Ultra-high molecular weight polyethylene (UHMWPE) was irradiated with accelerated electrons (1 MeV in air) using high dose rates (> 25 kGy/min) and thin specimens (thickness 1 mm). Parts of the specimens were remelted (200 degrees C for 10 min; 150 degrees C for 0, 2, 10, 30, 60 min). All specimens were stored in nitrogen in the dark at 5 degrees C. Supermolecular structure, extent of crosslinking, oxidative degradation, and macroradical content were studied by a number of methods (SAXS, WAXS, SEM, DSC, FTIR, ESR, TGA, solubility experiments, image analysis). The results obtained with irradiated samples were compared with those obtained with irradiated and remelted samples. It was confirmed that crosslinking predominates over chain scission at very high dose rates, even if the irradiation is performed in air. Discrepancies concerning supermolecular structure changes in UHMWPE after irradiation and thermal treatment, found in various studies in the literature, are discussed. A simple model, which describes and explains all supermolecular structure changes, is introduced. An effective way of eliminating residual macroradicals in UHMWPE is proposed.

Institute of Macromolecular Chemistry Academy of Sciences of the Czech Republic Heyrovsky Sq 2 16206 Prague Czech Republic

References provided by Crossref.org

Impact of Acid Hydrolysis on Morphology, Rheology, Mechanical Properties, and Processing of Thermoplastic Starch

The Impacts of the Sterilization Method and the Electrospinning Conditions of Nanofibrous Biodegradable Layers on Their Degradation and Hemocompatibility Behavior

European Database of Explanted UHMWPE Liners from Total Joint Replacements: Correlations among Polymer Modifications, Structure, Oxidation, Mechanical Properties and Lifetime In Vivo

Morphological Transformation in Polymer Composite Materials Filled with Carbon Nanoparticles: Part 1-SEM and XRD Investigations

Quantification of structural changes of UHMWPE components in total joint replacements