Mixed connectivity composite material characterization for electroactive sensors

Electroactive composites consisting of a ferroelectric ceramic in a polymer matrix have gained much interest as compliant electromechanical or pyroele ctric sensors. Of the various theoretical models developed to understand th e dielectric and electroactive properties of composites, the majority are b ased on a cube of unit dimensions representing the matrix with fractional i nclusions representing the ceramic. Composite properties are dictated by th e choice of constituent materials along with the intra- and inter-connectiv ity of the separate phases. A ceramic powder randomly dispersed in a polyme r matrix is referred to as having 0-3 connectivity, i.e. the ceramic phase possesses no intra-connectivity throughout the composite in the x, y, and z directions, whereas the polymer possesses full intra-connectivity in these directions. For thin composite films, where the ceramic grain size is comp arable to the Aim thickness, or for composites with high ceramic volume con tent, the degree of ceramic connectivity throughout the composite thickness will be enhanced over thick or low ceramic content composites, thus implyi ng an amount of 1-3 connectivity within the composite. In order to investig ate the properties of such composites, a cube model has been applied that d eals with mixed 0-3 and 1-3 connectivity composites. This paper reports on the experimental and theoretical characterization of two different mixed co nnectivity composites, one with a polar polymer matrix and another with a n onpolar matrix.