CTFE

Uses. Vinyhdene fluoride is used for the manufacture of PVDF and for copolymerization with many fluorinated monomers. One commercially significant use is the manufacture of high performance fluoroelastomers that include copolymers of VDF with hexafluoropropylene (HFP) (62) or chlorotrifluoroethylene (CTFE) (63) and terpolymers with HEP and tetrafluoroethylene (TEE) (64) (see Elastomers, synthetic-fluorocarbon elastomers). There is intense commercial interest in thermoplastic copolymers of VDE with HEP (65,66), CTEE (67), or TEE (68). Less common are copolymers with trifluoroethene (69), 3,3,3-trifluoro-2-trifluoromethylpropene (70), or hexafluoroacetone (71). Thermoplastic terpolymers of VDE, HEP, and TEE are also of interest as coatings and film. A thermoplastic elastomer that has an elastomeric VDE copolymer chain as backbone and a grafted PVDE side chain has been developed (72). 

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. 

The inability to process PTFE by conventional thermoplastics techniques has nevertheless led to an extensive search for a melt-processable polymer but with similar chemical, electrical, non-stick and low-friction properties. This has resulted in several useful materials being marketed, including tetrafluoro-ethylene-hexafluoropropylene copolymer, poly(vinylidene fluoride) (Figure 13.1(d)), and, most promisingly, the copolymer of tetrafluoroethylene and perfluoropropyl vinyl ether. Other fluorine-containing plastics include poly(vinyl fluoride) and polymers and copolymers based on CTFE. 

Copolymentation of CTFE and ethylene yields linear, semicrystalhne polymers known as ECTFE resins. They have a highly altemahng structure... 

Fluoroplastic FPs have superior heat and chemical resistance, excellent electrical properties, but only moderate strength. Variations include PTFE, FEP, PFA, CTFE, ECTFE, ETFE, and PVDF. Used for bearings, valves, pumps handling concentrated corrosive chemicals, skillet linings, and as a film over textile webs for inflatables such as pneumatic sheds. Excellent human-tissue compatibility allows its use for medical implants. 

MIR techniques have simplified obtaining infrared spectra of many materials important in packaging. These include rubber, plastics, laminations, and components of these materials that find use in pumps, sample packages, and devices. The combination of MIR and computerized pattern recognition techniques can be used for differentiating and classification of flexible packaging polymers such as polyvinyl chloride (PVC), polyvinylidene chloride (PVdC), acrylonitrile (Barex), and CTFE (Aclar) [22]. 

Laminated sheets made from PVC bonded to chlorotrifluoroethylene (CTFE) have the lowest water-vapor permeability of all the materials used in blister packaging. Compared to 250 pm PVC sheet, a lamination of 200 pm PVC-19 pm CTFE (8 mL PVC-0.8 mL CTFE) has a 15-fold lower water-vapor permeability. There are many grades of CTFE available with more or less barrier and ease of formability. Figure 1 shows the difference between flat sheet and formed blister moisture permeabilities. 

VF3), chlorotrifluoroethylene (CTFE), and hexafluoropropene (HFP), in order to avoid crystallization as described below. 

Figure 5.1. Basic strategy of well-architectured cotelomers of vinylidene fluoride (VDF), trifluor-oethylene (VTA chlorotrifluoroethylene (CTFE), hexafluoropropene (HFP), and ethylene (E).

Polymerizations were carried out in a jacketed, 1-gal, stirred, pressure tank reactor. Typical reactions were run by adding water, alcohol, or chain transfer agent, phosphate buffer, and persulfate to the reactor. The reactor was pressurized with CTFE monomer. Sulfite solution was fed at a rate to maintain reaction. Copper and iron ions were used at times as catalysts by adding cupric sulfate or ferrous sulfate.3 The product was filtered, washed with 90 10 water methanol followed with deionized water. The product was dried at 110°C. 

Many vinyl monomers were reported to have been grafted onto fluoropolymers, such as (meth)acrylic acid and (meth)acrylates, acrylamide, acrylonitryl, styrene, 4-vinyl pyridine, N-vinyl pyrrolidone, and vinyl acetate. Many fluoropolymers have been used as supports, such as PTFE, copolymers of TFE with HFP, PFAVE, VDF and ethylene, PCTFE, PVDF, polyvinyl fluoride, copolymers ofVDF with HFP, vinyl fluoride and chlorotrifluoroethylene (CTFE). The source of irradiation has been primarily y-rays and electron beams. The grafting can be carried out under either direct irradiation or through the use of preliminary irradiated fluoropolymers. Ordinary radical inhibitors can be added to the reaction mixture to avoid homopolymerization of functional monomers. 

Ethylene carbonate, 10 640, 665 in lithium cells, 3 459 molecular formula, 6 305t physical properties, 6 306t transesterification of, 13 651-652 Ethylene-carbon monoxide (ethylene-CO) copolymers, 5 9 10 197 Ethylene chlorohydrin process, 10 640 Ethylene-chlorotrifluoroethylene (E-CTFE) alternating copolymer (ECTFE), 15 248... 

CTFE was used as supplied from Daikin Kogyo Co, Ltd. (purity ... 

Procedure. The radiation-induced cross-linking was carried out as follows. About 0.1 g of polyethylene film was placed in a glass ampoule of 30 mm diameter and 200 mm long. Gaseous CTFE and the mixture of CTFE/butadiene was introduced into the ampoule under the gas pressure of 1 atm. after evacuation of the ampoule. The ampoule was irradiated by Y-ray with a cobalt-60 at the dose rate of 0.05Mrad/hr at room temperature. 

Role of Unsaturated Group in the Cross-Linking in the Presence of CTFE. In order to make clear the role of unsaturated group contained in polyethylene, the radiation-induced cross-linkings of the polyethylenes containing various concentrations of the unsaturated groups were carried out in the presence of CTFE. 

Figures 1-3 show the changes in the gel fraction of irradiated polymer, the degree of grafting of CTFE and the total concentration of the unsaturated groups ([U]) with the irradiation...

Figure 1. Plot of Gf vs. dose in the irradiation of various polyethylenes in the presence of CTFE (( ) HDPE (O) LDPE ((D) BG-LDPE-1 (C) BG-LDPE-2 (9) BG-LDPE-3 (Q) IG-LDPE) and in vacuum ((A) LDPE (A) HDPE)...

Figure 2. Plot of Dg vs. dose in the irradiation of various polyethylenes in the presence of CTFE (symbols are the same as in Figure 1)...

On the other hand, the rates of grafting of CTFE onto butadiene- and isoprene-grafted polyethylenes were lower than those onto original ones (Figure 2). As shown in Figure 3, the rate of consumption of the unsaturated groups, as well as the gel fraction, was remarkably accelerated by CTFE. 

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