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Title: Effect of cross-linking ultrahigh molecular weight polyethylene: Surface molecular orientation and wear characteristics

Abstract

Molecular orientation at the surface layer of cross-linked ultrahigh molecular weight polyethylene (UHMWPE) has been examined. Molecular orientation has been shown to affect the wear resistance and surface mechanical properties of UHMWPE under biomechanical loading conditions. This study utilizes a nondestructive synchrotron based soft x-ray technique; near edge x-ray absorption fine structure at the carbon K-edge to examine the degree of surface molecular orientation of UHMWPE subjected to various cross-linking/sterilization techniques as a function of stress and wear. UHMWPE samples prepared under gamma irradiation, ethylene-oxide (EtO) treatment, and electron beam irradiation were worn in a wear tester systematically. Results suggest that the cross-linking resists surface orientation when the samples were under tensile and biomechanical stresses. The molecular orientation in the C-C chains in the polymer showed a monotonic decrease with an increase in gamma irradiation dosage levels. EtO sterilized samples showed more C-C chain orientation than the electron beam irradiated samples, but lower than the 30 kGy gamma irradiated samples. Ordered C-C chains in UHMWPE samples have been associated with more crystallinity or large strain plastic deformation of the polymer. Higher levels of gamma irradiation appear to induce cross-linking of C-C chains and render a polymer with more amorphous phasemore » which resists orientation after wear and imparts wear resistance to the polymer.« less

Authors:
; ;  [1]
  1. Ceramics Division, Material Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)
Publication Date:
OSTI Identifier:
20979508
Resource Type:
Journal Article
Journal Name:
Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films
Additional Journal Information:
Journal Volume: 25; Journal Issue: 4; Other Information: DOI: 10.1116/1.2723767; (c) 2007 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1553-1813
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ABSORPTION SPECTROSCOPY; CARBON; CROSS-LINKING; ELECTRON BEAMS; ETHYLENE; FINE STRUCTURE; GAMMA RADIATION; IRRADIATION; LAYERS; MOLECULAR WEIGHT; OXIDES; PLASTICITY; POLYETHYLENES; SOFT X RADIATION; SURFACES; WEAR; WEAR RESISTANCE; X-RAY SPECTROSCOPY

Citation Formats

Sambasivan, Sharadha, Fischer, Daniel A, and Hsu, Stephen M. Effect of cross-linking ultrahigh molecular weight polyethylene: Surface molecular orientation and wear characteristics. United States: N. p., 2007. Web. doi:10.1116/1.2723767.
Sambasivan, Sharadha, Fischer, Daniel A, & Hsu, Stephen M. Effect of cross-linking ultrahigh molecular weight polyethylene: Surface molecular orientation and wear characteristics. United States. doi:10.1116/1.2723767.
Sambasivan, Sharadha, Fischer, Daniel A, and Hsu, Stephen M. Sun . "Effect of cross-linking ultrahigh molecular weight polyethylene: Surface molecular orientation and wear characteristics". United States. doi:10.1116/1.2723767.
@article{osti_20979508,
title = {Effect of cross-linking ultrahigh molecular weight polyethylene: Surface molecular orientation and wear characteristics},
author = {Sambasivan, Sharadha and Fischer, Daniel A and Hsu, Stephen M},
abstractNote = {Molecular orientation at the surface layer of cross-linked ultrahigh molecular weight polyethylene (UHMWPE) has been examined. Molecular orientation has been shown to affect the wear resistance and surface mechanical properties of UHMWPE under biomechanical loading conditions. This study utilizes a nondestructive synchrotron based soft x-ray technique; near edge x-ray absorption fine structure at the carbon K-edge to examine the degree of surface molecular orientation of UHMWPE subjected to various cross-linking/sterilization techniques as a function of stress and wear. UHMWPE samples prepared under gamma irradiation, ethylene-oxide (EtO) treatment, and electron beam irradiation were worn in a wear tester systematically. Results suggest that the cross-linking resists surface orientation when the samples were under tensile and biomechanical stresses. The molecular orientation in the C-C chains in the polymer showed a monotonic decrease with an increase in gamma irradiation dosage levels. EtO sterilized samples showed more C-C chain orientation than the electron beam irradiated samples, but lower than the 30 kGy gamma irradiated samples. Ordered C-C chains in UHMWPE samples have been associated with more crystallinity or large strain plastic deformation of the polymer. Higher levels of gamma irradiation appear to induce cross-linking of C-C chains and render a polymer with more amorphous phase which resists orientation after wear and imparts wear resistance to the polymer.},
doi = {10.1116/1.2723767},
journal = {Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films},
issn = {1553-1813},
number = 4,
volume = 25,
place = {United States},
year = {2007},
month = {7}
}