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Concentration effect of stearic acid on scorch behavior of epoxidized natural rubber
Author(s) -
Poh B. T.,
Tang W. L.
Publication year - 1995
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.1995.070550318
Subject(s) - stearic acid , vulcanization , natural rubber , materials science , chemistry , carbon black , composite material , polymer chemistry
The effect of stearic acid on Mooney scorch time of epoxidized natural rubber (ENR 25 and ENR 50) and one grade of unmodified natural rubber (SMR L) was investigated in the concentration range of 0.5 to 14.5 phr. Other parameters, namely accelerator systems, temperature, and fillers (carbon black and silica), on the scorch property of ENR 25 in the presence of excess loading of stearic acid were also studied. Results indicate that scorch time increases with stearic acid loading for all the rubbers investigated, the rate of increase being fastest in ENR 50, followed by ENR 25 and SMR L. Mooney scorch time of ENR shows strong dependence on stearic acid loading for delay‐action accelerators and at lower temperature of vulcanization. For a fixed filler loading, the dependence of scorch time on stearic acid concentration is similar to that of gum stock. The retardation effect exhibited by excess stearic acid on the vulcanization of ENR may be attributed to complex formation of chelates and the reduction in activation of adjacent double bonds in ENR resulting from interaction between stearic acid and the epoxide group of ENR. © 1995 John Wiley & Sons, Inc.