Influence of Polymer Coated CaCO3 on Vulcanization Kinetics of Natural Rubber/Sulfur/N-Oxydiethyl Benzthiazyl Sulfenamide (BSM) System

The effect of polymethyl methacrylate (PMMA)-encapsulated calcium carbonate on the kinetics of the vulcanization of natural rubber (NR) with a vulcanizing agent (sulfur) accelerated by N-oxydiethyl benzthiazyl sulfenamide (BSM) has been studied. The PMMA coating (4% by weight of CaCO3) was prepared by dispersion polymerization, and compositions of five NR composites were 10, 15, 20 phr of treated CaCO3 and 20 and 40 phr of untreated CaCO3. The vulcanization kinetics was determined by oscillating disc rheometry (ODR) and the kinetic parameters were determined by the model equations. The kinetic analysis suggests that the two-parameter auto catalytic model is the more appropriate one to elucidate the kinetics of the vulcanizing reaction of the present system. These parameters support the nature of the experimental ODR curves (degree of conversion-time plots). The encapsulated CaCO3 leads to a change in vulcanization reaction and has an effect on the kinetic parameters E, ln K-0, m and n, and consequently on the overall reactivity.