Impacts of rice husk ash filler loading on curing, morphological characteristics and tensile properties of natural rubber/ethylene propylene rubber blends

Abstract

Rice husk is an agro industrial waste that potentially used in biomaterial application. It contains high silica that could be utilized as a reinforcing filler to substitute commercially precipitated silica or other commercial fillers in rubber compounding application. This research studied the effect of rice husk ash (RHA) loading as reinforcing filler in Natural Rubber/Ethylene Propylene rubber (NR/EPR) blends. The effects were observed by applying 40, 50, 60, 70 phr of RHA filler in the rubber compounding for NR (100) and also for blending NR/EPR (70:30). The rubber compounding and vulcanization for the rubber compounding was conducted according to the ASTM D-3182. The results showed that RHA were successfully prepared and introduced as a new alternative filler for rubber industrial application. Based on the curing characteristics, the RHA loading influence slightly ts2, t90, ML, MH and cross link density on the NR blending with and without EPR addition. At the same RHA composition, the torque and cross link density of NR-EPR blending were much higher compared to only NR. RHA loading on NR with and without EPR composites caused a slight decreasing on tensile strength, elongation at break, and compression set. Conversely, the hardness of those composites tended to increase due to the RHA addition. The SEM micrographs provided additional evidences on the poor tensile properties as well as the matrix tearing and voids due to EPR addition into NR composites. To sum up, RHA may be used as an alternative filler for NR composites along with the EPR addition in order to improve compression set and hardness properties without losing tensile properties of the composites.