Ultra-high molecular weight EPDM composites via crossover curing agents: Stabilized crosslink network structure and performance properties

Abstract

This study investigates the impact of various crosslinking systems, such as those based on sulfur, peroxide, and their hybrid combinations, on the thermal degradation characteristics of ethylene propylene diene rubber (EPDM). During aerobic degradation, polymer networks undergo reversible physical and irreversible chemical changes. There are two kinds of irreversible chemical changes that may occur: chain scission reactions and crosslinking events. The impact of these reactions on the characteristics of the elastomer is antagonistic. When measuring the properties of an elastomer as it ages, most standard characterization techniques reveal the aggregate impact of two reactions. This work employs a straightforward approach based on compression set measurements to distinguish between the scission and crosslinking events that occur during thermal aging. This work has analyzed hybrid crosslinked materials using this method and demonstrated their remarkable thermal stability, as evidenced by their ability to maintain equilibrium between scission and crosslinking reactions. The stability of performance characteristics, such as tensile strength and crosslink density, in hybrid-cured samples during thermal aging supports the aforementioned. Furthermore, the investigation also delves into the potential of hybrid curing systems using crossover curing agents instead of coagents, which are multifunctional additives, to augment the durability of performance characteristics over an extended period of thermal aging.