Investigation of Mechanical Properties of Rice Straw Ash-filled Natural Rubber Compounds

Rice straw is the one of highest plant-based waste generated in Sri Lanka. Farmers burn rice straw without taking any advantage making substantial air pollution. It is found that rice straw ash contains a significant amount (62%-82%) of silica which is a prominent reinforcing filler material in rubber compounding. The present research work focuses on incorporation of rice straw ash as an alternative filler material in rubber compounding. Up to date, different ratios of rice straw ash has been incorporated with selected rubber compound replacing the silica filler loading and tensile, tear strength, hardness, compression set properties have been investigated. These properties were compared with those of the reference sample prepared according to the same formulation but without adding rice straw ash. The sample containing the same proportion of rice straw ash and silica showed the highest tensile strength compared with that of the control sample. Further, tensile strength of the sample which contained only rice straw ash was also higher than that of the control sample. The rice straw ash has a strong ability to improve the tensile properties of the rubber vulcanizates, while it negatively affects the other mechanical properties such as hardness, tear strength and compression set.