S021015 電子線照射dl-α-Tocopherol混合超高分子量ポリエチレン内におけるラジカルの同定([S02101]人工臓器におけるバイオメカニクス(1))

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In this study, Vitamin E radicals in electron-beam-irradiated UHMWPE were measured and identified using Electron Spin Resonance (ESR), and the effects of annealing on radical stabilization and crosslink density were examined. Both virgin UHMWPE and Vitamin E added (0.3% w/w) resin powder was used to produce bulk specimens via vacuum direct compression molding at 220-C under 25 MPa for 30 min. Cylindrical pins (3.5 mm diameter, 40 mm length) were then machined and placed in vacuum packaging. The pins were irradiated at 300 kGy, with half of each test group annealed at 80-C for 24 hours. Detection of Vitamin E radicals was performed by comparing the characteristic symmetrical spectrum of oxidized Vitamin E to the spectra observed for the pins using both g-value and linewidth as references, where the electron-beam-irradiated Vitamin E-blended specimens showed the same characteristic symmetrical spectrum as that of oxidized Vitamin E. The annealing treatments increased gel fraction and decreased the total number of primary free-radicals. Thus, the annealing treatment at 80-C for 24 hours was effective in stabilizing Vitamin E radicals and increasing gel fraction.
2011-09-11