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Poly(propy1ene) has been oxidized at temperatures between 240 and 289 "C. The products were GC separated and on-line identified by an interfaced GC peak identification system. The major products are CO,, H,O, acetaldehyde, acetone, butanal, formaldehyde, methanol and other ketones and aldehydes. Most of the products can be accounted for by well-known reactions of alkoxyl and peroxyl radicals; the major products are derived from the secondary alkoxy and peroxy species. Oxygen starvation is manifested in diffusion limited products of olefins and dienes, and the increase of CO, and H 2 0 formation in pure oxygen atmosphere. The first order rate constant at 240°C is 2,4.10-3 s-' with an overall activation energy of ca. 16 kcal.mo1-' (67 kJ.mol-'). If one assumes the oxidative pyrolysis to share the same reaction pathways as autoxidation at lower temperatures, then the observed rate constants and activation energy may be calculated from kinetic parameters measured earlier for autoxidation of poly(propy1ene) from 71 to 140°C. Good agreement was obtained implying a similarity of oxidative degradation of the polymers spanning a large temperature range.

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Amorphous and semi-crystalline polypropylene samples were pyrolyzed in He from 388°-438°C and in air from 240°-289°C. A novel interfaced pyrolysis gas chromato graphic peak identification system was used to analyze the products on-the-fly; the chemical structures of the produ were determined also by mass spectrometry. Pyrolysis of polypropylene in He has activation energies of 5-1-56 kcal mol -1 and a first-order rate constant of 10 -3 sec -1 at 414°C. The olefinic products observed can be rationalized by a mechanism involving intramolecular chain transfer processes of primary and secondary alkyl radicals, the latter being of greater importance. Oxidative pyrolysis of polypropylene has an activation energy of about 16 kcal mol -1 ; the first -order rate constant is about 5 X 10 -3 sec -1 at 264°C. The main products aside from CO 2 , H 2 O, acetaldehyde, and hydrocarbons are ketones. A simple mechanistic scheme ha been proposed involving C-C scissions of tertiary alkoxy radical accompanied by Η transfer, which can account for most of the observed products. Similar processes for sec ondary alkoxy radicals seem to lead mainly to formaldehyde Differences in pyrolysis product distributions reported here and by other workers may be attributed to the rapid re moval of the products by the carrier gas in our experiments sphere has been surprisingly little fundamental work reported on the chemistry of the process involved in the burning of polymers and its inhibition, despite the great technological and socio-economical impor tance of the subject. In our laboratories we have undertaken a funda-0-8412-0381-4/78/33-169-175$05.75/l