Transduction phenomena in ferroelectric polymers and their role in pressure transducers

Abstract The facts (1) that the piezo and pyroelectricity of polyvinylidene fluoride (PVF2) is largely secondary, and (2) that polymers in general have large thermal expansion coefficients, are responsible for transduction properties where piezo and pyroelectric effects may have to be considered together. In particular, in a PVF2 transducer subjected to compression, the adiabatic compressional heating of the polymer is calculated to give a pyroelectric response amounting to approximately -10 percent of the isothermal piezoelectric response to the same compression. The thermal time constant governing the heat exchange between the polymer and its surrounding thus is an important design parameter. This time constant sets a crossover frequency between adiabatic and nonadiabatic response.