Smart and active transducers for the detection of acoustic emission [ferroelectric ceramic/polymer composites]

Electroactive composites consisting of a ferroelectric ceramic in a polymer matrix have attracted a lot of interest as compliant electroactive sensors. Composite properties are generally dictated by the choice of constituent materials and the connectivity of the phases. A ceramic powder randomly dispersed in a polymer matrix is referred to as having 0-3 connectivity. For thin composite films, where the ceramic grain size is comparable to the film thickness, or with high ceramic volume content the degree of ceramic connectivity throughout the composite thickness will be enhanced over thick or low ceramic volume content composites. This paper reports on the experimental and theoretical characterisation of two different mixed connectivity composites, one with a polar polymer matrix and another with a non-polar matrix. Results are given on dielectric and piezoelectric measurements and compared with theoretical results.