Electronic Theses and Dissertations

Identifier

457

Date

2011

Document Type

Thesis

Degree Name

Master of Science

Major

Physics

Concentration

Materials Science

Committee Member

shah m. jahan

Committee Member

Sanjay Mishra

Committee Member

yu Lam

Abstract

oxidation degradation of ultra-high molecular weight polyethylene(UHMWPE) due to gamma-irradation has been a major concern in total hip and knee joint arthroplasty. Irradiation( gamma or electron beam) is used for sterilization or crosslinking of UHMWPE.However, in the past decade the use of the biocompatible stabilizer alpha-tocopherol (vitamin-E) has been introduced to reduce or eliminate radiation-induced oxidation of UHMWPE. While existing literature contains information about consolidated UHMWPE, we have studied UHMWPEpowder, because it more readily and uniformly reacts with oxygen or air, in an attempt to gain more knowledge about the antioxidative effect of vitamin-E on UHMWPE. In conjunction with electron spin resonance (ESR) and Fourier transform infrared (FTIR) spectroscopy, thermally stimulated luminescence(TSL) techniques was employed in this study. TSL of gamma irradiated UHMWPE with or without vitamin E shows multiple glow peaks orignating from the species resulting from reaction of free radicals with oxygen following irradiation. Major peaks near 140, 210, and 240 oC are observed only in UHMWPE, whereas an additional strong peak near 180 oC is observed in vitamin-E containing UHMWPE.The glow peaks in UHMWPE without vitamin-E are weak when irradiation is performed in nitrogen; they subsequently start to grow as a function of aging in air, suggesting that these peaks( or luminescence at these temperatures) are produced by species formed after the reaction of oxygen with the free radicals. However, in the presence of vitamin E, these peaks are found to decrease in intensity as a function of aging. The antioxidation effect of of vitamin E is found to be more pronounced in the TSL data than in those obtained fromESR or FTIR measurements.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to the local University of Memphis Electronic Theses & dissertation (ETD) Repository.

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