DETERIORATION OF FIBROUS MATERIALS BY ULTRAVIOLET LIGHT

This report discusses primarily the effects of ultraviolet light on the tensile properties of four polymeric materials - polyethylene terephthalate (Dacron), polybenzimidazole, a thiazole polymer, and a du Point experimental material designated as HT-1. Among these materials, exceptions were found to the al trend that degradation is more severe the shorter the wavelength of light. These exceptions are discussed in terms of an absorption of light near the surface of the material that, in effect, prevents the interior from being irradiated. Among materials studied, those that are known to contain hydrogen are more susceptible to irradiation damage in an oxygen atmosphere than in a nitrogen atmosphere or in a vacuum.