Electroactive PVDF thin films fabricated via cooperative stretching process

Wang, Hui; Chen, Qiusong; Xia, Wei; Qiu, Xunlin; Cheng, Qian; Zhu, Guodong

doi:10.1002/app.46324

Cited by 30 publications

(14 citation statements)

References 25 publications

(46 reference statements)

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“…The effect of tensile stress has been studied before. Stress plays a key role in the transformation from α phase to β phase by leading to the orientation of the polymer chain [ 37 , 38 , 40 , 41 , 50 , 51 ]. According to the simulation results on stress distribution and value, we argue that the uniform stress distribution should cause the same orientation level on different locations.…”

Section: Resultsmentioning

confidence: 99%

Crystallinity and β Phase Fraction of PVDF in Biaxially Stretched PVDF/PMMA Films

et al. 2021

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Polyvinylidene fluoride (PVDF) and poly(methyl methacrylate) (PMMA) blend films were prepared using biaxial stretching. The effects of PMMA content and stretching ratio on the crystallinity and β phase fraction of PVDF in blend films were investigated. The distributions of crystallinity and β phase fraction on variable locations were also studied. The results of FTIR and XRD showed that β phase appeared in PVDF/PMMA blends after extrusion and casting procedures. Although β phase fraction decreased after preheating, there was still an increasing trend during following biaxial stretching. More importantly, the increase in PMMA content improved β phase fraction, and the highest β phase fraction of 93% was achieved at PMMA content of 30 wt% and stretching ratio of 2×2. Besides, the reduction in PMMA content and the increase in stretching ratio improved the crystallinity of PVDF. The mechanical properties of the stretched films were significantly improved by increasing the stretching ratio as well. The uniform stress distribution on different regions of biaxial stretching films contributed to the uniform distribution of β phase fraction and crystallinity of PVDF with the aid of simulation. This work confirmed that biaxial stretching can be a candidate method to prepare PVDF/PMMA blend films with uniform distributions of comparable β phase and crystallinity of PVDF.

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Section: Resultsmentioning

confidence: 99%

Crystallinity and β Phase Fraction of PVDF in Biaxially Stretched PVDF/PMMA Films

et al. 2021

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“…[1][2][3][4] It can be stabilized in its distinct polymorphs, α (TGTG′, form II), β (TTTT, form I), γ (T 3 GT 3 G′, form III), δ and ε depending on the molecular chain conformation during the fabrication process. 3,[5][6][7][8][9][10] Various techniques and treatments such as mechanical (stretching), 11,12 thermal (heat temperature), 13 electrical (poling process) 14 and chemical treatments (effect of solvents or other additives) 9,[15][16][17][18][19] during the processing of PVDF affect the molecular phase stabilization in it and hence, the final properties. Among its all forms, β-PVDF is the most electroactive showing good ferro/piezoelectric properties.…”

Section: Introductionmentioning

confidence: 99%

Dielectric Properties and Phase Stabilization of PVDF Polymer in (1−x)PVDF/xBCZT Composite Films

Garg

Annapureddy

Sekhar

et al. 2021

J. Electron. Mater.

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Polyvinylidene fluoride (PVDF) is a semi-crystalline ferroelectric polymer which can be stabilized in its distinct electroactive polymorphs α and γ by selective processing techniques. In this article, to study the effect of processing temperature and barium calcium zirconium titanate (BCZT) ceramic-doping on PVDF phase stabilization, the pure PVDF and PVDF/BCZT composite films were fabricated by solution-casting and melt-pressing. The Fourier-transform infrared spectroscopy and x-ray diffraction studies showed that the pure PVDF and PVDF/BCZT composite films fabricated by solution-casting possessed the characteristic γ-PVDF peaks while melt-pressing stabilized PVDF mostly in the α-phase. The BCZT ceramic particles were found to have no significant effect on PVDF phase stabilization, but it enhanced the overall crystallinity of polymer matrix. The dielectric studies revealed that the relative permittivity (ε r ) of γ-and α-PVDF phases in pure PVDF film samples was ≈ 10 and 7.5 (at 120 Hz) respectively. The ε r of PVDF/BCZT composite films having 50 wt.% BCZT content synthesized by solution-casting and melt-pressing were estimated to be ≈ 31 and 20 (at 120 Hz), respectively, which was about three times that of pure PVDF film synthesized by the respective technique. The value of loss tangent (tanδ) for pure PVDF films synthesized by solution-cast and melt-press technique were ≈ 0.07 and 0.35 (at 120 Hz) respectively. In temperature-dependent dielectric studies, γ-PVDF showed distinct α-relaxation peak at ≈ 120°C and polymer melting at temperature > 130°C. For α-PVDF, the increase in ε r and tanδ was observed during α-relaxation transition at higher temperatures. The dielectric studies indicated that the introduction of BCZT ceramic particles in PVDF matrix increased the ε r -value by enhancing the dipolar and interfacial polarizations in composites, while the decrease in tanδ-value was observed due to decrease in molecular dipoles with a decrease in wt.% of PVDF content. These phenomena collectively improved the overall electric properties of ceramic/polymer composites which makes them suitable candidates to explore for flexible electroactive material form.

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“…Poly(vinylidene uoride)(PVDF) is the best piezoelectric polymer with excellent ferroelectric, piezoelectric and pyroelectric properties [1][2][3][4][5], and has potential applications for wearable electronics [6], self-powered electronic systems [7][8][9], energy storage [10], actuators [11][12][13][14][15][16], and so on [17][18][19][20]. PVDF has at least four various crystal forms: α, β, γ, δ [21,22], and the β-phase has the best ferroelectric, piezoelectric properties [23][24][25]. So, it is necessary to convert α-phase into β-phase effectively.…”

Section: Introductionmentioning

confidence: 99%

Studies on the transformation process of PVDF film from α to β phase by uniaxial stretch

Zhang¹,

Wei²,

Sun³

et al. 2021

Preprint

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Stretching process is an effective method to prepare high β- phase PVDF. PVDF film was prepared by extrusion casting in this paper, then stretched by means of uniaxial-stretching using a DMA(Dynamic mechanical analyzer), the effects of stretching conditions on the transformation from α to β phase of PVDF were studied, also with the changes regularity of mechanical properties during stretching. The phase composition was characterized by XRD, FTIR, DSC, the results show that, the optimum drawing temperature is 80°C, the optimum stretch ratio is related to the length-width ratio of the film, the increase of stretching rate is beneficial to the formation of β-phase, the β-phase can reach 80% under the optimum drawing conditions.

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Electroactive PVDF thin films fabricated via cooperative stretching process

Cited by 30 publications

References 25 publications

Crystallinity and β Phase Fraction of PVDF in Biaxially Stretched PVDF/PMMA Films

Crystallinity and β Phase Fraction of PVDF in Biaxially Stretched PVDF/PMMA Films

Dielectric Properties and Phase Stabilization of PVDF Polymer in (1−x)PVDF/xBCZT Composite Films

Studies on the transformation process of PVDF film from α to β phase by uniaxial stretch

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