Physical aging of poly(vinyl acetate).: A thermally stimulated depolarization current investigation

The influence of physical aging on the dielectric alpha -relaxation of poly(vinyl acetate) (PVAc) is investigated by means of the thermally stimulated depolarization currents (TSDCs) technique. The obtained TSDC data are analyzed in terms of the Kohlrausch-Williains-Watts (KWW) equation for an isothermal decay of a stored charge. Assuming that at temperatures less than the glass transition temperature the shape of the KWW function depends neither on the temperature nor on the thermal history, the generalized Bucci and Fieschi equation allows us to obtain the dependence of the KWW time. The results obtained are interpreted in the Adam and Gibbs theory framework. (C) 2001 Elsevier Science B.V. All rights reserved.