Dielectric alpha relaxation study of polyethylene by thermally stimulated depolarization currents and thermal sampling

Abstract

The dielectric alpha relaxation zone of branched low-density and linear high-density polyethylene has been studied by thermally stimulated depolarization currents. Two relaxations, alpha and alpha ', have been found, with maxima in the temperature range between 270 K and 300 K. Thermal sampling measurements showed that the alpha ' relaxation is distributed in both polyethylenes and appears at higher temperatures and with lower activation energy in the branched polyethylene than in the linear one. The activation energy of the alpha relaxation is not distributed, appearing at the same temperature in both polyethylenes. The behavior of the alpha ' relaxation agrees with the hypothesis of a molecular origin in the crystalline-amorphous interface of polyethylenes, the alpha relaxation being due to molecular motions within the crystalline phase.<>