期刊
JOURNAL OF APPLIED POLYMER SCIENCE
卷 120, 期 4, 页码 2282-2291出版社
WILEY
DOI: 10.1002/app.33454
关键词
polyethylene (UHMWPE); antioxidants (vitamin E/alpha-tocopherol); viscoelastic properties (DMTA); molecular mechanics; microstructure
资金
- Comision Interministerial de Ciencia y Tecnologia (CICYT), Spain
- Ministerio de Ciencia e Innovacion [MAT 2006-12603-C02-01, Consolider-Ingenio CDS2008-0023]
Vitamin E (or alpha-tocopherol) is an alternative via to thermal treatments to achieve oxidative stability of gamma or electron beam irradiated ultra-high molecular weight polyethylenes (UHMWPE) used in total joint replacements. Our aim was to study the effects of vitamin E on the molecular dynamics and microstructural properties of UHMWPE. We hypothesized that the antioxidant would plasticize UHMWPE. Vitamin E was incorporated into UHMWPE at different concentrations by diffusion and blending and detected by ultraviolet and infrared spectroscopies from 500 ppm and 4000 ppm, respectively. Dynamic mechanical thermal analysis was used to characterize the influence of this antioxidant in the relaxations of the raw material. Differential scanning calorimetry and transmission electron microscopy served to characterize thermal and microstructure properties, respectively. Vitamin E concentrations above 3% by weight significantly reduced the degree of crystallinity and increased the melting transition temperature of raw UHMWPE. The presence of increasing concentrations of alpha-tocopherol introduced and/or strengthened the beta relaxation, which was also shifted toward gradually lower temperatures and had rising activation energies up to 188 kJ/mol. In addition, the gamma relaxation remained unaltered on vitamin E addition. Therefore, no plasticizing effects of vitamin E on the molecular dynamics of UHMWPE could be confirmed from mechanical spectroscopy data. However, the alpha relaxation was modified in intensity and location due to the changes in the degree of crystallinity introduced by the incorporation of vitamin E. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 2282-2291, 2011
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