Fundamentals of Curing Elastomers with Peroxides an Coagents II: Understanding the Relationship Between Coagent and Elastomer

Previously, the structure-property relationships of multifunctional monomeric and polymeric coagents were explored using a compound based on a standard peroxidecurable elastomer, EPDM. While the system represented a good model to compare the relative activity of coagent structures, it did not address the more complex relationships between coagent and elastomer. A larger study has been recently completed in which a select group of representative coagents were evaluated in a series of model formulations based on commercially significant elastomers that can be cured with organic peroxides (NR, NBR, HNBR, EPDM, EVA, CM, CSM, FEPM, FKM). Cure kinetics and cured physical property data are summarized. The results are interpreted by considering the relative reactivity of different polymers towards hydrogen abstraction and other radical reactions, and the proposed chemistry of coagent vulcanization. The results provide a better understanding of coagent selection based not only on coagent structure but also on the composition and  microstructure of the elastomer being cured. The investigation furthers the understanding of coagent activity by exploring coagent and elastomer structure-property corelationships.