DIELECTRIC PIEZOELECTRIC AND PYROELECTRIC PROPERTIES OF VDF-TRFE COPOLYMERS.

The dielectric, piezoelectric and pyroelectric properties of vinylidene fluoride (VDF)-trifluoroethylene (TrFE) copolymers with 56:44 and 70:30 VDF:TrFE ratios have been determined as functions of temperature and poling field. Piezoelectric coefficients of d//3//1 equals d//3//2 equals 21. 4 pCN** minus **1 and d//3//3 equals -52 pCN** minus **1 have been measured on solvent-cast 56:44 films 70 mu m thick. Similarly, values of d//3//1 equals d//3//2 equals 17. 1 pCN** minus **1 and d//3 //3 equals -40. 6 pCN** minus **1 have been recorded for the 70:30 composition. The effects on the piezoelectric properties of aging the films at 70 degree C for periods up to 24 h are reported. Pyroelectric coefficients have been measured on poled films using a chopped source of infrared radiation to heat the samples. Pyroelectric coefficients of 20 multiplied by 10** minus **6 cm** minus **2K** minus **1 were recorded which are similar to those of PVDF. The potential of these materials for piezoelectric and pyroelectric applications is discussed.