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Studies on novel binary accelerator system in sulfur vulcanization of natural rubber
Author(s) -
Marykutty C. V.,
Mathew G.,
Mathew E. J.,
Thomas Sabu
Publication year - 2003
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.13023
Subject(s) - vulcanization , nucleophile , natural rubber , thiourea , materials science , polymer chemistry , reaction mechanism , nucleophilic addition , composite material , chemistry , chemical engineering , organic chemistry , catalysis , engineering
The synergistic activity of binary accelerator systems in rubber vulcanization is well known. Binary accelerator systems are being widely used in industry and are becoming increasingly popular because of the fact that such mixed systems can effectively prevent prevulcanization, permit the vulcanization to be carried out at a lower temperature in a shorter time, and produce a vulcanizate with superior mechanical properties compared to those of a stock cured with a single accelerator. Thiourea and its derivatives are important secondary accelerators in this context. It is suggested that thiourea containing binary accelerator systems cause rubber vulcanization to proceed by a nucleophilic reaction mechanism. In the present study 1‐phenyl‐5‐ ortho , ‐ meta , and ‐ para ‐tolyl derivatives of 2,4‐dithiobiurets, which are more nucleophilic than thiourea and vary in their nucleophilic reactivity, are used as secondary accelerators along with 2‐morpholinothiobenzothiazole in the vulcanization of natural rubber. The results show an appreciable reduction in the cure time for the mixes containing the dithiobiurets compared to the reference mix. These results are indicative of a nucleophilic reaction mechanism in the vulcanization reaction under consideration. These vulcanizates also demonstrate comparatively better tensile properties and good retention of these properties after aging. An attempt is also made to correlate the variation in physical properties to chemical crosslink formation in the various vulcanizates. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3173–3182, 2003