Dielectric Behavior Induced by Vitamin E and Electron Beam Irradiation in Ultra High Molecular Weight Polyethylene

Radiation cross-linked ultra high molecular weight polyethylenes (UHMWPEs) have been successfully used as wear resistant bearing surfaces in total joint arthroplasty. A recent development in this field is the incorporation of the antioxidant vitamin E into radiation cross-linked UHMWPE. This study investigates the effects of radiation cross-linking and vitamin E incorporation on the dielectric behavior of UHMWPE. The dielectric relaxations of virgin and 0.1 wt % vitamin E-blended UHMWPE and their irradiated counterparts (up to 300 kGy dose) were investigated. To determine the effect of vitamin E content alone, vitamin E-loaded UHMWPEs were used. The results showed that radiation cross-linking and vitamin E content both increased dielectric polarization in UHMWPE and under some conditions induced electrical conductivity. This result is significant because it shows that the conductive response of UHMWPE-bearing surfaces may depend on manufacturing processes and additives. (C) 2014 Wiley Periodicals, Inc.