Abstract: The influence of ferric chloride (FeCl₃) on photooxidative degradation of polypropylene (PP) has been studied by IR and UV spectrometric methods. Experimental results showed that FeCl₃ markedly accelerates photooxidation of PP, but the accelerating effect does not depend linearly on the contents of FeCl₃ in PP and there exists a maximum accelerating effect at a certain FeCl₃ content (Under our experimental conditions FeCl₃ shows the maximum accelerating effect when its content is 0.5%). It was also shown that the action of FeCl₃ possibly involves several mechanisms such as initiation of photooxidation of PP by free radicals produced in photolysis of FeCl₃, catalytic decomposition of hydroperoxide by FeCl₃, and light screening effect. On the basis of possible mechanisms of FeCl₃ action an explanation for the phenomenon of maximum accelerating effect of FeCl₃ was given.

Key words: ferric chloride, polypropylene, photooxidative degradation