• Title/Summary/Keyword: Polyvinylidene Fluoride (PVDF)

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Polarization behavior of polyvinylidene fluoride films with the addition of reduced graphene oxide

  • Lee, Junwoo;Lim, Sangwoo
    • Journal of Industrial and Engineering Chemistry
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    • v.67
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    • pp.478-485
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    • 2018
  • The effect of reduced graphene oxide (RGO) addition on the dielectric and piezoelectric behavior of the polyvinylidene fluoride (PVDF) films was studied. Dielectric constant increased by four times and piezoelectric coefficient also increased twice by the addition of RGO in the PVDF films. Based on capacitance-voltage and ellipsometry measurements and the Kramers-Kronig transformation, it is concluded that the enhanced dielectric and piezoelectric properties of the PVDF/RGO films resulted from the increased orientational polarization due to a phase transition from nonpolar crystalline ${\alpha}$ phase to polar crystalline ${\beta}$ phase in the PVDF structure.

Electrical Characteristics and Microwave Properties of MgO Bicrystal Josephson Junction with Polyvinylidene Fluoride Gate Electrode (Polyvinylidene Fluoride를 게이트 전극으로 이용한 MgO bicrystal Josephson junction의 전기 특성 및 마이크로파 특성 연구)

  • Yun, Yongju;Kim, Hyeoungmin;Park, Gwangseo;Kim, Jin-Tae
    • Progress in Superconductivity
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    • v.3 no.1
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    • pp.74-77
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    • 2001
  • We have fabricated a high-Tc superconductive transistor with polyvinylidene fluoride (PVDF) gate electrode on MgO bicrystal Josephson junction by spin-coating method. The PVDF ferroelectric film is found to be suitable fur a gate electrode of the superconductive transistor since it has not only small leakage current but also high dieletric constant at low temperature. For the application of superconducting-FET, we investigated millimeter wave properties (60 GHz band) of the Josephson junction with PVDF gate electrode.

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Characteristics of High Frequency Ultrasonic Transducer Employing Polyvinylidene Fluoride and Detectability of Flaw in Cr-Ni Steel (PVDF 수침용 고주파수 초음파 탐촉자의 검출장과 Cr-Ni 강에서의 결함 검출능 측정)

  • Kim, Byoung-Geuk;Lee, S.S.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.17 no.1
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    • pp.23-30
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    • 1997
  • Recently high frequency ultrasonic transducers to employ polyvinylidene fluoride(PVDF) or polyvinylidene fluoride trifluoroethylene P(VDF-TrFE) have been used to detect small flaws in immersion testing. The detection field depending on the water path between the transducer and a specimen and the path in a tested specimen was measured using a PVDF transducer with nominal frequency 80MHz. Also, C-scan and B-scan were performed for the specimens made of Cr-Ni steel with the artificial flaws, the flat-bottom holes with diameter ranging from $50{\mu}m$ to $560{\mu}m$ at 12mm depth. As the result, the flaws with diameter larger than $280{\mu}m$ were detected, but the flaws with the ratio of diameter to wavelength smaller than about 0.48 were not detected. That the smaller flaws could not be detected was attributed to the attenuation of high frequency components in the steel specimens.

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Designing Flexible Thin Film Audio Systems Utilizing Polyvinylidene Fluoride

  • Um, Keehong;Lee, Dong-Soo;Pinthong, Chairat
    • International journal of advanced smart convergence
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    • v.2 no.2
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    • pp.16-18
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    • 2013
  • In this paper, we develop a method to design a flexible thin film audio systems utilizing Polyvinylidene fluoride. The system we designed showed the properties of increased transparency and sound pressure levels. As an input terminal transparent oxide thin film is adopted. In order to provide dielectric insulation, a transparent insulating oxide thin film is coated to obtain double -layered structure. In the range of visible light, the output from the output of the system showed an increased and improved sound pressure level. The piezoelectric polymer film of polyvinylidene fluoride (PVDF) is used to produce mechanical vibration due to the applied electrical voltage signal. An analog electric voltage signal is transformed into sound waves in the audio system.

Enhancing Gamma-Neutron Shielding Effectiveness of Polyvinylidene Fluoride for Potent Applications in Nuclear Industries: A Study on the Impact of Tungsten Carbide, Trioxide, and Disulfide Using EpiXS, Phy-X/PSD, and MCNP5 Code

  • Ayman Abu Ghazal;Rawand Alakash;Zainab Aljumaili;Ahmed El-Sayed;Hamza Abdel-Rahman
    • Journal of Radiation Protection and Research
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    • v.48 no.4
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    • pp.184-196
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    • 2023
  • Background: Radiation protection is crucial in various fields due to the harmful effects of radiation. Shielding is used to reduce radiation exposure, but gamma radiation poses challenges due to its high energy and penetration capabilities. Materials and Methods: This work investigates the radiation shielding properties of polyvinylidene fluoride (PVDF) samples containing different weight fraction of tungsten carbide (WC), tungsten trioxide (WO3), and tungsten disulfide (WS2). Parameters such as the mass attenuation coefficient (MAC), half-value layer (HVL), mean free path (MFP), effective atomic number (Zeff), and macroscopic effective removal cross-section for fast neutrons (ΣR) were calculated using the Phy-X/PSD software. EpiXS simulations were conducted for MAC validation. Results and Discussion: Increasing the weight fraction of the additives resulted in higher MAC values, indicating improved radiation shielding. PVDF-xWC showed the highest percentage increase in MAC values. MFP results indicated that PVDF-0.20WC has the lowest values, suggesting superior shielding properties compared to PVDF-0.20WO3 and PVDF-0.20WS2. PVDF-0.20WC also exhibited the highest Zeff values, while PVDF-0.20WS2 showed a slightly higher increase in Zeff at energies of 0.662 and 1.333 MeV. PVDF-0.20WC has demonstrated the highest ΣR value, indicating effective shielding against fast neutrons, while PVDF-0.20WS2 had the lowest ΣR value. The Monte Carlo N-Particle Transport version 5 (MCNP5) simulations showed that PVDF-xWC attenuates gamma radiation more than pure PVDF, significantly decreasing the dose equivalent rate. Conclusion: Overall, this research provides insights into the radiation shielding properties of PVDF mixtures, with PVDF-xWC showing the most promising results.

Structural Changes of Polyvinylidene fluoride with $^{60}Co$ $\gamma-ray$ Irradiation (Polyvinylidene fluoride의 $^{60}Co$감마선 조사에 의한 구조 변화)

  • Lee Chung;Kim Ki-Yup;Ryu Boo-Hyung
    • Journal of the Korean Society of Safety
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    • v.19 no.3 s.67
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    • pp.26-31
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    • 2004
  • The radiation-induced changes taking place in poly(vinylidene fluoride) (PVDF) exposed to $^{60}Co$ $\gamma-ray$ irradiation were investigated in correlation with the applied doses. Samples were irradiated in air at room temperature by $^{60}Co$ $\gamma-ray$ to doses in the range of 200 to 1000kGy. Various properties of the irradiated PVDF were studied using FTIR, differential scanning calorimetry (DSC), gel fraction and elongation. $^{60}Co\gamma-ray$ irradiation was found to induce changes in chemical, thermal, mechanical and structural properties of PVDF and such changes vary depending on the radiation dose.

Superhydrophilic Surface Modification of Polyvinylidene Fluoride by Low Energy and High Flux ion Beam Irradiation (저에너지 고출력 이온빔을 이용한 polyvinylidene fluoride 표면의 초친수성화)

  • Park Jong-Yong;Jung Yeon-Sik;Choi Won-Kook
    • Korean Journal of Materials Research
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    • v.15 no.6
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    • pp.382-387
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    • 2005
  • Polyvinylidene fluoride (PVDF) surface was irradiated and became superhydrophilic by low energy (180 eV) and high flux $(\~10^{15}/cm{\cdot}s)$ ion beam. As an ion source, a closed electron Hall drift thruster of $\phi=70mm$ outer channel size without grid was adopted. Ar, $O_2$ and $N_2O$ were used for source gases. When $N_2O^+$ and $O_2^+$ reactive gas ion beam were irradiated with the ion fluence of $5\times10^{15}/cm^2$, the wetting angle for deionized water was drastically dropped from $61^{\circ}\;to\;4^{\circ}\;and\;2^{\circ}$, respectively. Surface energy was also increased up to from 44 mN/m to 81 mN/m. Change of chemical component in PVDF surface was analyzed by x-ray photoelectron spectroscopy. Such a great increase of the surface energy was intimately related with the increase of hydrophilic group component in reactive ion irradiated PVDF surfaces. By using an atomic force microscopy, the root-mean-square of surface roughness of ion irradiated PVDF was not much altered compared to that of pristine PVDF.

Shaping of piezoelectric polyvinylidene fluoride polymer film for tip position sensing of a cantilever beam

  • Lee, Young-Sup
    • Journal of Sensor Science and Technology
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    • v.14 no.4
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    • pp.225-230
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    • 2005
  • This paper describes a novel tip position sensor made of a triangularly shaped piezoelectric PVDF (polyvinylidene fluoride) film for a cantilever beam. Due to the boundary condition of the cantilever beam and the spatial sensitivity function of the sensor, the charge output of the sensor is proportional to the tip position of the beam. Experimental results with the PVDF sensor were compared with those using two commercially available position sensors: an inductive sensor and an accelerometer. The resonance frequencies of the test beam, measured using the PVDF sensor, matched well with those measured with the two commercial sensors and the PVDF sensor also showed good coherence over wide frequency range, whereas the inductive sensor became poor above a certain frequency.

Effects of sodium hydroxide cleaning on polyvinylidene fluoride fouled with humic water

  • Jang, Yoon-sung;Kweon, JiHyang;Kang, Min-goo;Park, Jungsu;Jung, Jae Hyun;Ryu, JunHee
    • Membrane and Water Treatment
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    • v.8 no.2
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    • pp.149-160
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    • 2017
  • This study investigated effects of NaOH cleaning on the intrinsic permeability of polyvinylidene fluoride (PVDF) membranes and flux recoveries and membrane resistances under various conditions encountered during ultrafiltration in water treatment plants. The NaOH cleaning using 10,000 mg/L NaOH led to discoloration of PVDF membranes and had little effect on water flux. The NaOH cleaning was efficient in removing the fouling layer caused by humic water. However, long filtration induced a fouling layer that was not removed easily by NaOH cleaning. The lower temperature during filtration yielded rapid increases in transmembrane pressure and decreases in NaOH cleaning efficiency. The alkaline cleaning of PVDF changed the membrane properties such as the hydrophobicity and morphology. Foulant properties, operational conditions such as temperature, and chemical agents should be considered for cleaning strategies for PVDF applied in water treatment.

A study on the manufacture and dielectric of the polyvinylidene fluoride thin films through vapor deposition method (진공증착법을 이용한 PVDF박막의 제작과 유전 특성에 관한 연구)

  • Park, S.H.;Im, U.C.;Cho, K.S.;Lee, D.C.
    • Proceedings of the KIEE Conference
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    • 1995.11a
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    • pp.420-422
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    • 1995
  • PVDF (polyvinylidene fluoride) has at least from known crystalline structure ( ; they are referred to as the $\alpha$, $\beta$, $\gamma$ and $\alpha_p$ phase or forms II, I, III and $IV_p$). In this study, the manufactured PVDF thin films through vapor deposition method had for II ( ; the substrate temperature at 30$^{\circ}C$). The dielectric behavior of poly(vinylidene fluoride) is affected by orientation and crystal modification. The very high value of the dielectric constant for high temperature conditioned film is believed to be due to the orientation effect. The loss peak caused by molecular motion of the molecules in crystalline regions.

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