Study on Effect of Surface Treating Method on Mechanical Behavior of Three Plant Fiber Reinforced Polypropylene Composites

The surface modification effects of triethoxysilane (KH-550), methacryloxy propyl tri-methoxy silane (KH-570), and maleic anhydride grafted polypropylene (MAPP) on sawdust (SD), wheat straw (WS) and cellulose (CE) were studied by a tensile test, as well as surface morphology observation on reinforced composites. The results revealed that MAPP was the most effective coupling agent, and SD composites performed better than WS and CE. The tensile test results indicated that the optimum conditions for coupling agents were 1 wt.% for silane coupling agents and 5 wt.% for MAPP. SEM studies confirmed the tensile test results, proving that adhesion was improved with the employment of MAPP. MAPP-treated composite samples presented a prevailed fiber broken pattern which resulted in strong fiber-matrix interface bonding, whereas silane treatments did not provide an obvious enhancement in adhesion between the fiber and the matrix.