EFFECT OF X-IRRADIATION ON OPTICAL-PROPERTIES OF TEFLON-AF

Radiation effects in optical-grade amorphous fluoropolymer, Teflon-AF, is investigated by UV-visible absorption and electron spin resonance (ESR) measurements. When irradiated with low-energy (40 kVp) X-rays at room temperature in air, Teflon-AF is found to develop a broad, struc tureless UV-absorption band in the wavelength interval 200-350 nm. Whi le the UV absorption increases as a function of X-ray dose, with relat ive rates of approx 2 x 10(-5) Gy-1 (1 x 10(-5) Gy-1) in Teflon-AF 160 0 (Teflon-AF 2400), its optical transparency for a given dose of 67.5 kGy, however, remains unaffected. Additional measurements conducted us ing electron spin resonance (ESR) technique reveal that the observed U V absorption is caused by the X-ray induced peroxy radical (POO.). The results also suggest that the inclusion of dioxole monomer in the PTF E chain not only improves the optical clarity of Teflon-AF, as reporte d, but also increases its radiation tolerance. During a post-irradiati on storage in air at RT for about 30 days the peroxy radical is observ ed to decay, with a concomitant decrease in UV absorption. A tentative model is proposed to explain the radiation damage and recovery mechan isms.