Mechanical and Physical Properties of Thermoplastic Natural Rubber Composites Reinforced with Rubberwood Sawdust

Abstract

This research aimed to investigate mechanical and physical properties of thermoplastic natural rubber composites reinforced with rubberwood sawdust, affecting from plastic types, wood sawdust contents and coupling agent contents. In manufacturing the composites, a twin-screw extruder was applied to blend mixture components. The composite pellets were then molded in a compression molding machine as composite panels. From results of experiment, two-way analysis of variance (ANOVA) indicated that the wood sawdust contents and coupling agent contents significantly (P-value < 0.05) affected tensile strength, modulus of rupture, modulus of elasticity, compressive strength and modulus, hardness, water absorption and thickness swelling. Increasing additions of wood sawdust from 30 wt% to 50 wt% into the composites resulting in the tensile strength, tensile strain and modulus of rupture decreased, but tensile modulus, modulus of elasticity, compressive modulus, hardness, water absorption and thickness swelling increased. Likewise, additions of coupling agent both maleic anhydride-grafted polyethylene and maleic anhydride-grafted polypropylene positively improved the mechanical and physical properties of the composites. However, the addition of too much coupling agent reduced the mechanical properties. The optimal coupling agent found was 4 wt% for the tensile strength, compressive strength, water absorption and thickness swelling. Furthermore, the composites with polypropylene and wood sawdust showed clearly higher tensile, flexural, compressive and hardness properties than the composites with high-density polyethylene and wood sawdust, when compared to the same composition rate.