Characterization of polymer-filler interactions for a model nanocomposite based on silicone rubber

The electrical characteristics of polymeric insulating materials can be significantly modified by adding nanoparticles. The present study investigates the dielectric response and tries to identify the origin of the changes from the pure polymer to the nanocomposite. The effect of the nanoparticles on the material properties is investigated with the high-voltage arc resistance test. For this purpose nanocomposites consisting of polydimethylsiloxane and hydrophobic silica nanoparticles were produced by means of laboratory methods. Cross-linked and uncured samples of the polymer and various filler contents up to 10 wt% are analyzed. The homogenous distribution of the particles, which have a finite random distance, is confirmed by transmission electron microscopy. The local maximum of the arc resistance time is interpreted by the Interphase Volume Model. The dielectric spectroscopy revealed that the molecular weight and the cross-linking have no effect on the relaxation processes, while in the spectrum of the nanocomposite an additional relaxation is identified. These results suggest that an interphase forms.