The effect of filler content on slow polarization behavior in composite of nano-SiOx or micro-SiO2 and low-density polyethylene

Nano-SiOx or micro-SiO2 can be homogeneously dispersed in polyethylene (LDPE) by a method using a double solution mixture. The dispersion status of nano-SiOx and micro-SiO2 was investigated with scanning electron microscopy (SEM). Polarization and depolarization current of the composite and pure LDPE was recorded with Keithley 6517 A. In order to know the dielectric loss of the composite, polarization and depolarization current with time was converted to the frequency domain with Fourier Transform Method (FTM). It was found that the depolarization intensity of composite containing nano or micro inorganic filler is lower than that of pure LDPE, and that of composite containing nano filler is lower than that of composite containing micro filler. At a higher temperature (333K), the depolarization loss peak location of the composite containing nano-SiOx is distinctly higher than that of the composite containing micro-SiO2. It is pointed out that the different slow polarization behavior has close relation with the physical characteristic of fillers, as well as the content of fillers. Finally, the polarization and depolarization phenomenon were discussed with space charge trapping and detrapping processes in the interfaces between nano-SiOx or micro-SiO2 and polyethylene.