Chemical Treatments for Modification of the Surface Morphology of Coir Fiber: A Review

Coir fiber is obtained from the hard outer shell of the coconut. They are cost-effective, easily available, and easily processed. Composites made from natural fibers also have much-varied applicability. Coir fiber has been used to reinforce many matrices like polyethylene, polypropylene, epoxy, etc. But one of the common problems observed is the hydrophilicity and weak adhesion of the fibers with matrix material, which leads to reduced strength and durability of the finished product. This paper is an attempt to study the Coir fibers and various types of techniques applied to improve the surface interaction of these fibers. The treatment techniques include mercerization, silane treatment, effect of coupling agents and their effect on the strength of composites prepared is reported. These techniques help improve the fiber-matrix adhesion, makes the fiber surface clean and rough, reduce the water absorption and increase the wettability of Coir fibers. fiber treatment leads to a drastic increase in the strength and morphology of final product as is evident from the mechanical and morphological results. Scanning Electron Microscopy (SEM) has shown that the modification of fibers leads to better fiber–matrix interaction due to the subsequent changes in the surface morphology.