Electric‐field‐induced phase changes in polyvinylidene fluoride: Effects from corona polarity and moisture

In this paper, molecular models are used to investigate and analyze the polarization switching in the polyvinylidene fluoride (PVDF) and poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) Langmuir-Blodgett (LB) nanofilms, in comparison with the experimental data at the nanoscale. Quantum-mechanical calculations and modeling, as well as molecular dynamics (MD) simulations based on semi-empirical quantum-chemical methods (such as PM3), show that the energy of the studied PVDF and P (VDF-TrFE) molecular structures, and their polarization switching proceed by the intrinsic homogeneous switching mechanism in the framework of the phenomenological theory of Landau-Ginzburg-Devonshire (LGD) in the linear approximation at low values of the electric field. The magnitude of the resulting critical coercive field is within the EC ~ 0.5 ... 2.5 GV/m, which is consistent with experimental data. It is also found that the uniform polarization switching mechanism of the polymer chains PVDF and P (VDF-TrFE) is due to the quantum properties of the molecular orbitals of the electron subsystem. This is clearly seen in both the polarization hysteresis loops, and the total energy changes. In this case, the turnover chain time, obtained by molecular dynamics within semi-empirical quantum-chemical PM3 approach in a limited Hartree-Fock approximation, when approaching this critical point, increases sharply, tending to infinity, which corresponds to the theory of LGD. Otherwise, at the high values of the applied electric field the polarization switching correspond to the extrinsic domain mechanism in the frame of the microscopic Kolmogorov–Avrami–Ishibashi (KAI) theory, describing bulk ferroelectric crystals and thick films. The performed analysis of computational and experimental data allows us to estimate the critical sizes of the possible transition region approximately on the order of 10 nm between intrinsic homogeneous and extrinsic domain switching mechanisms.

Download Full-text

Thermal stability of internal electric field and polarization distribution in blend of polyvinylidene fluoride and polymethylmethacrylate

Journal of Applied Physics ◽

10.1063/1.354562 ◽

1993 ◽

Vol 74 (5) ◽

pp. 3366-3372 ◽

Cited By ~ 13

Author(s):

Naoto Tsutsumi ◽

Yoshiaki Ueda ◽

Tsuyoshi Kiyotsukuri ◽

Aimé S. DeReggi ◽

G. Thomas Davis

Keyword(s):

Thermal Stability ◽

Electric Field ◽

Polyvinylidene Fluoride ◽

Internal Electric Field ◽

Polarization Distribution ◽

Thermal Stability Of

Download Full-text

Pre-Strained Piezoelectric PVDF Nanofiber Array Fabricated by Near-Field Electrospining on Cylindrical Process for Flexible Energy Conversion

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.566.462 ◽

2012 ◽

Vol 566 ◽

pp. 462-465 ◽

Cited By ~ 2

Author(s):

Zong Hsin Liu ◽

Li Wei Lin ◽

Cheng Teng Pan ◽

Zong Yu Ou

Keyword(s):

Electric Field ◽

Energy Conversion ◽

Polyvinylidene Fluoride ◽

Near Field ◽

Low Frequency ◽

Glass Tube ◽

Copper Electrode ◽

Ambient Vibration ◽

Induced Voltage ◽

Β Phase

In this study, near-field electrospining on hollow cylindrical (NFES) process was used to fabricate permanent piezoelectricity of polyvinylidene fluoride (PVDF) piezoelectric nanofibers. With in situ electric poling, mechanical stretching and heating during NFES process, the pre-strained piezoelectric PVDF nanofibers with high stretchability and energy conversion efficiency can be applied at low-frequency ambient vibration to convert mechanical energies into electrical signals. By adjusting rotating velocity of the hollow cylindrical glass tube on X-Y stage, electric field, baking temperature and carbon nanotube (CNT) concentration in PVDF solution, the crystalline of β phase, polarization intensity and morphology of piezoelectric fiber can be controlled. XRD (X-ray diffraction) observation of PVDF fibers was characterized. With electric field 0.5×107 V/m (needle-to-tube distance 2 mm and DC voltage 5 kV), rotating velocity 400 r.p.m, baking temperature 80 °C and 0.03 wt% CNT in NFES process, it reveals a high diffraction peak at 2θ=20.8° of piezoelectric crystal β-phase structure. Then the array nanofibers were transferred onto a parallel copper electrode by using flexible insulation epoxy/PI film to provide packaging protection. When the sensor was tested under 5 Hz vibration frequency, the maximum induced voltage was 29.4 mVp-p.

Download Full-text

Heartbeat Monitoring Technique Based on Corona-Poled PVDF Film Sensor for Smart Apparel Application

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.124-126.299 ◽

2007 ◽

Vol 124-126 ◽

pp. 299-302 ◽

Cited By ~ 18

Author(s):

You Min Chang ◽

Jong Soon Lee ◽

Kap Jin Kim

Keyword(s):

Electric Field ◽

Polyvinylidene Fluoride ◽

Ferroelectric Properties ◽

Computer Applications ◽

Polymer Materials ◽

Pvdf Film ◽

Internal Electric Field ◽

Film Sensor ◽

Β Phase ◽

Voltage Amplifier

Flexible piezoelectric polymer materials for smart apparel and wearable computer applications are of great interest. Among known ferroelectric and piezoelectric polymers, polyvinylidene fluoride (PVDF) exhibit β-phase under poling and is known to give highest piezo-, pyro-, and ferroelectric properties. Previous reports suggests that, during corona poling of the PVDF film, a high surface electric potential is generated resulting in a high internal electric field within the polymer film causing the polarization of the dipoles along the direction of the applied electric field. The resultant phase change from α- to β-phase and the dipole switching generates displacement of charges or piezoelectricity. And also mechanical variation would change dipole density of PVDF film. In this report, we measured human heartbeat signal from an DAQ interfaced with a custommade voltage-amplifier with specific frequency filtering function using the corona-poled PVDF film of various sizes and thickness as a piezoelectric sensor and analyzed it. We employed elastic textile band to sensor system for comfortable fit on wrist or ankle. And then, we found the feasibility of applying flexible PVDF film sensor to smart apparel application which can sense heartbeat rate, blood pressure, respiration rate, accidental external impact on human body, etc.

Download Full-text

Orientation Behaviors in Polyvinylidene Fluoride Film under Electric Field

Japanese Journal of Applied Physics ◽

10.1143/jjap.20.l59 ◽

1981 ◽

Vol 20 (1) ◽

pp. L59-L62 ◽

Cited By ~ 8

Author(s):

Nobuyuki Takahashi ◽

Akira Odajima

Keyword(s):

Electric Field ◽

Polyvinylidene Fluoride

Download Full-text

Electric‐field‐induced phase changes in poly(vinylidene fluoride)

Journal of Applied Physics ◽

10.1063/1.324446 ◽

1978 ◽

Vol 49 (10) ◽

pp. 4998-5002 ◽

Cited By ~ 436

Author(s):

G. T. Davis ◽

J. E. McKinney ◽

M. G. Broadhurst ◽

S. C. Roth

Keyword(s):

Electric Field ◽

Vinylidene Fluoride ◽

Phase Changes ◽

Poly Vinylidene Fluoride

Download Full-text

Pyroelectricity and the electric field dependence of crystallinity in polyvinylidene fluoride

Ferroelectrics ◽

10.1080/00150198408012759 ◽

1984 ◽

Vol 57 (1) ◽

pp. 151-158 ◽

Cited By ~ 19

Author(s):

R. G. Kepler ◽

R. A. Anderson ◽

R. R. Lagasse

Keyword(s):

Electric Field ◽

Field Dependence ◽

Polyvinylidene Fluoride ◽

Electric Field Dependence

Download Full-text

Hot pressing process ameliorates internal defects of PBZ/PVDF composite film for a high electrocaloric effect near room temperature

Functional Materials Letters ◽

10.1142/s1793604722510067 ◽

2021 ◽

Author(s):

Guoming Qian ◽

Kongjun Zhu ◽

Kang Yan ◽

Jing Wang ◽

Jinsong Liu ◽

...

Keyword(s):

Electric Field ◽

Composite Film ◽

Hot Pressing ◽

Polyvinylidene Fluoride ◽

Organic Polymer ◽

Interface Problem ◽

Pvdf Film ◽

Internal Defects ◽

Electrocaloric Effect ◽

The Impact

The poor interface compatibility between inorganic fillers and organic polymer matrix in nanocomposite has presented considerable challenges, which limit the applicable electric field ranges and reduce the interface polarization interaction. In this paper, Pb[Formula: see text]Ba[Formula: see text]ZrO3 (PBZ) nanofibers were introduced into the polyvinylidene fluoride (PVDF) matrix to prepare composite film, and the effect of hot pressing on interface compatibility was investigated at volume composite ratios of 3% and 4%. For the untreated film, [Formula: see text] and [Formula: see text] of the 3 vol.% composite film are 9.68 [Formula: see text]C/cm2 and 401 MV/m, respectively, and those for the 4 vol.% composite film are 9.15 [Formula: see text]C/cm2 and 408 MV/m, respectively. These differences are mainly due to the impact of internal defects. After hot pressing, [Formula: see text] and [Formula: see text] for the 3 vol.% composite film became 10.22 [Formula: see text]C/cm2 and 490 MV/m, respectively. Those for the 4 vol.% composite film are 9.85 [Formula: see text]C/cm2 and 485 MV/m. Experiment and simulation results showed the beneficial effect of hot pressing, which ameliorated poor interfacial compatibility, reduced internal defects, and improved the crystallinity of the composite film. A high electrocaloric effect (ECE) was obtained by using the direct measure method. At −30[Formula: see text]C, the [Formula: see text] values of hot-pressed PBZ/PVDF film at 3[Formula: see text] and 4[Formula: see text] vol.% were 23.81 and 19.73 K, respectively. When temperature increased to 70[Formula: see text]C, the [Formula: see text] values were 9.44 and 7.01 K, respectively, which were 1.58 times of the values of a non-hot-pressed film. These results indicated that hot pressing alleviated the interface problem and resulted in high EC performance under a high-strength electric field.

Download Full-text