The relationship between dielectric properties and the preparation method of nano-SiO2/epoxy composite

In this paper, the effect of preparation method on the permittivity and dielectric loss of nano-SiO₂/epoxy composites was studied. The nano-SiO₂ was dispersed into epoxy resin by three methods, which were “Ultrasonic Dispersion Method”, “High-speed Mixer Method” and “Sol-gel method”. The composites with 1wt%, 2wt%, 3wt% and 4wt% loading were made respectively. To compare the influence of the preparation methods to the permittivity and dielectric loss characteristics, dielectric spectra of the nanocomposites at the frequency range of 10⁶-10⁰ Hz were measured by Novo-control system. The results showed that the permittivity of nanocomposites made by the “High-speed Mixer Method” is lower than that made by the other methods. With the loading of nano-SiO₂ increased, the permittivity of nanocomposites increased then decreased, and reached its maximum at the 3wt% loading. The dielectric loss of nanocomposites is higher than the pure epoxy resin when the frequency is under 1 kHz and as the frequency exceeds 1 kHz, the dielectric loss of the nanocomposites is lower than the pure epoxy resin.