Ethylene tetrafluoroethylene properties

Copolymeis of ethylene [74-85-1] and tetiafluoioethylene [116-14-3] (ETFE) have been alaboiatory curiosity for more than 40 years. These polymers were studied in connection with a search for a melt-fabricable PTFE resin (1 5) interest in them fell with the discovery of TFE—HFP (FEP) copolymers (6). In the 1960s, however, it became evident that a melt-fabricable fluorocarbon resin was needed with higher strength and stiffness than those of PTFE resins. Earlier studies indicated that TFE—ethylene copolymers [11939-51 -6] might have the right combination of properties. Subsequent research efforts (7) led to the introduction of modified ethylene—tetrafluoroethylene polymer [25038-71-5] (Tefzel) by E. I. du Pont de Nemours Co., Inc, in 1970. 

Thermal properties. See also Temperature of aromatic polyamides, 19 718 of asbestos, 3 300-304 of diesel fuel, 12 423 of ethylene—tetrafluoroethylene copolymers, 18 319-321 of fibers, 11 167 of filled polymers, 11 309—310 of gallium, 12 342 of glass, 12 588... 

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. 

Polyvinylidene fluoride (PVDF) and Ethylene tetrafluoroethylene copolymer (ETFE) can be considered as diluted PTFE s, which in their structure and their properties... 

Ethylene Tetrafluoroethylene Copolymer - Thermoplastic comprised of an alternating copolymer of ethylene and tetrafluoroethylene. Has high impact resistance and good abrasion resistance, chemical resistance, weatherability, and electrical properties approaching those of fully fluori-nated polymers. Retains mechanical properties from cryogenic temperatures to 356°F. Can be molded, extruded, and powder-coated. Used in tubing, cable and wire products, valves, pump parts, wraps, and tower packing in aerospace and chemical equipment applications. Also called ETFE. 

T. Momose, H. Yoshioka, I. Ishigaki and J. Okamoto, Radiation drafting of a,a,(3-trifluorostyrene onto poly(ethylene-tetrafluoroethylene)film by preirradiation method. I. Effects of preirradiation dose, monomer concentration, reaction temperature, and film thickness, J. Appl. Polym. Sci., 1989, 37, 2817-2826 II. Properties of cation exchange membrane obtained by sulfonation and hydrolysis of the grafted film, 1989, 38, 2091-2101 III. Properties of anion exchange membrane obtained by chloro-methylation and quatemization of the grafted film, 1990, 39, 1221-1230. 

An increase in the high temperature (200 °C) tensile properties of the ethylene-tetrafluoroethylene copolymer, ETFE, after irradiation in nitrogen at room temperature followed by heat treatment at 162 °C in nitrogen for 20 min indicates some crosslinking [118]. On the other hand, irradiatimi carried out in air showed very little cross-linking [119]. ETFE behaves in some ways similar to poly-vinyUdene fluoride (PVDFO in that there is competition between crosslinking and scissimi. Some of the tensile properties, measured at 200 °C, of irradiated ETFE are shown in Table 52.14 [119]. 

Ethylene-tetrafluoroethylene copolymer (ETFE) is a linear macromolecule with the monomer unit [—(CHjlj—(CF l —] . ETFE exhibits physical properties similar to those of ethyl-ene-chlorotrifluoroethylene copolymer. 

Partially fluorinated materials include ECTFE (ethylene trifluoroethylene), ETEE (ethylene tetrafluoroethylene), and PVDE (polyvinylidene fluoride). The partially fluorinated materials have higher mechanical properties but lower temperature ratings (<300°E/149°C), and chemical resistance. 

The melt processible fluoroplastics are often desired due to the cost benefits of melt extrusion over paste extrusion. FEP, PEA and specially formulated melt processible perfluoroplastics are used in many of these applications however, in some of these applications, perfluoroplastics may not be the ideal choice. In cases where high cut-through resistance and better tensile properties are required, it is often desirable to employ a partially fluorinated polymer such as ETFE (ethylene-tetrafluoroethylene). ETFE is the copolymer of ethylene and TEE [16] that normally includes an additional termonomer to increase the flexibility required in commercial applications [17]. The increased physical and electronic interactions of the ETFE polymer chain are responsible for the comparatively enhanced physical properties. Additionally, the partially fluorinated polymers may be cross-linked to further improve physical properties. These benefits, however, are obtained at the expense of the unique properties of perfluoroplastics discussed in the Introduction and Overview. 

Standard injection and extrusion equipment is used with the lower-viscosity polymers fluorinated ethylene propylene (FEP), ethylene tetrafluoroethylene (ETFE), polyvinyli-denefluoride (PVDF), polyperfluoroalkoxyethylene (PFA), ethylene chlorotrifluoroethyl-ene (ECTFE), and others. This substitution, or copolymerization, where fluorine atoms have substitutes, results in property and processing changes. 

Ethylene-Tetrafluoroethylene Copolymer n A copolymer of ethylene and tetrafluoroethylene (DuPont Tefzel ), ETFE is readily processed by extrusion and injection molding. It has excellent resistance to heat, abrasion, chemicals, and impact, with good electrical properties. 

Poly(Ethylene-Tetrafluoroethylene) n (PE-TFE) A crystalline resin in which the proportion of ethylene to tetrafluoroethylene (E/TFE) may range, for the best combination of properties, between 2 3 and 3 2, modified with a vinyl copolymer for better toughness. It is stronger than either low-density polyethylene or polytetrafluoroethylene, has good electrical properties, high Izod-impact strength, and plastic memory that makes it useful for heat-shrinkable packaging. 

Weathering and light resistance of ethylene-tetrafluoroethylene-copolymer are excellent. After over 2000 h of weathering in a Weatherometer, its mechanical properties are not impaired [83]. 

Properties used in the characterization of ethylene tetrafluoroethylene (ETFE) polymers are defined in Table 5.73. ASTM Method D2116 classifies the different types of ETFE according to the specifications summarized in Table 5.74. 

Table 5.73. Definition of Basic Properties of Ethylene Tetrafluoroethylene Resins (ETFE) According to ASTM D3159...

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. 

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