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

In this paper, epoxy resin based composites filled with nano-Al
₂
O
₃
and nano-SiO
₂
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-SiO
₂
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 Al
₂
O
₃
, a similar phenomenon was observed. The tandelta of epoxy/ micro Al
₂
O
₃
composites was larger than that of epoxy/ nano Al
₂
O
₃
composite. Both epsiv
_r
and tandelta of Al
₂
O
₃
filled composites were larger than that of SiO
₂
filled composites for its high inherent permittivity.