Piezoelectric Properties in Polarized Poly(vinyl Fluoride)

Poly(vinyl fluoride) films were elongated twice the original length by rolling, subjected to a d.c. field of 350 kV/cm at 80°C for 90 minutes, and cooled down to room temperature for 2 hours. The piezoelectric strain-constant d of the electret films was about 1×10 -8 cgs esu at room temperature. The complex piezoelectric, elastic, and dielectric constants showed two dispersions at the low and high temperatures, respectively. The maximum value of piezoelectric loss factor tan δ d is roughly the same as the sum of the maximum values of elastic and dielectric loss factor tan δ E and tan δ ε . This fact may be explained by assuming that the piezoelectric constant h is a real quantity.