Download or read book Novel Ferroelectric Behavior in Poly vinylidene Fluoride co trifluoroethylene based Random Copolymers written by Lianyun Yang and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: High dielectric constant and low loss polymer dielectrics are desired for applications such as energy storage, electrocaloric cooling, and electrostrictive actuation. Several types of polarizations can be utilized to enhance dielectric constant of polymer dielectrics. Polymers with permanent dipoles can be good candidates to achieve high dielectric constant and low loss properties because of their dipolar polarization. There are several situations of dipolar polarization for polar polymers with permanent dipoles, which depend on different dipole/domain structures. Our work focuses on the novel ferroelectric behavior of ferroelectric polymers. The mechanism for novel ferroelectric behavior can be explained by the crystal pinning effect from crystal isomorphism. The physical pinning effect in P(VDF-TrFE-CFE) is weak and double hysteresis loop (DHL) is thus observed. The chemical pinning effect in e-beam P(VDF-TrFE) or P(VDF-TrFE-CTFE) is strong and only single hysteresis loop (SHL) is observed. Besides P(VDF-TrFE-CTFE), DHLs can also be achieved in P(VDF-TrFE-TrFE)-g-PS graft copolymer by the nanoconfined effect. Crystal orientation and temperature effects on the DHL behavior of the graft copolymer were studied. Clear dielectric, rather than ferroelectric, behavior is observed from the non-oriented graft polymer sample. But stable DHLs are observed for the oriented films up to 75 C. Above 100 C, huge broadening of the D-E loops shows up due to the electrical conduction and ion migrational losses. The electrical conduction loss plays an important role on the insulation property of dielectric polymers, especially at high temperatures and under high electric fields. As an example, a commercial biaxially oriented PVDF (BOPVDF) film was selected to study the electrical conduction under different electric poling conditions. The dipoles from either amorphous or crystalline phase do not have much influence on the electronic conduction. The electronic conductivity for the BOPVDF film is low below 25 C. Above 25 C, the electronic conductivity first increases, then decreases upon increasing the poling fields. These changes can be attributed to the effect from polarized ions. Above 75 C, electronic conductivity substantially increase due to injected space charges. Meanwhile, PVDF starts to undergo electrochemical reactions, emitting HF gas which can corrode metal electrodes.

Download or read book Investigations of the Ferroelectric and Piezoelectric Behavior of Poly vinylidene Fluoride trifluoroethylene Random Copolymers written by Michael C. Christie and published by . This book was released on 1999 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Confined Ferroelectric Properties in Poly vinylidene Fluoride PVDF based Random Copolymers and Graft Copolymers for Electric Energy Storage Applications written by Fangxiao Guan and published by . This book was released on 2010 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Water Interactions with the Crystalline Ferroelectric Copolymer Poly vinylidene Fluoride with Trifluoroethylene written by Luis G. Rosa and published by . This book was released on 2005 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ferroelectric Polymers written by E. Fukada and published by CRC Press. This book was released on 1989 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains four papers commencing with an introduction to early studies in piezoelectricity, pyroelectricity and ferroelectricity in polymers. Other topics discussed include - ferroelectric properties of fluoride copolymers; structural phase transition in ferroelectric fluorine polymers; and pressure effect on phase transition in ferroelectric polymers .

Download or read book Ferroelectric Materials for Energy Applications written by Haitao Huang and published by John Wiley & Sons. This book was released on 2019-01-04 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides a comprehensive overview of the emerging applications of ferroelectric materials in energy harvesting and storage Conventional ferroelectric materials are normally used in sensors and actuators, memory devices, and field effect transistors, etc. Recent progress in this area showed that ferroelectric materials can harvest energy from multiple sources including mechanical energy, thermal fluctuations, and light. This book gives a complete summary of the novel energy-related applications of ferroelectric materials?and reviews both the recent advances as well as the future perspectives in this field. Beginning with the fundamentals of ferroelectric materials, Ferroelectric Materials for Energy Applications offers in-depth chapter coverage of: piezoelectric energy generation; ferroelectric photovoltaics; organic-inorganic hybrid perovskites for solar energy conversion; ferroelectric ceramics and thin films in electric energy storage; ferroelectric polymer composites in electric energy storage; pyroelectric energy harvesting; ferroelectrics in electrocaloric cooling; ferroelectric in photocatalysis; and first-principles calculations on ferroelectrics for energy applications. -Covers a highly application-oriented subject with great potential for energy conversion and storage applications. -Focused toward a large, interdisciplinary group consisting of material scientists, solid state physicists, engineering scientists, and industrial researchers -Edited by the "father of integrated ferroelectrics" Ferroelectric Materials for Energy Applications is an excellent book for researchers working on ferroelectric materials and energy materials, as well as engineers looking to broaden their view of the field.

Download or read book Ferroelectric and Piezoelectric Properties of a Quenched Poly Vinylidene Fluoride Trifluoroethylene Copolymer written by and published by . This book was released on 1996 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ferroelectric and piezoelectric properties of melt-quenched unoriented poly(vinylidene fluoride-trifluoroethylene) (73:27) copolymer films as a function of the number of poling cycles have been studied. The investigation revealed that quenched films exhibit a decrease in D-E hysteresis behavior as the number of poling cycles increases when the samples are poled at room temperature. Corresponding decreases in remanent polarization, Pr, as well as small increases in the coercive field, Ec, were observed as the material was subjected to successive poling cycles. The piezoelectric coefficients, d31 and e31, also decreased as the number of poling cycles increased. In addition, a clear reduction in the 'apparent' Curie transition temperature between unpoled and poled material was observed. Preliminary evidence indicates that films quenched below Tc do not form a stable ferroelectric crystal phase as previously believed.

Download or read book Effects of Configurational Changes on Molecular Dynamics in Polyvinylidene Fluoride and Poly vinylidene Fluoride trifluoroethylene Ferroelectric Polymers written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Here, we present a comparative study of proton dynamics in unpoled non-ferroelectric polymer polyvinylidene fluoride (PVDF) and in its trifluoroethylene containing ferroelectric copolymer (with 70/30 molar proportion), using quasi-elastic neutron scattering. The neutron data reveal the existence of two distinct types of molecular motions in the temperature range investigated. Moreover, the slower motion, which is characterized in details here, is ascribed to protons jump diffusion along the polymeric carbon chains, while the faster motion could be attributed to localized rotational motion of methylene groups. At temperatures below the Curie point (T-c similar to 385 K) of the composite polymer, the slower diffusive mode experiences longer relaxation times in the ferroelectric blend than in the bare PVDF, although the net corresponding diffusion coefficient remains comparatively the same in both polymers with characteristic activation energy of E-A approximate to 27-33 kJ/mol. This arises because of a temperature dependent jump length r(0), which we observe to be effectively longer in the copolymer, possibly due to the formation of ordered ferroelectric domains below Tc. Above Tc, there is no appreciable difference in r(0) between the two systems. Our observation directly relates the known dependence of Tc on molar ratio to changes in r(0), providing fundamental insight into the ferroelectric properties of PVDF-based copolymers.

Download or read book Ferroelectric Polymers written by Hari Singh Nalwa and published by CRC Press. This book was released on 1995-06-20 with total page 904 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work covers the chemistry and physics of polymeric materials and their uses in the fields of electronics, photonics, and biomedical engineering. It discusses the relationship between polymeric supermolecular structures and ferroelectric, piezoelectric and pyroelectric properties.

Download or read book Understanding Ferroelectricity in Nylon Homopolymers Copolymers and Terpolymers written by Zhongbo Zhang and published by . This book was released on 2018 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the past half century, there has been tremendous growth in exploring the chemistry, physics and material science of poly(vinylidene fluoride) (PVDF)-based ferroelectric polymers. With high breakdown strength, easy processing, and outstanding insulating features, these all-organic electrically active materials are attractive for many advanced electrical (e.g., pyroelectric and piezoelectric) applications. Concurrently, the research about ferroelectricity in polymers also began for energy storage applications through controlling crystalline structure and tuning the corresponding ferroelectric properties, e.g., novel relaxor ferroelectricity with slim double- or single- hysteresis-loop (DHL and SHL) behavior in PVDF copolymers and terpolymers. On the other hand, research activities also focused on searching for other classes of ferroelectric polymers, such as ferroelectric polyamides, cyanopolymers, polyureas, and polyuerathane. However, not much progress has been achieved as considerable as what has been achieved for PVDF-based polymers. In this thesis, we focus on the novel ferroelectric behaviors in polyamide-based polymers, trying to deeply understand the origin of ferroelectricity in aliphatic and aromatic nylons, and generalize the relaxor ferroelectric behavior into this hydrogen-bonding system. It has been commonly considered that only odd-numbered nylons, which prefer polar crystalline structure, are able to show ferroelectric hysteresis loops. In contrast, even-numbered nylons, such as nylon-12 and nylon-6 should not exhibit any ferroelectricity due to their nonpolar crystalline structure. However, in our study, ferroelectric properties are also reported for mesomorphic even-numbered nylons. The structure of the mesophases in quenched samples was considered to contain multiple twists in the chain conformation and dangling/weak hydrogen bonds, which enabled dipolar switching, forming electric-field-induced ferroelectric domains. This study shows that different from ferroelectric PVDF-based polymers, the polar crystalline structure is not the prerequisite for ferroelectricity in nylons. Instead, mesophases with enlarged interchain spacing and disordered hydrogen bonds are the key to ferroelectricity. With the understanding of ferroelectricity in n-nylons, further weakened hydrogen bonding and more twisted chain conformation (e.g., the all-trans conformation of nylon-12 under poling) are expected to facilitate dipolar relaxation and prevent the large ferroelectric domain from growing up. The simplest way to weaken hydrogen bonds is to raise the temperature. Upon increasing temperature to 100 °C, the D-E loops became increasingly narrower, finally leading to slim DHLs for nylon-6 and nylon-12. The observed DHL behavior was attributed to the electric-field-induced reversible transitions between the paraelectric (less twisted chains) and ferroelectric (more twisted chains) states in the mesomorphic crystal of even-numbered nylons. Furthermore, the SHL relaxor ferroelectric property was successfully achieved in a polyamide terpolymer, PA(11-co-12-co-NM11) based on 11-aminoundecanoic acid (AUA), 12-aminododecanoic acid (ADA), and N-methyl-11-aminoundecanoic acid (NM11), utilizing the principle of nanosized ferroelectric domains (or nanodomains). The hydrogen-bonding interaction was intentionally weakened by chemically introducing defects in the crystalline phase of nylon terpolymers. More importantly, the N-CH3 groups were expected to participate in the isomorphic crystals, blocking the formation of hydrogen bonds and inducing chain twisted in the mesophase. Finally, the ferroelectric switching behavior in the amorphous phase of a nearly 100% amorphous nylon, Selar, was investigated. Similarly, ferroelectricity in the glassy phase was also highly dependent upon hydrogen-bonding interaction. When the hydrogen-bonding was weak such as in the quenched film, significant ferroelectric switching took place. Otherwise, the quenched and annealed films did not exhibit any ferroelectric switching. High-voltage broadband dielectric spectroscopy was used to study chain segmental motion in Selar. The result indicated that it was the cooperative short-range segmental motions in the main-chain dipolar glass polymer that primarily contributed to the observed ferroelectricity.

Download or read book Electrostrictive and Ferroelectric Properties of Poly vinylidene Fluoride hexafluroropropylene Copolymer and Its Blends with Poly vinylidene Fluoride trifluoroethylene Copolymer written by Adriana Schirokauer and published by . This book was released on 2002 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ferroelectric Properties and Polarization Switching Kinetic of Poly vinylidene Fluoride trifluoroethylene Copolymer written by Duo Mao and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book PVDF Based Ferroelectric Polymers written by and published by de Gruyter. This book was released on 2017-05-23 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book begins by introducing signals and systems, and then discusses Time-Domain analysis and Frequency-Domain analysis for Continuous-Time systems. It also covers Z-transform, state-space analysis and system synthesis. The author provides abundant examples and exercises to facilitate learning, preparing students for subsequent courses on circuit analysis and communication theory.

Download or read book New Properties and Applications of Polyvinylidene Based Ferroelectric Polymer written by J.L. Wang and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: There are different kinds of novel properties and applications of polyvinylidene difluoride (PVDF)-based ferroelectric polymer films. Several issues associated with the structure, properties, and applications of PVDF-based ferroelectric polymer films are discussed. The main achievements of the research include high electric tunability of relaxor ferroelectric Langmuir-Blodgett (LB) terpolymer films, the creep process of the domain switching in poly(vinylidene fluoride-trifluoroethylene) ferroelectric thin films, transition from relaxor to ferroelectric-like phase in poly(vinylidene fluoride-trifluoroethylene -chlorofluoroethylene) terpolymer ultrathin films, abnormal polarization switching of relaxor terpolymer films at low temperatures, huge electrocaloric effect in LB ferroelectric polymer thin films, self-polarization in ultrathin LB polymer films, enhanced dielectric and ferroelectric properties in artificial polymer multilayers, and transition of polarization switching from extrinsic to intrinsic in ultrathin PVDF homopolymer films.

Download or read book Fascinating Fluoropolymers and Their Applications written by Bruno Ameduri and published by Elsevier. This book was released on 2020-06-17 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluoropolymers are unique materials. Since the middle of the twentieth century fluropolymers have been used in applications where a wide temperature range, a high resistance to aggressive media, excellent tribological characteristics, and specific low adhesion are required. Today, researchers turn to fluoropolymers to solve new challenges and to develop materials with previously unattainable properties. Fascinating Fluoropolymers and Their Applications covers recent developments of fluoropolymer applications in energy, optical fibers, blood substitutes, textile coatings, membranes and other areas, written by experts in these fields. This volume in the Progress in Fluorine Science series is ideal for researchers and engineers who want to learn about the technology and applications of these special polymers, as well as industrial manufacturers who are interested in achieving new product characteristics in their respective industries. Written by a global team of fluoropolymer experts Includes use of fluoropolymer membranes for various applications in fuel cells, for gases separation, and more Covers fluoropolymer materials with shape memory, in cardiopulmonary bypass systems, in the production of textile materials, and in other areas

Download or read book Ferroelectrics written by Ashim Kumar Bain and published by John Wiley & Sons. This book was released on 2017-01-27 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: Combining both fundamental principles and real-life applications in a single volume, this book discusses the latest research results in ferroelectrics, including many new ferroelectric materials for the latest technologies, such as capacitors, transducers and memories. The first two chapters introduce dielectrics and microscopic materials properties, while the following chapter discusses pyroelectricity and piezoelectricity. The larger part of the text is devoted to ferroelectricity and ferroelectric ceramics, with not only their fundamentals but also applications discussed. The book concludes with a look at the future for laser printed materials and applications. With over 600 references to recent publications on piezoelectric and ferroelectric materials, this is an invaluable reference for physicists, materials scientists and engineers.

Download or read book High Energy capacitance Density Poly vinylidene Fluoride Based Polymers for Energy Storage Capacitor Applications written by Xin Zhou and published by . This book was released on 2009 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: The increased energy levels and continued demands for miniaturization of many devices such as hybrid electric vehicles, pulsed power systems, and switched-mode power supplies call for advanced polymer film capacitors with a high energy density (HED) [1], which cannot be met in current low dielectric constant (3.2) polymers(energy density ~ 2 J/cm^3) [2]. Poly(vinylidene fluoride) (PVDF) features a high dielectric constant (12) [3], and has the potential to reach a high energy density. This dissertation introduces general considerations leading to and the results of ultra-high energy density ( 25 J/cm^3) in PVDF-based copolymers P(VDF-HFP)(HFP: hexafluoropropylene) 95.5/4.5 mol% and P(VDF-CTFE) (CTFE: chlorotrifuoroethylene) 91/9 mol% [4], [5], which represents an order of magnitude improvement of the energy density over currently used polymers. In addition, this dissertation is devoted to developing a fundamental understanding of several newly observed phenomena in these HED polymers, which are not present in the currently low dielectric constant polymers. In polymer film capacitors, high fields have been used to realize high energy density. Therefore, the emphasis is paid to understand the response behaviors of these HED polymer dielectrics at high fields, particularly the losses and the breakdown mechanism. Based on these investigations and fundamental understandings, different approaches are introduced to further improve performance of these HED polymers. This dissertation demonstrates that in these HED fluoropolymer films the losses increase rapidly with applied electric fields. Immediately beyond the weak field, the losses can be caused by the ferroelectric domain wall type motions, similar to those in magnetic materials as described by Rayleigh's law [6]. On the other hand, a complex notation has been extensively used to describe the dielectric behavior [7]. In this dissertation, we extend this complex notation to the non-linear region to include the losses [8]. As the field increases further (> 100 MV/m), the loss due to the ferroelectric switching dominates. At very high fields (> 250 MV/m), it is the conduction loss that dominates. Even for state-of-the-art capacitor films that are widely regarded as "linear" dielectrics, the conduction loss can become higher at high fields due to a non-linear increase in the conduction [9]. In PVDF-based polymers, it is well known that polymer modifications and processing conditions can significantly influence the ferroelectric loss [10]. Therefore, two approaches were investigated to reduce the ferroelectric switching loss: (1) the irradiation method [11] to destabilize the polar conformation and correspondingly reduce the ferroelectric loss and (2) the biaxial stretching method. The film processing study revealed that the orientation of polymer chains parallel to the film surface improves the breakdown strength and reduces the conduction loss in PVDF-based polymers, while a random orientation of polymer chains along the film surface is desired to reduce the ferroelectric loss. In order to reduce the conduction loss, we take the general approach to employ a blocking layer which possesses a higher resistivity compared to the original film [12]. However, for these HED polymers, the blocking layer should also meet the requirements: (1) a dielectric constant closer to the original film (~ 13) to maintain a high energy density and (2) a low temperature fabrication because of the low melting temperature (~ 160 oC) of PVDF-based polymers. Hence, insulating polymers of low dielectric constants (3.2) cannot meet the first requirement and will significantly reduce the energy density. On the other hand, ceramics can meet the first requirement. However, their high temperature fabrication process ( 300 oC) [13] is not compatible with PVDF-based polymers. In this study, we demonstrated that very high resistivity with a dielectric constant of ~ 7 can be obtained with Si3N4 deposited at 100 oC and that the conduction loss of the resulting bilayered films can be much less than a single layer of PVDF-based copolymers. In the study of the electrical breakdown in these HED capacitor films, it was observed that although the temperature dependence of the breakdown strength in the P(VDF-HFP) 95.5/4.5 mol% films is consistent with the electromechanical (EM) breakdown [14], the widely accepted EM breakdown model of Stark-Garton significantly overestimates the breakdown strength. We show that this discrepancy lies in the fact that the Stark-Garton model fails to capture the mechanical properties of the polymers that experience a plastic deformation. Furthermore, we introduce a more general power law relation to characterize the elastic-plastic deformation of polymers. This newly developed model agrees well with the experimental data [15], and should be applicable to any polymer dielectrics in their electromechanical breakdown because of the universal validity of this model to describe the mechanical behavior of polymer dielectrics.