Abstract
The initial act of interaction of radiation in a polymer, irrespective of its chemical structure, is abstraction of an electron with formation of a positive ion. Neutralization of this ion by the electron leads to the formation of an excited molecule which subsequently breaks up with formation of free radicals. The pattern of changes occurring in the structure of the polymer will evidently depend upon the stabilization mechanism of these radicals. The fact that up to now the process of crosslinking during the radiolysis of polymers containing quaternary carbon atoms (polyisobutylene, polyβΞ±βmethylstyrene) has not been observed as well as the available data concerning the pattern of temperature dependence of the destruction rate, make it possible to draw the conclusion that, in these polymers, due to steric hindrances, the radicals formed as a result of the abstraction of side groups or hydrogen atoms react with each other with the breaking of the backbone chain of the polymer molecule. A study of the radiolysis of copolymers of styrene with Ξ±βmethylstyrene in a swollen state showed that, in this case, because of the absence of steric hindrances, the interaction between the polymer radicals and radicals formed from the solvent results in the insertion of the solvent molecules into the polymer chains (demonstrated by a tracer technique); in this case the rate of degradation is decreased. Data obtained during the study of the radiolysis of the mixture of low molecular radioactive polyisobutylene with the conventional high molecular polyisobutylene show that interaction of radicals formed during the radiolysis of this polymer represents a kind of a disproportionation reaction accompanied by a transferal of the low molecular groups from one polymer radical to another.