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 ? k₁(t ? t₀)^α, which is different from the famous equation of Vu_t = ?α(k₃/k₄)]ln(k₂e ? k₁e)/(k₂ ? k₁)] deduced by Coran. It was found that the rate constants of two vulcanization processes with different reaction mechanisms before and after t_dis 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. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3260–3265, 2004