About Some Peculiarities of Positron Annihilation and Sorption Methods in Microporosity Studies on Polymers

Abstract

Data on microporosity (micropore size distribution) in the range from several angstroms to several nanometers, obtained by measuring the positron annihilation lifetime (PALS method) and by measuring CO2 sorption (low-temperature gas sorption, LTGS) are collated for a number of polymers with amorphous (polyetherimides, PEI) and semicrystalline (polyphenylene oxides, PPO) structures. The microporosity estimates based on the positron annihilation and CO2 sorption data are compared with published data obtained bothexperimentally and by the group contribution method for the permeability of these materials. The discrepancies found and their possible causes are discussed.