SynopsisThermo-oxidative degradation of low density polyetylene (LDPE) at a low degree of volatilization (about 4%) at 266289°C was studied. Gas chromatography-mass spectrometric analysis was used to separate and identify the products of LDPE decomposition. Altogether 44 compounds representing hydrocarbons, alcohols, aldehydes, ketones, acids, cyclic ethers, cyclic esters, and hydroxycarhoxylic acids were identified. Sixteen oxygen-containing products were quantified. Among the components identified, the fatty acids and aldehydes predominated. The most abundant.product was formic acid. The mechanism of formation of the degradation products is discussed.

SynopsisThermal oxidation of isotactic polypropylene films at 120-280OC in air was studied. Separation and identification of the volatiles formed was carried out by gas chromatography-mass spectrometry. Sixteen products were tentatively identified for the first time. Altogether, 50 compounds representing hydrocarbons, ethers, alcohols, aldehydes, ketones, and acids are reported. Oxygen deficiency is manifested in diffusion-limited products of olefines, dienes, and aromatic compounds. The relative amounts of acetaldehyde and acetone are almost temperature independent in the range of 12G28OoC. This indicates a similarity of oxidative degradation of the polymer in a broad temperature range. Addition of an antioxidant to the polymer depresses the evolution of the main volatiles by 9-10 times at 280°C. The relative amounts of the volatiles formed are, nevertheless, the same as for the polymer without an antioxidant. The mechanism of formation of the degradation products is discussed.

SynopsisThermal oxidation of isotactic polypropylene (PP) at 220 and 280°C in air was studied. Gas chromatography-mass spectrometric analysis was used to separate and identify the volatile products of PP oxidation. Twenty-three products were identified and 15 substances were quantified. The aldehydes are the principal products formed, followed by ketones, acids, and alcohols. The main organic product quantified was acetaldehyde. The volatile organic products formed constitute about 3% of the amount of water formed. The relative amounts of the most volatile products formed in the range 220-280°C are practically independent on the temperature of oxidation. The mechanism of formation on the oxidation products is discussed.

No abstract