Unified dielectric description of the dynamics of polymeric systems undergoing either thermal or chemical vitrification

We discuss the behaviour of the dielectric relaxation times of an epoxy-amine system both undergoing a polymerisation reaction and cooled below the glass transition. The relaxation times versus conversion are suitably described by equations which parallel the Vogel-Fulcher and Arrhenius equations, commonly used to describe the behaviour of the relaxation time versus temperature. Under special conditions, the bilinear dependence of the glass-transition temperature on conversion, predicted by both theoretical models and experimental results, is verified and the increase with conversion of the activation energy of the secondary relaxation process is found to be linear.