Polytetrafluoroethylene membranes

FIG. 20-68 Stretched polytetrafluoroethylene membrane. Courtesy MiUi-pore Corporation.)... 

By electropolymerization of pyrrole in solvents containing polyelectrolytes such as potassium polyvinylsulfate, it is possible to prepare films of polypyrrole with polymeric counterions which have good conductivity (1-10 S cm-1) and strength (49 MPa) 303 304,305). Such a material could be used reversibly to absorb cations in an ion exchange system. Pyrrole has also been electrochemically polymerized in microporous polytetrafluoroethylene membranes (Gore-tex), impregnated with a perfluorosulphonate ionomer 3061. 

In developing a method that requires filtration, adsorption of the analyte onto the filter must be taken into account. For dilute solutions of adriamycin, >95% is adsorbed to cellulose ester membranes and about 40% to polytetrafluoroethylene membranes [19]. For more concentrated solutions, as would be encountered in bulk formulation testing, filter ad-... 

The nature of the supporting membrane also plays an important role in the performance of supporting ionic liquid membranes. In this context, de los Rios et al. [3] nsed two polymeric membranes, nylon and mitex, as supporting membranes. Nylon membrane was a hydrophilic polyamide membrane with a pore size of 0.45 pm and a thickness of 170 pm. Mitex membrane was a hydrophobic polytetrafluoroethylene membrane with a pore size of 10 pm and a thickness of 130 pm. It was observed that less ionic liquid was absorbed into the mitex membranes, which was explained by the different textural properties and the high hydrophobic character of these membranes, which probably restrict interaction with the hydrophilic ionic liquids used [27]. 

Analogous systems are commercially available as 3 M Empore Rad Disks. These come in the form of impregnated PTEE (polytetrafluoroethylene) membranes, which are used as filters for aqueous samples (Schmitt et al. 1990). Filter dimensions constrain this type of system to carrier-free separations. These filters with the retained radionuclide may then be washed, dried, and counted directly or the radionuclide may be eluted for further processing. Current products include filters for Ra, Sr, Tc, and Cs. 

Vrana DL, Meagher MM, Hutkins RW, Duffield B. 1993. Pervaporation of model acetone-butanol-ethanol fermentation product solutions using polytetrafluoroethylene membranes. Sep. Sci. Technol. 28 2167-2178. 

Chen, S., Lin, S., Chien, R., Hsu, R. 2010. Effects of shape, porosity and operating parameters on carbon dioxide recovery in polytetrafluoroethylene membranes. J. Hazard. Mater. 179 692-700. 

Self-excited oscillations have been reported to occur in L-B films of dioleyl lecithin (Y-fihns and Z-films). The films separated equimolar solutions of KCl and NaCl solutions, and also in polytetrafluoroethylene membrane doped with triolein and monolein [3, 4], No satisfactory theory has been proposed so far to explain self-excited oscillations in such systems. However, it has been postulated that such a situation can occur on account of any one of the following factors [5]... 

Wikol M., Hartmann B., Brendle J., Crane M., Beuscher U., Brake J. and Shickel T., Expanded polytetrafluoroethylene membranes and their applications in Filtration and Purification in Biopharmaceutical Industry, 2 edn, Joumitz, M. W. and Meltzer,T. H. (eds), Marcel Dekker Inc,pp. 619-640,1998. 

Artificial Internal Organs and Related Fields.— There has been a marked increase in certain aspects of the literature here, notably in the haemoperfusion field and in total artificial heart replacement. Some recent advances in haemodialysis techniques have been described involving high rates of ultra-filtration combined with optimal diffusion, the use of a resin-sorbent system for dialysate regeneration and the use of urease (E.C. 3.5.1.5) and an expanded polytetrafluoroethylene membrane in the development of a new method of urea removal. The effects of different membranes in the onset of haemodialysis-induced leucopenia have been discussed. ... 

Mader P, Vierheilig H, Streitwolf-Engel R, Boiler T, Frey B, Christie P, Wiemken A (2000) Transport of N from a soil compartment separated by a polytetrafluoroethylene membrane to plant roots via the hyphae of arbuscular mycorrhizal fungi. New Phytol 146 155-161... 

Alkyl-thio-s-triazines (H) 0.5 L RW Off-line Polytetrafluoroethylene-membrane 0.10 M H2SO4 [84]... 

Yamazaki N, Naganuma K, Nagai M, Ma GH, Omi S. 2003. Preparation of W/O (water-in-oil) emulsions using a PTFE (polytetrafluoroethylene) membrane A new emulsification device. / Dispersion Sci Technol 24 249-257. 

One of the most commonly used back-contact membranes is TPT [97]. T represents polytetrafluoroethylene membrane (PVF membrane, most commonly used Tedlar ). It has the following functions solar cell sealing, anti-aging, UV resisting and water proofing. P represents polyester film PET that obstructs the water moisture, which is electrically insulated. TPT consists of three thin membranes. The two external membranes are all T membranes, while the internal is P membrane. 

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