2 - The effect of alkaline treatment on natural fibers/biopolymer composites

Abstract

Natural fiber reinforced biopolymer composites are the future of “green composites” with the potential to address sustainability issues such as environmental pollution and the depletion of natural resources. Natural fiber/biopolymer composites are composed of natural fibers as the reinforcing material and biopolymers as the matrix. Interestingly, natural fibers and biopolymers are usually not compatible with each other, resulting in a weak fiber-matrix interfacial bond. This is for the most part due to the hydrophilic nature of the natural fibers and the hydrophobic nature of the biopolymers. Therefore, in order to improve the compatibility between the natural fiber and the biopolymer matrix, the natural fiber is usually immersed in an alkaline solution such as sodium hydroxide for a specific time duration at a specific temperature. It has been noted that the immersion of the natural fibers in an alkaline solution does not only improve the compatibility at the fiber-matrix interface, but it also reduces the degradability of the resultant biopolymer composites. Thus, a balance between improving the mechanical performance and maintaining the degradability of the biocomposites should be maintained during alkaline treatment. Therefore, this chapter focuses on providing more insight on the effect of alkaline treatment on the properties of natural fiber/biopolymer composites.