ROLES OF SULFUR AND ACCELERATORS IN THE VULCANIZATION OF SBR COMPOUNDS DEDUCED THROUGH SIMULATION

摘要

The roles of curatives such as sulfur (S), N-cyclohexylbenzothiazole sulfenamide (CBS), and diphenylguanidine (DPG) in the vulcanization of SBR compounds were deduced from a quantitative discussion of their contribution to the induction period (t(ind)) of cure and the rate constant (k(c)) for crosslinking reaction. t(ind) and k(c) of the SBR compounds with different S, CBS, and DPG were determined in the simulation of their rheocurves using a simple kinetic model with these two parameters. The increase of S content caused an appreciable increase of delta torque (Delta tau) with negligible influences on t(ind) and k(c). By contrast, the increase of the CBS content increased both k(c) and Delta tau while slightly extending t(ind). DPG significantly shortened t(ind) by accelerating the generation rate of the active sulfurizing species. The regression analysis of t(ind), k(c), and Delta tau provided not only a quantitative comparison of the effect of the curatives on rheocurves but also the optimization of the compositions of the SBR compounds in terms of the rate and extent of cure.