scholarly journals Effect of fabrication technique on the crystalline phase and electrical properties of PVDF films

2015 ◽  
Vol 33 (1) ◽  
pp. 157-162 ◽  
Author(s):  
P. K. Mahato ◽  
A. Seal ◽  
S. Garain ◽  
S. Sen
Keyword(s):  
Polyvinylidene Fluoride ◽  
Tape Casting ◽  
Dimethyl Formamide ◽  
Pvdf Film ◽  
X Ray Diffraction ◽  
Β Phase ◽  
Cast Films ◽  
Solvent Cast ◽  
Ft Ir ◽  
Ferroelectric Hysteresis

AbstractThe effect of different fabrication techniques on the formation of electroactive β-phase polyvinylidene fluoride (PVDF) has been investigated. Films with varying concentration of PVDF and solvent - dimethyl formamide (DMF) were synthesized by tape casting and solvent casting techniques. The piezoelectric β-phase as well as non polar β-phase were observed for both the tape cast and solvent cast films from X-ray diffraction (XRD) micrographs and Fourier transform infra-red spectroscopy (FT-IR) spectra. A maximum percentage (80 %) of β-phase was obtained from FT-IR analysis for a solvent cast PVDF film. The surface morphology of the PVDF films was analyzed by FESEM imaging. The dielectric properties as a function of temperature and frequency and the ferroelectric hysteresis loop as a function of voltage were measured. An enhancement in the value of the dielectric constant and polarization was obtained in solvent cast films.

ELECTROMECHANICAL CHARACTERISTICS OF POLYVINYLIDENE FLUORIDE FOR FLEXIBLE ELECTRONICS

2013 ◽  
Vol 37 (3) ◽  
pp. 325-333 ◽  
Author(s):  
Wen-Yang Chang ◽  
Cheng-Hung Hsu
Keyword(s):  
Flexible Electronics ◽  
Polyvinylidene Fluoride ◽  
Input Voltage ◽  
Pvdf Film ◽  
Resistive Load ◽  
X Ray Diffraction ◽  
Leakage Currents ◽  
Current Voltage ◽  
Current Voltage Characteristics ◽  
Stress Cycles

The electromechanical characteristics of PVDF are investigated, including the crystallization, frequency responses, hysteresis, leakage currents, current-voltage characteristics, and fatigue characteristics using X-ray diffraction and an electrometer. Results show that the frequency band of PVDF increases with increasing resistive load and capacitance. The hysteresis area of ΔH slightly increases with increasing input voltage. The magnitude of the current values increases with decreasing delay time at a given drive voltage. PVDF film induced larger degradation when the number of stress cycles was increased to about 105 cumulative cycles.

Structural and Electrical Changes in BIMNVOX Oxide-Ion Conductor

2011 ◽  
Vol 316-317 ◽  
pp. 7-22 ◽  
Author(s):  
Saba Beg ◽  
Shehla Hafeez ◽  
Niyazi A.S. Al-Areqi
Keyword(s):  
Solid Solutions ◽  
X Ray Diffraction ◽  
Structural Investigations ◽  
Ion Conductor ◽  
Polymorphic Transitions ◽  
Oxide Ion Conductor ◽  
Β Phase ◽  
Ft Ir ◽  
Increasing Temperature ◽  
Oxide Ion

Ceramic solid solutions Bi4MnxV2–xO11–(x/2)–δ in the composition range 0.07 ≤ x ≤ 0.30 were obtained by solid state synthesis. Structural investigations were carried out by using a combination of FT-IR and powder X-ray diffraction technique. Polymorphic transitions (β↔γ and γ′↔γ) were detected by DTA and variation in the Arrhenius plots of conductivity. The solid solutions with composition 0.07 ≤ x ≤ 0.17 are isostructural with the orthorhombic β-phase, and those with x ≤ 0.30 represent tetragonal γ-phase. With increasing Mn concentration, the conductivity of solid solutions increases from 3.684×10-6 (x = 0.07) to 2.467×10-5 (x = 0.17). AC impedance plots show that the conductivity is mainly due to the grain contribution which is evident in the enhanced short range diffusion of oxide ion vacancy in the grains with increasing temperature.

scholarly journals Characteristics and Preparation of PVDF Catalytic Membrane Modified by Nano-TiO2/Fe3+

2013 ◽  
Vol 7 (1) ◽  
pp. 39-43
Author(s):  
Xi Lijun ◽  
Zhang Li ◽  
Li Li ◽  
Chi Jingyuan ◽  
Lu Junchi ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Polyvinylidene Fluoride ◽  
Sol Gel ◽  
Water Flux ◽  
Catalytic Membrane ◽  
X Ray Diffraction ◽  
Pvdf Membrane ◽  
Tio2 Sol ◽  
Ft Ir ◽  
Good Filtration

The polyvinylidene fluoride (PVDF)/Fe3+-TiO2 catalytic membrane was prepared by sol-gel method. It was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), FT-IR spectrum (FT-IR), mechanics capability, water flux, pepsin retention, porosity and contact angle etc. The catalytic activity of PVDF/Fe3+-TiO2 catalytic membrane was evaluated by the degradation of refractory dye Orange IV in the presence of H2O2. The results show that the addition of appropriate nano-sized TiO2 sol in the preparation of PVDF membrane has greatly improved some properties of the membrane such as microstructure, hydrophilic ability, mechanics intensity and water flux etc. The addition of Fe3+ ion in the preparation of PVDF membrane has greatly improved its catalytic activity to decompose H2O2. The catalytic activity of PVDF/Fe3+ -TiO2 is increased with the increase of the content of Fe3+ ion. When the content of Fe3+ _TiO2 sol is 21%, the content of Fe3+ ion is from 0.02% to 0.12%, the discolorization rate of Orange IV in this Fenton-like oxidation is from 61.2% to 90.5%. The catalytic activity of PVDF/Fe3+-TiO2 is not changed with the increase of the content of nano-sized TiO2. This kind of PVDF/Fe3+ -TiO2 catalytic membrane has not only good filtration efficiency but also good catalytic activity to effectively decompose H2O2.

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

2007 ◽  
Vol 124-126 ◽  
pp. 299-302 ◽  
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.

scholarly journals Solvent-Mediated Eco-Friendly Synthesis and Characterization of Monodispersed Bimetallic Ag/Pd Nanocomposites for Sensing and Raman Scattering Applications

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
G. Sathiyadevi ◽  
B. Loganathan ◽  
B. Karthikeyan
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Dimethyl Formamide ◽  
X Ray Diffraction ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Bimetallic Nanocomposites ◽  
Ft Ir

The solvent-mediated eco-friendly monodispersed Ag/Pd bimetallic nanocomposites (BNCs) having thick core and thin shell have been prepared through novel green chemical solvent reduction method. Reducing solvent, dimethyl formamide (DMF) is employed for the controlled green synthesis. Characterization of the synthesized Ag/Pd BNCs has been done by x-ray diffraction (XRD) studies, high-resolution scanning electron microscopy (HR-SEM), energy-dispersive X-ray analysis (EDX), and high-resolution transmission electron microscopy (HR-TEM) with selected area electron diffraction (SAED) pattern. The nature of the interaction of L-cysteine with Ag/Pd BNCs has been studied by using surface plasmon spectroscopy, Fourier transform-infrared spectroscopy (FT-IR), cyclic voltammetry (CV), and theoretical methods.

Crystalinity Properties of Carbon Nanotube-Polyvinylidene Fluoride Composites

2008 ◽  
Vol 1134 ◽  
Author(s):  
Xiaobing Shan ◽  
Pei-xuan Wu ◽  
Lin Zhang ◽  
Zhong-Yang Cheng
Keyword(s):  
Differential Scanning Calorimetry ◽  
Carbon Nanotube ◽  
Acid Treatment ◽  
Polyvinylidene Fluoride ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Β Phase ◽  
Solution Cast ◽  
Solution Cast Method

AbstractSingle-wall and multi-wall carbon nanotube blends (0 to 0.5 vol% ) with polyvinylidene fluoride (PVDF) have been prepared using solution cast method and characterized. By acid treatment, it has been observed that nanotube has been well functionalized and uniformly dispersed into the polymer. X-ray diffraction analysis coupled with differential scanning calorimetry (DSC) has revealed that carbon nanotube alters the crystallinity of PVDF and thereby enhances the β-phase in PVDF. Experimental results have demonstrated that enhancement of β-phase is a function of carbon nanotube concentration.

Properties of PVDF films stretched in machine direction

2020 ◽  
pp. 096739112091059
Author(s):  
TS Roopa ◽  
HN Narasimha Murthy ◽  
DVN Harish ◽  
Anjana Jain ◽  
Gangadhar Angadi
Keyword(s):  
Electron Microscopy ◽  
Polyvinylidene Fluoride ◽  
Piezoelectric Properties ◽  
Gray Relational Analysis ◽  
X Ray Diffraction ◽  
Polar Solvents ◽  
Β Phase ◽  
Transmission Electron ◽  
Diffraction Peaks ◽  
Mechanical Stretching

Polyvinylidene fluoride (PVDF) films possess superior piezoelectric properties due to the β-phase obtained by methods, such as addition of nanofillers, application of high electric field, use of polar solvents and mechanical stretching. Simultaneous stretching and heating of the films can reduce porosity, increase transformation from α-phase to β-phase, and hence, improve their piezoelectric properties. This article presents the effects of stretching PVDF films on the β-phase formation and the resulting mechanical properties. A custom-designed stretching unit with roller mechanism and heating provision was employed for the purpose. The 200% stretched films at 100°C showed 86.79% β-phase, which is in correlation with X-ray diffraction peaks at 2 θ = 20.3–20.6°. Transmission electron microscopy and scanning electron microscopy of the stretched films revealed spherulitic to lamellar transformation and decrease in porosity. Stretching increased crystallinity from 32.99% to 44.84%. Nanoindentation results showed increase in hardness and Young’s modulus from 23.33 MPa to 93.3 MPa and 0.483 GPa to 1.816 GPa, respectively. Tensile strength increased from 4.72 MPa to 21.02 MPa. The experiments were conducted using L9 orthogonal array and the results were analyzed using analysis of variance and gray relational analysis.

Fabrication, Characterization and Investigation of Novel PVDF/ZnO and PVDF-TrFE/ZnO Nanocomposites with Enhanced β-Phase and Dielectricity

2020 ◽  
Vol 977 ◽  
pp. 277-282
Author(s):  
Ming Ran Liu
Keyword(s):  
Human Body ◽  
Polyvinylidene Fluoride ◽  
Pressure Sensors ◽  
Nucleating Agent ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Zno Nanostructure ◽  
Β Phase ◽  
Arterial Blood ◽  
Sensing Material

To date, flexible, sensitive and biocompatible pressure sensors for fluctuation signals in human body have been mainly demonstrated for detecting body and muscle motion, pulse rate, heart rate and arterial blood pressure. However, because of the lack of sufficient sensitivity and flexibility, pulse signals with relatively low intensity cannot be identified and captured, such as signals derived from microcirculation in human body. As confirmed and validated by researchers, once PVDF and its copolymer based nanocomposite sensing material are applied in piezoelectric sensors, its sensitivity and piezoelectricity are highly relevant. Therefore, as one of the most effective methods to improve the permittivity and piezoelectricity of PVDF and its copolymer based nanocomposite, the effect of increasing the content of β-phase crystal was investigated in this work. In this project, the sensor possessing a novel sensing layer with the nanofiller was investigated and fabricated. The proposed sensor was designed in a simple but efficient sandwich structure. The sensing layer of the proposed sensor was made of polyvinylidene fluoride (PVDF) and polyvinylidenefluoride-trifluoroethylene (PVDF-TrFE) based nanocomposite with Zinc Oxide (ZnO) nanostructure acting as a filler portion which was fabricated by the method of Chemical Bath Deposition (CBD). The fabricated nanocomposite sensing layers were characterized. The microstructures and morphologies of pristine PVDF (P), PVDF-TrFE (PT), PVDF/ZnO (P/Z) and PVDF-TrFE/ZnO (PT/Z) with different concentration were characterized by Scanning Electron Microscope (SEM). The degree of crystallinity for P, PT, P/Z and PT/Z was obtained by X-ray Diffraction meter (XRD). In conclusion, PT exhibited better performance in both morphology and crystallinity as a sensing membrane material. More β‐phase in PT was obtained than that in P. ZnO, as a semiconductor filler, would have substantial influence on enhancing the dielectric constant by acting as a nucleating agent and forming a nanostructure with large aspect ratio.

Leakage and Fatigue Characteristics of Polyvinylidene Fluoride Film

2013 ◽  
Vol 284-287 ◽  
pp. 158-162
Author(s):  
Wen Yang Chang ◽  
Cheng Hung Hsu ◽  
Chih Ping Tsai
Keyword(s):  
Flexible Electronics ◽  
Delay Time ◽  
Polyvinylidene Fluoride ◽  
Input Voltage ◽  
Pvdf Film ◽  
Resistive Load ◽  
X Ray Diffraction ◽  
Leakage Currents ◽  
Pass Filter ◽  
Fatigue Characteristics

The leakage and fatigue characteristics of polyvinylidene fluoride (PVDF) are investigated for flexible electronics. The crystallization, frequency responses, leakage currents, current-voltage characteristics, and fatigue characteristics of PVDF film are measured using X-ray diffraction and an electrometer. Results show that a PVDF model with a resistive load exhibits high-pass filter characteristics. The frequency band of PVDF film increases with increasing resistive load and capacitance. The break frequencies for 100 kΩ, 300 kΩ, 700 kΩ, and 1 MΩ at the break frequency are 611, 207, 88, and 61 Hz, respectively. The hysteresis area of ΔH slightly increases with increasing input voltage. The leakage current of PVDF film is higher for a lower delay time under a given applied electric field. The average leakage currents for delay times of 10 and 1000 ms are 0.565 and 73.8 pA, respectively. The magnitude of the current values increases with decreasing delay time at a given drive voltage. PVDF film induced larger degradation when the number of stress cycles was increased to about 105 cumulative cycles.

scholarly journals Development of poly (vinylidene fluoride)/silver nanoparticle electrospun nanofibre mats for energy harvesting

2021 ◽  
pp. 096739112110420
Author(s):  
Roopa Thotadara Shivalingappa ◽  
Hebbale Narayana Rao Narasimha Murthy ◽  
Pradeep Purushothaman ◽  
Prasanna Badiger ◽  
Swapnil Savarn ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Polyvinylidene Fluoride ◽  
Vinylidene Fluoride ◽  
Piezoelectric Materials ◽  
Applied Pressure ◽  
Fibre Diameter ◽  
X Ray Diffraction ◽  
Β Phase ◽  
Fourier Transformed Infrared Spectroscopy ◽  
Poly Vinylidene Fluoride

Energy harvesting using piezoelectric materials finds attention of researchers due to miniaturisation. Polyvinylidene fluoride (PVDF) is one such polymeric material with high piezoelectric and pyroelectric properties and hence is used for sensors, actuators, energy harvesting and biomedical devices. This study reports electrospinning of PVDF/Ag nanoparticles (AgNP) nanofibre mats for energy harvesting. Nanofibre mats were prepared by adopting voltage (20 kV), flow rate (1.5 mL/hour) and tip to collector distance (19 cm). The fibre mats were characterised using Fourier-Transformed Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). FTIR and XRD results showed 11.84% and 36.36% increase in β-phase and crystallinity, respectively, due to the addition of 1.5 wt. % AgNP to PVDF. SEM micrographs showed decrease in bead formation and increase in fibre diameter from 40 nm to 355 nm due to the addition of AgNP. Sensitivity and voltage output were studied. The fibre mats were used for development of a miniature burglar alarm system, and its response to the applied pressure was tested.

Sign in / Sign up

Export Citation Format

Share Document