Introduction to Biocomposites from Renewable Resources
The term “biocomposites” has been widely used to denote composites that are made using either the matrix or reinforcement or both from renewable resources that are biodegradable. Conventionally, biocomposites were developed using natural cellulose fibers such as jute and flax as reinforcement to replace glass fibers with polypropylene, polyethylene, epoxy, and other synthetic polymer-based matrices. The advent of biopolyesters such as poly(lactic acid) and poly(hydroxy alkoanates) led to a quantum jump in the research on developing biocomposites using both the matrix and reinforcement from renewable resources. In addition, efforts were made to utilize agricultural by-products such as corn stover, wheat straw, and coir fibers as reinforcement resulting in inexpensive and renewable composites. However, biopolyesters such as poly(lactic acid) are considerably more expensive and also do not have the performance properties comparable to that of the traditional synthetic polymers such as polypropylene and polyethylene. Therefore, resins/matrices have also been developed from agricultural byproducts. For instance, soy proteins and wheat gluten have been used as matrix in their native form and also after various chemical modifications.