps where a venting or drying system is not present. In general, the formation of water vapor and also various kinds of gases during the processing leads to the formation of voids within the developed composite structure, thereby deteriorating

So far, the biodegradability of Mater-Bi-based green composites has not been perfectly investigated. However, available scientific research regarding the biodegradability of this type of composite revealed that they become biodegradable after their burial within the soil [30–32]. Rutkowska et al. [33] studied the biodegradation of bi-based green composites in different natural environments and observed a complete biodegradation after 4 weeks, and conducted these investigations only in case of neat materials. While these investigations were conducted only in case of neat materials. In another study, Scaffaro et al. [34] have studied Mater-Bi/wood flour composite biodegradation in active sewage sludge, while their obtained results showed that the developed composites undergo biodegradation with higher weight loss rates than the neat Mater-Bi. This effect was attributed primarily to the obtained morphology and capability of wood fibers to act as support for the bacterial growth [34]. Huda et al. [35] investigated the properties of PLA/recycled cellulose composites prepared by extrusion and injection molding. Their outcome showed that an increase in the filler loading up to the 30wt% significantly improved the rigidity without affecting the crystallinity degree or thermal stability of the final product. In another research, Plackett et al. [36] prepared PLA/jute composites through a film stacking technique. Their obtained data showed that the addition of jute can lead to considerable enhancement in the tensile properties, while it can also increase the

brittle fracture and deteriorate the impact strength of the final product [9].

When a biodegradable material (neat polymer, blended product, or composite) is obtained completely from renewable resources, we usually call it a green polymeric material. Biopolymers from renewable resources have attracted much attention in recent years due to their advantages to nature [37]. Renewable resources of polymeric materials offer a solution to maintain sustainable development of economically and ecologically attractive technologies. The innovations in the development of materials from biopolymers, preservation of fossil-based raw materials, complete biological degradability of polymeric materials, reduction in the volume of garbage and composability in the natural cycle, protection of the climate through the reduction of carbon dioxide released, as well as the applications of agricultural resources for the production of bio/green materials are among the reasons that attracted the

Bio-based and biodegradable polymeric materials have a wide range of applications in diverse fields such as packaging, biomedical, and agricultural fields. The most common application of biodegradable materials is in case of blends for TPS and aliphatic/aromatic polyesters, such as PLA or polylactides, PCL, PBAT, and PHB [41]. Recently, PLA has attracted considerable attention toward itself due to its biodegradability in the composting situation. PLA has turned into an economically plastic material for industries which is commonly used for production of films and

**3. Bio-based and biodegradable polymeric composites**

public attention toward such materials [38–40].

**98**
