Polytetrafluoroethylene electrical conductivity

Except for gold and silver, copper is the best metallic electrical conductor and copper wires are commonly used as electrical conductors. They are also used as magnet wires in electric motors, transformers, generators, electromagnets, etc. Copper and aluminum are commonly used for magnet wire because of their good electrical conductivity. Magnet wires are frequently coated by a variety of polymers such as nylon, aramid, polyester, polytetrafluoroethylene, polymide, etc. 

Carbon reduces creep, increases hardness and elevates thermal conductivity of polytetrafluoroethylene. Wear resistance of carbon filled compounds improves, particularly when combined with graphite. Carbon-graphite compounds perform well in non-lubricated applications such as piston rings in compressor cylinders. Carbon-filled PTFE has some electrical conductivity. Close tolerances can be achieved... 

In recent decades, various electrode materials have been investigated to improve the performance of fuel cells [299]. A conventional low-temperature fuel cell electrode is composed of polytetrafluoroethylene, a high-surface-area carbon black loaded with a precious metal catalyst, and a current collector, as well as other minor components. The most challenging issue for electrode performance is the electrocatalyst [327]. Carbon has been established as the best catalyst support because of its good electrical conductivity, high surface area, surface hydro-phobicity, and stability [328-331]. In the past few years, template-synthesized carbons with various structures have been tried as components of fuel cells. 

Electrophoretic Deposition n A direct-current process analogous to electroplating, used to coat electrically-conductive articles with plastics, deposited from aqueous lattices or dispersions. The cathode may be a noncorrodible metal such as stainless steel, generally serving as the container in which the process is performed. The DC potential is usually under 100 V. The deposited coatings are baked to remove residual water. Among available polymer lattices suitable for the process are PVC, polyvinylidene chloride, acrylics, nylons, polyesters, polytetrafluoroethylene, and polyethylene. 

The bulk (or volume)-specific resistance is one of the most useful general electrical properties. Specific resistance is a physical quantity that may vary more than 10 in readily available materials. This unusually wide range of conductivity allows wide variety of electrical applications. Conductive materials, such as copper, have specific resistance values of about 10 fl-cm, whereas good insulators such as polytetrafluoroethylene and LDPE have values of about 10 fl-cm. Specific resistance is calculated from the following equation where R is the resistance in ohms, a is the pellet area in square centimeters, t is the pellet thickness in centimeter, and P is the specific resistance in ohm-centimeter ... 

Electrical properties. Fillers and additives significantly increase the porosity of polytetrafluoroethylene compounds. Electrical properties are affected by the void content as well as the filler characteristics. Dielectric strength drops while dielectric constant and dissipation factor rise. Metals, carbon, and graphite increase the thermal conductivity of PTFE compounds. Tables 3.19 and 3.20 present electrical properties of a few common compounds. 

Figure 15. HPLC conductivity detector [31J a) Connection lo column b) Platinum capillary c) Elecuical connection d) Polytetrafluoroethylene capillary e) Polytet-rafluoroelhylene f) Electrical connection g) Plastic delector housing h) Stainless steel capillary Measurement is performed between (b) and (h)...

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