Polytetrafluoroethylene PTFE, Teflon

The modified parfait method developed here replaced silica gel with porous polytetrafluoroethylene (PTFE, Teflon). Properly wetted Chromosorb T, an aggregate of aqueous dispersion-polymerized PTFE, is an efficient adsorbent for many hydrophobic substances in water... 

Polytetrafluoroethylene (PTFE Teflon) was discovered accidently by PlunkettCZ nd commercialized by DuPont in the 1940 s. This polymer has a solubility parameter of about 6H and a high melting point of 327°C and is not readily moldable. Poly-chlorotrifluoroethylene (CTFE, Kel-F), the copolymer of tetrafluoroethylene and hexafluoropropylene (FEP), polyvinylidene fluoride (PVDF, Kynar), the copolymer of tetrafluoroethylene and ethylene (ETFE), the copolymer of vinylidene fluoride and hexafluoroisobutylene (CM-1), perfluoroalkoxyethylene (PFA) and polyvinyl fluoride (PVF, Tedlar) are all more readily processed than PTFE. However, the lubricity and chemical resistance of these fluoropolymers is less than that of PTFE. 

Uncross-linked polystyrene grafted onto polytetrafluoroethylene (PTFE, Teflon) was adopted for oligonucleotide synthesis according to the phosphodiester scheme by Potapov et al. [167] To produce their support, the authors y-irradiated PTFE... 

Although stainless steels were discovered at the turn of the century and copper silicon alloys started to emerge at about the same time, the real explosion of materials research and development began at around the beginning of World War II. Polymer science and technology were no exception. Nylon was already developed at the DuPont Company. Alloy 20 was developed by DuPont in the late thirties. At about the same time, polytetrafluoroethylene (PTFE) (Teflon ) was discovered which led to further development of fluoropol5miers and ushered in an era of high-performance polymer materials for corrosion control. 

CF2=Cp2 (tetrafluoroethene) (CF CF2) Polytetrafluoroethylene, PTFE, Teflon Nonstick coating, electrical insulation, bearings... 

Toluene wets PET and nylon 6,6 but not polytetrafluoroethylene (PTFE, Teflon). 

Polymeric materials for MF membranes cover a very wide range, from relatively hydrophilic to very hydrophobic materials. Typical hydrophilic materials are polysulfone, poly(ether sulfone), cellulose (CE) and ceUiflose acetate, polyamide, polyimide, poly(etherimide) and polycarbonate (PC). Typical hydrophobic materials are polyethylene (PE), polypropylene (PP), polytetrafluoroethylene (PTFE, Teflon) and poly(vinylidene fluoride). 

Polytetrafluoroethylene (PTFE, Teflon, Fluorel) is best known for its excellent chemical stability and low coefficient of friction. Expanded PTFE (ePTFE) contains micropores created by stretching PTFE film and is used in small-diameter vascular grafts and for artificial heart valve sewing rings... 

GF2=GF2 Tetrafluoroethylene Polytetrafluoroethylene, PTFE Teflon , nonstick coatings... 

Traditionally, PEM fuel cells have been developed based on the use of PESA polymer membranes. These polymers contain a perfluorinated backbone similar to that of polytetrafluoroethylene (PTFE, Teflon ), which has pendent perfluorinated chains linked to the main chain by ether bonds, and a sulfonated... 

Figure 4.1 Thermogravimetric analysis curves of polytetrafluoroethylene (PTFE, Teflon) and PTFE-silica mixtures in air. Reproduced with permission from T.S. Light, L.R Fitzpatrick and J.P. Phanouf, Analytical Chemistry, 1965, 37, 1, 79.

Polytetrafluoroethylene (PTFE, Teflon) 18.5 Poly(ethylene terephthalate) (PET) 43... 

Membrane degasification units generally use hydrophobic hollow-fiber polypropylene or polytetrafluoroethylene (PTFE) (Teflon) microporous membrane (Wiesler, 1996). Hollow-fiber modules are made by potting the desired number of fibers into an external shell. The potting compound may be polyurethane, epoxy, polyolefin, or fluorinated polymers. Since the membranes are hydrophobic and have small pores (Fig. 13.15), water will not easily pass through the pores. 

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