scholarly journals Enhancement of the piezoelectric coefficient in PVDF-TrFe/CoFe2O4 nanocomposites through DC magnetic poling

2021 ◽  
Vol 12 ◽  
pp. 1262-1270
Author(s):  
Marco Fortunato ◽  
Alessio Tamburrano ◽  
Maria Paola Bracciale ◽  
Maria Laura Santarelli ◽  
Maria Sabrina Sarto
Keyword(s):  
Piezoelectric Coefficient ◽  
Vinylidene Fluoride ◽  
Piezoelectric Materials ◽  
Low Cost ◽  
Wearable Sensors ◽  
Polymer Nanocomposite ◽  
Sample Surface ◽  
Β Phase ◽  
Phase Alignment ◽  
Poly Vinylidene Fluoride

In the last years flexible, low-cost, wearable, and innovative piezoelectric nanomaterials have attracted considerable interest regarding the development of energy harvesters and sensors. Among the piezoelectric materials, special attention has been paid to electroactive polymers such as poly(vinylidene fluoride) (PVDF) and its copolymer poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFe), which is one of the most extensively investigated piezoelectric polymers, due to the high β phase content resulting from specific curing or processing conditions. However, to obtain a high piezoelectric coefficient (d33) alignment of the β phase domains is needed, which is usually reached through applying a high electric field at moderate temperatures. This process, usually referred to as electrical poling, requires the deposition of contact electrodes on the sample surface and the use of high-voltage apparatus. In the present work, in order to overcome these constraints, we have produced, characterized, and studied a polymer nanocomposite consisting of CoFe2O4 nanoparticles dispersed in PVDF-TrFe with enhancement of the β phase alignment through an applied DC magnetic field. The magnetic poling was demonstrated to be particularly effective, leading to a piezoelectric coefficient d33 with values up to 39 pm/V. This type of poling does not need the use of a top electrode or of high magnetic fields (the maximum value of d33 was obtained at 50 mT, using a current of 0.4 A) making the PVDF-TrFE/CoFe2O4 nanocomposite suitable for the fabrication of highly efficient devices for energy harvesting and wearable sensors.

scholarly journals Enhancement of Piezoelectric Coefficient (d33) in PVDF-TrFe/CoFe2O4 nanocomposites through DC magnetic poling

2021 ◽  
Author(s):  
Marco Fortunato ◽  
Alessio Tamburrano ◽  
Maria Paola Bracciale ◽  
Maria Laura Santarelli ◽  
Maria Sabrina Sarto
Keyword(s):  
Magnetic Fields ◽  
Electric Fields ◽  
Piezoelectric Coefficient ◽  
Vinylidene Fluoride ◽  
Piezoelectric Materials ◽  
Low Cost ◽  
Sample Surface ◽  
Special Focus ◽  
Phase Alignment ◽  
Poly Vinylidene Fluoride

In the last years flexible, low-cost, wearable and innovative piezoelectric nanomaterials, have attracted a considerable interest to develop energy harvesters and sensors. Among the piezoelectric materials, a special focus was paid on  electroactive polymers such as Poly(vinylidene fluoride) [PVDF] and on its copolymer Poly(vinylidene fluoride-co-trifluoroethylene) [PVDF-TrFe], which is one of the most investigated piezoelectric polymers, due to the high β-phase content resulting under specific curing or processing conditions. However, to get high piezoelectric coefficient (d33), alignment of the β-phase domains is needed, which is usually obtained by applying a high electric fields at moderate temperatures. This process, usually referred as electrical poling, requires the deposition of contact electrodes over the sample surface, and the use of high voltage apparatus.   In the present work, in order to overcome these constraints we have produced, characterized and studied a polymer nanocomposite, consisting of CoFe2O4 nanoparticles dispersed in PVDF-TrFe with enhancement of the β-phase alignment through and applied a DC magnetic fields. The magnetic poling was demonstrated to be particular effective, leading to a piezoelectric coefficient, d33, with values up to 39 pm/V. The magnetic poling does not need the use a top electrode and of high magnetic fields (the maximum value of d33 was obtained at 50 mT, using a current of 0.4 A) making the PVDF-TrFE/CoFe2O4 nanocomposite suitable for the fabrication of highly efficient devices for energy harvesting and wearable sensors.

scholarly journals Phase Inversion in PVDF Films with Enhanced Piezoresponse Through Spin-Coating and Quenching

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1096 ◽  
Author(s):  
Fortunato ◽  
Cavallini ◽  
De Bellis ◽  
Marra ◽  
Tamburrano ◽  
...  
Keyword(s):  
Spin Coating ◽  
Phase Inversion ◽  
Vinylidene Fluoride ◽  
Wearable Sensors ◽  
Polymer Concentration ◽  
Low Viscosity ◽  
Β Phase ◽  
Best Value ◽  
Poly Vinylidene Fluoride ◽  
Mechanical Stretching

In the present work, poly(vinylidene fluoride) (PVDF) films were produced by spin-coating, and applying different conditions of quenching, in order to investigate the dominant mechanism of the β-phase formation. The influence of the polymer/solvent mass ratio of the solution, the rotational speed of the spin-coater and the crystallization temperature of the film on both the β-phase content and the piezoelectric coefficient (d33) were investigated. This study demonstrates that the highest values of d33 are obtained when thinner films, produced with a lower concentration of polymer in the solvent (i.e., 20 wt.%), go through quenching in water, at room temperature. Whereas, in the case of higher polymer concentration (i.e., 30 wt.%), the best value of d33 (~30 pm/V) was obtained through quenching in liquid nitrogen, at the temperature of 77 K. We believe that in the former case, phase inversion is mainly originated by electrostatic interaction of PVDF with the polar molecules of water, due to the low viscosity of the polymer solution. On the contrary, in the latter case, due to higher viscosity of the solution, mechanical stretching induced on the polymer during spin-coating deposition is the main factor inducing self-alignment of the β-phase. These findings open up a new way to realize highly efficient devices for energy harvesting and wearable sensors.

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.

scholarly journals Influences of poling temperature and elongation ratio on PVDF-HFP piezoelectric films

2021 ◽  
Vol 10 (1) ◽  
pp. 1009-1017
Author(s):  
Zhaonan Jin ◽  
Dan Lei ◽  
Yang Wang ◽  
Liangke Wu ◽  
Ning Hu
Keyword(s):  
High Efficiency ◽  
Vinylidene Fluoride ◽  
Low Cost ◽  
Maximum Output ◽  
Elongation Ratio ◽  
Scanning Calorimetry ◽  
Poling Process ◽  
Β Phase ◽  
Poly Vinylidene Fluoride ◽  
Mechanical Stretching

Abstract Poly(vinylidene fluoride) (PVDF) and its copolymers exhibit excellent piezoelectric properties and are potential materials for high efficiency energy harvesting devices. In this study, poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) films are prepared by the solution casting method. The prepared film is then subjected to mechanical stretching and poling process. By adjusting the temperature of the poling process and the elongation ratio of the mechanical stretching process, the relative content of β-phase F(β) increases significantly, leading to high piezoelectric performance. The maximum output voltage of the PVDF-HFP films poled at 40°C reaches 3.67 V, 71% higher than that of the films poled at room temperature. Fourier transform infrared spectroscopy analysis (FTIR), XRD (X-ray diffraction), and differential scanning calorimetry are used to investigate the influences of mechanical stretching and poling process on the crystal structure to discover the enhancement mechanism. This work provides a straightforward and low-cost route to prepare high piezoelectric PVDF-HFP-based materials.

High Efficient and Continuous Triboelectric Power Harvesting based on Porous β-phase Poly (vinylidene fluoride) Aerogel

2021 ◽  
Author(s):  
Minmin Wang ◽  
Weiqun Liu ◽  
Xu Shi ◽  
Jinyang Pan ◽  
Bing Zhou ◽  
...  
Keyword(s):  
Vinylidene Fluoride ◽  
High Electron ◽  
Exchange Method ◽  
Power Harvesting ◽  
Β Phase ◽  
Output Performance ◽  
High Electron Affinity ◽  
High Efficient ◽  
Poly Vinylidene Fluoride ◽  
High Output

Non-additive β-phase porous poly (vinylidene fluoride) (PVDF) aerogel with high electron affinity is successfully prepared through simple solvent exchange method. The as-prepared additive-free PVDF aerogel shows high output performance used...

scholarly journals Comparative Study of PVDF Sheets and Their Sensitivity to Mechanical Vibrations: The Role of Dimensions, Molecular Weight, Stretching and Poling

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1637
Author(s):  
Miroslav Mrlík ◽  
Josef Osička ◽  
Martin Cvek ◽  
Markéta Ilčíková ◽  
Peter Srnec ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Comparative Study ◽  
Vinylidene Fluoride ◽  
Initial Thickness ◽  
Complementary Method ◽  
Β Phase ◽  
Vibration Sensing ◽  
Poly Vinylidene Fluoride ◽  
Processing Techniques ◽  
The Comparative Study

This paper is focused on the comparative study of the vibration sensing capabilities of poly(vinylidene fluoride) (PVDF) sheets. The main parameters such as molecular weight, initial sample thickness, stretching and poling were systematically applied, and their impact on sensing behavior was examined. The mechanical properties of prepared sheets were investigated via tensile testing on the samples with various initial thicknesses. The transformation of the α-phase to the electro-active β-phase was analyzed using FTIR after applying stretching and poling procedures as crucial post-processing techniques. As a complementary method, the XRD was applied, and it confirmed the crystallinity data resulting from the FTIR analysis. The highest degree of phase transformation was found in the PVDF sheet with a moderate molecular weight (Mw of 275 kDa) after being subjected to the highest axial elongation (500%); in this case, the β-phase content reached approximately 90%. Finally, the vibration sensing capability was systematically determined, and all the mentioned processing/molecular parameters were taken into consideration. The whole range of the elongations (from 50 to 500%) applied on the PVDF sheets with an Mw of 180 and 275 kDa and an initial thickness of 0.5 mm appeared to be sufficient for vibration sensing purposes, showing a d33 piezoelectric charge coefficient from 7 pC N−1 to 9.9 pC N−1. In terms of the d33, the PVDF sheets were suitable regardless of their Mw only after applying the elongation of 500%. Among all the investigated samples, those with an initial thickness of 1.0 mm did not seem to be suitable for vibration sensing purposes.

scholarly journals Studies on the electrostatic effects of stretched PVDF films and nanofibers

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Yixuan Lin ◽  
Yuqiong Zhang ◽  
Fan Zhang ◽  
Meining Zhang ◽  
Dalong Li ◽  
...  
Keyword(s):  
Vinylidene Fluoride ◽  
Polarized Light ◽  
Transition Process ◽  
Open Circuit ◽  
Wearable Electronics ◽  
Energy Harvesters ◽  
Β Phase ◽  
Poly Vinylidene Fluoride ◽  
Piezoelectric Effects ◽  
Energy Harvesting Devices

AbstractThe electroactive β-phase in Poly (vinylidene fluoride, PVDF) is the most desirable conformation due to its highest pyro- and piezoelectric properties, which make it feasible to be used as flexible sensors, wearable electronics, and energy harvesters etc. In this study, we successfully developed a method to obtain high-content β-phase PVDF films and nanofiber meshes by mechanical stretching and electric spinning. The phase transition process and pyro- and piezoelectric effects of stretched films and nanofiber meshes were characterized by monitoring the polarized light microscopy (PLM) images, outputting currents and open-circuit voltages respectively, which were proved to be closely related to stretching ratio (λ) and concentrations. This study could expand a new route for the easy fabrication and wide application of PVDF films or fibers in wearable electronics, sensors, and energy harvesting devices.

scholarly journals Flexible Multiscale Pore Hybrid Self-Powered Sensor for Heart Sound Detection

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4508
Author(s):  
Boyan Liu ◽  
Liuyang Han ◽  
Lyuming Pan ◽  
Hongzheng Li ◽  
Jingjing Zhao ◽  
...  
Keyword(s):  
Piezoelectric Coefficient ◽  
Heart Sound ◽  
Piezoelectric Materials ◽  
Ferroelectric Material ◽  
Flexible Sensor ◽  
Β Phase ◽  
Short Processing Time ◽  
Sound Detection ◽  
Corona Poling ◽  
Self Powered

This research introduces an idea of producing both nanoscale and microscale pores in piezoelectric material, and combining the properties of the molecular β-phase dipoles in ferroelectric material and the space charge dipoles in order to increase the sensitivity of the sensor and modulate the response frequency bandwidth of the material. Based on this idea, a bi-nano-micro porous dual ferro-electret hybrid self-powered flexible heart sound detection sensor is proposed. Acid etching and electrospinning were the fabrication processes used to produce a piezoelectric film with nanoscale and microscale pores, and corona poling was used for air ionization to produce an electret effect. In this paper, the manufacturing process of the sensor is introduced, and the effect of the porous structure and corona poling on improving the performance of the sensor is discussed. The proposed flexible sensor has an equivalent piezoelectric coefficient d33 of 3312 pC/N, which is much larger than the piezoelectric coefficient of the common piezoelectric materials. Experiments were carried out to verify the function of the flexible sensor together with the SS17L heart sound sensor (BIOPAC, Goleta, CA, USA) as a reference. The test results demonstrated its practical application for wearable heart sound detection and the potential for heart disease detection. The proposed flexible sensor in this paper could realize batch production, and has the advantages of flexibility, low production cost and a short processing time compared with the existing heart sound detection sensors.

scholarly journals Nanocomposite multilayer capacitors comprising BaTiO3@TiO2 and poly(vinylidene fluoride-hexafluoropropylene) for dielectric-based energy storage

2014 ◽  
Vol 04 (02) ◽  
pp. 1450009 ◽  
Author(s):  
Mojtaba Rahimabady ◽  
Li Lu ◽  
Kui Yao
Keyword(s):  
Energy Storage ◽  
Energy Density ◽  
Vinylidene Fluoride ◽  
Discharge Rate ◽  
Low Cost ◽  
Breakdown Field ◽  
High Discharge ◽  
High Discharge Rate ◽  
Poly Vinylidene Fluoride ◽  
Multilayer Capacitors

Multilayer dielectric capacitors were fabricated from nanocomposite precursor comprised of BaTiO 3@ TiO 2 core–shell nanosized particles and poly(vinylidene fluoride–hexafluoropropylene) (P(VDF–HFP)) polymer matrix (20 vol%). The multilayer capacitors showed very high discharge speed and high discharged energy density of around 2.5 J/cm3 at its breakdown field (~ 166 MV/m). The energy density of the nanocomposite multilayer capacitors was substantially higher than the energy density of commercially used power capacitors. Low cost, flexible structure, high discharge rate and energy density suggest that the nanocomposite multilayer capacitors are promising for energy storage applications in many power devices and systems.

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