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Enhanced wear resistance of orthopaedic bearing due to the cross‐linking of poly(MPC) graft chains induced by gamma‐ray irradiation
Author(s) -
Kyomoto Masayuki,
Moro Toru,
Miyaji Fumiaki,
Konno Tomohiro,
Hashimoto Masami,
Kawaguchi Hiroshi,
Takatori Yoshio,
Nakamura Kozo,
Ishihara Kazuhiko
Publication year - 2008
Publication title -
journal of biomedical materials research part b: applied biomaterials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.665
H-Index - 108
eISSN - 1552-4981
pISSN - 1552-4973
DOI - 10.1002/jbm.b.30874
Subject(s) - materials science , irradiation , composite material , polyethylene , substrate (aquarium) , gamma irradiation , cross linked polyethylene , layer (electronics) , bearing (navigation) , polymer , oceanography , physics , nuclear physics , geology , cartography , geography
We assumed that the extra energy supplied by gamma‐ray irradiation produced cross‐links in 2‐methacryloyloxyethyl phosphorylcholine (MPC) polymer grafted cross‐linked polyethylene (CLPE‐ g ‐MPC) and investigated its effects on the tribological properties of CLPE‐ g ‐MPC. In this study, we found that the gamma‐ray irradiation produced cross‐links in three kinds of regions of CLPE‐ g ‐MPC: poly(MPC) layer, CLPE‐MPC interface, and CLPE substrate. The dynamic coefficient of friction of CLPE‐ g ‐MPC slightly increased with increasing irradiation doses. After the simulator test, both the nonsterilized and gamma‐ray sterilized CLPE‐ g ‐MPC cups exhibited lower wear than the untreated CLPE ones. In particular, the gamma‐ray sterilized CLPE‐ g ‐MPC cups showed extremely low and stable wear. As for the nonsterilized CLPE‐ g ‐MPC cups, the weight change varied with each cup. When the CLPE surface is modified by poly(MPC) grafting, the MPC graft polymer leads to a significant reduction in the sliding friction between the surfaces that are grafted because water thin films formed can behave as extremely efficient lubricants. Such a cross‐link of poly(MPC) slightly increases the friction of CLPE by gamma‐ray irradiation but provides a stable wear resistant layer on the friction surface. The cross‐links formed by gamma‐ray irradiation would give further longevity to the CLPE‐ g ‐MPC cups. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008