Reduction of zinc oxide levels in rubber compounds
G. Heideman, J.W.M. Noordermeer - University of Twente
B. van Baarle - TNO Industrie
Zinc oxide is generally known as the best activator for sulfur vulcanisation. It reduces the vulcanisation time and improves rubber properties. Although zinc is considered one of the least harmful of the heavy metals, soluble zinc compounds are classified as ecotoxic to aquatic organisms. Release of zinc into the environment from rubber occurs during production in the scrap, during service through wear, especially wear of tyres, during disposal or recycling of rubber products, for instance through leaching in land-fill sites. The increasing concern regarding the potential environmental and health effects of release of zinc compounds into the environment led to several proposals for reduction of zinc in rubber compounding. Complete elimination would be rather ambitious and would involve a fundamental change of the current technology of rubber vulcanisation. A possibility to eliminate zinc oxide is by replacing it by a Multifunctional Additive (MFA).