Fluorocarbons tetrafluoroethylene

FLUORINECOMPOUNDS,ORGANIC - TETRAFLUOROETHYLENE-PERFLUOROVINYLETTiERCOPOLYTffiRS] (Vol 11) PFA. See Perfluoroalkoxy fluorocarbon resins. 

Reactions with Organic Compounds. Tetrafluoroethylene and OF2 react spontaneously to form C2F and COF2. Ethylene and OF2 may react explosively, but under controlled conditions monofluoroethane and 1,2-difluoroethane can be recovered (33). Benzene is oxidized to quinone and hydroquinone by OF2. Methanol and ethanol are oxidized at room temperature (4). Organic amines are extensively degraded by OF2 at room temperature, but primary aHphatic amines in a fluorocarbon solvent at —42°C are smoothly oxidized to the corresponding nitroso compounds (34). 

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. 

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). 

Heat and oil resistance coupled with its low swell have led automotive apphcations into laminated tubing and hoses (11) with this material. This resistance to the effects of ASTM No. 3 oil at service temperatures of 200°C makes it competitive with fluorocarbons and with the tetrafluoroethylene—propylene copolymer. Fluorosihcones are used to make exhaust gas recirculation (EGR) diaphragms for some passenger cars. 

Copolymers of propylene and tetrafluoroethylene, which are sold under the Aflas trademark by 3M, have been added to the fluorocarbon elastomer family (21—26). Also 3M has introduced an incorporated cure copolymer of vinyUdene fluoride, tetrafluoroethylene and propylene under the trademark Fluorel 11 (27). These two polymers (Aflas and Fluorel 11) do not contain hexafluoropropylene. The substitution of hexafluoropropylene with propylene is the main reason why these polymers show excellent resistance toward high pH environments (28). Table 1 Hsts the principal commercial fluorocarbon elastomers in 1993. 

Fluorocarbon—long-chain synthetic polymer composed of tetrafluoroethylene units. 1.0-2.0 F E E E G 2.30 5501... 

The introduction of the chlorofluorocarbon (CFC) fluids in the early 1930s marked the incepuon of the halofluorocarbon industry. Both in terms of tonnage produced and product value, the CFCs have dominated the organofluorocarbon industry and have provided the feedstocks for the development of other fluorocarbon products such as poly(tetrafluoroethylene). 

Group V. Fluorocarbon Resins Tetrafluoroethylene polymer (micronized) 0.11 0.11 670 570t 1 ... 

The influence of polyfunctional monomers—tripropyleneglycol diacrylate (TPGDA), TMPTA, TMPTMA, TMMT, and TAG on the stmctural changes of fluorocarbon terpolymer poly(vinylide-nefluoride-co-hexafluoropropylene-co-tetrafluoroethylene) has been investigated [425]. The ATR-IR studies show that the absorbance due to the double bond at 1632 cm decreases both in the... 

Principles and Characteristics In the Parr bomb extraction technique (see also Section 8.2.1.2), a Teflon-tetrafluoroethylene fluorocarbon resin lined vessel is used for sample containment. A sample (typically 1 g) is heated in a small volume of solvent at T, t, p of choice. 

In this work we have demonstrated that a new class of heavily fluorinated acrylic and methacrylic resins can be efficiently synthesized and then cured to solid form with radical initiator at elevated temperatures. These cured resins were found to have low dielectric constants, which are close to the minimum known values for Teflon and Teflon AF. In contrast to tetrafluoroethylene, our monomers are processable owing to the fact that they are liquids or low-melting solids, and moreover are soluble in common organic solvents. Lower dielectric constants are obtained as fluorine contents on the polymer backbone or side chain increase, when acrylate is replaced by methacrylate, when ether linkages are present in the fluorocarbon, and when aromatic structure is symmetrically meta-substituted. 

The first reactions of fluorinated olefins in C02 reported by DeSimone et al. involved the free-radical telomerization of 1,1 -difluoroethylene29 and tetrafluor-oethylene.30 This work demonstrated the feasibility of carrying out free-radical reactions of highly electrophilic species in solvents other than expensive fluorocarbons and environmentally detrimental chlorofluorocarbons. The work has since been more broadly applied to the synthesis of tetrafluoroethylene-based, nonaqueous grades of fluoropolymers,31,32 such as poly(tetrafluoroethylene-co-peduoropropylvinyl ether) (Scheme 2). These reactions were typically carried out at between 20 and 40% solids in C02 at initial pressures of between 100 and 150 bars, and 30-35°C (Table 10.1). 

However, there are many misconceptions concerning uses, applications, and attributes of fluorocarbons. The use of fluorocarbons can be classified into two major categories (1) use of inherent bulk properties, and (2) modification of the surface properties of underlying materials. Once this has been established, the proper choice of fluorocarbon can be evaluated. For the purpose of this discussion, fluorocarbons will be grouped into two categories (1) polymers based on highly fluorinated monomers such as tetrafluoroethylene (TFE), hexafluoropropylene. 

ELASTOMERS, SYNPHETIC - FLUOROCARBON ELASTOMERS] (Vol 8) Poly(tetrafluoroethylene-co-propylene) [27029-05-6]... 

Fluorinated dienophiles. Although ethylene reacts with butadiene to give a 99 98% yield of a Diels-Alder adduct [63], tetrafluoroethylene and 1,1-dichloro-2,2-difluoroethylene prefer to react with 1,3-butadiene via a [2+2] pathway to form almost exclusively cyclobutane adducts [61, 64] (equation 61). This obvious difference in the behavior of hydrocarbon ethylenes and fluorocarbon ethylenes is believed to result not from a lack of reactivity of the latter species toward [2+4] cycloadditions but rather from the fact that the rate of nonconcerted cyclobutane formation is greatly enhanced [65]... 

Commercially, ahoul MI fr of chloroform is used in production of fluorocarbon refrigerants and propellams. Cl is replaced by ireulmenl with lluonnaicd antimony pentaeliloride. The producl. CHCIF (R-22). is used for home air-conditioning units. It is also used as a feed for production or tetrafluoroethylene. which polymerizes to Teflon. Total demand for chloroform approximates 600 million pounds (136 million kilograms) per year. 

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. 

Commonly accepted practice restricts the term to plastics that serve engineering purposes and can be processed and reprocessed by injection and extrusion methods. This excludes the so-called specialty plastics, eg, fluorocarbon polymers and infusible film products such as Kapton and Upilex polyimide film, and thermosets including phenolics, epoxies, urea—formaldehydes, and silicones, some of which have been termed engineering plastics by other authors (4) (see Elastomers, synthetic-fluorocarbon elastomers Fluorine compounds, organic-tetrafluoroethylene copolymers with ethylene Phenolic resins Epoxy resins Amino resins and plastics). 

The first commercial fluoroelastomer, Kel-F, was developed by the M. W. Kellog Company in the early to mid-1950s and is a copolymer of vinylidene fluoride (VDF) and chlorotrifluoroethylene (CTFE). Another fluorocarbon elastomer, Viton A, is a copolymer of VDF and hexafluoropropylene (HFP) developed by du Pont was made available commercially in 1955. The products developed thereafter can be divided into two classes VDF-based fluoroelastomers and tetrafluoroethylene (TFE)-based fluoroelastomers (perfluoroelastomers).72 The current products are mostly based on copolymers of VDF and HFP, VDF and MVE, or terpolymers of VDF with HFP and TFE. In the combination of VDF and HFP, the proportion of HFP has to be 19 to 20 mol% or higher to obtain amorphous elastomeric product.73 The ratio of VDF/HFP/TFE has also to be within a certain region to yield elastomers as shown in a triangular diagram (Figure 2.2).74... 

Fluorocarbon elastomers, particularly copolymers of HFP and VDF, are cross-linked by low-level y radiation (up to 20 Mrad) in the same fashion as PVDF. Radiation degradation of a VDF-HFP copolymer was studied by Zhong and Sun.35 Their finding was that there is a linear relationship between the dose and the weight loss of the polymer. Fluorocarbon elastomers based on copolymers of IFF and propylene were found to be more resistant to y radiation than Viton elastomers.36 Cross-linking of VDF-HFP, VDF-TFE, and tetrafluoroethylene-propylene (TFE/P) copolymers as well as of terpolymers VDF-HFP-TFE by ionizing radiation (gamma... 

Tefzel ETFE (ethylenetetrafluoroethylene). This plastic is white, translucent, and slightly flexible. It is a close analog of the Teflon fluorocarbons, an ethylene tetrafluoroethylene copolymer. ETFE shares the remarkable chemical and temperature resistance of Teflon TFE and FEP and has even greater mechanical strength and impact resistance. 

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