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

The desire for a extensive improvement of the creation of polymer ma­ terials has turn into glaring. a majority of these fabrics are topic to numerous sorts of getting older (destruction); consequently, stabilizers which allow the stor­ age, reprocessing, and use of polymer fabrics with none appreci­ capable switch of their homes 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 overseas. The clinical foundation of the international reports could be present in a few theo­ retical premises, yet mainly the idea of chain reactions with un­ branched chains. within the Soviet Union, the strategies of Academician N. N. Semenov on chain reactions with degenerate branches became the place to begin of theoretical stories of the stabilization and destruction of polymers. Soviet scientists have constructed a concept of serious concentrations of antioxidants and feature proven that the techniques of stabilization have a really complicated chemical personality. the character of the polymers them­ selves enormously impacts those approaches and as a result, assorted stabil­ izers are required for polymers of other constructions. additionally, it's been proven that the antioxidants used up to now cannot merely reason chain termination, yet may also begin oxidation and provides upward push to de­ generate branches.

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L. Buchachenko, M. S. Khloplyankina, and M. B. Neiman, Doklady Akad. Nauk SSSR 143:146, 1962. 15. A. L. Buchachenko, Stable Radicals, Moscow, Academy of Sciences USSR Press, 1963. Chapter III SYNTHESIS OF STABILIZERS FOR POLYMER MATERIALS Depending on the purpose of stabilizers, it is now customary to divide them basically into photostabilizers, antioxidants, and thermal stabilizers. However, such a division is rather arbitrary in character, since many of them can simultaneously perform various functions, depending on the type of material to be stabilized, the conditions of its reprocessing, use, etc.

S. Torsueva, Doklady Akad. Nauk SSSR 136:647, 1961. 60. N. M. Emanuel', A. B. Gagarina, and Z. K. Maizus, Doklady Akad. Nauk SSSR 135:354, 1960. 61. D. Ryshavy, Vysokomolekulyarnye Soedineniya 3:464, 1961. 62. V. B. Miller, M. B. Neiman, V. S. Pudov, and L. 1. Lafer, Vysokomolekulyarnye Soedineniya 1:1696, 1959. 40 Chapter I 63. R. Goglev and M. B. Neiman, Vysokomolekulyarnye Soedineniya 5:1050, 1963. 64. G. 1. Likhtenshtein, M. B. Neiman, and N. Sysoeva, Tr. po Khim. i Khim. Tekhnol. p. 155, 1963.

7. THEORY OF SYNERGISM The introduction of the sulfide R2S into the polymer in sufficient concentration can make the denominator in the right-hand portion of equation (26) positive even if {j > 1, which makes it possible for a critical antioxidant concentration to be realized. The correctness of this conclusion was confirmed by the experiments described in [71]. 025 o 400 T ,min 200 Fig. 23. Consumption of 2,6-ditert -octylcresol in the oxidation of polypropylene (1) and in the presence of didecyl sulfide (2).

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