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

loading increased to 3 wt%. Besides, the low weight percentage of starch can convert polymers into the biodegradable polymer which has a variety of applications in the automotive industry. In this matter, SEM examinations of specimens justified the biodegradability of reinforced composites by adding starch and silica nanoparticles to their system. SEM image of developed specimen can be seen in **Figure 2**.

Also recently, Mousavi et al. [3] developed polypropylene-wood composite as a new source of raw material with a combination of maleic anhydride and eggshell nanoparticles in order to improve their overall performance. They indicated that by creating cross-link between these additives, the tensile properties of polypropylene improve at high temperatures. The obtained results also showed that the tensile strength and fracture strain of samples containing cross-linked fillers and matrix are higher than samples without it at high temperatures. They also revealed that an optimum amount of peroxide is needed to achieve the desired tensile properties. Furthermore, their results showed that an increase in the overall amount of natural polymers and additives such as starch, corn, and eggshell nanoparticles as fillers can significantly enhance the physical and mechanical properties of developed composites. Their obtained results can be seen in **Tables 4**–**6** and **Figure 3**.

In a study by Farazi et al. [78], they prepared an antimicrobial substrate using LDPE/EVA/PE-MA/clay nanoparticle blend along with PS and GO. In this regard, LDPE was selected due to its fine elasticity, transparency, low melting point, and simple reversible process. Besides, developed matrix was well-reinforced with various kinds of natural, biodegradable, and antimicrobial additives. In this case, a twin screw extruder was used to produce the related specimens. Furthermore, specifications of developed samples were examined using mechanical, SEM, TEM, XRD, water absorption, water vapor, permeability, oxygen permeability, and microbial permeability tests. Moreover, the outcome of their study showed that developed specimens have appropriate mechanical properties along with their antimicrobial performance. Additionally, the outcome of water absorption, water vapor, and oxygen permeability tests showed that the sample containing GO/clay nanoparticles is presenting the best results. In this matter, the outcome of mechanical tests can be seen in **Figure 4(a–c)**, while the cultivating conditions of microorganisms and antimicrobial performance of developed samples can be seen to be negative on antimicrobial films (**Table 7**).

**Figure 2.** *SEM image of a specimen containing 5 wt% starch and 18.7 wt% NBR [77].*

*Renewable and Sustainable Composites*

**5. Nano-biocomposites**

Corn, rice, and wheat

starches

**Table 3.**

other organs [72–74].

Nano-biocomposites are among the materials that contain bio-based polymers and low additions of nanoparticles of natural fibers such as cellulose and lignin for reinforcement purposes [68–70]. They are shaded orange in the bioplastics Spectrum because nanoparticles pose unknown hazards, and fibers are obtained via the craft method and can be treated with chemicals (isocyanates, alkalis) to enhance their properties as reinforcements [70]. Hazards of the craft method and these chemicals were described above. The health effects of nanoparticles are a major concern due to the lack of knowledge about their stability during processing, and there are potential toxicity concerns related to decomposition and/or migration during service [71]. Toxicologists hypothesize that nanoparticles may not be detected by the normal defense system of organisms; their small size can modify protein structures, and they can travel from respiratory system to the brain and

Corn starch *L. amylovorus* NRRL B-4542 0.935

*Starchy and cellulosic materials used for the production of lactic acid [46].*

*Lactobacillus amylovorus* ATCC 33620 <0.70

**Substrate Microorganism Lactic acid yield (g/l)**

Wheat and rice bran *Lactobacillus* sp. 129 Corn cob *Rhizopus* sp. MK-96–1196 90 Pretreated wood *Lactobacillus delbrueckii* 48–62 Cellulose *Lactobacillus coryniformis* ssp. *torquens* 0.89 Barley *Lactobacillus casei* NRRLB-441 0.87–0.98 Cassava bagasse *L. delbrueckii* NCIM 2025 and *L. casei* 0.9–0.98 Wheat starch *Lactococcus lactis* ssp. *lactis* ATCC 19435 0.77–1 Whole wheat *Lactococcus lactis* and *Lactobacillus delbrueckii* 0.93–0.95 Potato starch *Rhizopus oryzae* and *R. arrhizus* 0.87–0.97

In a work by Hubbe et al. [75], they investigated about cellulose nanocrystals for their possible applications within the industry and stated that retention of developed nanocrystal properties should be controlled and guaranteed by using water miscible polymer matrices (e.g., starch products, latex, polyvinyl alcohol) to ease production procedure of cellulose nanocrystals and make them much more compatible with matrix. In another study, Eichhorn et al. [76] reported possible procedures of cellulose nanofiller recovery and then focused on the usage of cellulose nanowhiskers for the manufacturing of shape memory nanocomposites, as well as on the interfacial phenomena occurring in polymer/nanocellulose filler composites [9]. In another study by Mousavi et al. [77], NBR was composed with the natural

polymers such as starch and glycerol. They also used silica nanoparticles to enhance the physical and mechanical properties of NBR. It was revealed that by the increase in the overall amount of starch, the mechanical properties of developed composite have considerably declined, while by an increase in the amount of starch, the module has increased, and impact resistance and also elongation at break have decreased. However, by the addition of silica nanoparticles, physical and mechanical properties of final composition were slightly improved, and the highest mechanical properties were achieved when silica nanoparticle filler

**102**


### **Table 4.**

*Composition of developed specimens [3].*


### **Table 5.**

*Physical and mechanical properties of polypropylene-based composite [3].*


*The test conditions were as follow: Standard ISO 180, humidity about 45.1%, temperature about 22.2°C, touch back width of 8 mm, weights of 1, and touch radius of 0.25 mm [3].*

### **Table 6.**

*Impact test of polypropylene composites based on ASTM 256 standard.*

#### **Figure 3.**

*Impact test results of polypropylene-based composites containing glycerol and starch. Sample 5 has the highest impact strength which is containing 3 wt% silica nanoparticles [3].*

**105**

**6. Conclusions**

*Microorganism, medium, and cultivating conditions [78].*

**Table 7.**

**Figure 4.**

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

Green composites have attracted great attention toward themselves due to the ecological issues and decline of petroleum-based resources because of their hazards. Different types of natural fibers and their properties have been studied as a potential replacement for synthetic fibers. In recent years, various kinds of polymer composites were reinforced with organic fillers (rather than mineral inorganic additives) to reduce the usage of whether petroleum-based or mineral products and replace them with renewable resources. These "green" composites have numerous industrial applications. One of the main advantages of these materials is their low cost and degradability which protect the environment against nondegradable products. On the other hand, these composites are suffering from some disadvantages including ductility, processability, and dimensional stability. To resolve the aforementioned problems, researcher from all around the globe conducted great efforts to provide practical and appropriate alternatives through chemical treatment of additives and the usage of adhesion promoters to improve the interaction between matrix and fillers. Additionally, to obtain a completely biodegradable composite structure, it is bare bone essential to reinforce polymeric matrices with biodegradable additives rather than obtained additives form mineral or nonrenewable

**Type of microorganism ISIRI standard Cultivating** 

*(a) Tensile strength, (b) elongation at break, and (c) Young's modulus of developed samples by Farazi et al. Sample A (LDPE-EVA-PE-MA), sample B (LDPE-EVA-PE-MA-PS), sample C (LDPE-EVA-PE-MA-GO),* 

*Plural* 10,899-1ISIRI 20–25°C/3–5 days *Yeast* 10,899-2ISIRI 20–25°C/3–5 days *E. coli* 2946ISIRI/gram negative 37°C/17 h *Staphylococcus aureus* 6806ISIR/gram negative 37°C/24 h *Salmonella* 1810ISIRI/gram negative 37°C/24 h *Coliform* 9263ISIRI/gram negative 37°C/24 h *Enterococcus* 2198ISIRI/gram positive 35°C/24 h *Lactic acid bacteria (LAB)* 13559ISIRI 30°C/72 h *Esporas Clostridium Sulfito reductor* 9432ISIRI 37°C/48 h *Bacillus cereus* 2324ISIRI/gram positive 30°C/18 h

**conditions**

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

*and sample D (LDPE-EVA-PE-MA-PS-GO) [78].*

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

### **Figure 4.**

*Renewable and Sustainable Composites*

**Propylene (wt%)**

*Composition of developed specimens [3].*

**Corn (wt%)** **Starch (wt%)**

 100 0 0 0 0 0 50 46 0 0 4 0 50 44 0 0 4 2 50 33 10 1 4 2 50 21 20 3 4 2 50 9 30 5 4 2

**Eggshell nanoparticles (wt%)**

**Bending module (MPa)**

*Physical and mechanical properties of polypropylene-based composite [3].*

*width of 8 mm, weights of 1, and touch radius of 0.25 mm [3].*

*Impact test of polypropylene composites based on ASTM 256 standard.*

*impact strength which is containing 3 wt% silica nanoparticles [3].*

**Bending strength (MPa)**

 522.57 7.249 6.08 17.42 1185.63 15.711 7.09 20.45 1224.27 15.908 6.68 19.8 1190.47 15.293 7.1 19.1 1025.55 13.713 1.66 18.49 925.1 12.478 12.41 19.59

**Sample number 1 2 3 4 5 6** Impact strength (J/m) 17.55 30.86 14.88 51.43 222.9 55.28 *The test conditions were as follow: Standard ISO 180, humidity about 45.1%, temperature about 22.2°C, touch back* 

*Impact test results of polypropylene-based composites containing glycerol and starch. Sample 5 has the highest* 

**Tensile modulus (MPa)**

**Compatibilizer (wt%)**

> **Tensile strength (MPa)**

**Foaming agent (wt%)**

**Sample number**

**Table 4.**

**Sample number**

**Table 5.**

**Table 6.**

**104**

**Figure 3.**

*(a) Tensile strength, (b) elongation at break, and (c) Young's modulus of developed samples by Farazi et al. Sample A (LDPE-EVA-PE-MA), sample B (LDPE-EVA-PE-MA-PS), sample C (LDPE-EVA-PE-MA-GO), and sample D (LDPE-EVA-PE-MA-PS-GO) [78].*


### **Table 7.**

*Microorganism, medium, and cultivating conditions [78].*
