Polyfluoroethylenes

Stirrers are usually made of glass, but those of monel metal, stainless steel or Teflon (a polyfluoroethylene) also find application in the labora tory. An important advantage of a stirrer with a Teflon blade is that it is... 

The incorporation of magnesium particles into fluorine-containing polymeric materials, such as polyfluoroethylene (Tf) or vinyUdene fluoride hexafluoropropene polymer (Vt), generates energetic pyrolants. The magnesium particles are oxidized by fluorine molecules eliminated from these polymers to produce high-tempera-ture magnesium fluoride. 

Similar data for plasma polytrifluoroethylene, plasma poly 1,1 difluoroethylene and plasma polyfluoroethylene are presented in Figure 10 (9 ) The components of the Cls spectra of the series of fluorinated ethylenes are assigned as in Table 1, where subscripts a and b refer to the structural type being in a largely fluorinated or largely hydrocarbon environment respectively. A full description of the lineshape analysis can be found elsewhere (1, 9). 

In the presence of alkaline catalysts alcohols can undergo nucleophilic addition to the C=C double bond of, / -unsaturated carbonyl compounds, nitriles, sulfones, or sulfoxides. Similarly the doubly bonded carbon atoms in polyfluoroethylenes are susceptible to nucleophilic attack by alcohols in the... 

The combination of properties that makes fiuorocarbons highly desirable engineering plastics also makes them nearly impossible to heat or solvent weld and very difficult to bond with adhesives withont proper snrface treatment. Fluorocarbons such as polytetraflu-oroethylene (TFE), polyfluoroethylene propylene (FEP), polychlorotrifluoroethylene (CTEE), and polymonochlorotriflnoroethylene (Kel-F) are notoriously difficult to bond because of their low surface tension and chemical resistance. However, epoxy and poly-nrethane adhesives offer moderate strength if the fluorocarbon is treated prior to bonding. 

For investigations of powders two methods have been established being effective In the first method, about 10 mg of powder are filled into the cavity between two silica plates (thickness of the layer 0.2 mm) [2, 17, 36-38] the same procedure can be used for foils or gels, in which, for example, insoluble materials may also be embedded [2]. For the second technique, sample is diluted by mixing it with potassium bromide or potassium chloride in a micromill [2, 37] (3-30 mg sample in 300 mg medium) and then pressing tablets of 5.0 mm diameter (thickness 0.20 0.01 mm pressure 1.2 t (120 MPa), i.e., 60 kg mm pressure time 120 s) as practiced in IR spectroscopy [2, 36]. It is preferable to use polyethylene or polyfluoroethylene powders (e.g., Hostaflon TF 9205,... 

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