Wear Minimization of Ultra High Molecular Weight Polyethylene by Benzophenone-assisted Photocrosslinking

Abstract

Ultra high molecular weight polyethylene (UHMWPE) containing benzophenone (BP) is photocrosslinked under continuous UV irradiation. BP addition as low as 0.77 mol% per repeating unit of UHMWPE is enough to increase the gel fraction up to 99.8 %. The crosslinks are formed through the recombination of methine radicals generated from the hydrogen abstraction of UHMWPE by the excited BP. The heat of fusion of UHMWPE reduces substantially and the peak decomposition temperature increases as much as 15.8 degrees C due to the crosslinked network, coupled with slight decrease in crystallinity. The tensile strength, modulus and toughness of the crosslinked UBMWPE film are significantly improved with increasing crosslinking density. The wear rate of the UHMWPE also remarkably decreases from 10.2 mg/million cycles to 1.9 mg/million cycles, which can minimize the wear of total hip joint anthroplasty bearings.