Vinylidene Fluoride-Chlorotrifluoroethylene Copolymer

Vinylidene fluoride-chlorotrifluoroethylene copolymers constitute the second class of vinylidene fluoride copolymers which have achieved commercial importance as elastomers. They were introduced in 1955. 

Vinylidene fluoride-chlorotrifluoroethylene copolymers may be vulcanized by methods similar to those described in the previous section for the vulcanization of vinylidene fluoride-hexafluoropropylene copolymers. The chemistry of the reactions which occur has not been investigated so fully but it is likely that a similar three-stage process is involved. In the first stage, hydrogen chloride rather than hydrogen fluoride is eliminated ... 

This may be inferred from the finding that treatment of vinylidene fluoride-chlorotrifluoroethylene copolymers with an amine produces the amine hydrochloride in high yield but very little amine hydrofluoride [3]. Since polychlo-rotrifluoroethylene is unreactive towards amines (RNH2), the following substitution may be discounted ... 

The chemical resistance of vinylidene fluoride-chlorotrifluoroethylene copolymer vulcanizates is excellent, though not generally quite so good as that of the vinylidene fluoride-hexafluoropropylene copolymers. However, the vinylidene fluoride-chlorotrifluoroethylene copolymers do have better resistance to strong oxidizing acids. 

Vulcanized vinylidene fluoride-chlorotrifluoroethylene copolymers also have good thermal stability, withstanding prolonged heating at 200°C without... 

Li, Z.M., Wang, Y.H. and Cheng, Z.-Y. (2006) Electromechanical properties of poly(vinylidene-fluoride-chlorotrifluoroethylene) copolymer, App. Phys Lett. 88, 062904. 

Vulcanized vinylidene fluoride-chlorotrifluoroethylene copolymers also have good thermal stability, withstanding prolonged heating at 200°C without serious deterioration. Low temperature performance is limited the glass transition temperatures of copolymers with 50 and 70 mole % vinylidene fluoride are 0°C and — 15°C respectively. The principal application of the elastomers is for components of systems handling strong mineral acids. 

The isoprene units in the copolymer impart the ability to crosslink the product. Polystyrene is far too rigid to be used as an elastomer but styrene copolymers with 1,3-butadiene (SBR rubber) are quite flexible and rubbery. Polyethylene is a crystalline plastic while ethylene-propylene copolymers and terpolymers of ethylene, propylene and diene (e.g., dicyclopentadiene, hexa-1,4-diene, 2-ethylidenenorborn-5-ene) are elastomers (EPR and EPDM rubbers). Nitrile or NBR rubber is a copolymer of acrylonitrile and 1,3-butadiene. Vinylidene fluoride-chlorotrifluoroethylene and olefin-acrylic ester copolymers and 1,3-butadiene-styrene-vinyl pyridine terpolymer are examples of specialty elastomers. 

Fluoroelastomers are copolymers containing fluorine in their structure. There are different kinds of fluoroelastomers depending on the chemical composition and on the production in which the comonomers are found in the chain. As examples of comonomers, we can mention vinylidene fluor-ide-hexafluoropropylene and vinylidene fluoride-chlorotrifluoroethylene. The vulcanization process is performed using peroxides, diamines, and bisphenol. 

E/TFE = ethylene/tetrafluoroethylene, E/CTFE = ethylene/chlorotrifluoroethylene, EPE = oxide, E/VAL = ethylene/vinyl alcohol, FEP = tetrafluoroethylene/hexafluoropropylene, FU = furan, pA = polyamide, PCTFE = polychlorotrifluoroethyl-ene, HDPE = high-density polyethylene, PF = propylene formaldehyde, PFA = perfluoro alkoxyalkane, PP = polypropylene, PTFE = polytetrafluoroethylene, PUR = polyurethane, PVC = polyvinyl chloride, PVDF = polyvinylidene fluoride, UP = unsaturated polyester, UP-GF = fiberglass-reinforced unsaturated polyester, VE-GF = fiberglass-reinforced vinyl ester, FU-GF = fiberglass-reinforced furane, EP-GF = fiberglass-reinforced ester, CR = chloroprene rubber, CSM = chlo-rosulfonyl polyethylene, FPM = vinylidene fluoride/hexafluoropropylene copolymer, HR = isobutane-isoprene rubber, NBR = nitrile-butadiene rubber, NR = natural rubber, SBR = styrene-butadiene rubber. 

Kellogg was then manufacturing a stable plastic poly-(chlorotrifluoro ethylene) which had been developed in the Atomic Energy program by Bill Miller and used in certain critical applications. Hanford remembered the early work at Du Pont and turned his new group toward Ford s vinylidene fluoride (VF2) copolymers. They found that a copolymer of VF2 with chlorotrifluoroethylene (CTFE) wa.s elastomeric and very stable[6]. 

The commercial production of polymers containing fluorine is very small compared to the output of many other synthetic polymers. Nevertheless, several fluoropolymers are used in various important specialized applications. The principal commercial fluoropolymers at the present time are the homopolymers of tetrafluoroethylene (I), chlorotrifluoroethylene (II), vinyl fluoride (III) and vinylidene fluoride (IV) and vinylidene fluoride-chlorotrifluoroethylene, vinyli-dene fluoride-hexafluoropropylene (V) and tetrafluoroethylene-hexafluoropro-pylene copolymers. These materials, together with a few other fluoropolymers of interest, form the contents of this chapter. 

Of these materials the most widely used and most studied are the vinylidene fluoride/hexafluoropropylene copolymers and the terpoly-mers which also contain tetrafluoroethylene. They are generally superior in heat and fluid resistance to the other types. The copolymer of vinylidene fluoride and chlorotrifluoroethylene has superior resistance of oxidizing acids such as fuming nitric acid. The copolymer containing 70 mole% vinylidene fluoride (Kel F 3700) has good low temperature flexibility. 

Zulfiqar, S., Zulfiqar, M., Rizvi, M., Munir, A. and McNeill, C. (1994) Study of the thermal degradation of poly-chlorotrifluoroethylene, poly(vinylidene fluoride) and copolymers of chlorotri-fluoroethylene and vinylidene fluoride. Polym. Degrad. Stab., 43, 423 -430. 

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. 

As will be seen from Table 13.4 elastomers are also available which are copolymers of vinylidene fluoride and chlorotrifluoroethylene. These materials... 

Poly(vinylidene fluoride) (PVDF) Ethylene-chlorotrifluoroethylene copolymer Ethylene-tetrafluoroethylene copolymer Poly(vinyl fluoride) (PVF)... 

Abbreviations for plastics ABS, acrylonitrile-butadiene-styrene CPVC, chlorinated poly vinyl chloride ECTFE, ethylene-chlorotrifluoroethylene ETFE, ethylene-tetrafluoroethylene PB, polybutylene PE, polyethylene PEEK, poly ether ether ketone PFA, perfluoroalkoxy copolymer POP, poly phenylene oxide PP, polypropylene PVC, polyvinyl chloride PVDC, poly vinylidene chloride PVDF, poly vinylidene fluoride. 

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

A study has been conducted on PBXs based on TATB using various binders such as polyurethane (Estane 5703-Goodrich), Viton-A (copolymer of vinylidene fluoride and hexafluoropropylene Du Pont), silicone resin (Chemlok), Kel-F800 [copolymer (3 1) of chlorotrifluoroethylene and vinylidene fluoride 3M Company] and Teflon [poly (tetrafluoroethylene), PTFE Du Pont] etc. and it was concluded that... 

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 ... 

Screening tests were conducted on potential construction materials. The candidate materials evaluated included the following polytetrafluoroethylene (PTFE, TFE), fluorinated ethylene-propylene copolymer (FEP), perfluoroalkoxy-alkanes (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (E-CTFE), poly vinylidene fluoride (PVDF), polypropylene (PP), and polyvinyl chloride (PVC). These materials were chosen based on cost, availability, and information from manufacturers on compatibility with acid solutions. 

Poly(vinylidene fluoride) (PVDF) Ethylene-chlorotrifluoroethylene copolymer... 

The first commercial fluoroelastomer, Kel-F, was developed by the M. W. Kellog Company in the early to mid-1950s and is a copolymer of vinylidene fluoride (VDF) and chlorotrifluoroethylene (CTFE). Another fluorocarbon elastomer, Viton A, is a copolymer of VDF and hexafluoropropylene (HFP) developed by du Pont was made available commercially in 1955. The products developed thereafter can be divided into two classes VDF-based fluoroelastomers and tetrafluoroethylene (TFE)-based fluoroelastomers (perfluoroelastomers).72 The current products are mostly based on copolymers of VDF and HFP, VDF and MVE, or terpolymers of VDF with HFP and TFE. In the combination of VDF and HFP, the proportion of HFP has to be 19 to 20 mol% or higher to obtain amorphous elastomeric product.73 The ratio of VDF/HFP/TFE has also to be within a certain region to yield elastomers as shown in a triangular diagram (Figure 2.2).74... 

Mandelkern, L., G. M. Martin and F. A. Quinn Glassy state transition of Poly-(chlorotrifluoroethylene), Poly-(vinylidene fluoride) and their copolymers. J. Research Nat. Bur. Standards 58, 137—143 (1957). 

Solutions of Biomer were obtained from Ethicon Inc. Biomer is poly (ether polyurethane) which contains urea linkage in the hard segment according to our IR analysis (19). Films of Biomer were cast on clean glass plates by diluting the polymer solution in dimethyl acetyl-amide. The films were dried in a vacuum oven at 50°C for 24 hr. The final film thickness was around 125/a. GPC analysis showed that the content of oligomers in Biomer was also negligible. Kel-F82, which is a copolymer composed of chlorotrifluoroethylene (97%) and vinylidene fluoride (3% ), was obtained from the 3M Company. 

Note ETFE, copolymer of ethylene and tetrafluoroethylene ECTFE, copolymer of ethylene chlo-rotrifluoroethylene PFA, copolymer of perfluoropropylvinylether and tetrafluoroethylene PVDF, poly(vinylidene fluoride) PCTFE, poly(chlorotrifluoroethylene). 

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