The Action of Light on Cellulose Acetate Rayon and Nylon dyed with Duranol, Dispersol, S. R. A., and Solacet Dyes

Abstract

A study has been made of the photochemical degradation of cellulose acetate rayon and nylon yarns dyed with dispersed and soluble acetate dyes. Measurements were made of the losses in tensile strength of the yarns after exposure to sunlight in atmospheres of dry and moisture–saturated air. Many of the acetate dyes increase the degradation of nylon to a considerable extent, but have a very much smaller effect on the degradation of cellulose acetate rayon. In several cases the loss in strength of the dyed cellulose acetate is less than that of the undyed yarn exposed under identical conditions. The photochemical degradation of both textile materials, whether dyed or undyed, is found to be due to oxidation processes. The acetate dyes that are particularly effective in increasing the degradation of nylon are capable of increasing the degradation of undyed cotton that is simultaneously irradiated in their vicinity. In these cases the dye may be present on nylon, on cellulose acetate rayon, or as a dye film on glass. A much smaller effect is observed when undyed cellulose acetate or nylon is irradiated in proximity to these acetate dyes. Cellulose acetate rayon delustred with titanium dioxide also increases the degradation of undyed cotton irradiated in its vicinity. The small influence of acetate dyes on the photochemical degradation of cellulose acetate rayon and their larger effect on that of nylon are interpreted in terms of a theory involving oxidation of the textile material by activated oxygen and hydrogen peroxide. The relation between the fading of the dyed yarns and the degradation of the textile substrate is discussed, and it is pointed out that many of the dyes that increase the photochemical degradation of nylon are least fast to light on this fibre.