Benzothiazole-accelerated sulfur vulcanization. III. 2-Bisbenzothiazole-2,2′-disulfide as accelerator for 2,3-dimethyl-2-butene

✍ Scribed by B. Morgan; W. J. McGill

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 208 KB
• Volume: 76
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(20000531)76:9<1395::aid-app4>3.0.co;2-8

✦ Synopsis

2-Bisbenzothiazole-2,2Ј-disulfide (MBTS)-accelerated sulfur vulcanization, in the absence of ZnO, was studied using 2,3-dimethyl-2-butene (TME) as a model for polyisoprene. Reactions were carried out in sealed tubes at 150°C and the residual curatives, intermediates, and products were analyzed by HPLC at various stages of the reaction. The formation of accelerator-terminated polysulfidic pendent groups is accompanied by the liberation of 2-mercaptobenzothiazole (MBT) and more MBT is liberated on crosslinking. Bis(alkenyl)-crosslinked products with varying degrees of sulfuration result. It was shown that crosslinking by a reaction between pendent groups and the model compound, and by disproportionation of pendent groups, leads to limited crosslinking. H 2 S was not evolved during crosslinking. 2,3-Dimethyl-2-butene-benzothiazole disulfide (TME-S 2 Bt) and 2,3-dimethyl-2-butene-1-thiol (TME-SH) were synthesized and it was shown that rapid crosslinking occurs between TME-S x Bt and TME-S x H (where x Ͼ 1), the reaction liberating MBT.