Dielectric Properties Of Polyaniline Nanofibers/low Density Polyethylene Composites

With the rapid development of modern power industry and the vigorous promotion of offshore wind energy,the requirements for high-voltage cable insulation materials are becoming higher,ordinary polymer materials are difficult to meet the need of the future development of the power industry.The research and development of high performance DC cable materials based on ordinary polymers have become a research focus.At present,one of the research hot spots in the field of dielectric is the blending modification of polymer with nano-materials in order to improve the performance of dielectric materials.In this thesis,doped polyaniline(PANI)nanofibers and dedoped PANI nanofibers were prepared first,and the morphology and structure were characterized by scanning electron microscope.The morphology of the prepared PANI nano-material is nanofiber.Doped PANI nanofibers/LDPE and dedoped PANI nanofibers/LDPE composites were obtained by melt blending with different doping concentration of doped PANI nanofibers and dedoped PANI nanofibers using low density polyethylene(LDPE)as the matrix resin.And the composites were studied by infrared spectrum.Based on the the location of the absorption peak,it was found that the doped PANI nanofibers and the dedoped PANI nanofibers had been added into the LDPE successfully.The results of DSC analysis of the composites indicated that: the composites with doped PANI nanofibers and dedoped PANI nanofibers were easier to crystallize and the crystallinity increased.Conductivity,DC breakdown strength and AC breakdown strength were performed on the nanocomposites with different content of doped PANI nanofibers and dedoped PANI nanofibers under different temperatures.The experimental results showed that adding the doped PANI nanofibers and the dedoped PANI nanofiber could greatly reduce the conductivity of the composites.DC breakdown experiments suggested that the breakdown strength of nanocomposites containing 0.2phr doped PANI nanofibers was a little higher than the pure LDPE when the experimental temperature was 30?.When the 0.2phr and 0.5phr dedoped PANI nanofibers were added,the breakdown strength of the composites were improved at the three test temperatures.AC breakdown tests showed that the addition of doped PANI nanofibers reduced the AC breakdown strength of the composites.The AC breakdown strength of the composites with dedoped PANI nanofibers has little change.The space charge distribution of the composites was measured by electroacoustic pulse method.The addition of doped PANI nanofibers and dedoped PANI nanofibers with different concentrations can inhibit the space charge accumulation in the composites.The relative dielectric constant and dielectric loss of composites were measured.The experimental results showed that,with the increasing concentration of doped PANI nanofibers,the relative dielectric constant of composites were decreased.The relative permittivity of the composites by adding dedoped PANI nanofibers increased,but the dielectric losses of the two composites increased.