INFLUENCE OF m-ZnO ON THE THERMAL, MORPHOLOGICAL, AND CROSSLINKING BEHAVIOR OF EPDM UNDER GAMMA IRRADIATION

Ethylene propylene diene monomer (EPDM) is a versatile elastomer known for its outstanding resistance to heat, oxygen, and radiation, making it suitable for applications involving prolonged exposure to ionizing radiation. This study evaluates the potential of zinc oxide microparticles (m-ZnO), traditionally used as activators in rubber compounding, to serve as effective radiation absorbers when incorporated into EPDM. Five formulations were developed with m-ZnO contents of 2, 4, 6, 8, and 10 parts per hundred rubber (phr) and exposed to gamma irradiation doses of 10, 100, and 1000 kGy. The results revealed that increasing m-ZnO content led to a rise in the glass transition temperature (Tg), indicating strong filler-polymer interaction and improved thermal stability. SEM confirmed uniform dispersion of fillers without aggregation, while irradiated samples showed intact morphology devoid of cracks or pores, highlighting the shielding role of m-ZnO. Gel fraction analysis further demonstrated that m-ZnO effectively reduced excessive crosslinking by absorbing gamma energy. However, at higher filler loadings, an opposite trend emerged, suggesting a saturation point beyond which the shielding efficiency diminished. Overall, the findings establish m-ZnO as a promising filler to enhance radiation resistance in EPDM composites, contributing to the development of sustainable and durable materials for nuclear, aerospace, and medical applications.