||January 1, 2008
Multifunctional acrylates have found utility as effective anti-reversion agents in sulfur-cured applications where overcure or high-temperature cure conditions exist. In this paper, a new multifunctional acrylate product is evaluated in sulfur vulcanization systems prone to the greatest amount of reversion. Sartomer SR534 is a proprietary blend of multifunctional acrylates on a silica carrier which can provide excellent reversion resistance while minimizing the impact on optimally cured physical properties. Reversion resistance and cured physical properties of conventional and semiefficient cure systems in natural rubber/carbon black vulcanizates are compared to other commercial products and efficient vulcanization systems. Torque rheometry is used to predict the efficiency of anti-reversion agents on preventing reversion in overcure or high-temperature cure conditions. Physical properties of optimally cured and overcured vulcanizates are provided, demonstrating the utility of anti-reversion agents. Further, flexural fatigue testing at elevated temperatures is used to differentiate the compounds with and without anti-reversion agents in simulated inservice conditions. The data provided suggests that SR534 is capable of forming additional, heat-stable crosslinks preferentially during overcure conditions which would typically result in reversion.