Does Positronium Feel Dynamics of Polymer Chain?

Abstract

The annihilation experiments on simple elastomers at wide temperature interval of (15-370) K will be described. The results are consistently interpreted using free-volume models of polymer structure. The procedure of deducing some parameters of theory of polymers (e.g. viscosity, Vogel-Fulcher temperature) from the positron annihilation experiments will be shown. A great potential of positron annihilation in the study of amorphous polymers will be emphasized.

Free volumes and occupied volumes in oligomeric polypropylenglycols

“…Monitoring of the free volume of polymers, subjected to variations of various parameters or conditions [8], is achieved by means of the positron annihilation lifetime spectroscopy (PALS); on the other hand, determinations of the occupied volume in organic materials are absent, at our knowledge, with the exception of a few recent measurements in some polymers [9,10]. It is often assumed that the occupied volume is constant, like hard-spheres-formed matter; however, experiments carried out on simple liquids [11] under very high pressures showed much larger decrements of the specific volume than the usual magnitude of the free volume; this suggests a dependence of the occupied volume on pressure and, more generally, on thermodynamic quantities.…”

An experimental study of the occupied volume in polyethylene terephthalate

“…10,11 It is often assumed that the occupied volume is constant, like hard spheres formed matter; however, experiments carried out by Bridgmann on simple liquids 12 under very high pressures showed much larger decrements of the specific volume than the usual magnitude of the free volume. This suggests a dependence of the occupied volume on the pressure and, more generally, on thermodynamic variables.…”