In applications such as rotor blades of wind turbines, where controlled fiber orientation is necessary, these biobased composites provide a good and reasonable technical performance. But finding their mechanical characterization becomes a prime necessity before using these composites in real‐time applications. This is because, in some cases, a highly complex loading has to be faced by the composite structure developed. Hence, a number of mechanical characterizations are carried out on the composite material before it is put to real‐time application. Some of the important mechanical tests that are carried out include Tensile test, compression test, flexural test, and impact test.
Awal et al. [4] utilized polylactic acid (PLA) as matrix and cellulosic wood fibers as reinforcement for manufacturing biocomposites. They used injection molding and extrusion molding processes for the fabrication of these composite materials. In order to increase the adhesive nature in between the fiber and matrix interfaces, they used an additive named Bioadimide and this also helped to increase the process speed of the biocomposites.
Boumhaout et al. [5] developed a biocomposite for the purpose of building insulation. The method used for carrying out the manufacturing process was the hand layup technique and the authors used date palm fiber mesh with mortar as the reinforcement material. Their research findings showed that these bioreinforcements are capable of increasing the insulation properties by decreasing 70% of its thermal conductivity. Ortega et al. [6] developed a PA11 (polyamide)‐based biocomposite using stone ground wood (SGW) as reinforcement. Extrusion–injection molding technique was used for the preparation of these samples. It was concluded that, when the weight percentage of SGW was about 50%, the tensile strength of the prepared biocomposites was at its maximum.
Shibata et al. [7] made a biopolymer using a biodegradable matrix (cornstarch) and kenaf/bamboo as reinforcement using press forming method. The cox model was used to predict the flexural modulus of unidirectional and random‐oriented fiber composites. The values predicted were in a greater agreement with the experimental values. Arao et al. [8] used PLA as a biodegradable matrix for preparing biobased composites. They used jute fibers as a reinforcement. They suggested that, by using a well‐compounded pallet in the injection molding process, the tensile strength and Young modulus of developed composites can be improved. A novel nanocomposite biodegradable material using graphene oxide as reinforcement and chitosan as the matrix has been developed by Khan et al [9]. For successfully preparing these composite films, a technique called solution casting technique was used. The developed biodegradable films are having very good tensile strength and thermal stability and hence they could be used successfully in several biomedical applications. Table 2.1 shows some of the examples of commercially available biobased thermosetting polymers.
2.2 Biobased Materials
Biobased materials are the materials which contain components of biorenewable origins. As time passes, there is no doubt that, by every chance, these novel biobased materials will replace the crude oil‐based polymer materials. Some of the most common examples of these biorenewable resources include biofibers, biomass feedstocks, and biopolymers [10]. Considering the adverse effects of petroleum‐based fuel resources, biobased materials have given a more ecofriendly and safe alternative resource, namely the Biomass feedstock. In the fabrication process of biobased composites, biofibers, such as hemp and flax, are most commonly used as reinforcements. Cellulosic plastics are one of the common examples of biopolymers [10]. One thing to be noted here is that, the biorenewable portion need not be on one side at all times during the manufacturing of biobased composites. It can be either a matrix or a filler or both.
Table 2.1 Examples of commercially available biobased thermosetting polymers.
| S. no. | Manufacturer | Trade name | Raw materials | Applications |
|---|---|---|---|---|
| 1. | DSM | Palapreg ECO P 55‐01 | Unsaturated polyester | SMC/BMC |
| 2. | Bioresin | Bioresin | Castor oil | Automotive, marine |
| 3. | Ashland | ENVIREZ 1807 | Unsaturated polyester, soybean oil (18% biobased) | Tractor panels |
| 4. | JVS Polymers Ltd | LAIT‐X/POLLIT | Lactic acid based | Coatings, biomedical applications |
| 5. | Amroy Europe Oy | EpoBiox | Natural phenols distilled from forest industry waste stream | Boats, glues, electrical cars |
Different types of composites require different kinds of processing methodologies. A variety of fillers and reinforcements are used for the development of these biobased composites, which make them suitable for various biomedical applications. In practical biomedical applications, both biobased and non‐biobased fillers/reinforcements with either biobased or non‐biobased polymers were used.
The use of biobased composites in the field of biomedicine will continue to expand as long as there is continuation of research in the field. Also, these materials will be having a direct positive impact on the society both economically and environmentally.
2.3 Processing Methods
Commercial and domestic fields have increased their usage of biobased composite materials as the demand for these biobased materials have been increasing during the past decade. A number of processing methods, developed by researchers, are now available for the successful production of these biobased components. Nevertheless, with these available processing techniques, there requires much improvement in the field in order to minimize the number of defects produced in the biobased composites. Some of the most prominent fabrication techniques used for biobased composites have been depicted in Table 2.2. The simplest and cheapest among them is the hand layup technique, which is used for producing relatively simple shapes. A method to improve the surface finish and dimensional accuracy of the products produced is the spray layup technique, which is a modified version of the hand layup technique.
Idicula et al. [11] used short randomly oriented banana and sisal fibers as reinforcing materials for developing a polyester‐based hybrid biocomposite. The composites were developed using a compression molding machine. They found that, the composites made by using compression molding techniques are having very good impact strength when compared to those produced using resin transfer molding. Sreekumar et al. [12] developed biocomposites using a compression molding machine and investigated their mechanical properties. Polyester has been used as the matrix and sisal fiber as reinforcement. They compared the mechanical properties of these developed composites with that of the composites made using resin transfer molding. They found out that the strength of the composites made by compression molding technique is lower than that made from resin transfer molding technique. Kim et al. [13] used an injection molding machine for developing biobased composites using pineapple and cassava flour as reinforcements and PLA as matrix. Here they found out that the tensile and flexural strength has increased and it is attributed to the use of compatibilizer with flour as