Characteristics on breakdown performance of polyethylene/silica dioxide nanocomposites

Compared with the conventional microcomposites, incorporating nanoparticles into polymeric matrix can better improve breakdown performance. Much works have been done to investigate the electrical properties of nanodielectrics since the first experimental results published. It is acknowledged that the interface between nanoparticle and polymeric matrix play a dominant role in the electric properties of polymer nanocomposites. This paper studied the characteristics on breakdown performances of low density polyethylene (LDPE)/silica dioxide (SiO₂) nanocomposites. In this study, polyethylene-silica nanocomposites were prepared by dispersing silica nanoparticles into LDPE by using Melt Blending method. The specimens were finally prepared by hot melt pressing at 135°C, and specimens with thickness of 0.2 mm were used for breakdown voltage measurements at room temperature. Scanning electron microscopy (SEM) measurements were used to evaluate the dispersion of nanocomposites. The breakdown strength of nanocomposites with different nanoSiO₂ particle loadings under alternating current (ac 50Hz), direct current (dc) and impulse voltages were measured. In addition, the results of conductivity as a function of particle loadings were also presented. From the experimental results, adding appropriate nanoSiO₂ particles improved the breakdown properties of specimens. The improvements are close associated with the interfacial region between nanoparticle and polymeric matrix. The mechanisms about these improvements have been discussed and needed to be investigated further.