Preparation and characterization of polypropylene composites reinforced with chemically treated coir

In the present work chemically treated coir reinforced polypropylene composites were fabricated by injection molding method. Raw coir was chemically treated by a simple two-step reaction. The mechanical properties of the treated coir reinforced polypropylene (PP) composites were found to be much improved compared to the corresponding values of the untreated ones. Water absorption of the composites increased with an increase in fiber content. However, treated coir-PP composites showed lower water uptake capacity compared to those prepared from untreated coir, indicating that upon chemical treatment the number of hydroxyl groups in the cellulose of coir has decreased, giving reduced the hydrophilic nature of the fiber. The surface morphology of the composites obtained from scanning electron microscopy (SEM) showed that raw coir-PP composites possess microvoids, fiber agglomerates and surface roughness with extruded fiber moieties. However, due to favorable interaction between the treated coir and the PP matrix, agglomerates and micro-voids in the composites have largely minimized showing better dispersion of the fiber in the matrix. It was concluded that upon surface modification hydrophilic nature of coir has largely minimized, giving better fiber-matrix interfacial adhesion and improved mechanical properties of the composites.