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A DSC study of curative interactions. II. The interaction of 2,2′‐dibenzothiazole with ZnO, sulfur, and stearic acid
Author(s) -
Kruger F. W. H.,
McGill W. J.
Publication year - 1991
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/app.1991.070421003
Subject(s) - stearic acid , sulfur , zinc stearate , differential scanning calorimetry , chemistry , vulcanization , dissolution , polymer chemistry , chemical engineering , organic chemistry , materials science , natural rubber , thermodynamics , raw material , physics , engineering
The interaction of combinations of sulfur, 2,2′‐dibenzothiazole (MBTS), ZnO, and stearic acid were studied by differential scanning calorimetry. A MBTS/stearic acid interaction was indicated as evidenced by the effect the MBTS/stearic acid combination had on the melting of sulfur, the S α → S β transition being suppressed in favor of a S α → S γ transition. The dissolution/interaction of MBTS in molten sulfur was also delayed by the MBTS/stearic acid interaction, which, it is proposed, involved protonation of the N atom in MBTS by stearic acid. MBTS did not affect the formation of zinc stearate from ZnO and stearic acid, but when sulfure was added to the mixture, the ZnO/stearic acid reaction did not go to completion. No direct evidence for the formation of 2,2′‐dibenzothiazole polysulphides was found, but the absence of the S γ → S μ transition in sulfur/MBTS mixes was interpreted as indirect evidence of a reaction between these curatives. There was no evidence for the formation of a sulfur/MBTS/ZnO compound of the type generally attributed the role of an active sulfurating agent in accelerated sulfur vulcanization.