Modification of the dielectric properties of 0-3 ceramic-polymer composites by introducing surface active agents onto the ceramic filler surface

In this work, the effect of surfactant on the properties of 0-3 barium strontium titanate (BST)-polymer composites was investigated. By introducing aliphatic carboxylic acids onto the filler surface, an increase in relative permittivity was observed. It was found that the permittivity of the composites obey the modified Lichtenecker's equation, log epsilon = log epsilon(p) + nu(b)(1 - k) log (epsilon(b)/epsilon(p)). The parameter k changed from 0.266 for unmodified BST composites to 0.250-0.224 for the modified BST composites. The result means that carboxylic acid with longer carbon chains enhances the relative permittivity of the composite more effectively. From a particle distribution study, it is shown that surface modification with longer carboxylic acid would give better dispersion of the particles in the matrix. Thermal and mechanical analyses of the composites showed that the surface modification does not have a large effect on the mechanical properties of the composites. (C) 2009 Elsevier Ltd. All rights reserved.