CURING OF EPOXIDIZED NATURAL-RUBBER WITH P-PHENYLENEDIAMINE

The curing of epoxidized natural rubber with p-phenylenediamine catalyzed by bisphenol A was investigated. The curing reaction was found to be first order with respect to the amine and to have an activation energy of 67.5 kJ/mol. Vulcanizates of tensile strength 12.5-16.0 MPa were obtained at cure times of 30-75 min at 180-degrees-C. The amine-cured vulcanizate was observed to be more rigid than the sulfur-cured one at room temperature consistent with its relatively high T(g). Stress-strain analysis and dynamic mechanical properties indicated that the high T(g) of the amine-cured vulcanizate could be attributed to the bulky amine crosslinks and hydrogen bonding effect of bisphenol A. (C) 1994 John Wiley & Sons, Inc.