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Effect of temperature on the course of thiuram‐accelerated sulfur vulcanization
Author(s) -
Ducháček Vratislav
Publication year - 1975
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.1975.070190613
Subject(s) - vulcanization , activation energy , curing (chemistry) , sulfur , polymer chemistry , induction period , chemistry , natural rubber , kinetics , reaction rate constant , atmospheric temperature range , kinetic energy , styrene , materials science , thermodynamics , copolymer , organic chemistry , catalysis , polymer , physics , quantum mechanics
Tetramethylthiuram disulfide‐accelerated sulfur vulcanization of styrene‐butadiene rubber has been investigated at temperatures from 100°C to 170°C over 0.5 to 600 min. Continuous measurements in a Vuremo curemeter were used to estimate the extent of crosslinking, which was plotted against cure time. Apart from the induction period ( t i ), the kinetic graphs are satisfactory represented by a rate equation assuming three independent first‐order reactions: fast crosslinking, degradation, and slow crosslinking. The rate equation contains seven kinetic parameters. Over the temperature range studied, there is no difference between the values of activation energy for t i −1 , for fast crosslinking, and for degradation. The activation energy of slow crosslinking only is significantly greater. Due to the presence of Aerosil, the reciprocal values of the induction periods and the values of the ultimate extents of fast crosslinking are increased, and the values of the rate constants of degradation and slow crosslinking are decreased. Simultaneously, the activation energy of slow crosslinking is also significantly decreased. On the basis of these results, the proposed theory of tetramethylthiuram disulfideaccelerated sulfur vulcanization supposing that zinc dimethyldithiocarbamate is the actual accelerator in this type of curing system is discussed.