Application of random walk model to the glass transition of unsaturated polyester resins cured with different styrene contents

Abstract Dielectric measurements have been performed on unsaturated polyester resins, cured with different styrene contents. Based on the random walk model (RWM), we have determined, as a function of the styrene content, the width of the density of states kT 0 , the average energy barrier height 〈 E A 〉 that a structural unit must crossover in order to relax, the fragility index α and the value of T c at which qualitative changes in the dynamics occur. The RWM data are in good agreement with the strong-fragile concept.