F Vinylidene fluoride

Vinyldiazomethane, see 3-Diazopropene, 1132a Vinylene carbonate, see l,3-Dioxol-4-en-2-one, 1084 f Vinyl fluoride, see Fluoroethylene, 0744 f Vinylidene chloride, see 1,1-Dichloroethylene, 0691 f Vinylidene fluoride, see 1,1-Difluoroethylene, 0696 Vinyllithium, 0754... 

F Vinylidene fluoride, hexafluoropropylene, tetrafluroethylene Oxygenated automotive fuels concentrated aqueous inorganic acids water steam... 

Mihtary interest in the development of fuel and thermal resistant elastomers for low temperature service created a need for fluorinated elastomers. In the early 1950s, the M. W. Kellogg Co. in a joint project with the U.S. Army Quartermaster Corps, and 3M in a joint project with the U.S. Air Force, developed two commercial fluorocarbon elastomers. The copolymers of vinyUdene fluoride, CF2=CH2, and chlorotrifluoroethylene, CF2=CFC1, became available from Kellogg in 1955 under the trademark of Kel-F (1-3) (see Fluorine compounds, ORGANic-POLYcm.OROTRiFLUOROETHYLENE Poly(vinylidene) fluoride). In 1956, 3M introduced a polymer based on poly(l,l-dihydroperfluorobutyl acrylate) trademarked 3M Brand Fluorombber 1F4 (4). The poor balance of acid, steam, and heat resistance of the latter elastomer limited its commercial use. 

The most chemical-resistant plastic commercially available today is tetrafluoroethylene or TFE (Teflon). This thermoplastic is practically unaffected by all alkahes and acids except fluorine and chlorine gas at elevated temperatures and molten metals. It retains its properties up to 260°C (500°F). Chlorotrifluoroethylene or CTFE (Kel-F, Plaskon) also possesses excellent corrosion resistance to almost all acids and alkalies up to 180°C (350°F). A Teflon derivative has been developed from the copolymerization of tetrafluoroethylene and hexafluoropropylene. This resin, FEP, has similar properties to TFE except that it is not recommended for continuous exposures at temperatures above 200°C (400°F). Also, FEP can be extruded on conventional extrusion equipment, while TFE parts must be made by comphcated powder-metallurgy techniques. Another version is poly-vinylidene fluoride, or PVF2 (Kynar), which has excellent resistance to alkahes and acids to 150°C (300°F). It can be extruded. A more recent development is a copolymer of CTFE and ethylene (Halar). This material has excellent resistance to strong inorganic acids, bases, and salts up to 150°C. It also can be extruded. 

Baltd-Calleja, F. J., Gonzalez Arche, A., Ezquerra, T. A., Santa Cruz, C., Batallon, F., Frick, B. and Lopez Cabarcos, E. Structure and Properties of Ferroelectric Copolymers of Poly(vinylidene) Fluoride. Vol. 108, pp. 1-48. 

A. 0. Pozdnyakov, B. M. Ginzburg, 0. F. Pozdnyakov, B. P. Redkov, Desorption of fullerene C60 from a mixture with a copolymer of trifluorochloroethylene and vinylidene fluoride, Technical Physics Letters, vol. 2, pp. 51-53,1997. 

Hietala, S., Skou, E. and Sundhokn, F. 1999. Gas permeation properties of radiation-grafted and sulfonated poly-(vinylidene fluoride) membranes. Polymer 40 5567-5573. 

Landis, F A. and Moore, R. B. 2000. Blends of a perfluorosulfonate ionomer with poly(vinylidene fluoride) Effect of counterion type on phase separation and crystal morphology. Macromolecules 33 6031-6041. 

The processability of fluorine-containing polymers is improved by replacement of one or more of the fluorine atoms. Replacing one of the eight fluorine atoms with a trifluoromethyl group gives a product called FEP or Viton, actually a copolymer of tetrafluoroethylene and hexafluoropropylene (Equation 6.53). Polytrifluoromonochloroethylene (PCTFE, Kel F) (Equation 6.54), in which one fluorine atom has been replaced by a chlorine atom, has a less regular structure and is thus more easily processed. Poly(vinylidene fluoride) (PVDF, Kynar) (Equation 6.55) is also more easily processable but less resistant to solvents and corrosives. 

Fluorocarbon Resins. This term includes polytetrafluoroethylene, polymers of chloro-trifluoroethylene (fluorothene), vinylidene fluoride (H2C CF2)j hexafluoropropylene (C3Ffl) and similar compds. These polymers are thermoplastic, inert to chemicals and oxidation. They have high heat stability, retain their useful props at both extremely low and high temps, have high electrical resistance to moisture. The materials are available as re sins, powders, and dispersions, and as films, sheets, tubes, rods and tapes. Some of them are rubber-like. Commercially available varieties are Kel-F , Teflon , Fluorel , Aclar and "Halon ... 

Kel-F (copolymer of chlorotrifluoroethylene and vinylidene fluoride) (3 1 ratio) Inert binder for main high explosive compositions... 

The copolymer of vinyl ferrocene (VF) and butadiene has also been reported in the literature for use as a binder for composite propellants. It does not require any burn-rate (BR) accelerator because of the presence of iron (Fe) in vinyl ferrocene which is converted to finely divided Fe203 (a well-known BR accelerator) during combustion. A few groups of scientists have also studied fluorocarbon polymers as binders for composite propellants because of their excellent compatibility with oxidizers and fuels coupled with high density. Accordingly, Kel-F elastomer (a copolymer of vinylidene fluoride and chlorotrifluoroethylene, trade name of 3M, USA) and Viton-A (copolymer of hexafluoropropylene and vinylidene fluoride, trade name of Du Pont, USA) have also been reported for this purpose. The structures of Kel-F 800 [Structure (4.13)] and Viton-A [Structure (4.14)] are ... 

Medinsky, M.A., Bechtold, W.E., Birnbaum. L.S., Chico, D.M., Gerlach, R.F. Henderson, R.F. (1988) Uptake of vinylidene fluoride in rats simulated by a physiological model. Fundam. appl. Toxicol., 11, 250-260... 

Fig. 23. Crystal structure of /Worm (modification-/) poly (vinylidene fluoride). Figures in broken lines represent chain rotation to avoid the steric hindrance between F atoms (Hasegawa and others, 1970)...

The first member of this family - vinylidene fluoride - readily adds fluoro-sulfonic acid, even in the absence of the catalyst, and it is nitrofluorinated by a HNO3/HF mixture six times faster than CFH=CF2 [15] however, HF/HS03F superacid does not react at ambient temperature with C1CF=CF2 or CF2=CF2. These two olefins show a similar reactivity in electrophilic reactions. Interaction of polyfluorinated propylenes CF2=CXCF3 (X=H,F) with trifluoro- and tetra-fluoroethylenes proceeds at room temperature in the presence of a Lewis acid catalyst to give the corresponding polyfluoropentenes-2 ... 

Vinylidene fluoride (CF2=CH2) exhibits a 19F chemical shift of -82 ppm. As seen in Scheme 4.55, one alkyl substitution at the 2-position leads to about 10 ppm of shielding, with two alkyl groups providing 6-7 ppm more. The two-bond F-F coupling constant in such AB systems is typically around 50 Hz. Modest shielding of the Z-fluorine is generally observed relative to the F-fluorinc of 1,1-difluoroalkenes. 

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