Poly vinyl fluoride

Vinyl fluoride monomer can be prepared by addition of HF to acetylene. The monomer is a gas at room temperature and boils at —72.2°C. Conunercially, vinyl fluoride is polymerized in aqueous medium using either redox initiation or one from thermal decomposition of peroxides. Pressures of up 

Poly(vinyl fluoride) is moderately crystalline. The crystal melting point, Tm, is approximately 200°C. The high molecular weight polymers dissolve in dimethylformamide and in tetramethyl urea at temperatures above 100°C. The polymer is very resistant to hydrolytic attack. It does, however, loose HF at elevated temperatures. 

Vinyl fluoride can be obtained from acetylene or ethylene  

Because of the low boiling point of vinyl fluoride ( —72°C), the free radical polymerization with BPO as initiator is carried out at 300 bar and 85 C. The polymer is partially crystalline and is more similar in its properties to poly(ethylene) than to poly(vinyl chloride). Since the melting point of the polymer is 2(XfC, it is processed at temperatures of 210°C. Films of poly(vinyl fluoride) are more stable to weathering than those of either PE or PVC. Consequently, poly(vinyl fluoride) is usually used for coating wood or metals. 

Several poly(fluorinated olefins) are used in practice. These include poly(vinyl fluoride), poly(vinylidene fluoride), poly(trifluoroethylene), poly(tetrafluoroethylene), and other fluorinated polyolefins such as poly(perfluoro-heptene) or poly(perfluoro-propylene). Poly(vinyl fluoride) with the general formula [-CH2CHF-]n and CAS 24981-14-4 is less common than its chlorinated analog, but still has numerous practical applications, mainly in coatings. Upon heating, the polymer begins losing HF at about 350° C with formation of double bonds in the carbon chain. At about 450° C the backbone of the polymer 

Polymers with saturated carbon chain backbone 

Less common in practice is poly(trifluoroethylene). Poly(trifluoroethylene) behaves during thermal decomposition similarly to poly(vinylidene fluoride). A study on thermal decomposition of this polymer between 380° C and 800° C showed the formation of high yields of HF and of some nonvolatile products [42]. 

The polymer generates by thermal degradation a high yield of monomer. Other perfluorinated polyolefins are known in practice. Table 6.3.7 indicates the results of some literature reports regarding the results of thermal decomposition of several perfluorinated polyolefins. 

Vlayl fluoride [75-02-5] (VF) (fluoroethene) is a colorless gas at ambient conditions. It was first prepared by reaction of l,l-difluoro-2-bromoethane [359-07-9] with ziac (1). Most approaches to vinyl fluoride synthesis have employed reactions of acetylene [74-86-2] with hydrogen fluoride (HF) either directly (2—5) or utilizing catalysts (3,6—10). Other routes have iavolved ethylene [74-85-1] and HF (11), pyrolysis of 1,1-difluoroethane [624-72-6] (12,13) and fluorochloroethanes (14—18), reaction of 1,1-difluoroethane with acetylene (19,20), and halogen exchange of vinyl chloride [75-01-4] with HF (21—23). Physical properties of vinyl fluoride are given ia Table 1. 

Vlayl fluoride undergoes free-radical polymerization. The first polymerization iavolved heating a saturated solutioa of VF ia tolueae at 67°C uader 600 MPa (87,000 psi) for 16 h (24). A wide variety of ioitiators and polymerization conditions have been explored (25—27). Examples of bulk (28,29) and solution (25,28,30,31) polymerizations exist however, aqueous suspension or emulsion methods are generally preferred (26,32—40). VF volatiflty dictates that moderately high pressures be used. Photopolymerizations, usually incorporating free-radical initiators, are also known (26,28,29,35). 

Copolymers of VF and a wide variety of other monomers have been prepared (6,41—48). The high energy of the propagating vinyl fluoride radical strongly influences the course of these polymerizations. VF incorporates well with other monomers that do not produce stable free radicals, such as ethylene and vinyl acetate, but is sparingly incorporated with more stable radicals such as acrylonitrile [107-13-1] and vinyl chloride. An Alfrey-Price value of 0.010 0.005 and an e value of 0.8 0.2 have been determined (49). The low value of is consistent with titde resonance stability and the e value is suggestive of an electron-rich monomer. 

Poly(vinyl fluoride) [24981-14-4] (PVF) is a semicrystaltiae polymer with a planar, zig-zag configuration (50). The degree of crystallinity can vary significantly from 20—60% (51) and is thought to be primarily a function of defect stmctures. Wide-line nmr and x-ray diffraction studies show the unit cell to contain two monomer units and have the dimensions of a = 0.857 nm, b = 0.495 nm, and c = 0.252 nm (52). Similarity to the phase I crystal form of poly (vinytidene fluoride) suggests an orthorhombic crystal (53). 

Kirk-Othmer Encyclopedia of Chemical Technology (4th Edition) 

The mechanism and incidence of transfer to various initiators is discussed in Chapter 3. See, in particular, Sections 3.2.10 (introduction), 3.3.2.1.4 (dialkyl diazenes including AIBN), 3.3.2.1.4 (diacyl peroxides including BPO), 3.3.2.3.1 (peroxyesters), 3.3.2.4 (dialkyl peroxides) and 3.3.2.5 (alkyl hydroperoxides). 

Principles of Polymer Chemistry, Cornell University Press Ithaca, New York, 1953. 

Chiefan, J, Rizzardo, E. In Handbook of Radical Polymerization-, Davis, T.P. Malyjaszewski, K., Eds. . lohn Wiley Sons Hoboken, NY, 2002 p 263. 

Kastmoiid, Ci.C. In Comprehensive Chemical Kinslics, Bamford, C.H. Tipper, 

In TelecheUc Polymers Synthesis and Applications Goethals, E.J., Bd.  

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Poly(vinyl Fluoride). Poly(vinyl fluoride) consists of linear chains in which the repeating unit is... 

VF copolymers [FLUORINE COMPOUNDS, ORGANIC - POLY(VINYL FLUORIDE)] (Vol 11)... 

Vinyl Fluoride. Vinyl fluoride [75-02-5] C2H2F, the monomer for poly(vinyl fluoride), is manufactured by addition of hydrogen fluoride to acetylene (see Fluorine COMPOUNDS, ORGANIC, POLY(viNYL FLUORIDE)). 

Perfluorinated ethylene—propylene copolymers, Tetrafluoroethylene—ethylene copolymers, Tetrafluoroethylene—perfluorovinyl ether copolymers, Poly(vinyl fluoride),... 

In 1954 the surface fluorination of polyethylene sheets by using a soHd CO2 cooled heat sink was patented (44). Later patents covered the fluorination of PVC (45) and polyethylene bottles (46). Studies of surface fluorination of polymer films have been reported (47). The fluorination of polyethylene powder was described (48) as a fiery intense reaction, which was finally controlled by dilution with an inert gas at reduced pressures. Direct fluorination of polymers was achieved in 1970 (8,49). More recently, surface fluorinations of poly(vinyl fluoride), polycarbonates, polystyrene, and poly(methyl methacrylate), and the surface fluorination of containers have been described (50,51). Partially fluorinated poly(ethylene terephthalate) and polyamides such as nylon have excellent soil release properties as well as high wettabiUty (52,53). The most advanced direct fluorination technology in the area of single-compound synthesis and synthesis of high performance fluids is currently practiced by 3M Co. of St. Paul, Minnesota, and by Exfluor Research Corp. of Austin, Texas. 

Table 2. Properties of Poly(vinyl fluoride) Film...

Poly(vinyl fluoride) is available from Du Pont both as a resia and as transparent and pigmented films under the trademark Tedlar PVF film. Films are available ia nonoriented and oriented grade ia several tensile modifications and thicknesses, with either adherable or nonadherable release-grade surfaces. The 1992 prices ranged from 30 to 70/kg, vs 24 to 62/kg ia 1988. Prices for specially tailored films were significantly higher. 

Vinyl fluoride (fluoroethene), is manufactured from the cataly2ed addition of hydrogen fluoride to acetylene. It is used to prepare poly(vinyl fluoride) which has found use in highly weather-resistant films (Tedlar film, Du Pont). Poly(vinyhdene fluoride) also is used in weather-resistant coatings (see Eluorine compounds, organic). The monomer can be prepared from acetylene, hydrogen fluoride, and chlorine but other nonacetylenic routes are available. 

See Fluorine compounds, organic-poly(vinyl) fluoride). 

Polymer Solvent. Sulfolane is a solvent for a variety of polymers, including polyacrylonitrile (PAN), poly(vinyhdene cyanide), poly(vinyl chloride) (PVC), poly(vinyl fluoride), and polysulfones (124—129). Sulfolane solutions of PAN, poly(vinyhdene cyanide), and PVC have been patented for fiber-spinning processes, in which the relatively low solution viscosity, good thermal stabiUty, and comparatively low solvent toxicity of sulfolane are advantageous. Powdered perfluorocarbon copolymers bearing sulfo or carboxy groups have been prepared by precipitation from sulfolane solution with toluene at temperatures below 300°C. Particle sizes of 0.5—100 p.m result. 

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