Chlorotrifluoroethylene properties

R. E. Mowers Cyogenic Properties ofPoly(Chlorotrifluoroethylene), Technical Document Report No. RTD-TDR-63-11, Air Eorce Contract No. AE04(611)-6354,1962. 

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. 

Copolymers of chlorotrifluoroethylene and ethylene were introduced by Allied Chemicals under the trade name Halar in the early 1970s. This is essentially a 1 1 alternating copolymer compounded with stabilising additives. The polymer has mechanical properties more like those of nylon than of typical fluoroplastic, with low creep and very good impact strength. Furthermore the polymers have very good chemical resistance and electrical insulation properties and are resistant to burning. They may be injection moulded or formed into fibres. 

Permeability Different plastics provide different permeability properties. As an example polyethylene will pass wintergreen, hydrocarbons, and many other chemicals. It is used in certain cases for the separation of gases since it will pass one and block another. Chlorotrifluoroethylene and vinyli-dene fluoride, vinylidene chloride, polypropylene, EVA, and phenoxy merit evaluation (Chapter 4, PACKAGING, Permeability). 

Its properties resemble those of ethylene-chlorotrifluoroethylene copolymer. 

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... 

A copolymer of ethylene and chlorotrifluoroethylene is mixed with 0.5 to 2 wt.% of boron nitride, the blend obtained is extruded at 260 to 300C, nitrogen is injected into the blend at 50 to 150 atmospheres and the pressure is lowered to produce the expanded article, which has high dielectric properties. 

The other major springboard for the fluorocarbon chemical industry was the "Manhattan Project to develop the atomic bomb. This required the large-scale production of highly corrosive elemental fluorine and uranium(VI) fluoride for the separation of the radioactive 235U isotope. Oils capable of resisting these materials were needed to lubricate pumps and compressors, and polymers were needed to provide seals. Peril uorinated alkanes and polymers such as PTFE and poly(chlorotrifluoroethylene) (PCTFE) proved to have the appropriate properties so practical processes had to be developed for production in the quantities required. In 1947 much of this work was declassified and was published in an extensive series of papers3 which described the fundamental chemistry on which the commercial development of various fluoro-organic products, especially fine chemicals, was subsequently based. 

For the current study, the source of PCTFE was Kel-F 6061, a solid homopolymer of chlorotrifluoroethylene, produced by the 3M company. Preliminary studies with other forms of PCTFE indicate that its chemistry is by no means unique. We chose this particular polymer for its insolubility and other physical properties. 

Examples of fluoroplastics include polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), ethylene—chlorotrifluoroethylene (ECTFE), ethylene—tetrafluoroethylene (ETFE), poly(vinylidene fluoride) (PVDF), etc (see Fluorine compounds, organic). These polymers have outstanding electrical properties, such as low power loss and dielectric constant, coupled with very good flame resistance and low smoke emission during fire. Therefore, in spite of their relatively high price, they are used extensively in telecommunication wires, especially for production of plenum cables. Plenum areas provide a convenient, economical way to run electrical wires and cables and to interconnect them throughout nonresidential buildings (14). Development of special flame-retardant low smoke compounds, some based on PVC, have provided lower cost competition to the fluoroplastics for indoors application such as plenum cable, Riser Cables, etc. 

Several plastics, with high resistance to chemical attack and high temperatures, deserve special mention for process designers of inherently safer plants. For example, tetrafluoroethylene (TFE), commonly called Teflon brand TFE, is practically unaffected by all alkalies and acids except fluorine and chlorine gas at elevated temperatures, and molten metals. It retains its properties at temperatures up to 260°C. Other plastics that have similarly excellent properties (but are different enough that they each have their niche) include chlorotrifluoroethylene (CTFE) Teflon FEP, a copolymer of tetrafluoroethylene and hexafluoropropylene polyvinylidene fluoride (PVF2) (also... 

Polychlorotrifluoroethylene (PCTFE) has better mechanical properties than PTFE because the presence of the chlorine atom in the molecule promotes the attractive forces between molecular chains. It also exhibits greater hardness and tensile strength, and considerably higher resistance to cold flow than PTFE. Since the chlorine atom has a greater atomic radius than fluorine, it hinders the close packing possible in PTFE, which results in a lower melting point and reduced propensity of the polymer to crystallize [7]. The chlorine atom present in ethylene chlorotrifluoro-ethylene (ECTEE), a copolymer of ethylene and chlorotrifluoroethylene (CTEE), has a similar effect on the properties of the polymer. 

In this chapter the solid state extrusion of different grades of polyethylene is discussed. The term coprdyetfaylene stands as weU for short and long branched PE as for the nearly alternating 1 1 oipolymer poly(ethjdene-aj-chlorotrifluoroethylene) (PECTFE). It is well known that even HDPE cxsitains a certain amount of ort branches. Therefore, it isi of interest to note that already one butyl side group per thousand main diain carboni atoms effects the solid state extrusion properties of PE remarkably. 

Chlorotrifluoroethylene monomer serves as a building block for the CTFE telomer oils as well as the solid higher polymer and various copolymers. CFC-113 also may be used in the production of trifluoroethylene monomer by vapor-phase reduction using hydrogen and a precious metal catalyst, usually palladium [reaction (9)]. Copolymers of trifluoroethylene and vinylidene fluoride show interesting piezoelectric properties. 

Solid perfluorocarbon surfaces also have extremely low surface energies Thus, poly(tetrafluoroethylene) (PTFE, Teflon) has a y value of 18.5 dyn cm which is the reason for the anti-stick and low-friction properties used for frying pans and other applications. That this effect is directly related to the fluorine content becomes obvious on comparison of the surface energies of poly(difluoro-ethylene) (25 dyn cm ), poly(fluoroethylene) (28 dyn cm ), and polyethylene (31 dyn cm Y If only one fluorine atom in PTFE is replaced by more polarizable chlorine, the surface energy of the resulting poly(chlorotrifluoroethylene) jumps to 31 dyn cm , the same value as for polyethylene [8]. 

Fluoropolymers. Melt processable fluoropolymers such as Teflon FEP, Tefzel ETFE, poly(vinylidene fluoride) (Kynar), and ethylene-chlorotrifluoroethylene copolymer (Halar) are suitable for wire insulation in special applications because they combine good physical properties with low flammability. They are used for instrumentation cable in process-control rooms, as well as for computer and aircraft wiring and in military applications. The... 

Thermoplastic comprised of an alternating copolymer of ethylene and chlorotrifluoroethylene. It has good impact resistance and good abrasion resistance, chemical resistance, weatherability, and electrical properties. It can be molded, extruded, and powder-coated with uses in tubing, cable and wire insulation, valves, pump parts, wraps, and tower packing and chemical equipment applications. 

Hyflon AD amorphous fluoropolymer is used in optical devices, pellicles in semiconductor manufacture, as a dielectric and as a separation membrane. Small amounts of TDD have been used as a modifier in ethylene-chlorotrifluoroethylene polymers to increase stress crack resistance. Minute amounts of TDD are used also as a modifier in polytetrafluoroethylene to improve elastic modulus, reduce creep and permeability and increase transparency. It has been suggested that the much higher reactivity of TDD and other fluorinated dioxoles relative to other modifiers gives a more uniform distribution of the modifier in the polymer chain that results in a greater increase in the desired properties at lower concentration of modifier in the polymer. 

The arrangement of elements in the molecule, the symmetry of the structure, and the polymer chains degree of branching are as important as the specific elements contained in the molecule. Polymers containing the carbon-hydrogen bonds such as pol5 ropylene and polyethylene, and the carbon-chlorine bonds such as PVC and ethylene chlorotrifluoroethylene are different in the important property of chemical resistance from a fully fluorinated pol)nner such as polytetrafluoroethylene. The latter has a much wider range of corrosion resistance. 

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