Dielectric studies of natural polyethylene at elevated temperatures

A two-terminal dielectric test cell for the study of the dielectric properties of viscous polymers above their softening temperature was developed and used to perform measurements of the dielectric constant and loss factor of low-density natural polyethylene above its crystalline melting temperature. The results show a strong dependence of the dielectric constant on the density of the material between 25°C and 160°C. Excellent agreement is found between the results and calculations using the Clausius-Mo sotti equation relating dielectric constant and specific volune. The results were also confirmed by detailed measurements using the two-fluid method over the same temperature range. Measurements of tan 6 over the same temperature range were seen to depend on the sample preparation procedure and test method used.