Recovery of radiation-damaged plastic light-guide materials


Radiation damage and subsequent recovery of PMMA-based and amorphous fluoropolymer (Teflon-AF) light guides (LG) were studied using uv-visible absorption, ESR, and thermally stimulated luminescence (TSL) techniques. No appreciable decay of the γ-ray-induced 420-nm band of the PMMA-based LG was observed in air at room temperature (RT) within a week after irradiation, while it was found to be annealable by isothermal heating at temperatures varying between 40 and 100°C or by heating in a microwave oven. Emission of light was also observed during the isothermal annealing of the LG. X- and γ-irradiated Teflon-AF showed a broad absorption band spreading from 200 to 350 nm with no observable degradation of its optical clarity. In conjunction with ESR measurements the uv absorption was attributed to the radiation-induced peroxy radicals formed at the polytetrafluoroethylene (PTFE) site of the main copolymer chain. The recovery of the Teflon-AF was obtained in a few days by post-irradiation storage in air at room temperature. However, a rapid recovery could be obtained by heating at higher temperatures (RT≤T≤95°C) as suggested by TSL result. © 1993.

Publication Title

Radiation Physics and Chemistry