Teflon powder

Two types of columns are used. A packed column is one filled with inert, solid particles coated with a liquid stationary phase. Standard tubing is about 0.5 cm in diameter, with lengths ranging from 1 m to 20 m however, columns for large-scale preparative work may be up to 5 cm in diameter and several meters long. Commonly used solid supports are diatomaceous earth, Teflon powder, and glass beads. The stationary liquid must be chosen on the basis of the compounds to be analyzed. A more recently developed and more widely used type of column is the open-tubular or capillary column. This is prepared by coating the inner wall of the column with the stationary liquid phase. The inside diameter of a typical capillary tube is 0.25 mm, and... 

Modification of the sensor structure. The above amperometric sensor has a rather complicated construction, because the sample gas (H2 + air) is separated from the reference air. So, we tried to simplify the sensor structure as shown in Figure 9. As proton conductor we used a thin antimonic acid membrane (mixed with Teflon powder) of 0.2 mm thickness. This membrane is thin and porous enough to allow a part of the sample gas to permeate. On the other hand, the counter Pt electrode was covered with Teflon and Epoxy resin in order to avoid a direct contact with the sample gas. 

The Oj-H cell reactor and the principle of the method for the oxygenation of hydrocarbons are demonstrated in Figure 1. A detailed description of the cell setup has been given elsewhere [13]. A silica-wool disk (thickness 2.0 mm and diameter 26 mm) impregnated with aqueous HjPO., (IM, 1 ml) as an electrolyte separates the anode and cathode compartments. The anode was prepared by a hot-press method from a mixture of graphite, Pt-black and Teflon powder. The cathodes were prepared from a mixture of carbon whiskers with various metal oxides or metal salts. The superficial surface area of both electrodes was 3.1 cm. ... 

The reactor for HjO-electrolysis used in the epoxidation of alkenes is shown schematically in Figure 2. The anode was prepared from metal blacks (70 mg) mixed with Teflon powder by the hot-press method. The cathode was prepared from a mixture of Pt black, graphite and Teflon powder. Propylene was bubbled into CH Clj (40 ml used as a solvent) in the anode compartment. In the case of 1-hexene epoxidation, 10 ml of the alkene was dissolved in 30 ml of CH2CI2. Argon (98 kPa) and water vapor (4 kPa) were... 

Graphite and Teflon powder are the same described in Subheading 2.1. 

Teflon powder (450 mg) is added and thoroughly mixed by hand with a glass rod until a homogeneous mixture is obtained. 

Teflon is incorporated to the mixture by adding 50mg Teflon powder and thoroughly hand mixing until complete homogenization. 

Rolling Teflon powder into nickel gauze 0.015 2.5 1000 6.5... 

Teflon powders may be used as chromatographic supports, and preheating at 300° improves their characteristics. A simple apparatus for reproducibly packing columns has been described a cold-packing method for Teflon is recommended. ... 

Several specimens were prepared by molding Teflon powder with various levels of chopped fiberglass filler. The effect of filler level on the load is shown in Fig. 2. Also shown... 

A low-temperature aqueous fuel cell, that employs conducting porous teflon electrodes (Pt-black imbedded in teflon powder), shows excellent performance (current densities up to 200mAcm ) in acidic and basic electrolytes. ... 

Concretely, there are some cases with the utilization of SiC powder or teflon powder. They are dispersed into a plating film to improve lubricant ability, etc. More possibilities will be designed and developed in the future. 

TL Injection molding Delrin 500 with 1.5% Teflon powder, low-friction and low-wear properties Specialty friction and wear applications, conveyor systems... 

The blank experiments required for this correction can be performed by using glass pearls [34] or Teflon powder [40], which are inert solids with small specific surface areas, as the column packing materials. 

Teflon powder from Azoty, Tarnow S.A., Poland... 

Dominguez and Willhite (1977) studied the retention and flow characteristics of an HPAM sample (Pusher 700, Dow Chemical Co.) in an 86 mD core of compacted Teflon powder. Static measurements indicated that the level of polymer adsorption on the Teflon was negligible (< 1 jUg/g limited... 

The integral enthalpy of displacement of water by butanol was determined in an LKB 2107 flow sorption microcalorimeter (Bromma, Sweden) at 298 0.01 K. Heats of mixing were not detected in blank nms when Teflon powder was used as an inert solid. Thus, the heat effects measured step-by-step could be directly assigned to the displacement process. 

Retention and flow characteristics of a solution containing Pusher 700 , a high-molecular-weight, partially hydrolyzed polyacrylamide, were studied in an 86-md core made by compacting Teflon powder. The quantity of polymer retained during linear displacement experiments ranged from 10 to 21 pgm/gm for polymer concentrations of 100 to 500 ppm in 2-percent NaCl solutions. Nearly all retention was attributed to mechanical entrapment because of low polymer adsorption on the Teflon surface. Flow rate affected polymer retention. An increase in velocity was accompanied by polymer retention. Polymer was expelled when the flow rate was reduced. Inaccessible pore volume was about 19 percent of the total pore volume. 

A single core was used in all experiments. The core was prepared by compressing Teflon powder in the coreholder using a compacting assembly. Compaction was performed on a hydraulic press. The method used to prepare the core was to slowly load the compacting rod with a force of 10,000 psi and then keep the load constant for 1 hour. The core expanded when the pressure was released. The final core was obtained by removing 4 cm from the top of the core and 2 cm from the bottom. Details of the preparation of the core are available in Ref. 20. 

Batch adsorption experiments were conducted to verify the assumption that polymer adsorption on Teflon powder was negligible. Seven separate determinations were made with equilibrium polymer concentrations ranging from 91 to 471 ppm. In each test, about 155 gm of Teflon powder were shaken intermittently with a known volume of polymer solution in a 250-ml Pyrex bottle. Samples of the supernatant liquid were analyzed for polymer concentration after 50 hours of contact. A material-balance calculation was made to determine the amount of polymer adsorbed. 

Table 2 shows that the amount of polymer retained in the Teflon core is significant and is several times larger than could be retained by adsorption on the Teflon powder. We conclude that mechanical entrapment was the principal mechanism of polymer retention in the Teflon core. 

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