The thermal oxidation of some hydrecarbon polymers differing by their degree of branching was studied simultaneously by chemiluminescence and infrared spectrophotometry. In the case of isotactic polypropylene, measurements were made at various temperatures ranging from 140 to 180°C. The other polymers—ethylene–propylene copolymer, low and high density polyethylene—were studied only at 160°C. In all cases, the induction times of chemiluminescence coincide with those of carbonyl growth. The previously proposed mechanisms of light emission are not consistent with the kinetic data or with the structure effects on luminescence, which seems directly related with the presence of tertiary hydrogens. A hypothetical mechanism based on the β scission of tertiary alkoxyls is proposed.
Infrared spectra of 2,2′‐alkylidene, 2,2′‐thiobisphenols, and 2,2′‐biphenyldiols have been measured in the range of the OH stretching vibrations. From these measurements the possible conformers present in dilute CCl4 solutions are proposed. A correlation between the amount of the free and the intramolecularly bound hydroxyl groups in 2,2′‐bisphenols and their antioxidative activity is discussed.
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