ABSTRACT
Composite materials have been in existence for centuries, but only within the past few decades the utilization of natural plant fiber-reinforced composites has attracted the attention of the scientific community. There is a growing interest in composites reinforced with natural fibers because of their low cost, light weight, high specific strength, renewability, and biodegradability. These are now finding extensive uses in packaging, furniture, building, and other common industries. Yet natural fibers, as a construction material for buildings, were known long before. For centuries, mixtures of straw and loam, dried in the sun, were employed as construction composite, e.g., in Egypt.1 Each fiber is a “natural composite” by itself, wherein the crystallites (mostly cellulosic) remain embedded in a matrix of hemicellulose and lignin in a given orientation. Cellulose is one of the stiffest and strongest organic constituents in a natural fiber. Nature provides a host of inexpensive cellulosic fibers like wood fiber, jute, coir, sisal, and PALF. Wood fibers are the most abundant fiber source for various applications such as timber, pulp, paper, and medium-density fiberboard. Wood fibers and wood fiberbased composites, themselves, constitute a vast area of study. However, in this chapter we will confine our discussion to natural plant fibers and natural plant fiber-reinforced thermoset composites and exclude wood fibers and wood fiber-based composites such as medium-density fiberboard, which have very low matrix (or mainly thermoset adhesive). Although these natural fibers have relatively poor mechanical properties compared to man-made synthetic fibers like carbon, glass, and kevlar, they form large renewable resources in developing countries such as India.
