Dielectric characteristics of SiO2/LDPE micro- and nanocomposites

Dielectric characteristics of LDPE filled with micro- and nano-sized particles of SiO₂ were studied in this paper. The dependence of the loss factor and dielectric constant of composites on frequency was investigated in a relatively wide frequency range, and the roles of the size and loading level of the filler are discussed. Compared with additive-free LDPE, incorporating nano-sized SiO₂ can effectively reduce tandelta of all nanocomposites in a low frequency range, while only loading an appropriate amount of micro-filler has the same effect. Peaks of tandelta were observed in any composite sample, and the peak-value location is almost frequency-independent for micro-composites, while there are no peaks for virgin LDPE. Tandelta values of the nanocomposites with proper filler content are much less than those of the microcomposites. For both nano- and microcomposites, by controlling the content of filler, the dielectric constant can be changed to a higher or lower value than that of virgin LDPE.