On the relation of post-irradiation molecular size distributions and relaxation measurements for polymers

The intensities of relaxation effects in irradiated linear chain polymers are related to the molecular size distribution by assuming a critical value p_c for the molecular chain length below which no contribution to the relaxation strength is obtained. For a number of chain length distribution functions, containing as parameters the cross-linking and scission densities as well as the molecular chain length, the resulting relaxation active fractions of the material are compared with those experimentally obtained for the β-relaxation in γ-irradiated polyvinylidene fluoride, as measured by thermally stimulated depolarization (TSD), internal friction and dielectric relaxation techniques. The derived values for the relevant physical quantities are found to be reasonably in agreement with literature data.