Abstract
Previous studies have shown that increased cross-link density, reduced free radicals, and increased antioxidant grafting resulting from electron-beam irradiation at elevated temperatures improved the wear performance and the oxidative stability of vitamin E blended UHMWPE. The current study explores the impact of elevated irradiation temperature on vitamin E blended UHMWPE using X-ray. We hypothesize that the effects of temperature would be similar to those observed after electron-beam irradiation due to the relatively high dose rate of X-rays. Two X-ray doses of 80 and 100 kGy and two irradiation temperatures, that is, room temperature and 100°C were considered. The reference was Vitelene®, a vitamin E stabilized polyethylene cross-linked with 80 kGy by e-beam at 100°C. Oxidation index and oxidation induction time, as well as cross-link density, gel fraction, and trans-vinylene index, were determined, as the oxidative and network properties are decisive for the long-term implant performance. Gel fraction and oxidation induction time were significantly improved subsequently to warm irradiation in comparison with the material irradiated at room temperature. In conclusion, X-ray irradiation at elevated temperatures resulted in an increase of cross-linking and oxidative resistance of vitamin E stabilized polyethylene comparable to those of e-beam irradiated UHMWPE.
Highlights
It is clinically established that the creation of a threedimensional polymer chain network by means of cross-linking increases the wear resistance of polyethylene orthopedic implants considerably [1, 2]
E Oxidation Index (OI) was measured with a Fourier Transform Infrared (FTIR) spectrometer by dividing the area of the carbonyl absorptions (>C=O) centered near 1720 cm− 1 by the area of the normalization peak (C-H absorptions) centered near 1370 cm− 1 according to ASTM F2102-17
Oxidation Index (Figure 1). e FTIR spectra revealed low oxidation indices (
Summary
It is clinically established that the creation of a threedimensional polymer chain network by means of cross-linking increases the wear resistance of polyethylene orthopedic implants considerably [1, 2]. During irradiation at high to very high radiation doses (50–10,000 kGy), the polyethylene undergoes two types of modification: cross-linking corresponding to the creation of a spatial network through the connection of macromolecular chains to each other [7, 8] and detrimental changes: scissions [2]. Dose rate, absorbed dose, processing conditions “prior to, during, and after” irradiation, as well as temperature, environment (air, inert, vacuum), time, and the presence of additives in the polymer influence the recombination ratio cross-linking/chain scission [5, 7, 10,11,12]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
