SULFUR VULCANIZATION OF SIMPLE-MODEL OLEFINS .4. VULCANIZATIONS OF 2,3-DIMETHYL-2-BUTENE WITH TMTD AND ACTIVATED ZINC DITHIOCARBAMATE XANTHATE ACCELERATORS AT DIFFERENT TEMPERATURES/

The mechanism of the accelerated sulfur vulcanization of rubber was st udied by the use of 2,3-dimethyl-2-butene (C6H12, TME) as a simple, lo w-molecular model alkene. Treatment of TME with a mixture of ZnO, S-8 and the classical accelerator TMTD at temperatures above 100 degrees C yields a mixture of addition products (C6H11-S-n-C6H11). In the tempe rature range of 50 up to 100 degrees C only intermediate products, C6H 11-S-n-S(S)CN(CH3)(2) are obtained. Room temperature vulcanization is feasible using highly reactive accelerators, such as xanthate derivati ves. These derivatives result in formation of the crosslink precursors which are converted to the actual crosslink in the presence of zinc d ithiocarbamates. The addition of (secondary) amines enhances the solub ility of the dithiocarbamates, and therefore the reactivity of the xan thate/zinc dithiocarbamate combination.