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Q.m. Zhang - One of the best experts on this subject based on the ideXlab platform.

  • large magnetoelectric coupling coefficient in poly Vinylidene Fluoride hexafluoropropylene metglas laminates
    Journal of Applied Physics, 2011
    Co-Authors: J Z Jin, Qing Wang, Xin Zhou, Z Fang, Q.m. Zhang
    Abstract:

    Poly(Vinylidene Fluoride-hexafluoropropylene) [P(VDF-HFP)] 90/10 wt% copolymers were fabricated by extrusion-blown and hot press-quench methods. The electric field induced phase transition was observed starting from 79 MV/m, and completing at 216 MV/m, in these copolymers. The transition was manifested by a change from a double hysteresis loop to a single hysteresis loop and supported by the x-ray diffraction measurement. Linear relationships between the magnetoelectric coupling coefficient and the in situ poling electric field, the remanent polarization and the field, were observed at electric fields less than 300 MV/m. A magnetoelectric coupling coefficient as large as 12 V/cm·Oe was obtained.

  • Electrical breakdown and ultrahigh electrical energy density in poly(Vinylidene Fluoride-hexafluoropropylene) copolymer
    Applied Physics Letters, 2009
    Co-Authors: Xin Zhou, Chen Zou, James Runt, Shihai Zhang, Zhigang Suo, Xuanhe Zhao, Sheng Liu, Q.m. Zhang
    Abstract:

    This paper investigates the electrical breakdown of a polar fluoropolymer, poly?Vinylidene Fluoride-hexafluoropropylene? which exhibits an exceptionally high discharged electrical energy density ??25 J/cm3?. It is shown that above room temperature, the breakdown strength decreases with temperature. It is further shown that such a temperature dependence of breakdown strength is consistent with the electromechanical breakdown model by taking into consideration of the plastic deformation of semicrystalline polymers. ©

  • large electric tunability in poly Vinylidene Fluoride trifluoroethylene based polymers
    Applied Physics Letters, 2008
    Co-Authors: S G Lu, Bret Neese, B J Chu, Y Wang, Q.m. Zhang
    Abstract:

    A tunability as high as 86% was obtained at the Curie temperature in poly(Vinylidene Fluoride-trifluoroethylene) [P(VDF-TrFE)] 55/45 copolymers when a 100 MV/m dc electric field was applied. The tunability was much higher than that in P[VDF-TrFE-chlorofluoroethylene (CFE)] 64.3/27.6/8.1 terpolymers, which demonstrated only 49% in a 50 MV/m electric field and at the phase transition temperature. The large difference was regarded to come from the domain size change when CFE was introduced into the copolymers, and the polymer changed from normal ferroelectric for copolymers to the relaxor ferroelectric for terpolymers.

  • dielectric properties of relaxor like Vinylidene Fluoride trifluoroethylene based electroactive polymers
    Macromolecules, 2003
    Co-Authors: Vid Bobnar, Adrijan Levstik, B. Vodopivec, Marija Kosec, Bozena Hilczer, Q.m. Zhang
    Abstract:

    The dynamic processes in poly(Vinylidene Fluoride−trifluoroethylene) (P(VDF−TrFE)) copolymer, lead lanthanum zirconate titanate (PLZT)−P(VDF−TrFE) composite, electron-irradiated P(VDF−TrFE) copolymer, and poly(Vinylidene Fluoride−trifluoroethylene−chlorofluoroethylene) (P(VDF−TrFE−CFE)) terpolymer have been studied by measurements of the temperature and frequency-dependent linear (e1) and third-order nonlinear (e3) dielectric constants. While a paraelectric-to-ferroelectric transition takes place in the crystalline region of the nonirradiated copolymer and composite, electron-irradiated P(VDF−TrFE) copolymer and P(VDF−TrFE−CFE) terpolymer show a significantly different dielectric response:  a broad frequency dispersion in e1 and e3, asymmetric temperature evolution of the relaxation spectrum as the longest relaxation time diverges at a finite freezing temperature while the shortest relaxation times remain active down to the lowest temperatures, and a paraelectric-to-glass crossover in the temperature depe...

  • ferroelectric and electromechanical properties of poly Vinylidene Fluoride trifluoroethylene chlorotrifluoroethylene terpolymer
    Applied Physics Letters, 2001
    Co-Authors: Haisheng Xu, Q.m. Zhang, Z Y Cheng, Dana C Olson, G Kavarnos
    Abstract:

    This letter reports the ferroelectric and electromechanical properties of a class of ferroelectric polymer, poly(Vinylidene-Fluoride–trifluoroethylene–chlorotrifluoroethylene) terpolymer, which exhibits a slim polarizationhysteresis loop and a high electrostrictive strain at room temperature. The dielectric and polarization behaviors of this terpolymer are typical of the ferroelectric relaxor. The x-ray and Fourier transform infrared results reveal that the random incorporation of bulky chlorotrifluoroethylene (CTFE) ter-monomers into polymer chains causes disordering of the ferroelectric phase. Furthermore, CTFE also acts as random defect fields which randomize the inter- and intrachain polar coupling, resulting in the observed ferroelectric relaxor behavior.

Qing Wang - One of the best experts on this subject based on the ideXlab platform.

Zhicheng Zhang - One of the best experts on this subject based on the ideXlab platform.

  • synergistic effects of maxwell stress and electrostriction in electromechanical properties of poly Vinylidene Fluoride based ferroelectric polymers
    Macromolecules, 2019
    Co-Authors: Baobao Qiao, Shaobo Tan, Weiwei Zhu, Xiao Wang, Zhicheng Zhang
    Abstract:

    Poly(Vinylidene Fluoride) (PVDF)-based relaxor ferroelectric polymers, synthesized from the physical or chemical modification of β-PVDF and P(VDF–TrFE) (TrFE refers trifluoroethylene), show high th...

  • dielectric phenomena and electrical energy storage of poly Vinylidene Fluoride based high k polymers
    Chinese Chemical Letters, 2017
    Co-Authors: Yingke Zhu, Pingkai Jiang, Zhicheng Zhang, Xingyi Huang
    Abstract:

    Abstract Polymeric dielectrics have wide range of applications in the field of electrical energy storage because of their light weight and easy processing. However, the state-of-the-art polymer dielectrics, such as biaxially orientated polypropylene, could not meet the demand of minimization of electronic devices because of its low energy density. Recently, poly(Vinylidene Fluoride) (PVDF) based ferroelectric polymers have attracted considerable interests for energy storage applications because of their high permittivity and high breakdown strength. Unfortunately, the high dielectric loss and/or high remnant polarization of PVDF-based polymers seriously limits their practical applications for electrical energy storage. Since the discovery of relaxor ferroelectric behavior was firstly reported in irradiated poly(Vinylidene Fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer, many strategies have been developed to enhanced the electrical energy storage capability, including copolymerization, grafting, blending and fabricating of multilayer. How these methods affect the polymorphs, crystallinity, crystal size of PVDF-based polymers and the connection between these microstructures and their corresponding energy storage properties are discussed in detail.

  • dielectric piezoelectric and ferroelectric properties of a poly Vinylidene Fluoride co trifluoroethylene synthesized via a hydrogenation process
    Polymer, 2013
    Co-Authors: Zhuo Xu, Zhicheng Zhang, Huayi Li
    Abstract:

    Abstract The dielectric, piezoelectric and ferroelectric properties of a poly (Vinylidene Fluoride-co-trifluoroethylene) (P (VDF-co-TrFE)) copolymer synthesized via a novel hydrogenation process are presented in this work. Comparing with the direct copolymerized P(VDF-co-TrFE), the head-to-head (H–H) connection of Vinylidene Fluoride (VDF) and trifluoroethylene (TrFE) units in hydrogenized P(VDF-co-TrFE) results in the increasing crystal domains and the improvement of overall crystallinity and. Therefore, excellent electric properties, including dielectric constant of 11 at a frequency of 100 Hz, a piezoelectric value (d33) of −23 pC/N, a remnant polarization (Pr) of 7 μC/cm2 and a maximum polarization (Ps) of 10 μC/cm2 were observed in hydrogenized P(VDF-co-TrFE), which are rather close to that obtained in copolymerized copolymer. The results indicate that the improved condensed structures offer the low cost and convenient hydrogenized P(VDF-co-TrFE) broader application scenery in piezoelectric devices than the direct copolymer.

  • electric energy storage properties of poly Vinylidene Fluoride
    Applied Physics Letters, 2010
    Co-Authors: Wenjing Li, Zhicheng Zhang, Qingjie Meng, Yuansuo Zheng, Zhuo Xu
    Abstract:

    High discharged energy density observed in poly(Vinylidene Fluoride) (PVDF) based copolymers has attracted considerable research interests in the past years. Crystalline properties exhibit great influence on their dielectric and energy storageproperties. To understand how crystalline properties influence the energy storageproperties of PVDF, PVDF films with three different crystal forms are investigated in this paper. It is shown that γ -PVDF is allowed to work under higher electric fields than α - and β -PVDF in the absence of phase transition in α -PVDF and early polarization saturation in β -PVDF. Consequently, γ -PVDF exhibits the highest energy density of 14 J / cm 3 under 500 MV/m electric field.

Jason Claude - One of the best experts on this subject based on the ideXlab platform.

S Lancerosmendez - One of the best experts on this subject based on the ideXlab platform.

  • recent advances in poly Vinylidene Fluoride and its copolymers for lithium ion battery separators
    Membranes, 2018
    Co-Authors: J C Barbosa, Jose P Dias, S Lancerosmendez, C M Costa
    Abstract:

    The separator membrane is an essential component of lithium-ion batteries, separating the anode and cathode, and controlling the number and mobility of the lithium ions. Among the polymer matrices most commonly investigated for battery separators are poly(Vinylidene Fluoride) (PVDF) and its copolymers poly(Vinylidene Fluoride-co-trifluoroethylene) (PVDF-TrFE), poly(Vinylidene Fluoride-co-hexafluoropropylene) (PVDF-HFP), and poly(Vinylidene Fluoride-cochlorotrifluoroethylene) (PVDF-CTFE), due to their excellent properties such as high polarity and the possibility of controlling the porosity of the materials through binary and ternary polymer/solvent systems, among others. This review presents the recent advances on battery separators based on PVDF and its copolymers for lithium-ion batteries. It is divided into the following sections: single polymer and co-polymers, surface modification, composites, and polymer blends. Further, a critical comparison between those membranes and other separator membranes is presented, as well as the future trends on this area.

  • dielectric relaxation ac conductivity and electric modulus in poly Vinylidene Fluoride nay zeolite composites
    Solid State Ionics, 2013
    Co-Authors: A C Lopes, C M Costa, Sabater R I Serra, Isabel C Neves, J Gomez L Ribelles, S Lancerosmendez
    Abstract:

    Abstract Poly(Vinylidene Fluoride)/zeolite composites prepared by solvent casting at 190 °C have been investigated by scanning electronic microscopy, Fourier transformed infrared spectroscopy and broadband dielectric relaxation spectroscopy. The inclusion of the NaY zeolite filler in the polymer matrix induces the crystallization of poly(Vinylidene Fluoride), PVDF, in the electroactive γ phase. The dielectric function, ac conductivity and electric modulus of the composites were investigated as a function of zeolite content in the frequency range from 0.1 Hz to 1 × 107 Hz at temperatures from − 120 to 150 °C. The main relaxation process (β-relaxation) of the amorphous phase of the polymer matrix is not affected by the presence of the zeolite, as verified by the similar relaxation parameters obtained for the pure polymer and for the PVDF/NaY4% composite. In a similar way, the zeolite low temperature relaxation is not significantly affected by the polymer phase. On the other hand, the electric modulus formalism reveals significant contributions of the fillers to the electrical permittivity and conductivity of the composites. The presence of the zeolite particles increases ac conductivity and the Maxwell–Wagner–Sillars contribution that is predominant at low frequencies with respect to ohmic contribution to permittivity.

  • poly Vinylidene Fluoride co trifluoroethylene membranes obtained by isothermal crystallization from solution
    Macromolecular Materials and Engineering, 2010
    Co-Authors: Armando Ferreira, Jaime Silva, Vitor Sencadas, Jose Luis Gomez Ribelles, S Lancerosmendez
    Abstract:

    Electroactive macroporous poly[(Vinylidene Fluoride)-co-trifluoroethylene] membranes have been produced by solvent evaporation at room temperature, starting with a diluted solution of the copolymer in dimethylformamide. The pore architecture consists of interconnected spherical pores. This architecture is independent of the membrane thickness. The thickness of the membranes ranges from a few to several hundred μm, using spin coating and evaporation in static conditions, respectively. The pore structure is explained by a spinodal decomposition of the liquid/liquid phase separation and crystallization in the copolymer-rich phase.