Effect of TiO2 size factor on the electrical properties of polyethylene matrix dielectrics

In this study, the TiO2 nanoparticles and TiO2 nanofibers were chosen as inorganic fillers to dope into the linear low density polyethylene (LLDPE). The TiO2 nanofibers were prepared by the electrospinning method, the diameter and length of TiO2 nanofibers were about 100 nm-200 nm and 3 μm-4 μm, respectively, and the size of the purchased TiO2 nanoparticles was about 100 nm-200 nm. The microstructure of TiO2 fillers and their composites was analyzed by the X-ray diffraction (XRD) and scanning electron microscopy (SEM). The breakdown field strength and space charge characteristics of the LLDPE/TiO2 nanoparticles and LLDPE/TiO2 nanofiber composites with different sizes of inorganic fillers were investigated. The results showed that the LLDPE/TiO2 nanofiber composites had higher breakdown strength than LLDPE/TiO2 nanoparticle composites at the same doping content. The breakdown strength of 0.5 wt% LLDPE/TiO2 nanofiber composites (237 kV/mm) was higher than that of pure LLDPE (223 kV/mm) and 0.5 wt% LLDPE/TiO2 nanoparticle composites (205 kV/mm). In addition, the space charge accumulation and electric field distortion in the composites were significantly relieved by doping TiO2 nanofibers compared with that of doping TiO2 nanoparticles.