Gel fraction measurements in gamma-irradiated ultra high molecular weight polyethylene

Ultra high molecular weight polyethylene (UHMWPE) was irradiated at room temperature in air using an industrial 60Co γ-source. Samples were exposed to integrated doses of 50, 250, 500, 750, 1000, 1500 and 1750 kGy and the soluble part of each irradiated specimen was extracted by exposure to refluxing boiling xylene solvent for 10 h using the Soxhlet method. From such extractions, the swelling ratio and the gel fractions were determined. It was found out that an increase in radiation dose leads to an increase in the gel fraction and a simultaneous decrease in the swelling ratio. These tendencies are attributed to the formation of a crosslinked network.