Cure characteristics and vulcanizate properties of a natural rubber compound extended with convoluted rubber powder

Fine convoluted rubber powder (RP) obtained from the sanding process of polishing rubber balls was used as an extender for a natural rubber compound. The cure characteristics of the extended compound were studied with the Monsanto MDR 2000 rheometer while the mechanical properties of the vulcanizates were measured in accordance with ASTM standards. The results indicated that the incorporation of rubber powder does not significantly increase the viscosity of the compounds but it reduces both scorch time and cure time. The tendency towards reversion increases with increasing rubber powder concentration. The compound can be extended with up to 30% RP without compromising tensile properties although the modulus increases continuously, albeit not so significantly. The resilience of the compounds remains almost unchanged even at higher loading, thus indicating that fine rubber powder is a true extender for rubber compounds. (C) 2000 Elsevier Science Ltd. All rights reserved.