RELAXATION BEHAVIOR IN THE TRANSITION REGION OF GLASSY SYSTEMS

Following the Adam-Gibbs procedure for describing the relaxation proce ss of glass-forming liquids, a Vogel-Fulcher type equation has been ob tained, determined by a new structural parameter called the isovolume fictive temperature, T(x). The resulting expression for the relaxation time has been applied satisfactorily to the experimental data of diel ectric relaxation during physical ageing of poly(vinyl acetate). For t esting the reliability of the proposed model, comparison with other ph enomenological approaches has been made.