The mechanical properties of lead-titanate/polymer 0–3 composites

The stiffness and brittleness of pure piezoelectric ceramics limit the application of these materials as embedded sensors within composites. Thin-film compliant sensors have recently been developed by incorporating piezoelectric ceramic particles in a polymer matrix. When embedded in thicker composite structures, these thin-film sensors may be useful in monitoring internal mechanical conditions such as the evolution of damage. The mechanical properties of 0–3 composite films of calcium-modified lead titanate in Epon 828 epoxy and poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) matrices have been investigated in this work. The linear viscoelastic properties of these thin-film composites are measured, and the influences of strain, frequency, and ceramic content on these properties are investigated. Analytical and finite-element modeling are used to predict the effective viscoelastic properties of the composites, and these predictions are compared with the experimental results. The storage moduli predicted by these models are comparable to experimental results, while the predicted loss moduli are significantly less than the measured loss moduli. It is shown that the introduction of a third “interphase” layer at the ceramic/polymer boundary within the finite element model results in a better fit to the experimental data.