Influence of extrusion, stretching and poling on the structural and piezoelectric properties of poly (vinylidene fluoride‐hexafluoropropylene) copolymer films

Abstract

Three types of poly (vinylidene fluoridehexafluoropropylene) (PVDF-HFP) copolymer films were prepared by extrusion, stretching as well as simultaneously stretching and static electric field poling (SSSEP), respectively, and measured by the differential scanning calorimetric, wide angle X-ray diffraction, fourier transformation infrared-attenuated total reflection, and Dynamic mechanical analysis. The experimental results showed that the films prepared by stretching and SSSEP have higher crystallinity and b phase than by extrusion. SSSEP improved the chain orientation enormously both in crystalline and amorphous regions, resulting in the highest storage modulus. Because of the lower b phase content, the extruded films exhibited the lowest piezoelectric coefficient d 33 . For the stretched and SSSEP films, although the b phase content was similar, the d 33 was distinct because of the different potential energy for the rotation of the dipoles. In addition, the SSSEP films gave the maximum d 33 (24 pC/N), higher than the other PVDF-HFP copolymer films that have been reported.

Thermal Stability and Magnetic Properties of Polyvinylidene Fluoride/Magnetite Nanocomposites

“…For instance, when electric field poling at 35 MV/m was chose as a point for comparison, the values of d 33 for poling samples are about five times in magnitude higher than the samples without electric field poling. The obtained d 33 values are almost the same order as those reported in the literatures, but the used electric field is much smaller [ 30 , 31 , 32 ]. The d 33 value of nanocomposites using the same experimental condition of electric field poling was higher than the data of pure PVDF matrix, which might be attributed to the incorporation of magnetite nanoparticles with negative surface charge.…”

Flexible tri-layer piezoelectric nanogenerator based on PVDF-HFP/Ni-doped ZnO nanocomposites

“…The samples were coated with silver paste prior to the piezoelectric experiments. Many studies observed the piezoelectric properties of PVDF-HFP and its nanocomposites, 53,54 but less attention was paid to the piezoelectric effect enhanced by lattice strain of the nanollers. 55 So far, the piezoelectric property of the composites was attributed to the b-phase fraction, ller dispersion and alignment of dipole moment.…”

A comparison of two different methods for formation of the beta phase in nanocomposites based on vinylidene fluoride-hexafluoropropylene copolymer

“…, where: A α and A β -are the heights of the peaks at 764 and 840 cm −1 , respectively, and the coefficient 1.26 represents the ratio of the absorption coefficients at 764 and 840 cm −1 [9][10][11].…”