Mechanical performance of electron-beam-irradiated UHMWPE in vacuum and in air

Ultra high molecular weight polyethylene (UHMWPE) was modified by a 5MeV energy electron beam at different temperatures before, during and after irradiation, both in air and in high vacuum. Wear resistance, hardness and tensile strength of irradiated polyethylene were compared with those of a untreated one. Physical analyses (like infrared spectroscopy and calorimetric analysis) were carried out in order to investigate about the changes in the material induced by irradiation. Experimental results suggested that structural changes (double bonds, cross links and oxidized species formation) occur in the polymer depending on the environmental conditions of the irradiation. Mechanical behaviour is related to the structural modifications. A temperature of 110°C before, during and after the in vacuum irradiation of UHMWPE produces a high amount of cross links and improves polymeric tensile and wear resistance, compared to that of the untreated material.