Materials Science Forum, Vol.514-516, 1462-1466, 2006
On the possibility to observe a compensation effect around the glass transition temperature
Compensation has been reported for the relaxation parameters: the activation energy W and the pre-exponential factor tau(0), determined from the Thermal Sampling of Thermally Stimulated Depolarization Current technique. Below the glass transition it is assumed that the relaxation time follows an Arrhenius equation. In the vicinity of glass transition temperature an experimental thermograrn may be analyzed using the Vogel-Fulcher-Tamman-Hesse (VFTH) or the Williams-Landel -Ferry equation. In this article we use the VFTH relationship to study the compensation effect in the range of glass transition. For an elementary peak obtained by TS there is a relationship between the activation energy W, the temperature of the maximum current T-m, the VFTH temperature, the compensation temperature T-c and the compensation time tau(c). We employ this relationship for a basic analysis of the compensation effect in the temperature range around T-g By numerical simulations, and assuming parameters similar to those measured experimentally, we show that it is possible to observe a compensation point in some well defined conditions.