Preparation, structure, and properties of the coir fiber/polypropylene composites

Coir fiber–reinforced polypropylene-based unidirectional composites were prepared by compression molding. Mechanical properties like tensile strength, tensile modulus and impact strength of the resulting composites were found to be increasing with increase in the loading of coir fibers, reached an optimum and thereafter decreased with further increase in fiber loading. Based on fiber loading, 30 wt% fiber-reinforced composites had the optimum set of mechanical properties. After alkali treatment of coir fiber, tetramethoxy orthosilicate treatment was conducted to promote adhesion between coir fiber and polypropylene matrix. Treatment of the coir fiber with tetramethoxy orthosilicate after the alkali pre-treatment enhanced the mechanical properties and water desorption of the resultant composites, resulting from the improved adhesion between the coir fiber and polypropylene matrix. These results were also confirmed by the scanning electron microscope observations of tensile fracture surfaces of coir fiber/polypropylene composites. The interfacial shear strength of the composites was also measured using a single-fiber fragmentation test and a microbond test.