Dielectric Relaxation at the Glass Transition as a Free Volume Process. II. A Continuous Distribution of Relaxation Times

A previous work describing the α dielectric relaxation in glasses by means of a single, free volumedependent, relaxation time, is generalized by allowing for a distribution of relaxation times. Such a distribution is assumed to arise from differences in free volume within the glass. A phenomenological parameter is introduced for describing the interaction among the different zones. By using a temperature independent, symmetric, distribution in the inverse of the free volume expansion coefficient the experimentally found, asymmetric and temperature‐ as well as thermal‐story dependent distribution of dielectric relaxation times is reproduced. The physical meaning of the assumed distribution is discussed together with some implications on the dielectric response of a glass. Comparison with measurements performed on PVC shows good agreement.