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- Title
Defect initiation at subsurface grain boundary as a precursor of delamination in ultrahigh molecular weight polyethylene.
- Authors
Nobuyuki Shibata; Naohide Tomita; Naoki Onmori; Koji Kato; Ken Ikeuchi
- Abstract
In order to examine the initiation mechanism of delamination in ultrahigh molecular weight polyethylene (UHMWPE) knee components, a bi-directional sliding fatigue test was performed for three types of UHMWPE specimens: nonirradiated, gamma-irradiated (25 kGy) and gamma-irradiated (25 kGy) with 0.1% vitamin E added. Sliding surfaces of post-tested UHMWPE specimens were observed using an optical microscope and a scanning electron microscope. Also, surface roughness was measured at the sliding surfaces of UHMWPE specimens. Delamination was observed only in gamma-irradiated specimens. A networked structure of surface asperity that resembled grain boundary was observed prior to delamination in gamma-irradiated specimens. Surface roughness in the gamma-irradiated specimens, higher than in any other specimen, showed a rapid increase prior to delamination. Detailed observation using an optical microscope and a scanning electron microscope showed microscopic crack initiation along subsurface grain boundaries in gamma-irradiated specimens. These results suggest that subsurface crack initiation is a precursor of delamination and is accelerated by oxidative degradation due to gamma irradiation. Of the three types of specimens, UHMWPE with vitamin E added showed the lowest surface roughness values at all measuring points. The addition of vitamin E is effective in improving wear resistance and fatigue performance of UHMWPE. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 276284, 2003
- Subjects
DELAMINATION of composite materials; MOLECULAR weights; POLYETHYLENE; KNEE
- Publication
Journal of Biomedical Materials Research, Part A, 2003, Vol 67, Issue 1, p276
- ISSN
1549-3296
- Publication type
Article
- DOI
10.1002/jbm.a.10133