Effect of treated coir fiber/coconut shell powder and aramid fiber on mechanical properties of vinyl ester

Abstract

The surfaces of coir fiber (CF) and coconut shell powder (CSP) were modified by alkali and silane treatment respectively to investigate the consequent effects on reinforcement of vinyl ester (VE) composites. Mono‐composites of VE with surface treated CFs and CSP as well as their hybrid composites with as‐received aramid fibers (AFs) have been prepared by hand layup followed by compression molding methods. The effectiveness of surface treated reinforcements in improving the mechanical properties of the composites was demonstrated. Significant differences between VE mono‐composites and their hybrid reinforcements on hardness and tensile properties of VE were observed, while no improvement in the above‐mentioned properties except for Young's modulus was observed for hybrid composite with AFs. It was also observed that surface treated CFs and CSP reinforced VE composites exhibited better hardness and tensile properties. SEM imaging confirmed decreased fiber pull‐out for VE reinforced with alkali treated CFs because of the enhanced adhesion between the CFs and the VE matrix. Flexural properties of all the composites decreased. This study has proved that the mechanical properties of hybrid VE composites can be enhanced by modifying the reinforcements by alkali and silane into their formulations. These results have been explained on the basis of structure and morphology in terms of fractography of VE composites. Furthermore, this study demonstrates that alkali treatment is a promising technique for improving the mechanical properties such as hardness and tensile properties of CF reinforced hybrid polymer matrix composites. POLYM. COMPOS., 39:4542–4550, 2018. © 2017 Society of Plastics Engineers