Broadband Dielectric Spectroscopy of Silicone Rubber Nano-composites

In this paper, the impact of nano-fillers on the dielectric characteristics of nano-Al2O3/silicone rubber nano-composites is studied. Silicone rubber composites with the loading of 1%, 2%, 3% and 4% nano-Al2O3 are made by "bubble method", and coupling agent is used in this preparation process to improve the dispersion further. The dispersion of nano-fillers in the matrix is observed by transmission electron microscope (TEM). The permittivity and tan delta of the composites at frequency 10(6)-10(-3)Hz is measured by Novo-control impedance analyzer. The results show that, at the frequency from 10(6) to 10(1) Hz, the permittivity of all the composites remains almost constant and tan delta increases gradually, and at 10(1) to 10(-3) Hz, real permittivity epsilon' tends to increase, especially in the unfilled and 1% loading sample. With the increasing of filler loading from 1% to 3%, the permittivity and tan delta of the composites decrease and then increase when the loading reaches 4% in all the test frequency. Cole-Cole plot is used to analyze the change of the conductivity of the composites.