MASS-SPECTROSCOPY ANALYSIS OF VOLATILE PHOTOPRODUCTS IN PHOTOOXIDATION OF POLYPROPYLENE

Depending on their structure, photooxidising polymers can produce significant concentrations of low molecular weight products formed by multiple fragmentations of the main or branched chains. These photoproducts can migrate out of the polymer matrix and consequently are not taken into account by analysis only of the solid sample. In some cases this may complicate the elucidation of the photooxidation mechanisms of the corresponding polymers. This is why an analysis of the volatile products is sometimes required. We describe experiments based on the analysis by mass spectroscopy of the gas phase obtained by photooxidation of polypropylene. Because the photooxidation of this polymer is fairly well characterized, it was a good candidate to calibrate the apparatus and the analytical mode. One of the main advantages of using mass spectroscopy to analyse the gas phase is that this method requires virtually no separation of the different constituents before analysis. However, we show that by using the different volatilities of the products formed in the polymer and in the gas phase, separation of the constituents can be obtained, which facilitates further analysis by mass spectroscopy.