AbstractDielectric γ relaxation in polyethylene with various degrees of branching and/or with various heat treatment has been measured in the ranges of frequency 10–104Hz and temperature−90 to−130°C. The difference between the dispersion maps obtained from the frequency dependence of the dielectric loss and from the temperature dependence suggests that the temperature dependence of the relaxation intensity in polyethylene is not negligible. With an increase in crystallinity owing to the decrease in branching, the relaxation time shifts to longer time or higher temperature side and the activation energy increases steeply, whereas the quite opposite tendency was observed for the heat treated polyethylene with different crystallinity. The distribution of relaxation times becomes narrower with increasing temperature. At higher temperatures, the distribution in the specimens with various degrees of branching becomes narrower with the increase in the crystallinity, whereas in the specimens with various heat treatments, the dependence of the distribution on crystallinity tends to cease. Defects in the crystalline phase increase with an increase in branching and in crystallinity through heat treatments, and the dielectric γ relaxation in polyethylene differs depending on the branching and/or heat tr
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