Abstract:

The effects of three organic zinc salt accelerators, such as zinc dibutyl dithiocarbamate （ BZ）, zinc O,O′-dibutyldithiophosphate （ZnDBDP） and zinc dibenzothiazole disulphide （MZ）, on the curing characteristics and vulcanization reversion of natural rubber （NR） were investigated, and the mechanical properties of three vulcanizates respectively accelerated by the three kinds of salts were comparatively analyzed. Moreover, the crosslinking densities of the vulcanizates were determined by means of the equilibrium swelling method, and the content of polysulphidic cross-links in vulcanizates was detected via a special chemical reagent method. Finally, the mechanism of sulfur vulcanization catalyzed by the three accelerators was analyzed. The results show that both the catalysis and the reversion of ZnDBDP are greater than those of MZ but less than those of BZ, and that the stronger the ionization of accelerator, the more rapid the vulcanization.

Key words: natural rubber, vulcanization, zinc dibutyl dithiocarbamate, zinc dibenzothiazole disulphide, zinc O, O′-dibutyldithiophosphate, accelerator