Effect of photosensitizers on the photodegradation of blow molding poly (vinyl chloride)

Abstract

PVC resin together with the photosensitizers (benzopenone, anthraquinone) were processed into films, in order to examine the changes of mechanical and physical properties of irradiated films both in outdoor exposure test and accelerated irradiation test and to compare the efficiency of the 2 types of photosensitizers at the same concentration. After an irradiation time of 9 months for outdoor exposure and 240 hours using a medium pressure mercury lamp, the progress of the photodegradation and the effect of the photosensitizers were studied by observing the change of molecular weight, tensile strength, elongation at rupture, Fourier Transform infrared absorption, UV absorption, and visual inspection. The details of photodegradation mechanisms for unsensitized and sensitized PVC sheets were proposed on the basis of the experimental results. The results indicated that sensitized PVC films showed a greater decrease in properties than unsensitized PVC films. At the same concentration, anthraquinone was strongly sensitized in comparison with benzophenone. As the concentration increased, the rates of degradation increased but the difference in the photodegradation was small.