By Professor M. B. Neiman (auth.), Professor M. B. Neiman (eds.)
The want for a large improvement of the creation of polymer ma terials has turn into glaring. a lot of these fabrics are topic to varied varieties 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 homes needs to be brought into them. in recent times, 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 international experiences could be present in a few theo retical premises, yet mainly the speculation of chain reactions with un branched chains. within the Soviet Union, the ideas of Academician N. N. Semenov on chain reactions with degenerate branches became the start line of theoretical reviews of the stabilization and destruction of polymers. Soviet scientists have constructed a idea of serious concentrations of antioxidants and feature proven that the strategies of stabilization have a really complicated chemical personality. the character of the polymers them selves tremendously impacts those procedures and hence, diversified stabil izers are required for polymers of alternative buildings. furthermore, it's been proven that the antioxidants used up to now can't merely reason chain termination, yet may also begin oxidation and provides upward thrust to de generate branches.
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Additional resources for Aging and Stabilization of Polymers
A. Razuvaev, and M. B. Neiman, Doklady Akad. Nauk SSSR 140:5, 1961. Stable Radicals of Inhibitors 55 12. A. L. Buchachenko, Optika i Spektroskopiya 13:6, 795, 1962. 13. O. L. Harle and J. R. Thomas, J. Am. Chern. Soc. 79:2973, 1957. 14. A. 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.
An analogous spectrum is given by tetramethyldiphenylazotoxide (X) OCHs OCHa I I CHaO -~- N _;f~ - OCHa "=/ ~ ! OCHa O· X '===/ I OCHa 52 Chapter II (Fig. 39). 2 Oe. The large number of lines of the proton hyperfine structure gives evidence that the unpaired electron easily transmits its influence through the oxygen atom to the protons of the substituents. When phenothiazine interacts with peroxide radicals, radicals of the corresponding azotoxide (XI), the EPR spectrum of which is shown in Fig.
In this case the induction period increases greatly, but the molec- ular weight of the polymer drops catastrophically (Fig. 19). Thus, the combination of the known facts leads to the conclusion that the first assumption that antioxidants do not influence initiation is erroneous. The second premise also is doubtful - the formation of two active radicals in the decomposition of the hydroperoxide. It has been shown in a number of studies [69, 70] that hydroperoxides can decompose in solution without forming radicals, giving rise to no chain generation.
Aging and Stabilization of Polymers by Professor M. B. Neiman (auth.), Professor M. B. Neiman (eds.)