Volume recovery of polystyrene: evolution of the characteristic relaxation time

We have developed a new experimental technique that uses intermittent temperature perturbations during volume recovery in order to obtain quantitative information concerning the evolution of the characteristic relaxation time for volume during structural recovery. The experiments are analogous to the intermittent creep experiments developed by Struik. Using an automated capillary dilatometer and a polystyrene sample, the time-temperature history dependence of the characteristic relaxation time for volume was investigated. Our preliminary results show that for the set of temperature down jumps and memory experiments investigated, the characteristic relaxation time appears to depend only on the instantaneous state of the material. However, the results are not totally consistent with the Tool-Narayanaswamy model/Kovacs-Aklonis-Hutchinson-Ramos model. (C) 2002 Elsevier Science B.V. All rights reserved.