THE DEGRADATION OF POLYMERS BY ULTRAVIOLET IRRADIATION PART 1- WHEN SUBJECTED TO RADIATION OF THE “NEAR” ULTRAVIOLET REGION IN AIR

摘要

One phase of a research program to develop suitable coatings for space vehicles is concerned with studying the effects of ultraviolet radiation on typical polymeric coatings in air. These coatings may be used to control the absorption and emission of radiant energy by the underlying bodies, and to be effective the coatings must be physically and chemically stable to the high-altitude environments in which they should serve.nThe initial study under this general program required irradiating a number of typical polymeric coatings with a near-ultraviolet source at ambient conditions for about 300 hours. Infrared absorption data were collected on the film samples before, during, and after this expo¬sure to determine the degradation brought about by the radiation. It was observed that the relative stability of the polymeric materials which were irradiated roughly parallels their relative order of stability to gamma radiation. The infrared data indicate the relative stability, in decreasing order, to be as follows: polystyrene, melamine formalde¬hyde, urea formaldehyde, styrenated alkyd, soya oil alkyd, silicones, and polyvinyl chloride.