Some Problems of the Free Volume Studies in Porous Polymers Using Positron Annihilation and Auxiliary Techniques

Membrane materials and polymer sorbents, polymers with highly developed free volume and specific surface, are of great technical importance. Positron annihilation lifetime (PAL) studies of these materials and some additional experiments give a chance to learn about the character of size distributions of elementary free volumes (EFV) of these materials. Particularly to answer the question whether the distributions of o-Ps lifetimes are of Gaussian type, as it is suggested in a number of publications, or they have some asymmetry or even some multi-component character, also to check some ideas on the ways of o-Ps trapping. In this aspect, large scale of o-Ps lifetimes (pore sizes) in these materials is very important, since enables comparison with the results of auxiliary techniques.