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Benzothiazole‐accelerated sulfur vulcanization. I. 2‐Mercaptobenzothiazole as accelerator for 2,3‐dimethyl‐2‐butene
Author(s) -
Morgan B.,
McGill W. J.
Publication year - 2000
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(20000531)76:9<1377::aid-app2>3.0.co;2-a
Subject(s) - vulcanization , sulfur , chemistry , benzothiazole , ethanethiol , polymer chemistry , isothermal process , free radical reaction , reaction mechanism , organic chemistry , natural rubber , radical , catalysis , physics , thermodynamics
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. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1377–1385, 2000