Synthesis and antioxidation behavior in EPDM of novel macromolecular antioxidants with crosslinking and antioxidation effects

• A high-molecular-weight antioxidant with crosslinking and antioxidation functions denoted as HVA-2@MB was synthesized. • HVA-2@MB reduces the inhibitory effect of antioxidant MB on rubber vulcanization and improves the crosslinking degree of rubber. • HVA-2@MB is chemically bonded to the rubber network, significantly reducing the migration of antioxidants. • HVA-2@MB endows the EPDM material with better thermal oxidation stability than the commercial antioxidant MB. A novel antioxidant denoted as HVA-2@MB was synthesized through the reaction of N,N'-1,3-phenylene bismaleimide (HVA-2) and 2-mercaptobenzimidazole (MB) catalyzed by triethylamine. This antioxidant had high molecular weight as well as crosslinking and antioxidation functions. Then, the effect of HVA-2@MB on the crosslinking and antioxidation behaviors of ethylene-propylene-diene rubber (EPDM) was investigated. HVA-2@MB greatly reduced the inhibitory effect of antioxidants on rubber vulcanization and improved the crosslinking density of rubber. In addition, due to the reactivity of HVA-2@MB, the antioxidant groups were chemically bonded to the rubber network, which significantly reduced the migration of antioxidants in the thermo-oxidative environment, thereby improving the thermo-oxidative stability of the rubber. Therefore, compared with MB/EPDM composites, HVA-2@MB/EPDM composites exhibited better mechanical properties and thermo-oxidative stability during thermo-oxidative aging.