Factors Influencing the Evaluation of Actinic Degradation of Fibers

Abstract

A procedure giving reproducible data has been devised for the preparation, exposure, and testing of yarns in fabric form for resistance to actinic degradation. Effects of season, test location, and sample presentation have been considered. It has been shown that ultraviolet radiation is a more useful index of exposure than total incident radiation. It is suggested that the cyclical seasonal variation of ozone in the upper atmosphere is responsible for the observed seasonal variations in ultraviolet radiation. It is also sug gested that the difference in degradation rate noted between South Florida and Arizona are primarily a function of the observed large difference in relative humidity between those sites. Preliminary accelerated tests in Xenon and Sunshine Carbon Arc Weather ometers are shown to correlate with direct-to-weather tests based on an ultraviolet radiation index.