Effect of two concentrations SiO₂ nanoparticles on molecular mobility and dielectric response of single component resin based on polyesterimid

This study aims to present the influence of two weight concentrations of Silicone Dioxide (SiO₂) nanoparticles on the dielectric properties of single component impregnating resin based on polyesterimide (PEI) (UP 343 from Elantas producent). In this study the SiO₂ nanoparticles were dispersed into PEI (with 0.5 and 1.0 wt.%) to prepare nanocomposites. The capacitance method based on the three-electrode measurement method to measure the frequency dependence of the real and imaginary parts of complex permittivity within the frequency range of 1 mHz to 1 MHz at temperature range of all conventional rotating and stationary windings from (+20 °C to +120 °C) was used. The presence of SiO₂ nanoparticles in matrix of UP343 caused an increase of the real permittivity at higher temperatures compared to the pure matrix due to higher mobility of polymer chains. At low temperatures the decrease of the real permittivity was caused by the presence of highly immobile polymer chains in the interfacial regions around nanoparticles. The presence of different weight concentration of nanoparticles in the PEI resin had impact on the segmental dynamics of the polymer chains and changed a charge distribution in the given system. The shift of local relaxation peaks to lower eigenfrequency in the spectra of imaginary permittivity of investigated nanocomposites was observed.