ANALYSIS OF THE MECHANISM OF N-T-BUTYL-2-BENZOTHIAZOLE SULFENAMIDE ACCELERATED SULFUR VULCANIZATION OF CIS-POLYISOPRENE

Results of previously published work involving network analysis and ac celerator intermediate analysis of cis-polyisoprene were compared to h elp correlate and rationalize network/chemistry relationships. Both cl assical chemical probe network analysis and further NMR measurements ( DEPT analysis) were used as necessary to verify NMR peak assignments. Furthermore, samples of the conventional formulation were vulcanized i n the absence of zinc oxide and stearic acid to help elucidate the rol e of zinc in the vulcanization process. Polysulfidic dibenzothiazole a ccelerator intermediates were proposed to produce allylic substituted cis-polysulfides both with and without double bond migration, while zi nc polysulfidic dibenzothiazole accelerator intermediates were propose d to produce allylic cis and trans polysulfides substituted structures with no double bond migration. Polysulfidic substitution on the isopr ene methyl carbon was shown to result from exchange reactions during n etwork maturation. The network-chemistry relationships were compared w ith earlier mechanistic studies and several points of agreement were n oted.