FEP Tetrafluoroethylene-hexafluoropropylene

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. 

D. Fluorocarbon Polymers. Four different fluorocarbons account for the bulk of the laboratory applications polytetrafluoroethylene, Teflon PTFE po-ly(chlorotrifluoroethylene), KEL-F tetrafluoroethylene-hexafluoropropylene copolymer, Teflon FEP and tetrafluoroethylene-perfluorovinyl ether copolymer, PFA. These polymers are inert with most chemicals and solvents at room temperature and exceptionally inert with oxidizing agents. They also have an exceptional resistance to temperature extremes. However, they are decomposed by liquid alkali metals, solutions of these metals in liquid ammonia, and carban-ion reagents such as butyllithium. Teflon retains some of its compliance at liquid hydrogen temperature. The maximum temperature which is recommended for continuous service is 260°C for Teflon PTFE and PFA, and about 200°C for Kel-F and Teflon FEP. 

Copolymers of tetrafluoroethylene were developed in attempts to provide materials with the general properties of PTFE and the melt process-ability of the more conventional thermoplastics. Two such copolymers are tetrafluoroethylene-hexafluoropropylene (TFE-HFP) copolymers (Teflon FEP resins by Du Pont FEP stands for fluorinated ethylene propylene) with a melting point of 290°C and tetrafluoroethylene-ethylene (ETFE) copolymers (Tefzel by Du Pont) with a melting point of 270°C. These products are melt processable. A number of other fluorine containing melt processable polymers have been introduced. 

Tetrafluoroethylene Copolymers. Tetrafluoroethylene-hexafluoropropylene copolymer (FEP)and tetrafluoroethylene-perfluoroalkoxyethylene (PFA) are used as dispersion coatings in the same way as PTFE, taking advantage of their low melt viscosity and low viscosity at baking temperature. 

The question about the existence and the stability of pure carbon chain polymers has been repeatedly discussed in many papers. These polymers are called carbynes and are believed to consist of alternating triple and single bonds (polyynes) rather than of non alternating double bonds (polycumulenes) because of the lower ground state energy of the former. Thus, vibrational spectra of such materials are characterized by a more or less expressed structure around 2000 cm which is typical for the triple bond. A very efficient way to obtain such triple bonded carbon polymers nses an internal electrochemical reduction of fluorinated polymers such as poly(tetrafluoroethylene) (PTFE) or poly(tetrafluoroethylene/hexafluoropropylene) (FEP) by alkali metal amalgam according to the reaction... 

Synonyms Ethylene/propylene copolymer, fluorinated FEP FEP resin Fluorinated ethylene/propylene resin Fluoroethylene polymer Hexafluoropropylene/tetrafluoroethylene copolymer Petfluoroethylene propylene Tetrafluoroethylene/hexafluoropropylene copolymer TFE/ HFP... 

Hostaflon FEP Tetrafluoroethylene-co-hexafluoropropylene Hoechst Celanese Corp. 

Tetrafluoroethylene-hexafluoropropylene co-polymer (FEP) See fiuorinated ethylene-propylene resin. 

A phase transition occurs in Teflon at 19°C, and this involves a change in the degree of helical structure. It may be observed [59] as a spectral change in a weak doublet-type Raman band at 598 and 577 cm A few copolymers of tetrafluoroethylene exist, including tetrafluor-oethylene-hexafluoropropylene (FEP), tetrafluoroethylene-perfluoroalkyl-vinylether (PFA), and tetrafluoroethylene-hexafluoropropylene-perfluo-roalkylvinylether (EPE). An example of the IR and Raman spectra of EPE is provided in Reference Spectrum 24. Although these three copolymers have similar IR spectra, the bands around 990 cm are used to distinguish these copolymers [60]. The hexafluoropropylene moiety of FEP produces a band at 982 cm while the perfluoroalkyl vinylether moiety of PFA has a band at 993 cm As expected, EPE exhibits both the 993 and the 982 cm bands. The IR spectrum in Reference Spectrum 24 shows the 993 cm band as a shoulder on the 982 cm band. 

Most organic materials are slowly attacked by wet chlorine gas. Rubber-lined iron is successfully used up to 100 °C. At low pressure and temperature the use of plastic materials like PVC, chlorinated PVC, and reinforced polyester resins is advantageous. Polytetrafluoroethylene (PTFE), polyfvinylidene fluoride) (PVDF), and fluorinated copolymers like tetrafluoroethylene-hexafluoropropylene (FEP) are resistant even at higher temperature. Ceramics have been progressively replaced by plastics. Impregnated graphite is suitable up to 80 C the impregnation should be resistant to wet chlorine. 

Tetrafluoroethylene-Hexafluoropropylene Copolymer (FEP) See Fluorinated Ethylene-Propylene Resin. 

A. Bhattacharya, A. De, and S. N. Bhattacharyya, Preparation of polypyrrole composite with acrylic acid-grafted tetrafluoroethylene-hexafluoropropylene (Teflon-FEP) copolymer, Synth. Met. 65 35 (1994). 

Hexafluoropropylene—tetrafluoroethylene copolymers are available in low melt viscosity, extmsion grade, intermediate viscosity, high melt viscosity, and as dispersions. The low melt viscosity (MV) resin can be injection molded by conventional thermoplastic molding techniques. It is more suitable for injection molding than other FEP resins (51). 

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. 

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