EXAMINATION OF THE FREE-VOLUME ELEMENTS I N POLYMERIC SYSTEMS BY POSITRON-ANNIHILATION SPECTROSCOPY

Two ternary ethylene-propylene-norbornene copolymers, the polymers wit h high free volume [poly(trimethylsilyl propyne), and the perfluorodio xol-terrafluoroethylene] copolymer were studied using positron annihil ation lifetime spectroscopy, Characteristics of positron annihilation lifetime spectra (I-i, tau(i)) were calculated using the PATFIT comput er program, and their dependence on the number and size of defects (fr ee-volume holes) in polymers was considered. Analysis of the kinetics of diffusion and trapping of positrons and positronium in defects show s that the number of defects is not proportional to the intensities of the corresponding components in the lifetime spectrum and depends, in particular, on the ratio between the positronium annihilation rate in the defect and the annihilation rate of nonlocalized positrons, This actor should be taken into account in lire qualitative estimates based on the positron annihilation lifetime measurements, which allow one t o reveal the role of defects with different sizes in variations of phy sicochemical properties of the materials.