Photo and thermal decomposition of iPP hydroperoxides

Products resulting from the photo and thermal decomposition under vacuum of a pre-oxidized isotactic polypropylene (iPP) containing a known content of hydroperoxide have been examined. In contrast to the case of polyethylene, few products were retained in the polymer matrix. Detailed analysis of the gas phase was performed by gas chromatography, Fourier transform infra-red spectroscopy and mass spectrometry. It was revealed that about 70% of the hydroperoxides were converted into gaseous products such as acetone, acetic acid and methanol. Mechanisms for their formation are suggested, and the consequences of such a phenomenon for the evaluation of ageing in PP are discussed. (C) 1997 Published by Elsevier Science Limited.