Mechanical properties poly vinylidene fluoride

The first major application of microfiltration membranes was for biological testing of water. This remains an important laboratory application in microbiology and biotechnology. For these applications the early cellulose acetate/cellulose nitrate phase separation membranes made by vapor-phase precipitation with water are still widely used. In the early 1960s and 1970s, a number of other membrane materials with improved mechanical properties and chemical stability were developed. These include polyacrylonitrile-poly(vinyl chloride) copolymers, poly(vinylidene fluoride), polysulfone, cellulose triacetate, and various nylons. Most cartridge filters use these membranes. More recently poly(tetrafluo-roethylene) membranes have come into use. 

The preceding structural characteristics dictate the state of polymer (rubbery vs. glassy vs. semicrystalline) which will strongly affect mechanical strength, thermal stability, chemical resistance and transport properties [6]. In most polymeric membranes, the polymer is in an amorphous state. However, some polymers, especially those with flexible chains of regular chemical structure (e.g., polyethylene/PE/, polypropylene/PP/or poly(vinylidene fluoride)/PVDF/), tend to form crystalline... 

Jin et al. (65) used poly(vinylidene fluoride) (PVDF) as a compatibilizer to assist dispersion of CNTs in PMMA. Multi-walled carbon nanotubes were first coated with PVDF and then melt-blended with PMMA. Poly(vinylidene fluoride) served as an adhesive to improve wetting of CNTs by PMMA and to increase the interfacial adhesion resulting in improved mechanical properties of MWCNT-PMMA composites. 

The mechanism of the polarity inversion of tautomeric molecules is totally different from the orientation polarization of conventional organic dielectrics, such as camphor and poly(vinylidene fluoride), and the dielectric response of this new type of dielectric should be much faster. Furthermore, a significant contribution of the proton-tunnelling mechanism to the proton tautomerism is frequently observed. Consequently, the dielectric property derived from proton tautomerization should have a high chance of being related to quantum phenomena. 

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... 

Piezoelectricity links the fields of electricity and acoustics. Piezoelectric materials are key components in acoustic transducers such as microphones, loudspeakers, transmitters, burglar alarms and submarine detectors. The Curie brothers [7] in 1880 first observed the phenomenon in quartz crystals. Langevin [8] in 1916 first reported the application of piezoelectrics to acoustics. He used piezoelectric quartz crystals in an ultrasonic sending and detection system - a forerunner to present day sonar systems. Subsequently, other materials with piezoelectric properties were discovered. These included the crystal Rochelle salt [9], the ceramics lead barium titanate/zirconate (pzt) and barium titanate [10] and the polymer poly(vinylidene fluoride) [11]. Other polymers such as nylon 11 [12], poly(vinyl chloride) [13] and poly (vinyl fluoride) [14] exhibit piezoelectric behavior, but to a much smaller extent. Strain constants characterize the piezoelectric response. These relate a vector quantity, the electrical field, to a tensor quantity, the mechanical stress (or strain). In this convention, the film orientation direction is denoted by 1, the width by 2 and the thickness by 3. Thus, the piezoelectric strain constant dl3 refers to a polymer film held in the orientation direction with the electrical field applied parallel to the thickness or 3 direction. The requirements for observing piezoelectricity in materials are a non-symmetric unit cell and a net dipole movement in the structure. There are 32-point groups, but only 30 of these have non-symmetric unit cells and are therefore capable of exhibiting piezoelectricity. Further, only 10 out of these twenty point groups exhibit both piezoelectricity and pyroelectricity. The piezoelectric strain constant, d, is related to the piezoelectric stress coefficient, g, by... 

He, X. Yao, K, (2006), Crystallization mechanism and piezoelectric properties of solution-derived ferroelectric poly(vinylidene fluoride) thin films. Applied Physics letter. Vol. 89, No. 11, pp. 112909-1 -112902-3, ISSN 0003-6951. 

The alternating copolymer of trifluorochloroethylene and ethylene has a higher melting temperature of 240° C. It has similar mechanical properties to poly(vinylidene fluoride) or the alternating copolymer of tetrafluoroethylene and ethylene. 

The objective of this chapter is to review the latest progress in the preparation of radiation-grafted PEMs for fuel cells using EB. In particular, the results associated with the preparation and the properties of two types of membranes having polystyrene sulfonic acid (PSSA) grafted to poly(vinylidene fluoride) (PVDF) films are reviewed. The fundamentals of RIG operation with EB accelerators are also briefly reviewed to furnish a clear understanding of the mechanism of PEM formation and how membrane composition and, consequently, their properties can be controlled. 

Chen ZH, Christensen L, Dahn JR (2004) Mechanical and electrical properties of poly (vinylidene fluoride-tetrafiuoroethylene-propylene)/super-S carbon black swelled in liquid solvent as an electrode binder for lithium-ion batteries. J Appl Polym Sci 91 2958-2965... 

Ho K C, Kolliopoulos A, Lamoriniere S, Greenhalgh E S and Bismarck A (2010) Atmospheric plasma fluorination as a means to improve the mechanical properties of short-carbon fiber reinforced poly(vinylidene fluoride). Compos Pari A 41 1115-1122. 

Chen et al. [71] investigated the electrical and mechanical properties of carbon black-poly vinylidene fluoride-tetrafluoroethylene-propylene films cross-linked with... 

Polymer electrolyte is composed of polymer substrate and metal salt. Possible polymer substrates include polyethylene oxide, poly vinylidene fluoride, poly(methyl methacrylate), polyvinylidene chloride, and polyacrylonitrile. Examples of cations of metal salt are li, Na, K, and Mg. Possible anions are BF, SCN, SO3CF3, AsF PF and NfCFjSOj). An inorganic modifier such as nanopartide Ti02 can be added to increase mechanical properties of supercapadtor. Mass is divided so that polymer substrate is 30 to 90 wt%, metal salt is to 2 to 30 wt%, and nanotube modifier is 3 to 30 wt%. 

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