Measurements of free radicals over a period of 4.5 years in gamma-irradiated ultra-high molecular weight polyethylene

摘要: Abstract Gamma irradiation-induced free radicals have been investigated for 4.5 years in medical grade ultra-high molecular weight polyethylene resins, GUR 4120, 4150 and Himont 1900, at room temperature (23 °C) absence (vacuum) or presence of oxygen (air), 75 °C vacuum. In vacuum, the primary (predominantly allyl) decayed following Y=YR+ae−bt and, 30 days 100 23 °C, their concentration was reduced from ∼1017 radical/g (initial) to a minimum YR∼1015 remained this level as long samples were kept When exposed air, any time during study, these residual found decay very stable, polyenyle-type terminal radical.