Magnetic Field Assisted Electrospinning of Nanofibers Using Solutions with PVDF and Fe3O4Nanoparticles

2014 ◽  
Vol 1659 ◽  
pp. 155-162
Author(s):  
Juan A. Gonzalez ◽  
Rogerio Furlan ◽  
Raymond Lopez ◽  
Luis M. Martinez ◽  
Esteban Fachini
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Vinylidene Fluoride ◽  
Particle Diameter ◽  
Polymer Flow ◽  
Field Response ◽  
Poly Vinylidene Fluoride ◽  
Polymeric Solutions ◽  
Fiber Deposition ◽  
20 Nm

ABSTRACTThis study aims at investigating the formation of nanofibers containing poly (vinylidene fluoride) (PVDF) and Fe3O4 nanoparticles using magnetic field assisted electrospinning. For this purpose, two Helmholtz coils were mounted on the electrospinning apparatus in order to create a uniform magnetic field. Different separations, angles and magnetic fields are being analyzed. Polymeric solutions containing PVDF, DMF and acetone with a concentration of 18 wt% were adopted (DMF to Acetone ratio of 3 to 1). Iron Oxide Nanopowder (Fe3O4, particle diameter of 20 nm to 30 nm) to PVDF ratios are 1:5, 1:10 and 1:15. The application of the electromagnetic field during fiber deposition results in better orientation of the polymer flow towards the grounded electrode and leads to smoother fibers with diameters in the range of hundreds of nanometers. Blisters, probably related to Fe3O4 agglomerates, were distributed on the surface of all samples of this study. A magnetic field response of the nanofibers with higher magnetic fields was clear observed. By adding more Fe3O4 to the polymeric solution the ferromagnetic response on thin films and nanofibers was improved. The analysis of circular capacitors revealed a full dielectric response.

Magnetic field induced formation of ferroelectric β phase of poly (vinylidene fluoride)

2020 ◽  
Vol 126 (8) ◽  
Author(s):  
Jie Wu ◽  
Xiaoyu Sun ◽  
Shunjin Zhu ◽  
Jin Bai ◽  
Xuebin Zhu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Vinylidene Fluoride ◽  
Β Phase ◽  
Poly Vinylidene Fluoride

Enhanced Piezoelectricity of Nanoimprinted Sub-20 nm Poly(vinylidene fluoride–trifluoroethylene) Copolymer Nanograss

2012 ◽  
Vol 45 (3) ◽  
pp. 1580-1586 ◽  
Author(s):  
Chien-Chong Hong ◽  
Sheng-Yuan Huang ◽  
Jiann Shieh ◽  
Szu-Hung Chen
Keyword(s):  
Vinylidene Fluoride ◽  
Poly Vinylidene Fluoride ◽  
20 Nm

Effect of a static magnetic field on the preparation of MnOOH and Mn3O4 by a hydrothermal process

RSC Advances ◽  
2016 ◽  
Vol 6 (25) ◽  
pp. 21037-21042 ◽  
Author(s):  
L. C. Dong ◽  
Y. B. Zhong ◽  
S. Zhe ◽  
T. Y. Zheng ◽  
H. Wang
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Static Magnetic Field ◽  
Hydrothermal Process ◽  
Single Crystalline ◽  
20 Nm ◽  
The Magnetic Field

In this paper, the shape of the samples was changed by the magnetic field. Single-crystalline nanowires (20 nm in diameter and 1 μm in length) of MnOOH were obtained under zero magnetic fields. However, cubic particles of Mn3O4 were formed when a magnetic field was applied.

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 Magnetoelectric Membrane Filters of Poly(vinylidene fluoride)/Cobalt Ferrite Oxide for Effective Capturing of Particulate Matter

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2601
Author(s):  
Kyujin Ko ◽  
Su-Chul Yang
Keyword(s):  
Magnetic Field ◽  
Particulate Matter ◽  
Surface Charge ◽  
Vinylidene Fluoride ◽  
Shape Change ◽  
Membrane Surface ◽  
Public Health Issue ◽  
Membrane Filters ◽  
Phase Alignment ◽  
Poly Vinylidene Fluoride

In the last decade, particulate matter (PM) has gradually become a serious public health issue due to its harmful impact on the human body. In this study, we report a novel filtration system for high PM capturing, based on the magnetoelectric (ME) effect that induces an effective surface charge in membrane filters. To elucidate the ME effect on PM capturing, we prepared electrospun poly(vinylidene fluoride)(PVDF)/CoFe2O4(CFO) membranes and investigated their PM capturing efficiency. After electrical poling under a high electric field of 10 kV/mm, PM-capturing efficiencies of the poled-PVDF/CFO membrane filters were improved with carbon/fluorine(C/F) molar ratios of C/F = 4.81 under Hdc = 0 and C/F = 7.01 under Hdc = 700 Oe, respectively. The result illustrates that electrical poling and a dc magnetic field could, respectively, enhance the surface charge of the membrane filters through (i) a strong beta-phase alignment in PVDF (poling effect) and (ii) an efficient shape change of PVDF/CFO membranes (magnetostriction effect). The diffusion rate of a water droplet on the PVDF/CFO membrane surface is reduced from 0.23 to 0.05 cm2/s by covering the membrane surface with PM. Consequently, the PM capturing efficiency is dramatically improved up to 175% from ME membranes with the poling process and applying a magnetic field. Furthermore, the PM was successfully captured on the prototype real mask derived from the magnetoelectric effect induced by a permanent magnet with a diameter of 2 cm without any external power.

Investigation of Polymer Micro-Actuators Based on Electrostrictive Poly(vinylidene fluoride-trifluoroethylene) Copolymers

2002 ◽  
Vol 741 ◽  
Author(s):  
Tian-bing Xu ◽  
Feng Xia ◽  
Z.-Y. Cheng ◽  
Q. M. Zhang
Keyword(s):  
High Frequency ◽  
Vinylidene Fluoride ◽  
High Strain ◽  
Large Field ◽  
Force Output ◽  
Elastic Energy Density ◽  
Poly Vinylidene Fluoride ◽  
Micro Actuators ◽  
20 Nm ◽  
Ac Fields

ABSTRACTMicromachined actuators based on the electrostrictive P(VDF-TrFE) copolymer, which possesses a high strain (∼5%) and high elastic energy density (∼ 1 J/cm3), have been designed and fabricated. The performance of the devices have been characterized and modeled in terms of the properties of the copolymer and dimensions of the devices. The experimental results on the device responses under high AC fields (electrostrictive mode), weak AC fields in DC field biased state, and frequency dependence, are very close to the modeling results. Due to the large field induced strain and high frequency capability of the electrostrictive P(VDF-TrFE), the device possesses the capability of operation at non-resonance mode with high displacement and force output, and hence, the device is capable to be used over a broad frequency range. For example, for a device of 1 mm lateral dimension, the displacement output can reach more than 50 μm and the ratio of the displacement/applied voltage is more than 20 nm/Vrms. Furthermore, over more than 3 frequency decades (up to 100 kHz), the dispersion of the displacement is less than 20%. The observed performance of the devices indicates that this class of the electrostrictive P(VDF-TrFE) based micro-actuators is attractive for micropumps and valves.

Calculated Coronal Magnetic Fields and Their Comparison with the Coronal Structures as Observed during Five Solar Eclipses

1994 ◽  
Vol 144 ◽  
pp. 559-564
Author(s):  
P. Ambrož ◽  
J. Sýkora
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Coronal Magnetic Field ◽  
Coronal Magnetic Fields ◽  
Solar Eclipses ◽  
Coronal Structures

AbstractWe were successful in observing the solar corona during five solar eclipses (1973-1991). For the eclipse days the coronal magnetic field was calculated by extrapolation from the photosphere. Comparison of the observed and calculated coronal structures is carried out and some peculiarities of this comparison, related to the different phases of the solar cycle, are presented.

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