Vulcanization kinetic of styrene-butadiene rubber by sulfur/TBBS

Torque curves, measured with a moving die rheometer at temperatures between 413 and 473 K, were used to characterize the vulcanization of styrene-butadiene rubber with different cure systems based on sulfur and TBBS (N-t-butyl-2-benzothiazole sulfenamide). Several compounds were prepared varying the amount of sulfur and accelerator between 0.5 and 2.5 phr in the formulation. By means of normalized torque curves, the kinetic of cure of these samples was evaluated considering the model of isothermal curing proposed by Kamal and Sourour. In this frame, the parameters of the kinetic model were obtained. The effect of the amount of sulfur and accelerator in the compound on the kinetic parameters was investigated and a maximum of the rate parameter k for the compound with formulation with 1.0 phr of sulfur and 2.0 phr of accelerator was found. A marked decrease in the activation energy of the cure process of the elastomer was observed at higher levels of TBBS in the compound. (c) 2006 Wiley Periodicals, Inc.