Regular Article

The effect of SiO₂ nano-filler on dielectric properties of epoxy resin

¹ Department of Physics, Faculty of Electrical Engineering, University of Žilina, Žilina, Slovak Republic
² Department of Electrical Power Engineering, Faculty of Electrical Engineering and Informatics, Technical University of Košice, Košice, Slovak Republic

^* e-mail: kudelcik@fyzika.uniza.sk

Received: 20 July 2018
Received in final form: 23 November 2018
Accepted: 8 January 2019
Published online: 6 February 2019

Abstract

The paper presents the impact of SiO₂ nano-filler in epoxy resin (ER) on changes of dielectric properties and time to the breakdown. Several composites were tested with the mass fraction of 0.5 wt%, 1 wt% and 2 wt% of SiO₂, respectively. The frequency spectra of the real and imaginary parts of complex dielectric constant were measured by a capacitance method within the frequency range from 1 mHz to 1 MHz. The mass fraction 0.5 wt% nanoparticles (NPs) in ER caused the evident decrease of the complex permittivity, while 1 wt% or 2 wt% yielded similar permittivity as measured in the pure ER sample. This change of the permittivity with the nano-filler concentration is discussed on the basis of the multi-core model. Moreover, SiO₂ NPs also caused the frequency shift of the local maximum of permittivity to lower frequencies which corresponds with the α-polarization process. The internal partial discharges in the ER and its mixtures with the SiO₂ nano-filler by the galvanic method and acoustic method are presented. The decrease of the time to breakdown with the increase of SiO₂ the mass fraction is reported, too.