Effect of γ ‐Irradiation Dose on the Structural and Tribological Properties of EPDM Rubber

ABSTRACT In this paper, changes in the tribological property of ethylene propylene diene monomer (EPDM) rubber were investigated, subjected to eight γ‐irradiation doses (0–5000 kGy). Swelling tests showed that crosslink density increased with irradiation dose. FTIR and XPS analyses indicated oxidative degradation, where CH and CC bonds broke, forming alkyl radicals that generated CO, CO, and OCO functional groups. These oxidation products accumulated at the surface, leading to embrittlement and cracking. Structural and property changes were primarily driven by crosslinking and oxidation. Mechanical testing showed that irradiation induced a ductile‐to‐brittle transition in fracture behavior. The elastic modulus and surface hardness increased with dose, whereas tensile strength decreased. Friction coefficient trended downward initially, then rose. The wear rate decreased sharply between 0 and 1000 kGy and slightly increased between 2000 and 5000 kGy. The dominant wear mechanism shifted from adhesive wear (0–1000 kGy) to fatigue wear (2000–5000 kGy). These findings provided theoretical support for optimizing EPDM's tribological properties and designing long‐life, high‐reliability nuclear power equipment.