Piezoelectric properties of rolled vinylidene fluoride and trifluoroethylene copolymer

Abstract

Abstract Rolled film of a 52/48 mol% vinylidene fluoride (VDF) and trifluoroethylene (TrFE) copolymer is found to have a large value of piezoelectric strain constant (d 31) as 49 pC/N (110 Hz at 23°C). All of the rolled VDF 52, 65 and 73 mol% films show large values of piezoelectric stress constant (e 31) as 51, 50 and 50 mC/m2, respectively. The rolled VDF 52 mol% film shows a small value of the tensile modulus (G 11) as 10.4 × 108 N/m2, while the rolled VDF 65 and 73 mol% films exhibit large values of G 11 as 20 and 36 × 108 N/m2, respectively. The equation, e 31 = G 11 d 31, indicates that a large value of d 31 of the rolled VDF 52 mol% film is due to a large value of e 31 and a small value of G 11. It is found that a large value of e 31 arises from a large value of the remanent polarization (Pr) as 102 mC/m2 and to a large value of e 31/Pr as 0.5, and that a small value of G 11 arises from the low crystallinity.