Ethylene with tetrafluoroethylene

Copolymers of ethylene with tetrafluoroethylene (ETFE) and chlorotrifluoroethylene (ECTFE) are mechanically stronger than perfluoropolymers, with some reduction in their chemical resistance and continuous use temperature and an increase in the coefficient of friction. 

Ethylene and tetrafluoroethylene are copolymerized in aqueous, nonaqueous, or mixed medium with free-radical initiators. The polymer is isolated and converted into extmded cubes, powders, and beads, or a dispersion. This family of products is manufactured by Du Pont, Hoechst, Daikin, Asahi Glass, and Ausimont and sold under the trade names of Tefzel, Hostaflon ET, Neoflon EP, Aflon COP, and Halon ET, respectively. 

Tetrafluoroethylene of purity suitable for granular or dispersion polymerizations is acceptable for copolymerization with ethylene. Polymerization-grade ethylene is suitable for copolymerization with tetrafluoroethylene. Modifying termonomers, eg, perfluorobutylethylene and perfluoropropylene, are incorporated by free-radical polymerization. 

The equimolar copolymer of ethylene and tetrafluoroethylene is isomeric with poly(vinyhdene fluoride) but has a higher melting point (16,17) and a lower dielectric loss (18,19) (see Fluorine compounds, organic-poly(VINYLIDENE fluoride)). A copolymer with the degree of alternation of about 0.88 was used to study the stmcture (20). Its unit cell was determined by x-ray diffraction. Despite irregularities in the chain stmcture and low crystallinity, a unit cell and stmcture was derived that gave a calculated crystalline density of 1.9 g/cm. The unit cell is befleved to be orthorhombic or monoclinic (a = 0.96 nm, b = 0.925 nm, c = 0.50 nm 7 = 96%. 

The synthesis of 2-chloro-2,3,3-trifluorocyclobutyl acetate illustrates a general method of preparing cyclobutanes by heating chlorotrifluoroethylene, tetrafluoroethylene, and other highly fluorinated ethylenes with alkenes. The reaction has recently been reviewed.11 Chlorotrifluoroethylene has been shown to form cyclobutanes in this way with acrylonitrile,6 vinylidene chloride,3 phenylacetylene,7 and methyl propiolate.3 A far greater number of cyclobutanes have been prepared from tetrafluoroethylene and alkenes 4,11 when tetrafluoroethylene is used, care must be exercised because of the danger of explosion. The fluorinated cyclobutanes can be converted to a variety of cyclobutanes, cyclobutenes, and butadienes. 

There is a tendency toward alternation in the copolymerization of ethylene with carbon monoxide. Copolymerizations of carbon monoxide with tetrafluoroethylene, vinyl acetate, vinyl chloride, and acrylonitrile have been reported but with few details [Starkweather, 1987]. The reactions of alkenes with oxygen and quinones are not well defined in terms of the stoichiometry of the products. These reactions are better classified as retardation or inhibition reactions because of the very slow copolymerization rates (Sec. 3-7a). Other copolymerizations include the reaction of alkene monomers with sulfur and nitroso compounds [Green et al., 1967 Miyata and Sawada, 1988]. 

PVC, another widely used polymer for wire and cable insulation, crosslinks under irradiation in an inert atmosphere. When irradiated in air, scission predominates.To make cross-linking dominant, multifunctional monomers, such as trifunctional acrylates and methacrylates, must be added. Fluoropolymers, such as copol5miers of ethylene and tetrafluoroethylene (ETFE), or polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVF), are widely used in wire and cable insulations. They are relatively easy to process and have excellent chemical and thermal resistance, but tend to creep, crack, and possess low mechanical stress at temperatures near their melting points. Radiation has been found to improve their mechanical properties and crack resistance. Ethylene propylene rubber (EPR) has also been used for wire and cable insulation. When blended with thermoplastic polyefins, such as low density polyethylene (LDPE), its processibility improves significantly. The typical addition of LDPE is 10%. Ethylene propylene copolymers and terpolymers with high PE content can be cross-linked by irradiation. ... 

Copolymer of ethylene and tetrafluoroethylene (ETFE)is an alternating copolymer that can be cross-linked by irradiation.112 Further improvement is achieved with the use of prorads, such as TAC or TAIC in amounts up to 10%. 

Firstly from a comparison of the integrated area ratios for the F ls and Cls levels and secondly from the individual components of the Cis levels. This readily establishes that the materials are copolymers of ethylene and tetrafluoroethylene which are largely alternating in character and that the outermost surface sampled by ESCA is identical in composition to the bulk. This is shown in Table 4 where a comparison is drawn with compositions determined by standard microanalysis (carbon by combustion, fluorine by potassium fusion). ESCA is highly competitive as a routine means of establishing compositions for fluoropolymers in particular, in terms of accuracy, nondestructive nature and speed. 

Loss of stereochemical relationships present in starting alkenes in product cyclobutanes was demonstrated as well for additions involving ethylene or the 2-butenes with tetrafluoroethylene (TFE). The cis and trans isomers of 1,2-dideuterioethylene and TFE gave a mixture of both (77) and (78) in comparable proportions.The isomers of 2-butene give (80) and (81) (42 58 from c/s-2-butene, 28 72 from trans-2-butene). ° ... 

The reaction of (ethylene)bis(triphenylphosphine)nickel(0) with tetrafluoroethylene (153, 463) involves a rearrangement of the tri-phenylphosphine ligands to produce the air-sensitive compound (C2F,)Ni[P(CflHs)3]3. 

H.P. Brack, H.G. Buhrer, L. Bonorand, and G.G. Scherer. Grafting of pre-irradiated poly(ethylene-alt-tetrafluoroethylene) films with styrene Influence of base polymer film properties and processing parameters. Journal of Materials Chemistry 10, 1795-1803 2000. 

Figure 18.6 Zimm s plot of an alternating copolymer of ethylene and tetrafluoroethylene (PETFE) in diisobutyl adipate at 240 °C. Source Reprinted with permission from Chu B, Wu C. Macromolecules 1987 20 93-98. Copyright 1987 American Chemical Society.

To prepare PSSA-grafted fluoropolymers, poly(vinylidene fluoride-co-hexafluoropropylene), poly (ethylene-co-tetrafluoroethylene) and poly(tetrafluoroethylene-co-hexafluoropropylene) were used as base polymers. Each polymer was molded into a film (200-300 pm thick) and irradiated with y-ray at room temperature at the rate of 6.8 kGyh using a cobalt-60 source to obtain a total absorbed dose of 50 kGy. The irradiated film was immersed in nitrogen-purged styrene at 70°C for 8 h for... 

Poly(ethylene-co-tetrafluoroethylene) grafted with poly(styrene sulfonic acid)... 

With copolymerisation the long-chain molecules are created. In a chemical reaction the two monomer units ethylene and tetrafluoroethylene are linked together. Catalysts crack the carbon compound of the macromolecules and hence additional monomer units can link. The product of copolymerisation is an aqueous solution. 

The first of these copolymers was with tetrafluoroethylene and hexa-fluoropropylene (FEP). Later, a copolymer of tetrafluoroethylene with small amounts of perfluoropropyl vinyl ether was made, and finally, an alternating copolymer of tetrafluoroethylene and ethylene was developed. All of these copolymers have similar properties to PTFE, but in contrast to the latter, they can be melt processed (see also Section 36.4). 

He et al. have prepared phosphonated aiyl trifluorovinyl ethers containing flexible oligo(ethylene oxide) units and subsequently homopolymerized these monomers by thermal cyclopolymerization in bulk at 180 °C. The resulting polymer was treated with bromotrimethylsilane to obtain the phosphonic acid derivative. The phosphonated trifluorovinyl ether monomers were also copolymerized with tetrafluoroethylene via free radical pol3Tnerization in an autoclave at 70 °C using l,l,2-trichloro-l,2,2-tri-fluoroethane as solvent. Moreover, radical terpolymerizations of the same trifluorovinyl ether monomers were performed with mixtures of... 

Hexafluoropropylene is produced by the pyrolysis of tetrafluoro-ethylene. The copolymer of hexafluoropropylene with tetrafluoroethylene is a medium-grade thermoplast with a crystallinity of 40-50% (drawn) to 50-70 % (annealed). The copolymer has similar mechanical and chemical properties to poly(tetrafluoroethylene), but can be molded and extruded. 

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