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

In this study, the TiO 2 nanoparticles and TiO 2 nanofibers were chosen as inorganic fillers to dope into the linear low density polyethylene (LLDPE). The TiO 2 nanofibers were prepared by the electrospinning method, the diameter and length of TiO 2 nanofibers were about 100 nm–200 nm and 3 μm–4 μm, respectively, and the size of the purchased TiO 2 nanoparticles was about 100 nm–200 nm. The microstructure of TiO 2 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/TiO 2 nanoparticles and LLDPE/TiO 2 nanofiber composites with different sizes of inorganic fillers were investigated. The results showed that the LLDPE/TiO 2 nanofiber composites had higher breakdown strength than LLDPE/TiO 2 nanoparticle composites at the same doping content. The breakdown strength of 0.5 wt% LLDPE/TiO 2 nanofiber composites (237 kV/mm) was higher than that of pure LLDPE (223 kV/mm) and 0.5 wt% LLDPE/TiO 2 nanoparticle composites (205 kV/mm). In addition, the space charge accumulation and electric field distortion in the composites were significantly relieved by doping TiO 2 nanofibers compared with that of doping TiO 2 nanoparticles.