Effect Of Polypyrrole Nanobowls On The Dielectric Properties Of Polyethylene

China has abundant offshore wind power,and for this type of new energy,the best transmission mode of the generated electricity is to employ flexible HVDC transmission.With the development of voltage source converter(VSC)and pulse width modulation(PWM)technology and the improved manufacturing level of DC cable,flexible HVDC transmission will become one of the most important ways for DC power grid.But the localization of XLPE insulation material required by flexible HVDC cable are still not achieved,which is very unfavorable for the development of Chinese wire and cable industry.Therefore,to develop crossing-linkable polyethylene insulation material with high performance for HVDC cable and strive to fill our gaps in HVDC cable insulation material has not only important scientific significance but also economic and social benefits,and will promote the holistic development of Chinese wire and cable industry.This experiment prepared polypyrrole nanomaterials first,and the morphology of polypyrrole nanomaterials prepared before was characterized as bowl by scanning electron microscope(SEM),and then low density polyethylene(LDPE)was selected as the matrix resin to obtain polypyrrole nanobowls/LDPE composites and polypyrrole nanobowls/XLPE composites by melt blending with different doping concentration of polypyrrole.Fourier transform infrared spectrometer(FTIR)was used to ascertain polypyrrole nanobowls successfully doped into nanocomposite materials with respect to the position of absorption peak.X-ray diffraction(XRD)analysis was carried out on the nanocomposites,it suggested that the existence of the polypyrrole nanoparticles bowl does not change the crystallization of matrix.The gel content test performed on polypyrrole nanobowls/XLPE composites showed that the content of polypyrrole nanobowls had no effect on the crosslinking degree of XLPE.Conductivity test and breakdown strength were performed on nanocomposites with different content of polypyrrole nanobowls under different temperatures.Conductivity test results showed that the addition of polypyrrole nanobowls reduced the conductivity of the nanocomposite drastically.DC breakdown experiments suggested that the conductivity of nanocomposites containing 0.2 phr nanobowls was 7% higher than the pure LDPE when the experimental temperature was 30 ℃.Breakdown strength of nanocomposites overall decreased with the increase of temperature in different degree.Space charge was measured using pulse electroacoustic method and the result showed that different proportions of polypyrrole nanobowls had different inhibition effect on space charge.Dielectric spectrum tests showed that adding appropriate proportion of polypyrrole nanobowls can reduce the dielectric constant of the nanocomposites.Polypyrrole nanobowls made dielectric loss of polypyrrole nanobowls/LDPE composites increase slightly and polypyrrole nanobowls/XLPE composites reduce.