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 suggested 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 Weatherometers are shown to correlate with direct-to-weather tests based on an ultraviolet radiation index.

A Systems Approach to the Service Life Prediction Problem for Coating Systems

“…For example, it has long been recognized that dominant failure mode for nominally identical specimens exposed for the same duration and at the same time often changes from one environment to another [Scott, 1983] and that the rankings of outdoor exposure results do not agree for coated specimens exposed 1) at the same site and at the same time of year, but in different years [Grinsfelder, 1967] 2) at the same site, but at different times [Stieg, 1975;Ellinger, 1977;Lindberg, 1982;Stieg, 1966;Rosendahl, 1976;Grossman, 1993;Greathouse and Wessel, 1954;Morse, 1964;Singleton et al, 1965;Grinsfelder, 1967;Rosato, 1968;Mitton et al, 1971;Gaines et al, 1977;Scott, 1977] 3) at the same site, same year, and the same time of year, but for different durations [Reinhart, 1958], and 4) at different sites, but at the same time of the same year [Stieg, 1975;Kamal, 1966;Hoffman and Saracz, 1969;Morse, 1964;Singleton et al, 1965]. In fact, no study was found claiming that outdoor exposure results are reproducible.…”

Rapid assessment of TiO2 pigment durability via the acid solubility test

“…4 This is because the exposure times are shorter during the winter months (shorter days) and the UV content of winter sunlight is between one-third and one-thirtieth that of summer sunlight. 5,6 Yearly variations can change the absolute rates of degradation by a factor of two. 7,8 Thermal variations across a single exposure rack can lead to significant variability in gloss retention and chalking results.…”

Light Stability of Dyed Fibers

“…Furthermore, the relationships of chemical changes in the structure of a polymeric material to c hanges in mechanical properties have not been fully established. For this reason it is difficult to predict quantitatively how initial chemical changes in the properties [45]. It is, therefore, understandable when an increasing number of papers are devoted to the quantitative study of the photochemical processes that occur in dyed materials [2, 3, 11-13; 32, 48-51].…”