Enhanced dielectric constant of polymer-matrix composites using nano-BaTiO3 agglomerates

Abstract

The epoxy/matrix composites incorporating with dispersed and agglomerated nano-BaTiO3 fillers were investigated. The relative dielectric constants of the composites with the agglomerated particles were significantly improved, compared to those of the composites with the well-dispersed particles. In addition, the experimental data were in better agreement with the values calculated by the Lichteneker's model than with those of the conventional Maxwell-Garnett's model which has been widely employed for the calculation of the dielectric constant of polymer/filler composites. In order to promote an agglomeration by interlocking between the nanciparticles, the BaTiO3 powders were heat-treated at various temperatures. An epoxy composite with 40 vol% BaTiO3 heat-treated at 800 degrees C for h exhibited an excellent relative dielectric constant of 67, along with high polarizability, low dielectric loss, and low leakage current. Similarly, the epoxy composites with agglomerated SrTiO3 fillers provided a higher dielectric constant than that of their dispersed counterparts. The origin of the increase in the relative dielectric constant achieved by the agglomeration effect is also suggested. (C)2010 The Ceramic Society of Japan. All rights reserved.