Investigation of the effects of nano-filler on dielectric properties of epoxy based composites

In this paper, epoxy resin based composites filled with nano-Al₂O₃ and nano-SiO₂ individually were fabricated. The relationships between the dielectric properties and fillers properties (contents and particle size etc.) were investigated. The results showed that, for nano-SiO₂ filled epoxy, relative permittivity (epsiv_r) and loss factor (tandelta) increased obviously when filler content was lower than about 0.1 wt.%, continue to increase filler content, it appeared a minmium value while filler increased to 0.3 wt.%, and above this loading, epsivr and tandelta start to increase again increased with increasing filler content. While for the composites with nanosized Al₂O₃, a similar phenomenon was observed. The tandelta of epoxy/ micro Al₂O₃ composites was larger than that of epoxy/ nano Al₂O₃ composite. Both epsiv_r and tandelta of Al₂O₃ filled composites were larger than that of SiO₂ filled composites for its high inherent permittivity.