Francois Bauer

Francois Bauer
AIFP

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114
Publications
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Publications

Publications (114)
Article
Full-text available
We investigate the development of a sensor for dynamic pressure measurement. The sensor relies on a Bauer shock gauge of 25-μm thin Polyvinylidene fluoride (PVDF) film [AIP Conf. Proc 706:1121–1124, [21]. These gauges unfortunately require some skills to be integrated in an acquisition chain and the obtained results are strongly “experiment depende...
Article
In this paper, we will present electromechanical behavior of the poly(vinylidene fluoridetrifluoroethylene- 1,1-chlorofluoroethylene) [P(VDF-TrFE-CFE)] terpolymer under hydrostatic pressure. The dielectric data obtained under controlled hydrostatic pressure suggest a reversible pressure-induced crossover from the relaxor state to a ferroelectric st...
Article
Coaxial filaments based on Poly (vinylidene fluoride-co-trifluoroethylene) and copper filament was developed, their mechanical properties characterized. They were then instrumented in textile structure and their detection capabilities were observed. P(VDF-TrFE)/copper coaxial filaments were obtained by a melt spinning process, the mechanical drawin...
Article
We designed and fabricated multilayered relaxor ferroelectric poly(vinylidene fluoride-trifluoroethylene-clorotrifluoroethylene) [P(VDF-TrFE-CTFE)] actuators in this study. To minimize the driving voltage of the P(VDF-TrFE-CTFE) actuator, which produces bending deformation, we designed a multilayered structure and analyzed the structure using compo...
Patent
Full-text available
A process for manufacturing terpolymers by polymerization of VDF (vinylidene difluoride), TrFE (trifluoroethylene), and CFE (1-chloro-1-fluoroethylene) or CTFE (chlorotrifluoroethylene) monomers in the presence of a radical polymerization initiator, characterized in that: i) an initial mixture of VDF and of TrFE, free of CFE and of CTFE, is fed in...
Article
It has been found that by introducing defects into the P(VDF-TrFE) copolymers, it is possible to convert the polymer from a normal ferroelectric to a relaxor ferroelectric. A new class of ferroelectric polymers, i.e., the terpolymers of P(VDF-TrFE-CFE) or of P(VDF-TrFE-CTFE), was developed from the normal ferroelectric PVDF-TrFE polymer by employin...
Article
Full-text available
Hybrid nanocomposites based on crystalline nanoparticles dispersed in polymer matrix have been widely studied in the past few years because of the ability of these materials to combine the properties of organic polymer and inorganic nanoparticles. The aim of this work is to tune the mechanical properties of a piezoelectric polymer by adding nanopar...
Article
The effects of frequency, temperature and hydrostatic pressure on the dielectric properties, molecular relaxations, and phase transitions of PVDF and a copolymer with 30 mol% trifluoroethylene will be discussed. Pressure causes large slowing down of the β molecular relaxations as well as large increases in the ferroelectric transition temperatures...
Conference Paper
We designed and fabricated the multilayered P(VDF-TrFE-CTFE) actuators, which can be operated by the applied voltage of only 40 V. To fabricate P(VDF-TrFE-CTFE) films having a thickness of about 1~2 μm, we also developed a new film transfer method, with which the P(VDF-TrFE-CTFE) films of about 1.5 μm thickness were fabricated and stacked. The defl...
Article
r Abstract-It has been found that by introducing defects into the P(VDF-TrFE) copolymers, it is possible to convert the polymer from a normal ferroelectric to a relaxor ferroelectric. A new class of ferroelectric polymers, i.e., the terpolymers of P(VDF-TrFE­ CFE) or of P(VDF- TrFE-CTFE), was developed from the normal ferroelectric PVDF-TrFE polyme...
Article
It has been found that by introducing defects into the P(VDF-TrFE) copolymers, it is possible to convert the polymer from a normal ferroelectric to a relaxor ferroelectric. A new class of ferroelectric polymers, i.e., the terpolymers of P(VDF-TrFE-CFE) or of P(VDF-TrFE-CTFE), was developed from the normal ferroelectric PVDF-TrFE polymer by employin...
Article
Full-text available
It has been found that by introducing defects into the P(VDF-TrFE) copolymers, it is possible to convert the polymer from a normal ferroelectric to a relaxor ferroelectric. A new class of ferroelectric polymers, i.e., the terpolymers of P(VDF-TrFE-CFE) or of P(VDF-TrFE- CTFE), was developed from the normal ferroelectric PVDF-TrFE polymer by employi...
Article
Hybrid nanocomposites based on crystalline nanoparticles dispersed in polymer matrix has been widely studied in the past few years because of the ability of these materials to combine both properties of organic polymer and inorganic nanoparticles. The aim of this work is to tune mechanical properties of piezoelectric polymer by adding nanoparticles...
Article
Full-text available
Alumina nanoparticles were incorporated into copolymer of vinylidene difluoride and trifluoroethylene (P(VDF-TrFE)) to form nanocomposite. Thin films were prepared on silicon wafers and some acoustic, optical and mechanical properties were studied by Brillouin spectroscopy. The morphology of the polymer and the dispersion quality of the nanoparticl...
Chapter
Full-text available
The science and technology of piezoelectric polymers has long been dominated by ferroelectric polymers from the polyvinylidene fluoride (PVDF) family. The piezoelectricity in this polymer class arises from the strong molecular dipoles within the polymer chain and from the resulting change of the dipole density upon application of a mechanical stimu...
Article
Full-text available
Induced stresses in textiles play a major role in their mechanical properties, either during fabrication or use. The aim of this work is to present the development of a dedicated sensor, which could be directly inserted in a fabric. The study is focused on seat-cover fabrics. The developed sensor is based on polyvinylidene fluoride films, which can...
Article
Purpose – For size reasons, adapted sensors, able to measure intrinsic mechanical properties of fabrics, have not been developed yet. The study aims at developing a sensor that can be inserted within a specific textile, a “complex” fabric used as seat-cover fabrics, and consisting of an assembly of three layers. Design/methodology/approach – Piezoe...
Conference Paper
The study presented here aims at developing a PVDF sensor that can be inserted within a seat-cover fabric. The final objective is to measure accurately the mass of a passenger sitting in a car. The measurement method consists in analyzing the response under compressive stress of a PVDF disc using the resonant frequency of the material. The maximal...
Article
Full-text available
Ferroelectric materials are intrinsically multifunctional and have found a broad range of applications. A new class of semicrystalline terpolymers comprising vinylidene fluoride (VDF), trifluoroethylene (TrFE), and 1,1-chlorofluoroethylene (CFE), were prepared at Institut de Saint-Louis (ISL) via a suspension polymerization process. Relevant studie...
Article
This paper investigates the relaxor ferroelectric polymer-poly(vinylidene fluoride/trifluoroethylene/chlorofluoroethylene) terpolymer for energy storage capacitors. It is found that the high dielectric constant (>50 at 1 kHz) and high reversible polarization in the terpolymer lead to a high electric energy density ~ 10 J/cm<sup>3 </sup>, achieved u...
Article
The relaxor ferroelectric polymer, based on poly(vinylidene fluoride-trifluoroethylene- chlorofluoroethylene) (P(VDF-TrFE-CFE)) terpolymer, exhibits high electromechanical response and dielectric response, suitable for a wide range of army applications such as micro-actuators, high efficiency pulse power capacitors, and solid state cooling devices....
Article
The relaxor ferroelectric polymers, i.e., the poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] based terpolymers and high energy electron irradiated copolymers, provide unique opportunity to investigate the ferroelectric relaxor behavior in polymeric materials. Experimental evidence shows that there is fundamental difference in the microst...
Article
Yarn pressure variations in the bobbin generate problems during winding. The Research Institute of Saint-Louis (ISL) has designed a piezo film sensor for use as a pressure variation measuring device. The sensor employs polyvinylidene (PVDF) piezo film sensors. To be used as a sensor PVDF is first extruded in a thin sheet and then stretched at a tem...
Article
Full-text available
Dielectric polymers with high dipole density have the potential to achieve very high energy density, which is required in many modern electronics and electric systems. We demonstrate that a very high energy density with fast discharge speed and low loss can be obtained in defect-modified poly(vinylidene fluoride) polymers. This is achieved by combi...
Article
The science and technology of piezoelectric materials has long been dominated by the availability of specific materials with particular properties. Piezoelectric PVDF (Poly(vinylidene fluoride) polymer and copolymers of PVDF with trifluoroethylene have shown to have the potential for new shock‐wave sensors. Since 1981 through 1995, the piezoelectr...
Conference Paper
Ferroelectric materials are intrinsically multifunctional and have found a broad range of applications. A new class of semicrystalline terpolymers comprising vinylidene fluoride (VDF), trifluoroethylene (TrFE), and 1,1-chlorofluoroethylene (CFE), were prepared at the Institut Franco-Allem and de Recherches in Saint-Louis (ISL) via a suspension poly...
Conference Paper
Ferroelectric materials are intrinsically multifunctional and have found a broad range of applications. A new class of semicrystalline terpolymers comprising vinylidene fluoride (VDF), trifluoroefhylene (TrFE), and 1,1-chlorofluoroefhylene (CFE), were prepared at the Institut Franco-Allemand de Recherches in Saint-Louis (ISL) via a suspension polym...
Article
The behavior of various PZT compositions under shock loading shows that obtaining high energy densities requires ceramics having a high remanent polarization and a low permittivity, which release their energy by a ferroelectric → antiferroelectric phase transition. Few “hard” PZT ceramics have these properties. The results are presented and discuss...
Article
Besides the high electrostriction in the relaxor P(VDF-TrFE-CFE) terpolymers, the high dielectric constant (> 50) and high breakdown field lead to a high electric energy density (∼10 J/cm), which is attractive for the high efficiency charge storage capacitors. This paper presents charging and discharging behavior, as well as the discharged energy d...
Conference Paper
Ferroelectric materials are intrinsically multifunctional and have found a broad range of applications. A new class of semicrystalline terpolymers comprising vinylidene fluoride (VDF), trifluoroethylene (TrFE), and 1,1-chlorofluoroethylene (CFE), were prepared at ISL via a suspension polymerization process. A cooperative research program between ou...
Article
We investigate the influence of the composition, especially the chlorofluoroethylene content, on the ferroelectric and electromechanical properties of the poly(vinylidene fluoride-trifluoroethylene- chlorofluoroethylene) (PVDF-TrFE-CFE). It was found that increasing the CFE from 0 to 9 mol % gradually converts the normal ferroelectric of the copoly...
Conference Paper
Normal ferroelectric poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer have been converted into relaxor ferroelectrics by introducing appropriate amount of defects into the original polar crystallites, which is achieved either by high-energy electron irradiation or by copolymerizing with a third bulky monomer 1,1-chlorofluoroethyl...
Article
Full-text available
Early works have shown that highly reproducible piezoelectric film PVDF (Poly(vinylidene fluoride)) can be reliably used in a wide range of precise stress and stress-rate measurements. The direct stress-derivative or stress-rate PVDF signals have nanosecond resolution and higher operating stress limits than any other technique. PVDF stress gauges h...
Article
The electro-optical (EO) properties of the ferroelectric relaxor poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) terpolymer were investigated in the wavelength region from 3 to 5 μm. A large Kerr effect was observed in which a refractive index change of −2.6% can be induced under an electric field of 80 V/μm. When combined with the...
Article
In 1998, Q. Zhang et al. demonstrated that large doses of high-energy beta radiation could transform certain vinylidene fluoride-trifluoroethylene (PVDF-TrFE) copolymers into high-strain electrostrictors. Since that time, many laboratories, as well as ISL, have processed electron irradiation of P(VDF50-TrFE50) and P(VDF70-TrFE30) copolymers. Electr...
Article
Making use of defects modification to P(VDF-TrFE) via either high energy electron irradiation treatment or copolymerizing VDF-TrFE with a small amount of chlorinated monomer to form a random terpolymer, we demonstrate that high electromechanical responses can be realized in P(VDF-TrFE) based polymers. It will be shown that in the stretched and irra...
Article
This paper reports two classes of electroactive polymers developed recently which exhibit very high strain and elastic energy density. In the first class of the electroactive polymer, i.e., the defects modified poly(vinylidene fluoridetrifluoroethylene)(P(VDF-TrFE)) polymers, an electrostrictive strain of more than 7% and an elastic energy density...
Article
BioMEMs and microfluidic devices have gained a lot of attention in recent years due to their emerging applications in biochemical analysis, medical diagnosis, chemical analysis and synthesis, drug discovery and drug delivery, biosensing and biomimetic systems. The materials requirements for bioMEMs are biocompatible, chemically modifiable, easy to...
Article
Full-text available
Stress gauges based on ferroelectric polymer (PVDF) studies under very high pressure shock compression have shown that the piezoelectric response exhibits a precise reproducible behavior up to 25 GPa. Shock pressure profiles obtained with “in situ” PVDF gauges in porous H.E. (Formex) in a detonation regime have been achieved. Observations of a fast...
Conference Paper
Electrical processing of ferroelectric polymer (PVDF) with the Bauer cyclic poling method can produce individual films with a well-defined polarization up to 9 μC/cm<sup>2</sup>. The piezoelectric response PVDF stress gauges subjected to shock loading exhibits a reproducible behavior up to 25 GPa. Shock pressure profiles obtained with "in situ" PVD...
Article
Ferroelectric polymers (PVDF) with well-defined and precisely known electrical properties are now routinely available from commercial sources. Electrical processing with the Bauer cyclic poling method can produce individual films with well-defined remanent polarization up to 9 /spl mu/C/cm/sup 2/. These polymers provide an unusual opportunity to st...
Conference Paper
The present paper briefly summarizes the advances in new poling technology, as well as the development of high fidelity, reproducible, time-resolved dynamic stress gauges with small areas. The shock induced polarization for 1 and 9 mm<sup>2</sup> precisely poled gauges are compared. The analysis of the response of these gauges in the “thin mode reg...
Article
Our studies of the shock compression response of PVDF polymer are continuing in order to understand the physical properties under shock loading and to develop high fidelity, reproducible, time-resolved dynamic stress gauges. New PVDF technology, new electrode configurations and piezoelectric analysis have resulted in enhanced precision gauges. Our...
Article
A method of polarizing selected areas of a foil of ferroelectric material, wherein electrodes are deposited in such a way on the opposite surfaces of the foil that the zone to be polarized extends between these two electrodes. The zone to be polarized is compressed and a variable voltage is applied across the electrodes. Each electrode is connected...
Article
Full-text available
A new generation of thermal uncooled focal plane array has been developed in the context of PROMETHEUS PROCHIP European Program (EUREKA) as a passive infrared obstacle detection applied to automotive [1]. The infrared detection uses the pyroelectric effect in VDF/TrFE copolymer. VDF/TrFE pyroelectric sensors have now definitely reached the level of...
Article
Piezoelectric elements made of polyvinylidene‐fluoride‐trifluoroethylene copolymer P(VDF/TrFE) have been used to measure the pressure induced on the rear surface of metallic foils irradiated by infra‐red laser pulses of 1.5 ns duration, with intensities up to 3 TW/cm<sup>2</sup>. The application of such piezoelectric materials under those condition...
Article
Standard 25‐μm‐thick polyvinilydene fluoride (PVDF) piezoelectric gauges and new 450‐μm‐thick P(VDF 70%, TrFE 30%) piezoelectric copolymer have been used to record shock profiles at the back face of metallic targets irradiated by laser pulses of 2.5 and 0.6 ns duration at a 1.06 μm wavelength. The records are fully explained with simplified space–t...
Article
The electrical response of the PVDF shock sensor is here revisited. An analysis with a lagrangian hydrocode shows that the electrical charge liberated during the 1D deformation of the PVDF film is strictly proportional to the true strain of the PVDF film. On the experimentally studied range (until 30 GPa), the electrical response of the PVDF gauge...
Article
The most common piezoelectric polymer is PVDF, based on the monomer CH2-CF2. Electrical processing with the Bauer cyclic poling method can routinely produce individual samples with a range of remanent polarizations up to 9 mC/cm2. The behavior of PVDF has been studied over a wide range of pressures with the destructive, but precise, method of very-...
Article
The most common piezoelectric polymers are PVDF, and copolymers PVDF with C2F3H. A unique application of these polymers are time-resolved dynamic stress gauges based on PVDF studies under shock loading. P(VDF-TrFE) copolymers exhibit unique piezoelectric properties over a wide range of temperature depending on the compositions. The materials may be...
Article
Ferroelectric polymers are the most recent class piezoelectric and pyroelectric materials developed. The most common piezoelectric polymers are PVDF, based on the monomer CH2CF2 and copolymers PVDF with C2F3H. The effects of frequency, temperature and hydrostatic pressure on the dielectric properties, molecular relaxations, and phase transitions o...
Conference Paper
A new generation of focal plan array has been developed for low cost infrared applications. The Infrared detection uses the pyroelectric effect in a copolymer and its specific technology is stacked on an industrial CMOS readout technology. For this feasibility demonstration, readout circuit design is low complexity (32*32) and low density (100 ¿m...
Article
The analysis of a VDF/TrFE detector integrated on a silicon chip is assessed from a model based on the solution of the heat equation applied to an ideal structure absorbing an IR incident chopped radiation. Sensitivity to parameters like the nature of the thermal insulator, of the substrate thickness and of the front absorber is presented. The perf...
Article
In hydrophone applications, PVDF and its copolymers provide high sensitivity because of their high piezoelectric voltage coefficient gh and large figure of merit dhgh. By mechanically clamping the surface of the sample perpendicular to the poling direction, the piezoelectric response perpendicular to the poling direction can be greatly reduced. The...
Article
Thermal stability studies of PVDF polymer are presented. A high hydrostatic pressure cell is designed in order to apply simultaneously high pressure and high temperature up to 3500 bar and 300°C respectively. A high percentage of the Extended β-polar form can be induced by crystallization of PVDF films under high temperature and high hydrostatic pr...
Article
Ferroelectric polymers with well defined and precisely known electrical properties are now routinely available from commercial sources. Electrical processing with the Bauer cyclic poling method can routinely produce individual samples with a range of remanent polarizations up to 9 μC/cm. Such well defined samples provide an unusual opportunity to c...
Article
The copolymer VDF-TrFE (VF2/C2F3H, derived from polyvinylidene fluoride with 30 mol% trifluoroethylene) used in a pyroelectric mode to develop IR focal plane arrays for civilian applications is compared to the barium strontium titanate BST used in a dielectric bolometer approach to implement a low cost IR imager. Comparison of the respective techno...
Conference Paper
The effects of frequency, temperature and hydrostatic pressure on the dielectric properties, molecular relaxations, and phase transitions of PVDF and a copolymer with 30 mol% trifluoroethylene will be discussed. Pressure causes large slowing down of the β molecular relaxations as well as large increases in the ferroelectric transition temperatures...
Article
PVDF shock stress sensors were subjected to X-ray deposition at nominal absorbed levels of 1, 11/2, 3, and 5 cal/gm (SiO2 equiv.) and to neutron fluence above 1013 n/cm2 while stressed at a peak level of about 2 GPa. Moderate transitory electrical noise that occurred briefly during the radiation did not persist. PVDF shock sensors with aluminum ele...
Conference Paper
Shock Pressure measurements are made with the use of PVDF gauges applied on the back face of 0.1 to 1 mm thick targets, covered with glass windows and irradiated by laser pulses of 25 ns duration, at incident intensity between 10⁸ and 10¹⁰ W/cm². Standard PVDF gauges of 25 μm thickness and also new copolymer gauges of 450 μm thickness are used. Res...
Article
A passive pyroelectric IR 32 × 32 focal plane array (FPA), used for obstacle detection, has been implemented. The previous approach using polyvinylidene fluoride (PVDF) has been improved with a copolymer, P(VDF-TrFE), integrated on a silicon read-out circuit to allow the design of a multifusion system, coupling IR passive, active and microwave dete...
Article
PVDF piezoelectric polymer shock stress sensors have been used to measure the shock and impulse generated by soft X-rays and by filter debris in the SATURN Plasma Radiation Source at Sandia National Laboratories, NM. SATURN was used to generate 30 to 40 kJ, 20-ns duration, line radiation at 2 to 3 keV. Fluence on samples was nominally 40, 200, and...
Chapter
Prior work has shown that the piezoelectric response of shock-compressed PVDF film prepared with careful attention to mechanical and electrical processing exhibits precise, well defined, reproducible behavior to 10 GPa. Although higher pressure responses continue to pressures approaching 50 GPa, and appear to provide a basis for a very high pressur...
Article
The effects of hydrostatic pressure on the dynamics and energetics of the β molecular relaxation process and on the ferroelectric (Tc) and melting (Tm) transition temperatures of the ferroelectric copolymer P(VDF0.7TrFE0.3) have been investigated. Pressure causes a large slowing down of the β relaxation as well as large increases in Tc and Tm, but...
Article
Increasing interest is being shown in poly(vinylidene fluoride) (PVDF) in an attempt to develop high-quality, low-cost acceleration-sensing systems. In this context, the potential applications of PVDF in the field of high value acceleration ( 100 000 g) are presented. The investigation is focused on three main points: thin-film elaboration: the Bau...
Conference Paper
The design of an integrated sensing system including a silicon structure and a P(VDFO.7-TRFEO.3) copolymer is presented. The monolithic integrated sensor is based on a pyroelectric thermal P(VDF.7-TRFEO.3) copolymer detector, a polyimide microelectronic photoresist for thermal insulation, and a standard process silicon read-out circuit. Studies und...
Conference Paper
Studies in progress undertaken to increase the precision of the polarization of shock-compressed PVDF (polyvinylidene fluoride) and to develop optimum sensors and shock gauge package designs are described. Results obtained on such carefully prepared PVDF shock gauges show that differences in electrical charge response of less than a few percent are...
Conference Paper
Ferroelectric polymers are the most recent class piezoelectric and pyroelectric materials developed. The most common piezoelectric polymers are PVDF, based on the monomer CH<sub>2</sub>-CF<sub>2</sub> and copolymers PVDF with C<sub>2</sub>F<sub>3</sub>H. Under high hydrostatic pressure, piezoelectric polymers exhibit well defined piezoelectric resp...
Article
Ferroelectric properties of PVDF polymers and VF2/C2F3H copolymers are presented. The polarization process of these organic materials influences the piezoelectric properties and their behavior under dynamic compression and shock loading. Using pressure wave propagation (PWP), the polarization distribution obtained by our “ISL” process is measured....
Conference Paper
The polarization of VF<sub>2</sub>/VF<sub>3</sub> copolymers and their piezoelectric response under shock loading were studied with the objective of completing the understanding of the mechanical-electrical conversion process of piezoelectric polymers. The results achieved on a VF<sub>2</sub>/VF<sub>3</sub> copolymer with 70 mol.% of VF<sub>2</sub>...
Article
Vinylidene fluoride and trifluoroethylene (VFâ/VFâ) copolymers are known to be of ferroelectric nature. Their piezoelectric properties are strong dependent on the polarization process as well as on the value of the remanent polarization. VFâ/VFâ films of 55 microns in thickness have been pressed at ISL. The polarization process is based on that use...
Article
A formal consensus standard for a version of the generic Bauer Polyvinylidene Di-Fluoride (PVDF) shock stress sensor is being defined by a panel broadly experienced in the techniques of PVDF sensor application. The evolving standard addresses points essential to accurate shock measurement with PVDF gauges. It covers the materials, dimensions, propo...
Article
The standardized improved PVDF shock gauge is described. The response under shock loading of well controlled poled PVDF (Pr ≈ 9 μC/cm) is presented. First, PVDF gauges operating over 30 GPa open up an entirely new range of measurement applications. Experimental results show that such ISL gauges provide a direct measure of the stress rate with resol...
Article
Ferroelectric properties of PVDF (polyvinylidene fluoride) polymers are presented. The polarization process of these organic materials influences the piezoelectric properties and their behavior under dynamic compression and shock loading. Using pressure wave propagation the polarization distribution obtained by the process is measured. The polariza...
Conference Paper
Time-resolved measurements of pressure profiles from the detonation of explosive devices have proven to be essential for detailed study of device performance. At present such measurements are routinely carried out with laser velocity interferometer (VISAR) systems, electromagnetic particle velocity gauges or piezoresistant (Manganin) gauges. One of...
Article
Vinylidene fluoride/trifluoroethylene (VF2/VF3) copolymers with more than 50% of VF2 mole content are of ferroelectric nature. They can be formed into plates from 1 to 500 μ thick from the molten state. Studies conducted at ISL show that such copolymers can be poled to a high level of remnent polarizationPr ⩾7 μC/cm². They exhibit a high piezoelect...
Article
Full-text available
Earlier reports have described work to establish feasibility for a shock-compression, stress-rate or stress gauge based on a high quality polymer film, polyvinylidene difluoride (PVDF). We have now established standardized procedures to provide large quantities of PVDF guage elements with highly reproducible electrical characteristics based on the...
Article
The frequency, temperature, and hydrostatic pressure dependences of the dielectric properties, molecular relaxation, and phase transition in PVF2 (polyvinyl fluoride) and a copolymer with 30 percent trifluorethylene are presented. The dynamic melting temperature shows a large increase with pressure. The electrical response of film shock gages with...
Article
The research work presented here shows the progress realized in the studies of the ferroelectric and piezoelectric properties of Polyvinylidene Flouride (PVDF). An attempt has been made to understand the fundamental phenomena of the mechanism responsible for the functioning of the shock loaded ferroelectric PVDF. Fundamental questions have not yet...
Article
Studies concerning the development and polarization of ferroelectric polymer gages for acceleration measurements are summarized. The acceleration intensities may reach 300,000 g. Polyvinylidene fluoride films of 40 microns, of polarized active surface between 1 and 25 sq mm, are obtained. The gages piezoelectric coefficient is about 48 pC/N. The ac...
Article
A cooperative program has been initiated among our laboratories to provide a reproducible PVF sub 2 polymer film for use as a gauge under shock-compression loading. The material source and electrical treatment are based on prior work of Bauer. The primary effort of the program focused on developing electroding and poling capabilities in the US. The...