Benzothiazole-accelerated sulfur vulcanization. I. 2-Mercaptobenzothiazole 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: 156 KB
• Volume: 76
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(20000531)76:9<1377::aid-app2>3.0.co;2-a

✦ Synopsis

2,3-Dimethyl-2-butene (TME) was used as a model compound for polyisoprene in a study of 2-mercaptobenzothiazole (MBT)-accelerated sulfur vulcanization. Mixes that contained curatives only were heated in a DSC to various temperatures, while those that also contained TME were heated isothermally at 150°C in evacuated, sealed glass ampules. Heated mixtures were analyzed for residual curatives, intermediates, and reaction products by HPLC. It is proposed that MBT forms polysulfidic species (BtS x H) in the presence of sulfur and that these react with TME via a concerted, substitutive reaction pathway to form polysulfidic hydrogen-terminated pendent groups of varying sulfur rank (TME-S x H). MBT is released as a by-product of this reaction. Crosslinking occurs slowly as a result of the interaction of polythiol pendent groups, the rate being dependent on the pendent group concentration. H 2 S is released on crosslinking. 2,3-Dimethyl-2-butene-1-thiol was synthesized and reacted in the presence of sulfur to confirm the formation of crosslinked products (TME-S x -TME). Benzothiazole-terminated pendent groups (TME-S x Bt) were not observed.