Measurements of Long-Lived Radicals in Ultra-High Molecular Weight Polyethylene

ORAL

Abstract

Ultra-high molecular weight polyethylene (UHMWPE), a polymer of choice for orthopedic applications, was gamma-irradiated in air, nitrogen or vacuum at 22\r{ }C and subsequently aged for 10 years in its own environment at 22\r{ }C, 37\r{ }C, or 75\r{ }C. Free radical measurements were conducted using an X-band electron spin resonance (ESR) spectrometer. The samples aged in sealed environments (nitrogen or vacuum) show the presence of the primary radicals (alkyl, allyl, polyenyl), although the concentration of these radicals in each case is very low to insignificant. However, there is no detectable transformation from the primary to oxygen-induced radicals (OIR). The ESR spectra of the open samples, on the other hand, show the presence of only OIR. Similar OIRs are detected in retrieved hip- and knee-joint parts 18 years after retrieval. These joints were gamma-irradiated in air prior to implantation, and were retrieved 6-8 years after use. OIRs are also detected in vitamin-E-doped UHMWPE after gamma irradiation in nitrogen and subsequent exposure to air for one year.

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Authors

  • Muhammad Jahan

    Department of Physics, The University of Memphis, TN 38152

  • Rebecca Scott

    UCSB, LBNL, NCSU, University of North Carolina at Chapel Hill, Wright State University, Department of Physics, The University of Memphis, TN 38152, North Carolina State University, Department of Chemical and Biomolecular Engineering, Raleigh, NC, Clemson University, Fisk University, University of North Dakota (Grand Forks), Southern Illinois University, The University of Tennessee Space Institute, SC Governor's School for Science and Mathematics, Francis Marion University, University of North Alabama, Lousiana State University, Department of Physics, Dhaka University, Dhaka, Bangladesh, Head of Government Relations, American Physical Society, Vanderbilt University, Mississippi State University, Emory University, College of William and Mary, University of Tennessee Space Institute, Morehead State University

  • Rebecca Scott

    UCSB, LBNL, NCSU, University of North Carolina at Chapel Hill, Wright State University, Department of Physics, The University of Memphis, TN 38152, North Carolina State University, Department of Chemical and Biomolecular Engineering, Raleigh, NC, Clemson University, Fisk University, University of North Dakota (Grand Forks), Southern Illinois University, The University of Tennessee Space Institute, SC Governor's School for Science and Mathematics, Francis Marion University, University of North Alabama, Lousiana State University, Department of Physics, Dhaka University, Dhaka, Bangladesh, Head of Government Relations, American Physical Society, Vanderbilt University, Mississippi State University, Emory University, College of William and Mary, University of Tennessee Space Institute, Morehead State University

  • Benjamin Walters

    Department of Physics, The University of Memphis, TN 38152, Department of Physics, The University of Memphis, TN 38152, Mentor: M. Shah Jahan