Effect of ultrasonication and other processing conditions on the morphology, thermomechanical, and piezoelectric properties of poly(vinylidene difluoride-trifluoroethylene) copolymer films (original) (raw)
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Journal of Applied Polymer Science, 2004
Piezoelectricity of ferroelectric thin polymer films strongly depends on the poling condition. We can classify them as conventional electrical and novel nonelectrical poling. These experiments show the comparative results on piezoelectricity induced from various poling processes (i.e., electrical corona poling, nonelectrical surfaceenergy poling, and a combination of both methods simultaneously in various poling conditions). The most interesting result confirmed that the piezoelectricity increased significantly when the combination poling was applied with appropriate metal substrate and temperature decreasing rate.
Journal of Physical Chemistry C, 2018
Poly(vinylidene fluoride-trifluoroethylene), P(VDF-TrFE), microstructures have been produced using different solvents, including green ones, by different techniques, such as solvent casting, screen-printing, replica molding, electrospray, and electrospinning. The obtained microstructures span from simple porous and dense films to spheres, fibers, and patterned three-dimensional architectures, with no significant variation in their physicochemical and electrical properties. The simplicity, low cost, and reproducibility of the processing techniques allied to their versatility to adapt to other materials to produce controlled and tailored microstructures with specific properties demonstrate their potential in a wide range of technological applications, including biomedical, energy storage, sensors and actuators, and filtration.
Polymer films and membranes of poly(vinylidene fluoride co-hexafluoropropylene), PVDF-HFP, have been prepared by thermally induced phase separation (TIPS), allowing the tuning of microstructure and morphology. The obtained microstructure is explained by the Flory-Huggins theory, depending on polymer concentration and solvent evaporation temperature. The formation of a porous membrane is attributed to a spinodal decomposition of the liquid-liquid phase separation. The effect of the processing conditions on the morphology, degree of porosity, degree of crystallinity and crystalline polymorph, thermal, dielectric and piezoelectric properties of the PVDF-HFP polymer were evaluated. The crystalline phase and degree of crystallinity depend on the processing conditions and further influence the dielectric and piezoelectric response. The piezoelectric coefficient is correlated with the b-phase content and decreases with decreasing polymer concentration in the initial solution at a given evaporation temperature.
Journal of Polymer Science Part B: Polymer Physics, 2014
The influence of annealing between the Curie transition and the melting point of solvent cast polyvinylidene fluoride trifluoroethylene copolymer films on the crystalline structure, mechanical and electrical properties, and oxygen permeability is investigated. Annealing leads to remarkable changes in the structure and properties of the copolymer, within the first four hours of treatment, and with kinetics depending on the temperature. The crystallinity increases by 19% (relative), resulting in a 10 K increase in the Curie transition, a 4 K increase of the melting temperature and a 2 K decrease in the glass transition temperature. A crystalline phase transition from the paraelectric a-phase to the ferroelectric b-phase is also evidenced using in-situ X-ray diffraction. The elastic modulus is found to increase by more than three-fold at room temperature and the loss peak at the glass transition is considerably reduced. The piezoelectric coefficient is found to increase by 40% and the dielectric properties are significantly changed. The most remarkable influence is the tenfold reduction of the oxygen permeability, with a drastic reduction of the activation energy for oxygen transport. The improvement in oxygen barrier properties of the annealed copolymer is attributed to the restricted mobility of oxygen molecules in the semicrystalline polymer with nanometer sized crystallites.
Different Scale Confinements of PVDF-TrFE as Functional Material of Piezoelectric Devices
IEEE Sensors Journal, 2000
The effect of micro and nanostructuration on the piezoelectric properties of polymeric samples was studied in the present work. We prepared micro-sized pillars and nano-wires (thus one-dimensional structures) of a piezoelectric polymer Poly(VinyliDene Fluoride-Tri FluoroEthylene) PVDF-TrFE and we compared their structural and piezoelectrical properties with a thin film (thus two-dimensional) of the same material. X-ray diffraction and infrared spectroscopy measurements showed that the crystallization of the polymer into the ferroelectric β-phase is affected by the size of the confinement. The piezoelectric characterization of the three polymeric structures showed important improvements as far as the nanostructuration is reached. Application as tactile sensor devices is therefore under development.
Structural impact on piezoelectricity in PVDF and P(VDF-TrFE) thin films
Applied Physics A, 2014
PVDF and its mostly used copolymer P(VDF-TrFE) are known to possess piezoelectric properties which strongly vary with processing conditions. As the final target of processing ultimately is the structure of the polymer, establishing a more detailed link between structure and properties would ease both the understanding and the practical usage of films piezoelectric activity. In spite of a number of thorough studies exploiting the nature of piezoelectricity in PVDF, available data does not generally exhibit reliable level of consistency and, in some cases, elements of contradiction are observed. Making no claim to be exhaustive in this vast area, we present a survey and discuss on a number of results both available and obtained by ourselves in an effort to assist to better interpretation and further progress in the field.
Nano Energy, 2014
In this paper, a flexible nanogenerator based on direct piezoelectric effect using a spin-coated poly(vinylidenefluoride-co-trifluoroethylene) (PVDF-TrFE) thin film as functional layer has been fabricated on polyimide substrate. The as-prepared nanogenerator exhibits the open-circuit voltage up to 7 V and short-circuit current of 58 nA with current density of 0.56 μA/cm 2. The impact of the variation of strain rate on the electrical outputs of the nanogenerator has been characterized experimentally and analyzed theoretically. An analytical model that explains well the experimental results has been established.