Temperature dependence of tan δ in polyethylene

The authors measured the temperature characteristics of tan δ in commercial grade low-density polyethylene (LDPE) and very low-density PE produced by the high pressure polymerization process of linear low-density PE (LLDPE) and high-density PE (HDPE) produced by the low pressure production process, and of medium-density PE (MDPE) produced by the medium pressure production process. The measurement revealed that values of tan δ at high temperature were different according to the kind of PE. It is suggested that the temperature dependence of tan δ in PE can be changed by such factors influencing the conductivity of PE as ionic carriers and trapped electrons. DC leakage-current-temperature characteristics of these types of PE were measured in order to examine the effect of impurities contained in these samples. The relation between tan δ characteristics and the impurities derived from the production processes is discussed