Synergistic Reinforcing and Stabilizing Effect of Carbon Black–Zinc Dimethacrylate on the Ethylene Propylene Diene Monomer and Improving Mechanism of Sealing Resilience

Abstract

Ethylene propylene diene monomer (EPDM)/carbon black (CB)–zinc dimethacrylate (ZDMA) vulcanizate as a sealing material was prepared. Compared with EPDM, the addition of CB–ZDMA resulted in a remarkable increase in tensile/compressive properties, storage/loss modulus, and glass transition temperature, superior to that of vulcanizates with CB or ZDMA. Moreover, the increase in the compression set and decrease in the stress relaxation coefficient were inhibited during stress-thermal oxidation aging, resulting in enhancement of durable sealing resilience performance of vulcanizate. Combination of CB–ZDMA not only facilitated dispersion of CB in the matrix but also improved interface interaction and dispersion of ZDMA. A multiple covalent/ionic cross-linking network structure with increasing cross-linking density formed in composite during vulcanization, which maintained a stable free radical signal and cross-linking density, presented minimum degradation rate and carbonyl index growth rate, and surface damage was inhibited during aging, leading to retardation of cross-linking, degradation, and oxidation of EPDM molecules. Thus, synergistic reinforcing and the stabilization effect of CB–ZDMA on EPDM were achieved.