Polytetrafluoroethylene chemical inertness

Polytetrafluoroethylene and fluorinated ethylene-propylene are the only resins composed wholly of fluorine and carbon. The polymer consists of fluorine atoms surrounding the carbon chain as a sheath, giving a chemically inert and relatively dense product from the strong carbon-fluorine bonds. Polytetrafluoroethylene must be molded at high pressure. Fluorinated ethylene-propylene c.m be injection molded and extruded as thin fdm. Both plastics have exceptional heat resistance... 

Fluoropolymers. These form one of our oldest and most spectacular families of engineering plastics. Polytetrafluoroethylene was developed by DuPont over two decades ago, and more recently by Allied Chemical, Hoechst, ICI, Pennwalt, and other manufacturers as well. It combines unusually low adhesion and friction, high temperature and flame resistance, excellent electrical properties, and extreme chemical inertness. Its high melting point and melt viscosity make thermoplastic processing extremely difficult, so that many... 

The almost universal chemical inertness of polytetrafluoroethylene has been attributed to the strength of the carbon-fluorine bond and the way in which the fluorine atoms protect the carbon chain from chemical attack (Doban, Sperati, and Sandt). From the theory of solubility, it is expected that the miscibility of hydrocarbons and fluorocarbons will be low. Experimental measurements indicate that the miscibility is even less than was expected from the theory. The possible explanations for this have been discussed by Scott. 

Plunkett and his assistant decided to cut open the containers. When they did, they found a white, waxy powder inside. Plunkett tested the powder. He found that it was chemically inert and heat resistant. He also found out that it had a very low surface friction. Because of this low surface friction, most things would not stick to the powder. The TFE gas in the container had polymerized to produce this new substance. The new substance s chemical name is polytetrafluoroethylene (PTFE). It was later named Teflon. Teflon is used to protect fabrics and in bakeware to prevent food from sticking to pots and pans. 

Teflon (polytetrafluoroethylene) is a chemically inert polymer used to create nonstick frying pans. Polytetrafluoroethylene can be modified to form a coating, Gore-Tex, which allows the passage of water vapor, but not liquid water, and is used in many articles of clothing. Polymeric perfluorinated ethers are widely used as high performance oils and lubricants. 

Perfluoroelastomers represent a special subgroup of fluorocarbon elastomers. They are essentially rubbery derivatives of polytetrafluoroethylene (PTFE) and exhibit exceptional properties, such as unequaled chemical inertness and thermal stability. Currently, there are two types of known commercial perfluoroelastomers Kalrez and Perlast. These have ASTM designation FFKM. 

Of the organic polymeric plastics, polytetrafluoroethylene (PTFE) was one of the earliest to be investigated as a solid lubricant because of its chemical inertness and its low surface energy. Kay and Tingle... 

Graphite filled polytetrafluoroethylene has an extremely low coefficient of friction due to the low friction characteristics of graphite. Graphite is chemically inert. It is also incorporated in combination with other additives such as carbon and glass. Graphite imparts excellent wear properties to PTFE, especially in contact against soft metals,and high PV (pressure-velocity) values. 

Tetrafluoroethylene CFp=CF2 Polytetrafluoroethylene (PTFE) (-CF,—CF,—A- High temperature resistance, chemically inert, excellent electrical insulator, very low coefficient of friction, expensive moldings, films, coatings used for non-stick surfaces, insulation, gaskets e.g.. Teflon, Fluon. 

Polytetrafluoroethylene (PTFE), also known by its generic DuPont tradename of Teflon, is a linear polymer that has a molecular structure similar to PE, but with all the hydrogen-atoms replaced by fluorine atoms (CE2-CE2) . Since fluorine-atoms prefer contact with fluorine-atoms, while repelling all others, this repulsion reduces the friction coefficient of the system and produces a non-adhesive surface (with self-lubricating properties). The strong C-C and C-F bonds make PTFE chemically inert, with excellent chemical resistance. 

Polytetrafluoroethylene is linear and highly crystalline. Absence of terminal CF2=CF-groups shows that few, if any, polymerization terminations occur by disproportionation but probably all take place by combination. The molecular weights of commercially available polymers range from 39,000-9,000,000. Polytetrafluoroethylene is inert to many chemical attacks and is only swollen by fluorocarbon oils at temperatures above 300 °C. The Tm value of this polymer is 327 °C and 7g is below -100 °C. 

POLYTETRAFLUOROETHYLENE. HEAT RESISTANT CHEMICALLY INERT PLASTIC. 

All product contact surfaces are composed of polytetrafluoroethylene or polypropylene. Both polymers are highly chemically inert and have a high degree of compatibility with a variety of fluids. As with other processing aids, the user, who is most knowledgeable about the formulation of the product, is responsible for ensuring the compatibility of his/her formulation with LYOGUARD trays. 

The van der Waals interactions in perfluoroplastics are extremely low. As a result, polytetrafluoroethylene (PTFE) has the lowest coefficient of friction of any known polymer. This property is due to the chemistry and structure described above which also give rise to the excellent electrical properties, thermal stability and chemical inertness. 

The excellent electrical insulation properties and chemical inertness over a wide temperature range account for the two main fields of use of polytetrafluoroethylene, namely electrical and chemical applications. Electrical applications include wire coatings, holders and spacers for use in aggressive conditions whilst chemical applications include gaskets, pump parts and laboratory equipment. Other uses include non-stick coverings for kitchen utensils, low-friction linings for hoppers, and diaphragms for low temperature equipment. 

The free-radical reactions in solid polymers in the presence of NO are of particular significance for the preparation of spin-labelled polymers. This method has become particularly important for chemically inert, rigid and insoluble polymers, for instance, polytetrafluoroethylene (PTFE), because of the difficult problem of introducing spin labels by chemical reactions of nitroso compounds, nitrons or nitroxyl biradicals [31], Oriented PTFE films y-irradiated at room temperature in air after prolonged NO exposure contain nitroxyl radicals whose ESR spectra are displayed in Figure 3 [32],... 

Polytetrafluoroethylene, more commonly known as the trademarked brand name Teflon, is formed from the addition polymerization of tetrafluoroethylene. Tetrafluoroethylene, shown in Figure 25.4(c), is an analogue of ethylene in which fluorine atoms have replaced all four of the hydrogen atoms. Teflon is a very good electrical insulator, so it is commonly used to coat wires. It is probably best known, though, as a nonstick substance used to coat bakeware, frying pans, and pots. It is also used in films that can be inserted into threaded joints between metal pipes to make it easier to unscrew the connection when necessary. Because Teflon is chemically inert, it is not possible to cross-link the chains like an elastomer. The structures of some addition polymers, including the structures of their respective monomers and what they are typically used for, are summarized in Table 25.1. 

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