Ferroelectric and piezoelectric polymers

Ferroelectric and Piezoelectric Polymer-Polymer Composite Systems. 517... 

Anodier class of representative ferroelectric and piezoelectric polymers is odd-numbered polyamides (nylons). Hydrogen bonding formed by -NH and -C=0 groups provides essential polar elements in the polymer for piezoelectricity. The significant piezoelectiic properties of nylon 11 was studied and reported in the early 1980s (Newman et al. 1980 Mathur et al. 1988). Its ferroelectricity was predicted based on a study on its chemical structures and crystal phases. However, the synopsis of ferroelectiicity in nylons was not confirmed until 1991 when Scheinbeim et al. 

The existenee of the two classes of ferroelectric and piezoelectric polymers, PVDF and its eopolymers and odd-numbered nylons, makes it possible to develop polymer-polymer eomposite systems. Ferroelectric and piezoelectric PVDF-nylon 11 bilaminates and nylon 11-PVDF blends were studied by Su (1992) and Gao et al. (1999), respectively. Significant enhancements in ferroelectric and piezoelectric properties were observed in both polymer-polymer composite systems. Interfacial polarization plays an important role for the enhancement. 

The development of the two ferroelectric and piezoelectric polymers - PVF2 and odd-numbered nylons - provides a possibility to make all polymer ferroelectric and piezoelectric composite system. Using PVDF and nylon 11, Su et al. developed nylon ll-poly(vinylidene fluoride) bilaminates by a co-melt-pressed-stretched process in 1992 (Su et al.). The bilaminate exhibits a typical ferroelectric D-E hysteresis... 

Newnham RE, Sundar V, Yimnirun R, Su J, Zhang QM (1997) Electrostriction nonlinear electromechanical coupling in solid dielectrics. J Phys Chem 101 10141-10150 Ploss B, Ploss B, Shin FG, Chan HLW, Choy CL (2000) Pyroelectric or piezoelectric compensated ferroelectric composites. Appl Phys Lett 76 2776-2778 Poddar S, Ducharme S (2013) Measurement of the flexoelectric response in ferroelectric and relaxor polymer thin films. Appl Phys Lett 103 202901... 

To summarize the ferroelectric and piezoelectric properties of the discussed polymers, some important ferroelectric and piezoelectric parameters are tabulated in Table 4. As discussed in the previous sections, the ferroelectric and piezoelectric properties of polymeric and polymeric composite systems depend on various factors, such as crystallinity, pohng conditions, glass transition temperature, and before and after electrical poling treatments (electrical, mechanical, and thermal treatments). In addition to the factors mentioned above, for composite systems, laminates or blends, fraction of constituents, and interfacial polarization are also important. Therefore, the... 

Slichter (1959) Molecular motion in polyamides. J Polym Sci A 35(128) 77-92 Su (1992) Ferroelectricity and piezoelectricity of nylon 11-PVF2 bilaminates. Internal Technical report, Rutgers, The State University of New Jersey Su J et al (1999) Electrostrictive graft elastomers and applications. In Proceedings of MRS Symposium, vol 600, pp 131-136, MRS Conference Publication Su J et al (2003) Electrostrictive graft elastomers, U.S. Patent No. 6,515,077, 4 Su J et al (1995) Ferroelectric and piezoelectric properties of nylon 1 l/poly(vinylidene fluoride) bilaminate films. J Polym Sci Part B Polym Phys 33 85... 

In this chapter piezoelectric crystals and polymers ferroelectric and ferromagnetic solids resistance of metals shock-induced electrical polarization electrochemistry elastic-plastic physical properties. 

In this chapter studies of physical effects within the elastic deformation range were extended into stress regions where there are substantial contributions to physical processes from both elastic and inelastic deformation. Those studies include the piezoelectric responses of the piezoelectric crystals, quartz and lithium niobate, similar work on the piezoelectric polymer PVDF, ferroelectric solids, and ferromagnetic alloys which exhibit second- and first-order phase transformations. The resistance of metals has been investigated along with the distinctive shock phenomenon, shock-induced polarization. 

The piezoelectric polymer investigations give new physical insight into the nature of the physical process in this class of ferroelectric polymers. The strong nonlinearities in polarization with stress are apparently more a representation of nonlinear compressibility than nonlinear electrical effects. Piezoelectric polarization appears to be linear with stress to volume compressions of tens of percent. The combination of past work on PVDF and future work on copolymers, that have quite different physical features promises to provide an unusually detailed study of such polymers under very large compression. 

Vinylidene fluoride-trifluoroethylene (VF2-F3E) copolymers exhibit a ferroelectric-paraelectric phase transition, the first such case found for a synthetic polymer. In this transition, the electric polarization and piezoelectric constant of the film disappear above the Curie point (Tcurie)- The temperature dependence of the dielectric constant, , obeys the so called Curie-Weiss law ... 

MAJOR PRODUCT APPLICATIONS thermistors, capacitors, optics, ferroelectric ceramics, filler for ferroelectric polymers, pyro and piezoelectric composites... 

Ferroelectric composites are alternatives to standard piezoelectric and pyroelectric ceramics such as lead zirconate titanate (PZT) and BaHOs (BT). They combine the strong ferroelectric and dielectric properties of ceramics with the easy processing and good mechanical properties of polymers. Dispersion of micrometer-sized ferroelectric particles in an electrically passive epoxy matrix was first published by Furukawa et al. [1976] and later extended to ferroelectric matrices such as poly(vinylidene fluoride) (PVDF) and poly(vinylidene fluoride-co-3-fluoroethylene) (PVDF-TrFE) [Hsiang et al., 2001 Hilczer et al., 2002 Gimenes et al., 2004 Lam et al., 2005 Beloti et al., 2006]. However, the necessity of miniaturization of electronic components and... 

Pyro- and Piezoelectric Properties The electric field application on a ferroelectric nanoceramic/polymer composite creates a macroscopic polarization in the sample, responsible for the piezo- and pyroelectricity of the composite. It is possible to induce ferroelectric behavior in an inert matrix [Huang et al., 2004] or to improve the piezo-and pyroelectricity of polymers. Lam and Chan [2005] studied the influence of lead magnesium niobate-lead titanate (PMN-PT) particles on the ferroelectric properties of a PVDF-TrFE matrix. The piezoelectric and pyroelectric coefficients were measured in the electrical field direction. The Curie point of PVDF-TrFE and PMN-PT is around 105 and 120°C, respectively. Different polarization procedures are possible. As the signs of piezoelectric coefficients of ceramic and copolymer are opposite, the poling conditions modify the piezoelectric properties of the sample. In all cases, the increase in the longitudinal piezoelectric strain coefficient, 33, with ceramic phase poled) at < / = 0.4, the piezoelectric coefficient increases up to 15 pC/N. The decrease in da for parallel polarization is due primarily to the increase in piezoelectric activity of the ceramic phase with the volume fraction of PMN-PT. The maximum piezoelectric coefficient was obtained for antiparallel polarization, and at < / = 0.4 of PMN-PT, it reached 30pC/N. 

Like the ferroelectric liquid crystal polymers,the co-polymers of the PVDF type require poling. By contrast, the polarization of an LB film is solidly built into the structure, and is only removed,if fields in excess of the dielectric breakdown field are applied. The main practical disadvantage associated with VF2/VF3 co-polymers is their microphonic activity. Fortunately, the LB films studied to date, with the exception of the azobenzene compounds, have piezoelectric coefficients low enough to be undetectable. 

Symposium on Advanced Dielectrics, Piezoelectric, Ferroelectric, and Multiferroic Materials Geopolymers and other Inorganic Polymers Materials for Solid State Lighting Advanced Sensor Technology for High-Temperature Applications... 

Bauer, F., PVFj polymers ferroelectric polarization and piezoelectric properties under dynamic pressure and shock wave action, Ferroelectrics, 49, 231-240 (1983). 

Examples of polymers that have a piezoactive response are poled poly(vinylidene fluoride) (PVDF) (151) and its copolymers with trifluo-roethylene co(VDF-TrFE) (152), and the family of odd nylons (153) (see Piezoelectric Polymers). These are partially crystalline materials in which the crystalline regions have a permanent electric dipole moment. These polymers show ferroelectric switching behavior indicating that after poling they have a net... 

Ferroelectric materials are a subclass of pyro- and piezoelectric materials (Fig. 1) (see Piezoelectric Polymers). They are very rarely foimd in crystalline organic or polymeric materials because ferroelectric hysteresis requires enough molecular mobility to reorient molecular dipoles in space. So semicrystalline poly(vinylidene fluoride) (PVDF) is nearly the only known compoimd (1). On the contrary, ferroelectric behavior is very often observed in chiral liquid crystalline materials, both low molar mass and poljuneric. For an overview of ferroelectric liquid crystals, see Reference 2. Tilted smectic liquid crystals that are made from chiral molecules lack the symmetry plane perpendicular to the smectic layer structure (Fig. 2). Therefore, they develop a spontaneous electric polarization, which is oriented perpendicular to the layer normal and perpendicular to the tilt direction. Because of the liquid-like structure inside the smectic layers, the direction of the tilt and thns the polar axis can be easily switched in external electric fields (see Figs. 2 and 3). 

Banno H (1983) Recent developments of piezoelectric ceramic products and composites of synthetic rubber and piezoelectric ceramic particles. Ferroelectrics 50 3-12 Bauer F, Brown LF, Fukada E (eds.) (1995) Special issue on piezo/pyro/ferroelectric polymers. Ferroelectrics 171 1 03... 

The storage effects could also be realized in polymer liquid crystals. On cooling, ferroelectric liquid crystal polymers with the electric field applied, the macroscopic polarization is frozen in the glassy state [74]. Thus, the polymer film becomes a pyroelectric and a piezoelectric. Unfortunately, the glassy state is too viscous to allow the field-induced reorientation of the polarization and the film cannot be considered to be a ferroelectric. 

Fukada, E. (2000) History and Recent Progress in Piezoelectric Polymers, IEEE Transactions of Ultrasonics, Ferroelectrics and Frequency Control, 47, 1110-9. 

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