Investigation of dielectric behavior of water and thermally aged of XLPE/BaTiO3 composites in the low-frequency range

Cross-Linked Polyethylene (XLPE) is widely used as insulation in electrical engineering, especially as cable insulation sheaths. In order to improve the dielectric properties susceptible to be modified under the effects of thermal aging and water in an absorption environment, polymers are mixed with ceramics. In this paper, the influence of barium titanate (BaTiO3), on the dielectric properties of XLPE has been studied. Dielectric parameters have been measured using an impedance analyzer RLC (WAYNE KERR 6420 type). Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy and X-ray diffraction were used as characterization techniques. The study has been carried out on two samples of XLPE. A pure sample of each were studied as a unloaded samples to be compared with samples of 5%wt, 10%wt, 15%wt and 20%wt. BaTiO3 loaded XLPE. Afterwards, the composites were subject to humidity and to thermal aging. The incorporation of BaTiO3 1 degrees C does not modify the crystallinity and morphology of the XLPE and 2 degrees C reduces the space charges therefore the dielectric losses. tg delta, epsilon r and loss index are measured. Frequency response analysis has been followed in the frequency range (20-300 Hz). Experimental results show well that BaTiO3 as nano-filler improves the dielectric properties of XLPE but in excessive content can drive to the cracking and therefore to absorption of water.