Points at issue and measures in accelerated deterioration test of polymers under radiation exposure

This paper classified the methods and conditions of accelerated deterioration test, and divided the methods into the acceleration method of radiochemical reaction with and without air and the single thermochemical reaction not related to radiation. A simplified model formula was set for each and analyzed. Radiochemical reactions of polymers include radical formation reaction, crosslinking reaction, and oxidation reaction. In the radiochemical reaction without air, since the crosslinking reaction is proportional to the product of dose rate and time, dose rate is increased as an acceleration method. In the radiochemical reaction with air, since the oxidation reaction is proportional to the product of dose rate and time, recommended acceleration method is based on extrapolation method, heating method, oxygen pressurization method, or model experiment method, while raising the dose rate. In the single thermochemical reaction, regardless of the presence or absence of air, a temperature raising method at temperatures based on time-temperature conversion rule is considered to be appropriate. Among them, the model experiment method utilizes the relationship that test size is proportional to the -1/2th power of dose rate. This relationship is derived from the formula consisting of Fick's law of diffusion and dose rate, and generally considered to be applicable to general events in which oxygen diffusion and oxygen consumption due to radicals compete, but empirical research is necessary in the future. (A.O.)