Teflon, sintered

Test polymers for visualization studies were polyurethane (Pellethane, 2363-80A, Upjohn), filler-free polydimethylsiloxane (Sil-Med Corporation), two forms of Teflon, sintered (TFE, DuPont) and Fluorofilm (Dilectrix Corporation), and polyurethane-silicone rubber copolymer (AVCOthane 51, AVCO). Samples of 1 cm2 or, for shear studies, 5 X 20 X 0.5-cm sheets, were washed in ionic detergent solution (Alconox) at 60°C for 1 h, rinsed in deionized water, and refluxed in absolute ethanol for 1 h. Materials were dried and stored in a desiccator until use. 

The packaging approach utilized for tliis battery is similar to that for nickel—hydrogen single cylindrical cells as shown in Figure 23. The sdv er electrode is typically the sintered type used in rechargeable sdv er—zinc cells. The hydrogen electrode is a Teflon-bonded platinum black gas difhision electrode. 

Cotton Wool I O f Polypropylene Nylon Nomex (hl h temp. Nylon) Rayon Dynel Teflon Paper 1 Sintered Metal Woven Wire Cloth Porous Ceramics... 

MEAs used in this study were prepared in the following procedure [5]. The diffusion backing layers for anode and cathode were a Teflon-treated (20 wt. %) carbon paper (Toray 090, E-Tek) of 0.29 mm thickness. A thin diffusion layer was formed on top of the backing layer by spreading Vulcan XC-72 (85 wt. %) with PTFE (15 wt. %) for both anode and cathode. After the diffusion layers were sintered at a temperature of 360 C for 15 min., the catalyst layer was then formed with Pl/Ru (4 mg/cm ) and Nafion (1 mg/cm ) for anode and with Pt (4 mg/cm ) and Nafion (1 mg/cm ) for cathode. The prepared electrodes were placed either side of a pretreated Nafion 115 membrane and the assembly was hot-pressed at 85 kg/cm for 3 min. at 135 C. 

Polytetrafluoroethylene (Teflon) (PTFE) is the most corrosion-resistant thermoplastic polymer. This polymer is resistant to practically every known chemical or solvent combination and has the highest useful temperature of commercially available polymers. It retains its properties up to 500°F (260°C). Because of its exceedingly high molecular weight PTFE is processed by sintering. The PTFE resin is compressed into shapes under high pressure at room temperature and then heated to 700°F (371°C) to complete the sintering process. 

Fig. 9.3. The electrolyte dropping electrode REj, RE2 - reference electrodes CE2 - auxilliary electrode 1 - aqueous phase formed by dropping of the electrode 2 - nitrobenzene phase 3 - Teflon capillary 4 - sintered glass. The arrow denotes the connection to the reservoir with the aqueous electrolyte and the auxiliary electrode CEi. (After Samecefai. [20].)...

A large filter area is recommended. A 1-cm layer of Celite is pressed on a sintered-glass funnel (6 cm x 17 cm). The Celite is dried in an oven at 120°C for 12 hr. A 6-mm Teflon tube is used to connect the flask and the filter funnel through the septa, and the stirred slurry is then transferred to the funnel with the aid of nitrogen pressure. Inner pressure of the receiver flask and the funnel Is leaked through oil bubblers. The... 

Freeze-drying. For a 7000-fold concentration, 70 L of drinking water was lyophilized in a Virtus Unitrap II. The dried residue was then divided into equal weights and packed into two columns (25 X 1.5 cm) with a sintered glass filter. The organic material was eluted consecutively with acetone, ether, and DMSO. The ether in the ether eluate was removed by rotary evaporation, and the dried residue was dissolved in DMSO. The DMSO concentrates were sterilized by filtration over a 0.2-/xm Teflon filter (Millipore). The acetone and DMSO concentrates were tested in the Ames test. 

Since improvements achievable with bulky electrodes are limited by the structure of the electrode itself, sintered, porous, Teflon bonded, or phosphate-bonded Ni electrodes have been proposed [386, 391, 399, 400]. A mere increase in surface area is observed without any change in Thfel slope. The same is the case with Ni wiskers in spite of their very large surface area and small particle size [401, 402], A decisive modification of the kinetic pattern is indeed obtained as Raney Ni is used [93, 403] (see Fig. 11). This form of Ni is well known also in the field of hydrogenation catalysis. As an electrocatalyst it was proposed by Justi et al. [404] long ago. Raney Ni is obtained by allowing Ni with a component (usually Al or Zn) which is then... 

Microfiltration membranes usually have a nominal pore diameter in the range of 0.1-10 pm. However, the membrane specification is not an absolute parameter. The membranes usually present a pore size distribution around the nominal value and the shape of the bioparticles can determine whether they are retained or pass through the membrane. The membranes are manufactured from polymers, such as Teflon, polyester, PVC (polyvinyl chloride), Nylon, polypropylene, polyethersulfone, and cellulose, or from inorganic materials, such as ceramic and sinterized stainless steel. 

It is difficult to achieve a gas-tight seal to the anode current connections, which must also be electrically insulated against the cover of the electrolyzer, to which the cathodes are attached. Formerly, fused calcium fluoride was used as sealing material. This is, however, brittle and sometimes even porous recently sintered corundum has been used and for the external packing teflone (polymerized tetrafluoro-ethylene), buna, and polyvinylchloride. 

Compared with a Teflon -bonded commercial electrode, the composite electrode showed lower polarization losses at high current densities, even though the composite material did not contain Pt. The ohmic and mass transfer resistances were lower in the composite electrode than in the commercial electrode. The sintered contacts and interlocked networks formed in the composite structure permitted better electrical and physical contact between the carbon fibres and metal fibres, leading to a composite electrode with a high void volume and large macroscopic porosity, which increased the accessibility of carbon to the reactants [22],... 

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