Studying the destruction of various fluoropolymers caused by y-irradiation and MeV protons

Abstract

While fluoropolymers are normally used as anti-adherent coating, they are intensely investigated for potential use in various radiation dosimeter applications as well as space technology. In order to understand the discrepancy between high chemical and thermal stability and low radiation stability of various fluoropolymers, we are bombarding them with 1 MeV protons to fluences up to 2*10^15 protons/cm^2 as well as subjected some of them to у-irradiation by dose of 10 kGy. During bombardment we are monitoring the emission of chemical species with a residual gas analyzer (RGA). у - irradiated samples were tested by Radio thermoluminescence (RTL) method. The results we present here are a good indicator that material damage happens much earlier than 2*10^15 protons/cm^2 and that further work should be addressed at much smaller exposures. RTL also can be used at small doses of Irradiation (10-30 kGy). The thermomechanical curve (TMC) of radiation-free polyvlnyledenefluoride (PVDF) is characteristic for topologlcally di-block amorphous polymer of quasi-crossing structure. In the temperature range of from 173 К up to 228 К polymer is vitrified. The vitrification temperature of PVDF is 228 K. All molecular-relaxation and quantitative characteristics of PVDF were determined before and after its Irradiation by protons. Protons caused significant changes in PVDF. From di-block amorphous it transformed in to amorphous-crystalline structure. An appreciable influence of dose at proton irradiation of polymer was revealed both on topological level and on molecular-relaxation one.