AbstractTetramethylthiuram disulfide‐accelerated sulfur vulcanization of natural rubber has been investigated at temperatures from 100°C to 140°C. Continuous measurements in a Vuremo curemeter were used to estimate the extent of crosslinking, which was plotted against cure time. The linearized forms of the cure curves clearly show that at lower cure temperatures, the course of vulcanization differs significantly from the first‐order rate law. These digressions were removed by the addition of thiourea, which simultaneously speeds up the course of vulcanization and diminishes its activation energy on the one hand but, on the other hand, diminishes the ultimate extent of crosslinking. On the basis of the above results, the mechanism of thiuram‐accelerated sulfur vulcanization, in which ionic and radical reactions take place, is di
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