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

Abstract

AbstractIn view of the facile reaction between carboxyl groups and zinc oxide (ZnO), Zn2+‐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 Zn2+‐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 Zn2+‐carboxyl salt‐bonding before breakage of covalent bonds during compression aging process, revealing the effective enhancement of durable sealing resilience performance.