Oil palm ash (OPA) as filler was compounded with natural rubber (NR) using conventional
laboratory-sized two roll mills. For comparison purposes, two commercial fillers (i.e. silica
and carbon black) were also studied. The optimum loading of each type of filler was
investigated and compared in terms of, curing characteristics, tensile properties, rubberfiller
interaction and dynamic mechanical analysis. Results showed that scorch time and
cure time of carbon black filled vulcanizates was the lowest compared to OPA and silicafilled
NR vulcanizates. However, the incorporation of OPA offers the highest cure rate
index. From a reinforcement perspective, the carbon black-filled vulcanizates had the
highest tensile strength (26 MPa), followed by OPA (25 MPa) and silica (23 MPa). It is
worth noting that the incorporation of OPA increased the elongation at break by 7.4%
whereas silica and carbon black reduced the elongation at break of the NR compound.
Further evidence of interaction was supported by the measurement of rubber-filler
interaction, dynamic mechanical analysis and morphological studies.