Piezo-electric properties of polypropylene laminates with a non-woven layer

In the paper piezoelectric properties of non-uniform dielectric structures with elastic layers made from unwoven fabric are presented. Piezoelectric properties of the samples were studied through measurement of piezoelectric d coefficient, and carried out in dependence on static pressure. The characteristics d =f (p) obtained for the laminates were hyperbolic type. In order to elucidate this kind of relationship, a theoretical model has been proposed. Based on the new model, the calculated d piezoelectric coefficients showed good agreement with the experimental results. According to the model developed, the d (p) 33 33 33 33 dependence is related to the changes of the unwoven structure elastic modulus Y under the influence of static pressure. The magnitude of this change is strongly influenced by the structure of the non-uniform layer, including the fiber diameter, the number of fibers and their arrangement, and the fiber elasticity modulus.