Dielectric spectroscopy of aluminium hydroxide particles filled silicone rubber and dielectric model analysis with modified numerical solutions

In numerical solutions of Hanai equation widely used in heterogeneous systems, the uncertainty of conductivity at high frequency affects the accuracy of phase parameters results (permittivity and conductivity of components). To overcome this limitation, broadband dielectric spectroscopy of eight groups of silicone rubber (SR) was measured at a frequency from 10⁻¹ Hz to 10⁵ Hz and at a temperature from 0 °C to −40 °C. An obvious relaxation peak related to the interface between aluminium hydroxide (ATH) and SR was observed and confirmed. Based on the interfacial polarization, phase parameters of ATH and SR were calculated by modified numerical solutions, which was verified by other information. It was found that with the increase of ATH concentration, polarization strength increased and relaxation time decreased, which indicated that the number of charges accumulated at the interface increased in interfacial polarization process and the Debye length of interface decreased. Because of the surface conductivity around ATH, the conductivity of ATH is higher than that of SR. This paper is beneficial for the studies on the interface properties of ATH filled silicone rubber and provides supports for studying the electrical parameters of particles dispersed in continuous medium systems without physical transition or chemical changes with enhanced accuracy. (paper)