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The chemistry of sulfur curing. Part I. Kinetics of vulcanization of an EPDM elastomer accelerated by zinc dimethyldithiocarbamate
Author(s) -
Wolfe James R.
Publication year - 1968
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.1968.070120515
Subject(s) - vulcanization , curing (chemistry) , sulfur , natural rubber , elastomer , materials science , zinc , kinetics , butyl rubber , order of reaction , rheometer , reaction rate , solubility , polymer chemistry , chemistry , composite material , reaction rate constant , organic chemistry , metallurgy , catalysis , physics , quantum mechanics , rheology
The maximum cure rates of an EPDM rubber were determined by using the Monsanto oscillating disk rheometer and correlated against the initial concentrations of curing ingredients. Unaccelerated and ZnDMDC‐accelerated sulfur curing systems were used. The results were interpreted to indicate that both unaccelerated and ZnDMDC‐accelerated curing reactions proceed simultaneously in ZnDMDC‐accelerated stocks. The maximum cure rates of the ZnDMDC‐accelerated crosslinking reactions were found to be first‐order in initial ZnDMDC concentration, second‐order in initial cure site concentration, variable fractional order in initial sulfur concentration, and approximately zero‐order in initial zinc oxide concentration. The maximum cure rates of the ZnDMDC‐accelerated reaction were shown to be limited by the low solubility of ZnDMDC in the polymer. The maximum cure rates of the unaccelerated crosslinking reaction were found to be 0.6‐order in initial sulfur concentration, 1.2‐order in initial cure site concentration, and of a positive variable order in initial zinc oxide concentration.