Facile Construction of Zn²⁺‐Carboxyl Salt‐Bonding as Sacrificial Unit in EPDM Rubber toward Mechanical and Sealing Resilience Performance Enhancement

Abstract

Abstract In view of the facile reaction between carboxyl groups and zinc oxide (ZnO), Zn 2+ ‐carboxyl salt‐bonding is constructed in ethylene propylene diene monomer (EPDM) rubber system by grafting reaction of glutamic acid (Glu), serving as sacrificial unit endowed EPDM‐g‐Glu/ZnO sample with excellent reprocessing and recycling ability. Through reaction of ZnO/methacrylic acid (MAA), EPDM‐g‐Glu/zinc dimethacrylate (ZDMA) composite is further prepared by in situ formation of ZDMA, and ZDMA is rapidly polymerized to form poly‐ZDMA (PZDMA) containing massive Zn 2+ ‐carboxyl ion pairs once vulcanized, which exhibits fuzzy interface with the matrix. Relative to EPDM/ZDMA, the higher polymerization degree of ZDMA is achieved with the reduction of the size of PZDMA clusters, demonstrating the improvement of interfacial bonding, which results in the formation of a developed crosslinking network structure for EPDM‐g‐Glu/ZDMA. The mechanical strength, fracture toughness, and hysteresis loss of EPDM‐g‐Glu/ZDMA‐40% show a significant increase in comparison with EPDM/CB‐40% and EPDM/ZDMA‐40%, meanwhile the relatively lower compression set and slower contact stress relaxation are achieved by energy dissipation mechanism of preferential rupture of Zn 2+ ‐carboxyl salt‐bonding before breakage of covalent bonds during compression aging process, revealing the effective enhancement of durable sealing resilience performance.