Information AboutTeflon |
| CATEGORIES ABOUT POLYTETRAFLUOROETHYLENE | |
| plastics | |
| fluoropolymers | |
| lubricants | |
| dupont | |
| dielectrics | |
| pyrotechnic oxidizers | |
In Chemistry , polytetrafluoroethylene ('''PTFE''') is a synthetic Fluoropolymer which finds numerous applications. PTFE's most well known trademark in the industry is the DuPont brand name '''Teflon'''. PTFE has an extremely low Coefficient Of Friction and is used as a non-stick coating for pans and other cookware. It is very non-reactive, and so is often used in containers and pipework for reactive and corrosive chemicals. Where used as a lubricant, PTFE significantly reduces friction, wear and energy consumption of machinery. HISTORY The common statement that PTFE is a spin-off from the 2006. While attempting to make a new CFC refrigerant, the Perfluorethylene polymerized in its pressurized storage container. (In this original chemical reaction, iron from the inside of the container acted as a catalyst.) DuPont patented it in 1941 and registered the Teflon trademark in 1944. The story of Teflon It was first sold commercially in 1946. By 1950, DuPont was producing over a million pounds (450 t) per year in Parkersburg, West Virginia . In 1954, French engineer Marc Grégoire created the first pan coated with Teflon non-stick resin. An early advanced use was in the Manhattan Project as a material to coat valves and seals in the pipes holding highly reactive Uranium Hexafluoride in the vast Uranium Enrichment plant at Oak Ridge, Tennessee , when it was known as ''K416''. PROPERTIES s as it has very low friction and high heat resistance.]] PTFE is a white solid at room temperature, with a 2006. The s means that it is the only known surface that a Gecko cannot stick to.http://socrates.berkeley.edu/~peattiea/research_main.html PTFE has excellent Dielectric properties. This is especially true at high Radio Frequencies , making it suitable for use as an Insulator in Cable s and Connector assemblies and as a material for Printed Circuit Board s used at Microwave frequencies. Combined with its high melting temperature, this makes it the material of choice as a high-performance substitute for the weaker and lower melting point Polyethylene that is commonly used in low-cost applications. Its extremely high bulk Resistivity makes it an ideal material for fabricating long life Electret s, useful devices that are the Electrostatic analogues of Magnet s. Because of its chemical inertness, PTFE cannot be cross-linked like an Elastomer . Therefore it has no "memory," and is subject to Creep (also known as "cold flow" and "compression set"). This can be both good and bad. A little bit of creep allows PTFE seals to conform to mating surfaces better than most other plastic seals. Too much creep, however, and the seal is compromised. Compounding fillers control unwanted creep, as well as to improve wear, friction, and other properties. Sometimes metal springs apply continuous force to PTFE seals to give good contact, while permitting some creep. APPLICATIONS is made of 20 acres of teflon-coated fiberglass]] Due to its low friction, it is used for applications where sliding action of parts is needed: Bearings , Bushing s, Gear s, Slide Plate s, etc. In these applications it performs significantly better than Nylon and Acetal ; it is comparable to Ultra High-molecular Weight Polyethylene (UHMWPE), although UHMWPE is more resistant to wear than Teflon. For these applications, versions of teflon with mineral oil or Molybdenum Disulfide embedded as additional Lubricant s in its matrix are being manufactured. Gore-Tex is a material incorporating fluoropolymer membrane with micropores. The roof of the Hubert H. Humphrey Metrodome in Minneapolis is one of the largest applications of Teflon PTFE coatings on Earth, using 20 Acre s (about 8 Hectare s) of the material in a double-layered, white dome, made with PTFE-coated fiberglass, that gives the stadium its distinctive appearance. The Millennium Dome in London is also substantially made of PTFE. Powdered PTFE is used in Pyrotechnic Composition s as Oxidizer together with powdered metals such as Aluminum and Magnesium . Upon ignition these mixtures form carbonaceous Soot and the corresponding metal Fluoride and release large amounts of heat. Hence they are used as Infrared Decoy Flare s and Igniter s for Solid-fuel Rocket Propellant s.E.-C. Koch "Metal-Fluorocarbon Pyrolants:III. Development and Application of Magnesium/Teflon/Viton" Propellants Explosives Pyrotechnics (2002),27(5),pp. 262-266. PTFE is also used in Body Piercing , such as a sub-clavicle piercing, due to its flexibility and bio-compatibility. In optical Radiometry , sheets made from PTFE are used as measuring heads in spectroradiometers and broadband radiometers (e.g. Illuminance meter and UV Radiometer ) due to its capability to diffuse a transmitting light nearly perfectly. Moreover, optical properties of PTFE stay constant over a wide range of wavelengths, from UV up to near Infrared . In this region, the relation of its regular transmittance to diffuse transmittance is negligibly small so light transmitted through a Diffuser (PTFE sheet) radiates like Lambert's Cosine Law . Thus, PTFE enables cosinusoidal angular response for a detector measuring the power of optical radiation at a surface, e.g., in solar Irradiance measurements. PTFE is also used to coat certain types of hardened, Armor-piercing Bullets , so as to reduce the amount of wear on the firearm's rifling. These are often mistakenly referred to as "cop-killer" Bullets by virtue of PTFE's supposed ability to ease a bullet's passage through Body Armor . PRODUCTION PTFE is either synthesized by the Emulsion Polymerization of Tetrafluoroethylene monomer under pressure, using free-radical catalysts, or it may be produced by the direct substitution of hydrogen atoms on Polyethylene with fluorine, using polyethylene and Fluorine gas at 20 °C.Mike Orthner, Polytetrafluoroethylene/"Teflon" Synthesis , accessed on 02 Oct 2006. SAFETY While PTFE itself is chemically inert and non-toxic, it begins to deteriorate after the temperature of cookware reaches about 460 °F (237 °C), and decompose above 660 °F (350 °C). These degradation products can be lethal to Bird s, and can cause flu-like symptoms in humans. By comparison, cooking fats, oils, and butter will begin to scorch and smoke at about 392 °F (200 °C), and meat is usually fried between 400–450 °F (200–230 °C), but empty cookware can exceed this temperature if left unattended on a hot burner. |
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