Investigation of Polymer Relaxation after Deformation by Positron Annihilation

Abstract

The relaxation of polyimid films after the axial tension has been investigated by measuring life-time of positrons and angular correlation of annihilation photons. The nonmonotonic change of mean life-time while relaxing the free film has been found. Two range of changes of positron-sensitive properties can be seen: "rapid" relaxation for 4-5 hours (characterized by reducing life-time of short-lived component) and "slow" relaxation (characterized by reducing the intensity of longlived component).The results of this investigation have been compared with those of measuring of sample density and dielectric losses. The possible explanations and the changes of mechanizms of relaxation with the conditions of deformation and "the rest" of polymers are analyzed.