Synergistic effect of oil palm ash filled natural rubber compound at low filler loading

This work studied the possibility of utilizing oil palm ash (OPA) as filler to reinforce natural rubber (NR) compounds. The OPA loading used in this study ranged from 0 to 9 phr. The properties of low filler loading OPA filled natural rubber were investigated in terms of curing characteristics, tensile properties, rubber-filler interaction and morphology of tensile fractured surface. From the results, it was observed that the scorch and cure times decreased with the addition of OPA whereas maximum torque, tensile modulus (M100 and M300) and hardness increased. With the addition of OPA, it was worthwhile to note that the tensile strength and elongation at break improved 16% and 7.4%, respectively, up to an optimum level of 1 phr. Beyond this point, there was a detrimental effect on the strength and flexibility due to agglomeration of hydrophilic OPA. The measurement of rubber-filler interaction by FT-IR and morphological studies of tensile fracture surface of oil palm ash filled natural rubber vulcanizates supported the result obtained from tensile properties.