Effect of irradiation dose on plastic deformation of vacuum hot pressed ultra high molecular weight polyethylene

Ultra high molecular weight polyethylene is a type of semi-crystalline polymer which is widely used in artificial joints. Degradation of it's mechanical properties under irradiation is an important aspect for its applications. In this study, molded and ram extruded material were gamma irradiated in vacuum at doses of 50 kGy, 100 kGy and 150 kGy and its uniaxial tensile properties were investigated at room temperature. The results showed that the tensile modulus, true ultimate stress and true ultimate strain were reduced as the dose increased. There was no significant difference of the true yield strain between non-crosslinked and crosslinked material, but the true yield stress of non-crosslinked material was significantly higher than the crosslinked material. The curvature of the true stress-true strain curve after yielding did not exhibit a significant relationship as a function of dose. However, both molded and ram extruded material showed a significant exponent relationship with dose.