Use of paramagnetic substances in studying shear deformation in solid polymers

The concentration and the mobility of free radicals produced by degradation of the arylindan dimer dissolved in PMMA or PS upon plastic deformation of the polymers in Bridgman's anvils were studied by the ESR technique. The most intense degradation of the arylindan dimer takes place in the localization zones of shear plastic strain. The radical concentration increases with increasing the strain (rotation angle of the anvils) reaching saturation at angles of 50°-70°. The decay rate of arylindan radicals was found to be noticeably increased by shear strain of a sample. Two types of radicals with different decay rate constants were found to exist, thus reflecting the nonuniformity of plastic flow in polymer glasses. The results obtained show that the arylindan dimer can be used to quantitatively study the localization of shear strains in solid polymers and non-polymeric solids.