Fabrication of Poly(Vinylidene Fluoride)/Graphene Nano-Composite Micro-Parts with Increased β-Phase and Enhanced Toughness via Micro-Injection Molding

Based on poly(vinylidene fluoride)/graphene (PVDF/GP) nano-composite powder, with high β-phase content (>90%), prepared on our self-designed pan-mill mechanochemical reactor, the micro-injection molding of PVDF/GP composite was successfully realized and micro-parts with good replication and dimensional stability were achieved. The filling behaviors and the structure evolution of the composite during the extremely narrow channel of the micro-injection molding were systematically studied. In contrast to conventional injection molding, the extremely high injection speed and small cavity of micro-injection molding produced a high shear force and cooling rate, leading to the obvious “skin-core” structure of the micro-parts and the orientation of both PVDF and GP in the shear layer, thus, endowing the micro-parts with a higher melting point and crystallinity and also inducing the transformation of more α-phase PVDF to β-phase. At the injection speed of 500 mm/s, the β-phase PVDF in the micro-part was 78%, almost two times of that in the macro-part, which was beneficial to improve the dielectric properties. The micro-part had the higher tensile strength (57.6 MPa) and elongation at break (53.6%) than those of the macro-part, due to its increased crystallinity and β-phase content.

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Influence of the β-phase content and degree of crystallinity on the piezo- and ferroelectric properties of poly(vinylidene fluoride)

Smart Materials and Structures ◽

10.1088/0964-1726/19/6/065010 ◽

2010 ◽

Vol 19 (6) ◽

pp. 065010 ◽

Cited By ~ 231

Author(s):

J Gomes ◽

J Serrado Nunes ◽

V Sencadas ◽

S Lanceros-Mendez

Keyword(s):

Vinylidene Fluoride ◽

Ferroelectric Properties ◽

Degree Of Crystallinity ◽

Phase Content ◽

Β Phase ◽

Poly Vinylidene Fluoride

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Influence of molecular weight on dielectric properties and piezoelectric constant of poly(vinylidene fluoride) membranes obtained by electrospinning

Polimery ◽

10.14314/polimery.2021.10.4 ◽

2021 ◽

Vol 66 (10) ◽

pp. 532

Author(s):

Aminatul Sobirah Zahari ◽

Muhammad Hafiz Mazwir ◽

Izan Izwan Misnon

Keyword(s):

Molecular Weight ◽

Dielectric Properties ◽

Vinylidene Fluoride ◽

Electrochemical Impedance ◽

Piezoelectric Constant ◽

Phase Content ◽

X Ray Diffraction ◽

X Ray ◽

Β Phase ◽

Poly Vinylidene Fluoride

A significant influence of the molecular weight on the dielectric properties and piezoelectric constant of poly(vinylidene fluoride) (PVDF) membranes obtained by electrospinning was demonstrated. Electrochemical impedance spectroscopy and d33 meter were used to evaluate dielectric properties and piezoelectric constant respectively. The presence of the β-phase was determined by Fourier transform infrared spectroscopy (FTIR) and X-Ray diffraction (XRD). The membranes with the lowest molecular weight (180,000 g/mol) possessed the best dielectric properties. They also had the highest piezoelectric constant (21 pC/N) and dielectric constant (2.9 at 50 Hz) as well as the highest β-phase content (80.25%).

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Ultrahigh β-phase content poly(vinylidene fluoride) with relaxor-like ferroelectricity for high energy density capacitors

Nature Communications ◽

10.1038/s41467-019-12391-3 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 39

Author(s):

Nan Meng ◽

Xintong Ren ◽

Giovanni Santagiuliana ◽

Leonardo Ventura ◽

Han Zhang ◽

...

Keyword(s):

Energy Density ◽

High Efficiency ◽

Vinylidene Fluoride ◽

Dielectric Materials ◽

High Energy ◽

High Energy Density ◽

Polar Phase ◽

Phase Content ◽

Β Phase ◽

Poly Vinylidene Fluoride

Abstract Poly(vinylidene fluoride)-based dielectric materials are prospective candidates for high power density electric storage applications because of their ferroelectric nature, high dielectric breakdown strength and superior processability. However, obtaining a polar phase with relaxor-like behavior in poly(vinylidene fluoride), as required for high energy storage density, is a major challenge. To date, this has been achieved using complex and expensive synthesis of copolymers and terpolymers or via irradiation with high-energy electron-beam or γ-ray radiations. Herein, a facile process of pressing-and-folding is proposed to produce β-poly(vinylidene fluoride) (β-phase content: ~98%) with relaxor-like behavior observed in poly(vinylidene fluoride) with high molecular weight > 534 kg mol−1, without the need of any hazardous gases, solvents, electrical or chemical treatments. An ultra-high energy density (35 J cm−3) with a high efficiency (74%) is achieved in a pressed-and-folded poly(vinylidene fluoride) (670-700 kg mol−1), which is higher than that of other reported polymer-based dielectric capacitors to the best of our knowledge.

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Enhancing β-phase content and tensile properties in poly(vinylidene fluoride) by adding halloysite nanotubes and injecting water during extrusion

Materials & Design ◽

10.1016/j.matdes.2016.07.022 ◽

2016 ◽

Vol 108 ◽

pp. 761-768 ◽

Cited By ~ 13

Author(s):

Min Wu ◽

Han-Xiong Huang ◽

Jun Tong

Keyword(s):

Tensile Properties ◽

Vinylidene Fluoride ◽

Halloysite Nanotubes ◽

Phase Content ◽

Β Phase ◽

Poly Vinylidene Fluoride

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Facile preparation of highly oriented poly(vinylidene fluoride) uniform films and their ferro- and piezoelectric properties

RSC Advances ◽

10.1039/c7ra00586e ◽

2017 ◽

Vol 7 (28) ◽

pp. 17038-17043 ◽

Cited By ~ 7

Author(s):

Fan Xu ◽

Kaili Zhang ◽

Ying Zhou ◽

Zhichao Qu ◽

Haijun Wang ◽

...

Keyword(s):

Vinylidene Fluoride ◽

Piezoelectric Properties ◽

Phase Content ◽

Β Phase ◽

Poly Vinylidene Fluoride ◽

Facile Preparation

The shear-induced PVDF films present preferentially orientation with a high β-phase content and exhibit excellent ferro- and piezoelectric properties.

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

New Journal of Chemistry ◽

10.1039/d0nj05134a ◽

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...

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

Nanomaterials ◽

10.3390/nano11071637 ◽

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.

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Studies on the electrostatic effects of stretched PVDF films and nanofibers

Nanoscale Research Letters ◽

10.1186/s11671-021-03536-9 ◽

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.

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