Effect of 2-mercaptobenzothiazole level on kinetics of natural rubber vulcanization

The kinetics of natural rubber vulcanization were investigated by use of a vulcameter. The vulcanization process before t(dis) (the time when the accelerators and/or intermediates react to depletion) was expressed in an equation as ln(M-H - M-t) = ln A - k(1)(t - t(0))(alpha), which is different from the famous equation of Vu(t) = -[alpha(k(3)/k(4))ln-[(k(2)e(k1t) - k(1)e(k2t))/(k(2) - k(1))] deduced by Coran. It was found that the rate constants of two vulcanization processes with different reaction mechanisms before and after tdis increase and their activation energies decreased with an increase in 2-mercaptobenzthiazole (MBT) level. The considerable effect of MBT level on the activation energies of the vulcanization process before t(dis) and the obvious temperature dependency of the reaction rate of vulcanization process after t(dis) were observed. The time t(dis) was shortened with an increase in MBT level, whereas the degree of vulcanization at t(dis) remained unchanged. (C) 2004 Wiley Periodicals, Inc.