Effect of filler concentration on dielectric properties of RTV silicone rubber/TiO2 nanocomposite

Silicone rubber is a polymer with low dielectric permittivity which needs to be improved for outdoor insulation applications. However, the addition of semiconducting materials with high dielectric constants, like TiO₂ (ε~80), to silicone rubber (SR) can improve its dielectric properties and electrical conductivity. The presence of these inorganic fillers allows the homogenization and distribution of the insulator electric field, thus considerably reducing electrical stress. In this paper, a RTV SR/TiO₂ nanocomposite was synthesized and characterized. Also, to further understand its dielectric behavior, experiments were carried out to measure the dielectric permittivity of the nanocomposite by using an impedance analyzer. The influence of the filler concentration (up to 20 wt% TiO₂) on the dielectric behavior of the nanocomposite over a frequency range of (40 Hz to 2 MHz) was discussed. Moreover, it was characterized by means of scanning electron microscopy by studying the nanofiller distribution in the polymer. The results showed that the surfactant Triton-X-100 improves the dispersion of the nanoparticles. Furthermore, it was found that the real relative permittivity (ε_r), as well as the imaginary relative permittivity (ε_r”) increase as the nanofiller concentration increases.