Aging and Stabilization of Polymers by Professor M. B. Neiman (auth.), Professor M. B. Neiman

By Professor M. B. Neiman (auth.), Professor M. B. Neiman (eds.)

The desire for a large improvement of the construction of polymer ma­ terials has develop into glaring. these kinds of fabrics are topic to varied sorts of getting older (destruction); for that reason, stabilizers which enable the stor­ age, reprocessing, and use of polymer fabrics with none appreci­ capable swap of their houses has to be brought into them. lately, this challenge of stabilizing polymers has attracted the eye of many scientists and technologists, either within the USSR and in a foreign country. The clinical foundation of the overseas stories could be present in a couple of theo­ retical premises, yet mainly the idea of chain reactions with un­ branched chains. within the Soviet Union, the innovations of Academician N. N. Semenov on chain reactions with degenerate branches became the place to begin of theoretical reports of the stabilization and destruction of polymers. Soviet scientists have built a thought of serious concentrations of antioxidants and feature proven that the approaches of stabilization have a truly complicated chemical personality. the character of the polymers them­ selves tremendously impacts those techniques and for this reason, diverse stabil­ izers are required for polymers of other buildings. moreover, it's been proven that the antioxidants used up to now can't in simple terms reason chain termination, yet may also begin oxidation and provides upward thrust to de­ generate branches.

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40. EPR spectra of radicals [formula (xI)]. a) In concentrated solutions; b) in dilute solutions. Since the radicals RO· and R02 ' which are carriers of the kinetic oxidation chains, are formed in the catalytic decomposition of hydroperoxides, the appearance of phenoxyl radicals in such model systems of oxidation [14] gives evidence of stripping of the hydroxyl hydrogen of phenol by the active radicals, as the primary elementary event of inhibition, the reactivity of the OH-bond in the phenol being one of the most important characteristics of the effectiveness of the phenol as an inhibitor.

Absorption of oxygen in the oxidation of pure polypropylene (1) and stabiliz ed by di -tettbutyl-p-cresyl disulfide and pyrocatechol phosphite naphthol (2); (3) shows the drop in viscosity in the latter case. An important fact indicating the initiation of a reaction, connected to consumption of the antioxidant, is the drop in the molecular weight of the polymer during the induction period. In this case the number of resorbed bonds is proportional to the consumption of the antioxidant [67]. This phenomenon is especially evident for the example of the thermooxidative destruction of polypropylene with an admixture of di-tert-butyl-p-cresyl disulfide, investigated by A.

Privalova, Intern. J. Appl. Radiation and Isotopes 7:111, 1959. 38. Z. K. Maizus, 1. P. Skibida, N. M. Emanuel', and V. N. Yakovleva, Kinetika i Kataliz 1:55, 1960. Mechanism of Thermooxidative Destruction and Stabilization 39 39. L. K. Obukhova and N. M. EmanwW, Izvest. Akad. Nauk SSSR, Otdel. Khim. Nauk, p. 1544, 1960. 40. E. T. Denisov, Doklady Akad NaukSSSR 130:1055, 1960. 41. C. H. Bamford and M. J. S. Dewar, Proc. Roy. Soc. A198:252, 1949. 42. L. T. Koritskii, Yu. N. Molin, B. N. Shamshev, N.

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