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

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