STUDY OF COOPERATIVE RELAXATION MODES IN COMPLEX-SYSTEMS BY THERMALLY STIMULATED CURRENT SPECTROSCOPY

Cooperative relaxation modes associated with transitions of various systems have been experimentally resolved into elementary processes characterized by activation enthalpies and entropies following a compensation law. Two transitions with no kinetic effect-solid-solid transition and Curie transition have been studied, In both cases, the corresponding dielectric relaxations are characterized by a compensation phenomenon with transition temperature as the compensation temperature. Dielectric relaxations liberated at the glass transition, T-g, have also been studied. They are also associated with a compensation law but, in that case, the compensation temperature is T-g + 10/30 degrees. This lag has been attributed to the kinetic character of T-g. Note that it is lower in amorphous polymers than in semicrystalline polymers. The distribution function of activation parameters is broader in amorphous polymers than in semicrystalline ones.