STP1445: The Effect of Reduced Fracture Toughness on Pitting and Delamination Type Wear of Elevated Cross-Linked Polyethylene

    Maher, SA
    Assistant Scientist, Research Engineer, and Laboratory Director, Laboratory for Biomedical Mechanics and Materials, Hospital for Special Surgery, New York, NY

    Furman, BD
    Assistant Scientist, Research Engineer, and Laboratory Director, Laboratory for Biomedical Mechanics and Materials, Hospital for Special Surgery, New York, NY

    Wright, TM
    Assistant Scientist, Research Engineer, and Laboratory Director, Laboratory for Biomedical Mechanics and Materials, Hospital for Special Surgery, New York, NY

    Pages: 14    Published: Jan 2004


    Abstract

    We hypothesized that the reduced fracture toughness associated with elevated cross-linking of ultra high molecular weight polyethylene would lead to an increase in pitting and delamination in specimens tested in a knee wear apparatus. Two blocks of compression molded polyethylene were electron beam irradiated, one block at 120 kGy, the other at 65 kGy; a third block was not irradiated to serve as a control. The 120 and 65 kGy blocks were post-irradiation heat treated. Wear, J-integral and tensile test specimens were machined from the blocks, and all specimens were sterilized, aged and tested. 65 kGy and 120 kGy irradiated material had significantly lower fracture toughness compared to the control material. Despite the reduced fracture toughness, no evidence of pitting, delamination, or subsurface damage occurred in the corresponding wear specimens after 2 million cycles. In contrast, half of the control specimens exhibited extensive pitting. Our hypothesis was rejected: reduced fracture toughness associated with the elevated cross-linked polyethylene groups was not associated with an increase in pitting and delamination type wear.

    Keywords:

    Polyethylene, fracture toughness, wear, cross-linking


    Paper ID: STP11927S

    Committee/Subcommittee: F04.48

    DOI: 10.1520/STP11927S


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