Dielectric properties of High-Density Polyethylene foil samples at low frequency

Abstract This paper presents the dielectric behavior of high-density polyethylene (HDPE) thin-film samples having approximately 50µm thickness in frequency from 100Hz to 10kHz. The HDPE foil samples exhibit a single peak in dielectric loss maxima, which is found to be shifting from 100°C to 145°C with the rise in frequency. The dielectric loss maxima correspond to the α-relaxation peak of the TSDC thermogram. The shifting of peak can be explained due to the entanglement of polymer chains present at the interfacial region of the polymer. The variation of dielectric constant with temperature is also observed and could be due to the effect of linear thermal expansion in the lower temperature region. The orientation of dipoles increases with the rise in temperature in the close range of glass transition temperature (Tg) of the polymer i.e. −125°C and the disordered random motion of molecules above Tg. The polymer interface act as charge-carrier trapping sites in the polymeric system. Therefore, it is inevitable to investigate the effect of polymer interfacial sites on their charge-carrier transport and charge storage mechanism. The results of the experiments and the mechanisms involved have been presented on the background of available theories.