Poly tetrafluoroethylene

Poly(vinyl fluoride) is included, although it shows greater similarities to poly(vinyl chloride) than to the other fluoropolymers. It also should be mentioned that a wide variety of fluoropolymer elastomers is used under extreme conditions of temperature and chemical environment. 

Fluorine-free polymers find particular use in high-temperature and corrosion-resistance environments, and some consideration will be given to them in this chapter. 

There is a large number of companies manufacturing PTFE this is surprising when the difficulties and hazards associated with the industrial preparation of 

Lower crystallinity, and consequently density, are associated with higher-molecular-weight polymer. This is a useful relationship, since the normal solution methods of molecular weight determination are precluded by the insolubility of PTFE in all solvents except at temperatures above 300°C, which property is exploited in many applications. PTFE is chemically inert, attack being limited to materials such as molten sodium. It may be dissolved by highly fluorinated liquids near its melting point. It has excellent weathering resistance and is stable in air to at least 250°C for continuous service. 

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Figure 12.1. Perfluoriiiated resinsulfonic acid similar to Nafion-H, showing clustering of SO3H groups PTFE = poly(tetrafluoroethylene).

Poly(tetmfluoroethylene). Poly(tetrafluoroethylene) is prepared from tetrafluoroethy-lene and consists of repeating units in a predominantly linear chain ... 

Properties Homopolymer Copolymer 20% glass-reinforced homopolymer 25% glass-reinforced copolymer 21% poly(tetrafluoroethylene)- filled homopolymer... 

Casting resin Novolac resin Poly(tetrafluoroethylene) Poly(chloro- trifluoro- ... 

Class A conforms to specifications in ASTM E694 for standard taper stopcocks and to ASTM E287 for Teflon or poly-tetrafluoroethylene stopcock plugs. The 10-mL size meets the requirements for ASTM D664. ... 

POWDERS,PiANDLING - DISPERSION OF POWDERS IN LIQUIDS] (Vol 19) Poly(tetrafluoroethylene)... 

FLUORINECOPPPOUNDS,ORGANIC - FLUORINAPED ALIPPiATIC COPPPOUNDS] (Vol 11) Poly(tetrafluoroethylene-co-perfluoro(methyl vinyl ether)... 

The Fe, Co, and Ni deposits are extremely fine grained at high current density and pH. Electroless nickel, cobalt, and nickel—cobalt alloy plating from fluoroborate-containing baths yields a deposit of superior corrosion resistance, low stress, and excellent hardenabiUty (114). Lead is plated alone or ia combination with tin, iadium, and antimony (115). Sound iasulators are made as lead—plastic laminates by electrolyticaHy coating Pb from a fluoroborate bath to 0.5 mm on a copper-coated nylon or polypropylene film (116) (see Insulation, acoustic). Steel plates can be simultaneously electrocoated with lead and poly(tetrafluoroethylene) (117). Solder is plated ia solutioas containing Pb(Bp4)2 and Sn(Bp4)2 thus the lustrous solder-plated object is coated with a Pb—Sn alloy (118). 

Jippliance wires require a higher temperature rating (105°C or higher). Therefore, the insulation is made of duorinated thermoplastics, such as poly-tetrafluoroethylene (PTEE) or duorinated ethylene—propjdene (EEP). 

Fluonnation usually strengthens C-C bonds, and the effect of partial fluorma-tion can be especially pronounced. The C-C bonds m poly(tetrafluoroethylene) are about 8 kcal/mol stronger than those in poly(ethylene), and CF CFj has a 10 kcal/mol stronger C-C bond than CFI3CH3, but CF3CFI3 has an even stronger, polar... 

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). 

When the tetrafluoroethylene molecule polymerizes, its poly-tetrafluoroethylene, more commonly known as Teflon. 

Temperature dependence (related to the temperature dependence of the conformational structure and the morphology of polymers) of the radiation effect on various fluoropolymers e.g., poly (tetrafluoroethylene-co-hexafluoropropylene), poly(tetrafluoroethylene-co-perfluoroalkylvinylether), and poly(tetrafluoroethylene-co-ethylene) copolymers has been reported by Tabata [419]. Hill et al. [420] have investigated the effect of environment and temperature on the radiolysis of FEP. While the irradiation is carried out at temperatures above the glass transition temperature of FEP, cross-linking reactions predominate over chain scission or degradation. Forsythe et al. [421]... 

Such polymers are as hydrophobic as poly(tetrafluoroethylene) (Teflon), with water contact angles in the range of 107°. But, unlike Teflon, polyphosphazenes of this type are easy to fabricate, are flexible or elastomeric, and can be used as coatings for other materials. ... 

Subcutaneous in vivo testing of these polymers (13,14) has shown minimal tissue response—similar, in fact, to the response to poly-(tetrafluoroethylene). These materials are candidates for use in heart valves, heart pumps, blood vessel prostheses, or as coating materials for pacemakers or other implantable devices. 

When X = Y, as in polyethylene, poly-(tetrafluoroethylene), polyisobutylene, and poly -(vinylidene chloride), the polymers are highly crystalline products with sharply definable melting points (except for polyisobutylene, which crystallizes readily on stretching but with difficulty on cooling). Oriented specimens of high strength may be obtained, exactly as in the crystalline condensation polymers. 

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