Polymer polytetrafluoroethylene

It should not be thought, however, that perfluorocarbons are completely inert toward combustion. Even the very inert perfluorocarbon polymer polytetrafluoroethylene [PTFE, Du Pont s Teflon F(CF2CF2)nF] is thermodynamically unstable in oxygen with respect to CO2 and CF4 (Exercise 12.6) and can burn in a 95% 02/5% N2 mixture at 0.1 MPa, although combustion is hard to initiate because of the nonvolatility of PTFE and the resistance of the thermal degradation products to oxidation. Conflagrations involving more reactive, volatile fluorocarbons such as perfluoro-toluene have been reported.15... 

Figure 2.33 shows an example of WAXS curves for a polymer (polytetrafluoroethylene). It is a crystalline polymer at room temperature and its crystalline structure is revealed by the sharp... 

For at least two polymers, polytetrafluoroethylene 25, 62) and poly- trans-l,4-butadiene) 4, 25), relaxation processes accompanying crystal-crystal phase transitions are found. Sharp NMR line narrowing has been observed at the transition temperature for various normal paraffins 44)-... 

Tests have shown that the polymers polytetrafluoroethylene and polypropylene arc suitable packing materials for columns using concentrated sulphuric acid or acid water as liquids [143]. 

Figure 13.17 Compressive stress-strain data for two crystalline polymers polytetrafluoroethylene (PTFE) and polychlorotrifluoroethylene (PCTFE). (From Kaufman, H.S. and Falcetta, J.J., Eds., Introduction to Polymer Science and Technology, John Wiley Sons, New York, 1977. With permission.)... 

Fluoropolymers also low flammability. The fully fluorinated polymer polytetrafluoroethylene, for example, burns only in 95% oxygen under the test conditions of LOI. The burning, however, produces a highly toxic and corrosive gas hydrogen fluoride. 

The perfluorohydrocarbon polymers are among the most thermally resistant organic polymers. Polytetrafluoroethylene (PTFE), polytrifluoroethylene and various copolymers of fluorine-containing monomers are the most important among them. 

Rf - Polymer Polytetrafluoroethylene Contact Angle Water 86° Contact Angle n-Hexadecane 38° ... 

Polymers Polytetrafluoroethylene (PTFE) Suitable below 280 C with eutectic mixtures. 

Perfluorinated Polymers, Polytetrafluoroethylene Polyamides, Aromatic Polyamides, Plastics Polyarylates Poly(arylene sufide)s Polycarbonates Cyclohexanedimethanol Polyesters Polyesters, Main Chain Aromatic Polyesters, Thermoplastic Polyethers, Aromatic Poly(ethylene naph-thanoate) Polyimides Polyketones Poly(phenylene ether) Polysulfones Poly(trimethylene terephthalate) Rigid Rod Polymers Syndiotactic Polystyrene . 

Biomedical Applications. Dillon (114) synthesized IPN membranes from polytetrafluoroethylene (PTFE) and poly(dimethyl siloxane) (PDMS) (see Perfluorinated Polymers, Polytetrafluoroethylene Silicones). These flexible membranes are used for a variety of medical purposes, especially second-degree bum care. These materials are commercially available under the trade name Silon. The PDMS component rapidly transports body fluids away from the bum site, while the PTFE provides mechanical strength. The PTFE is also waterproof, so that when the woimd area is washed, water beads up on the film. An additional valuable feature is that the Aims are highly transparent, so that the doctor can observe the wound area easily, making early treatment of any infection or other problem possible. 

Fully Fluorinated Polymers. The radiation chemistry of fully fluorinated polymers shows remarkable temperature dependence, with all of the fluorinated thermoplastics undergoing degradation, ie, chain scission, at ambient temperatures, but with an increasing yield of cross-linking reactions at elevated temperatures. Over the past 10 years, this has led to renewed interest in the radiation chemistry and applications of these materials (see Perfluorinated Polymers, Polytetrafluoroethylene). 

Copolymers of VF with vinylidene fluoride [75-38-7] and tetrafluoroethylene [116-14-3] also have been prepared with this initiation system. VF tends toward alternation with tetrafluoroethylene and incorporates preferentially in copolymerization with vinylidene fluoride [see Perfluorinated Polymers, Polytetrafluoroethylene Vinylidene Fluoride Polymers]. 

Thermal, thermal-oxidative 674 Polystyrene, see Styrene polymers Polysulfone. see High-temperature polymers Polytetrafluoroethylene. see Fluoropolymers Polytrifluorochloroethylene. see Fluoropolymers Polyurethane... 

Gangal SV, Brothers PD. Perfluorinated polymers, polytetrafluoroethylene. Ency Polymer Sci Technol Jun 2010 . 

Although traditionally associated with inorganic crystals, polymorphism is not unknown for high polymers. Polytetrafluoroethylene has four different crystalline phases [Koningsveld et al., 2001, 11]. 

In a solid polymer electrolyte, such as used in the PEFC, ion mobility is a result of an electrolyte solution integrated into an inert polymer matrix. Early electrolyte membranes developed for the United States space program consisted of treated hydrocarbons, which resulted in poor longevity due to the relatively weaker hydrocarbon bonds [3]. Most modem solid electrolytes are perflourinated ionomers with a fixed side chain of sulphonic acid bonded covalently to the inert, but chemically stable, polymer polytetrafluoroethylene (FIFE) stracture. As a result, the membrane consists of two very different sub-stractures 1) a hydrophilic and ionically conductive phase related to the bonded sulphonic acid groups... 

When the polymer polytetrafluoroethylene is made from the monomer tetrafluoroethene, there is no loss of atoms from each monomer molecule. Classify the polymerization as either addition or condensation. 

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