Temperature dependence of the electromechanical properties of ceramic polymer composite materials for hydrophone applications

Abstract

The real and imaginary parts of the complex elastic, dielectric, and piezoelectric properties of two types of commercial piezoelectric composite materials were studied as a function of temperature from − 70°C to + 50°C using an electrical resonance technique described previously [J. Acoust. Soc. Am. Suppl. 1 82, S101 (1987)]. These materials consist of ceramic particles embedded in a polymer material and possess improved hydrostatic sensitivity as well as mechanical flexibility in comparison with conventional piezoelectric ceramics. Measurements of the temperature dependence of the hydrostatic piezoelectric coefficients have also been performed. The interrelationship of the properties is complicated by the presence of the glass transition of the elastomeric phase of the composite material where sharp changes in the electmechanical transition causes typical relaxation behavior in the complex elastic coefficients and a peak in the dielectric properties. The transition was studied further by the use of differential scanning calorimetry in order to corroborate the results of the resonance measurements. The results demonstrate some difficulties in using these particular materials and indicate that other polymeric materials should be investigated for use in these composite materials. [Work supported by ONR.]