Determination of polymer shear modulus with quartz crystal resonators

Abstract

The dependence of the electrical response of polymer-coated acoustic wave sensors on the viscoelastic properties of the coating material is used for the determination of the complex shear parameter of thin polymer films. We discuss the acoustic behaviour and the electrical response of a coated quartz crystal vibrating in the thickness shear mode at its fundamental frequency as well as its third and fifth harmonic. The changes in material properties were induced by temperature changes. Both a glassy and a rubbery polymer consistency were investigated. We also discuss the concept of impedance analysis and parameter fitting to extract the coating shear parameters and we introduce a double layer concept for the direct calculation of the polymer shear parameters.