Enhancement of aging resistance of EPDM rubber by natural rubber‐ g ‐N (4‐phenylenediamine) maleimide as a grafted antioxidant

Abstract A new antioxidant was prepared by graft copolymerization of N (4‐phenylenediamine) maleimide ( p PDAM) onto natural rubber (NR). Fourier transform infrared technique was used to confirm the grafting of ( p PDAM) onto the NR backbone. The grafted copolymer (NR‐ g ‐ p PDAM) was incorporated into the ethylene propylene diene monomer rubber (EPDM) rubber mix as an antioxidant. For comparison purposes, a widely used antioxidant N ‐(1,3‐dimethylbutyl)‐ N ′‐phenyl‐ p ‐phenylenediamine (6PPD) was used in addition to a blank sample without antioxidant. The rheometric characteristics of EPDM vulcanizates were determined using an oscillating disc rheometer. Different mechanical properties of the EPDM vulcanizates were measured before and after exposure to thermal and ultraviolet/ozone (UV/O 3 ) accelerated aging. The results revealed that the grafted antioxidant NR‐ g ‐ p PDAM is more efficient, for EPDM rubber vulcanizates than the commercial antioxidant (6PPD). EPDM containing grafted (NR‐ g ‐ p PDAM) antioxidant exhibited promising properties, such that it is expected to fulfill major requirements of industrial, automotive, and construction applications.