Preparation of Polypyrrole Nanospheres and Their Effect on Space Charge Behavior of Polyethylene

The accumulation of space charges will lead to the electric field distortion in the cable insulation, affect the insulation strength and accelerate the aging of the insulation materials. Therefore, the key for the development of insulation materials is to solve the problem of space charge accumulation in the insulation. In this paper, polypyrrole nanomaterials were prepared by soft template method. It was confirmed by scanning electron microscopy (SEM) that the prepared polypyrrole nanomaterial had a spherical structure with uniform diameter and smooth surface, which indicated that the microstructure of polypyrrole nanospheres has been synthesized successfully. With low density polyethylene (LDPE) as matrix resin, polypyrrole nanospheres/LDPE composites with the doping contents of 0, 0.2, 0.5, and 1phr (phr: parts per hundreds of polyethylene) were prepared by melt blending method. The structure of pristine LDPE and the nanocomposites was characterized by Fourier transform infrared spectroscopy (FTIR). The space charge distribution of pristine LDPE and polypyrrole nanospheres/LDPE composites with different doping contents was measured by pulsed electroacoustic method (PEA) at room temperature. The space charge accumulation in pristine LDPE was relatively serious. After polypyrrole nanospheres were added into LDPE, the amount of space charges near the cathode and the anode in the polypyrrole nanospheres/LDPE composites were reduced to some extent. With the increase of the doping content of polypyrrole nanospheres, the amount of space charges in the nanocomposites decreased first and then increased slightly. The results showed that polypyrrole nanospheres could inhibit the space charge accumulation in the polypyrrole nanospheres/LDPE composites. After depolarization, the amount of space charges in pristine LDPE gradually decreased with the increase of depolarization time, while the amount of space charges in the polypyrrole nanospheres/LDPE composites decreased slowly.