Dielectric response of high density polyethylene/SiO2 composites

The objective of this research is to measure and quantitatively model the complex permittivity of PE composites. Dielectric mixing laws are helpful in designing and modeling composites. However, simple algebraic mixing laws do not accurately predict the effective permittivity of multiphase composites. Popular algebraic mixing laws are based on volume fractions and complex permittivities of both phases only. Thus, they do not distinguish between material types with different microstructures. Most of the different two-phase mixing laws inaccurately predict the measured complex permittivities of HDPE composites. Nanocomposites have been prepared by melt compounding using a twin screw extruder. The imaginary part of the complex permittivity of the three-phase composites depends significantly on the presence of a water layer at the surface of the nanoparticles. In this paper, a comparison between the analytical solution for heterogeneous material with an interfacial layer between filler particles and the PE matrix and the experimental results is presented for various PE/SiO₂ nanocomposites. The experimental results were obtained from frequency domain dielectric spectroscopy in the 10^-1 Hz to 10⁵ Hz frequency range.