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Modeling the oxidative degradation of ultra-high-molecular-weight polyethylene

Authors

  • Vinay Medhekar,

    1. Department of Chemical Engineering, Worcester Polytechnic Institute, 100 Institute Road, Worcester, Massachusetts 01609
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  • Robert W. Thompson,

    Corresponding author
    1. Department of Chemical Engineering, Worcester Polytechnic Institute, 100 Institute Road, Worcester, Massachusetts 01609
    • Department of Chemical Engineering, Worcester Polytechnic Institute, 100 Institute Road, Worcester, Massachusetts 01609
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  • Aiguo Wang,

    1. Stryker Howmedica Osteonics, 300 Commerce Street, Mahwah, New Jersey 07430
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  • W. Grant McGimpsey

    1. Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Road, Worcester, Massachusetts 01609
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Abstract

Understanding the sequence of reactions that occur in ultra-high-molecular-weight polyethylene (UHMWPE) following 60Co γ irradiation has been the focus of numerous experimental studies. In the study reported here, we have incorporated recent experimental findings into a mathematical model for UHMWPE oxidation. Simulation results for shelf aging and accelerated aging are presented. It is shown that very reasonable simulations of shelf-aging and accelerated-aging data can be obtained. It is also shown that simulations of shelf aging in reduced oxygen environments predict that the subsurface peaks of ketones will be shifted to the exterior surface. In vivo aging can be simulated if we assume that the oxygen level in the synovial fluid is about one-eighth that of atmospheric levels. Some reduced irradiation doses are predicted to significantly reduce the ketone formation for shelf-aging periods of up to 10 years. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 814–826, 2003

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