Application of Radical Cage Reactions in Studies of Microstructures of Polymers and Composites -[103 refs.]. -(DAVYDOV, E. YA.; VOROTNIKOV, A. P.; PUSTOSHNYI, V. P.; PARIISKII, G. B.; Russ. Chem.
The character of nonexponential kinetics of the low-temperature decay of triplet carbenes in polymers has been given consideration. The temperature dependencies of the decay rate and the kinetic isotope effect were found at 77-180 K. The controlling factor in the kinetic nonequivalence of carbenes is the distribution of distances of the hydrogen atom tunneling from the matrix molecules. The effect of magnetic field on the rate of the carbene decay has been seen at 77 K. On the basis of the magnetic dependence view, the mechanism of the carbene decay involving spin and chemical dynamics of intermediate short-lived radical pairs has been advanced. The nature of magnetic effect in polymers shows the configuration inhomogeneity of radical pairs.
The mechanism of reactions of nitrogen dioxide with polyvinylpyrrolidone at 295-363 K has been considered. The nature of the molecular and free radical products of reactions has been studied by UV and ESR spectroscopy. The main molecular products are nitrites and nitrozoamides. The formation of stable acylalkylnitroxyl and iminoxyl radicals was registered. The influence of the structural-physical modification of the polymer at filling by aerosil has been established on kinetics of the formation of radicals.
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