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Encyclopedia > Polytetrafluoroethylene
Polytetrafluoroethylene
IUPAC name Polytetrafluoroethylene
Systematic name poly(tetrafluoroethylene)
Other names Teflon
Identifiers
Abbreviations PTFE
CAS number 9002-84-0
Properties
Molecular formula CnF2n
Density 2200 kg m−3
Melting point

327 °C Image File history File links Teflon_structure. ... Image File history File links Download high resolution version (1000x556, 209 KB) Categories:Molecules File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Polytetrafluoroethylene ... IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. ... IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... A chemical formula is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... For other uses, see Density (disambiguation). ... The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. ...

Supplementary data page
Structure and
properties
n, εr, etc.
Thermodynamic
data
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

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. Categories: | | | | | ... Categories: | | | | | ... The refractive index (or index of refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium. ... The relative dielectric constant of a material under given conditions is a measure of the extent to which it concentrates electrostatic lines of flux. ... Categories: | | | | | ... Categories: | | | | | ... Ultraviolet-Visible Spectroscopy or Ultraviolet-Visible Spectrophotometry (UV/ VIS) involves the spectroscopy of photons (spectrophotometry). ... Infrared spectroscopy (IR Spectroscopy) is the subset of spectroscopy that deals with the IR region of the EM spectrum. ... Nuclear magnetic resonance spectroscopy most commonly known as NMR spectroscopy is the name given to the technique which exploits the magnetic properties of certain nuclei. ... Mass spectrometry (also known as mass spectroscopy (deprecated)[1] or informally, mass-spec and MS) is an analytical technique used to measure the mass-to-charge ratio of ions. ... In chemistry, the standard state of a material is its state at 1 bar (100 kilopascals) and 25 degrees Celsius (298. ... For other uses, see Chemistry (disambiguation). ... A fluoropolymer is a polymer that contains atoms of fluorine. ... Dupont, DuPont, Du Pont, or du Pont may refer to: // E.I. du Pont de Nemours and Company, the worlds third largest chemical company Du Pont Motors Gilbert Dupont, a French stock brokerage part of retail banking network Crédit du Nord ST Dupont, a French manufacturer of fine... Teflon is polytetrafluoroethylene (PTFE), a polymer of fluorinated ethylene. ...


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. The resistance to lateral motion when one attempts to slide the surface of one object over another surface is called friction or traction. ...

Contents

History

The common statement that PTFE is a spin-off from the United States space program is an urban legend. PTFE was discovered accidentally by Roy Plunkett of DuPont in 1938.[1] 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.[2] This page is a summary of the US government space programme, part of a series of such summaries and covers all aspects pertinent to the nations space progamme. ... An urban legend or urban myth is similar to a modern folklore consisting of stories often thought to be factual by those circulating them. ... Roy J. Plunkett (June 26, 1910 - May 12, 1994) was the chemist who accidentally invented Teflon in 1938. ... Dupont, DuPont, Du Pont, or du Pont may refer to: // E.I. du Pont de Nemours and Company, the worlds third largest chemical company Du Pont Motors Gilbert Dupont, a French stock brokerage part of retail banking network Crédit du Nord ST Dupont, a French manufacturer of fine... Possible meanings: Certified Financial Consultant Chelsea Football Club Child and Family Canada Chlorofluorocarbon Combined Federal Campaign haloalkane This page concerning a three-letter acronym or abbreviation is a disambiguation page—a list of articles associated with the same title. ... Tetrafluoroethylene (TFE), also known as tetrafluoroethene or perfluoroethylene, is a chemical compound composed of only carbon and fluorine with the molecular formula C2F4. ... For other uses, see 1941 (disambiguation). ...


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. Location in Wood County in the State of West Virginia Coordinates: , Country United States State West Virginia County Wood Incorporated 1810 Government  - Mayor Robert Newell Area  - City  12. ...


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. The Manhattan Project resulted in the creation of the first nuclear weapons, and the first-ever nuclear detonation, known as the Trinity test of July 16, 1945. ... Uranium hexafluoride (UF6), referred to as hex in industry, is a compound used in the uranium enrichment process that produces fuel for nuclear reactors and nuclear weapons. ... These pie-graphs showing the relative proportions of uranium-238 (blue) and uranium-235 (red) at different levels of enrichment. ... Oak Ridge is an incorporated city in Anderson and Roane Counties in East Tennessee, about 25 miles northwest of Knoxville. ...


Properties

PTFE is often used to coat non-stick frying pans as it has very low friction and high heat resistance.

PTFE is a white solid at room temperature, with a density of about 2.2 g/cm³. According to DuPont its melting point is 327 °C (620.6 °F), but its properties degrade above 260 °C (500 °F).[3] Image File history File linksMetadata Download high resolution version (2032x1524, 3103 KB) Summary Freshly cooked frozen w:blintzes in a frying pan. ... Image File history File linksMetadata Download high resolution version (2032x1524, 3103 KB) Summary Freshly cooked frozen w:blintzes in a frying pan. ... “Skillet” redirects here. ... For other uses, see Density (disambiguation). ...


The coefficient of friction of plastics is usually measured against polished steel.[4] PTFE's coefficient of friction is 0.1 or less[3], which is the lowest of any known solid material. PTFE's resistance to van der Waals forces means that it is the only known surface to which a gecko cannot stick.[5] The resistance to lateral motion when one attempts to slide the surface of one object over another surface is called friction or traction. ... In chemistry, the term van der Waals force originally referred to all forms of intermolecular forces; however, in modern usage it tends to refer to intermolecular forces that deal with forces due to the polarization of molecules. ... For other uses, see Gecko (disambiguation). ...


PTFE has excellent dielectric properties. This is especially true at high radio frequencies, making it suitable for use as an insulator in cables and connector assemblies and as a material for printed circuit boards 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 electrets, useful devices that are the electrostatic analogues of magnets. A dielectric, or electrical insulator, is a substance that is highly resistant to electric current. ... It has been suggested that this article or section be merged with Radio waves. ... This article or section is in need of attention from an expert on the subject. ... 6 or 15cm outside diameter, oil-cooled cables, traversing the Grand Coulee Dam throughout. ... Look up connector in Wiktionary, the free dictionary. ... Part of a 1983 Sinclair ZX Spectrum computer board. ... This article is about the type of Electromagnetic radiation. ... This article does not cite any references or sources. ... Electrical resistivity (also known as specific electrical resistance) is a measure of how strongly a material opposes the flow of electric current. ... Electret (formed of elektr- from electricity and -et from magnet) is material that has been permanently electrically charged (polarised). ... Electrostatics is the branch of physics that deals with the force exerted by a static (i. ... For other uses, see Magnet (disambiguation). ...


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. The term elastomer is often used interchangeably with the term rubber, and is preferred when referring to vulcanisates. ... Creep is the term used to describe the tendency of a material to move or to deform permanently to relieve stresses. ...


Property values

Characteristics of PTFE (Teflon)
Property Units Value
Density g/cm³ 2.2
Melting point °C 327
Young's modulus GPa 0.5
Yield strength MPa 23
Coefficient of friction (measured against polished stainless steel) 0.05-0.10
Dielectric constant ε=2.1,tan⁡(δ)<5(-4)
Dielectric constant (60 Hz) ε=2.1,tan⁡(δ)<2(-4)
Dielectric strength (1 MHz) MV/m 60

For other uses, see Density (disambiguation). ... The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. ... In solid mechanics, Youngs modulus (E) is a measure of the stiffness of a given material. ... Yield strength, or the yield point, is defined in engineering as the amount of strain that a material can undergo before moving from elastic deformation into plastic deformation. ... The resistance to lateral motion when one attempts to slide the surface of one object over another surface is called friction or traction. ... The relative dielectric constant of a material under given conditions is a measure of the extent to which it concentrates electrostatic lines of flux. ... The relative dielectric constant of a material under given conditions is a measure of the extent to which it concentrates electrostatic lines of flux. ... In physics, the term dielectric strength has the following meanings: Of an insulating material, the maximum electric field strength that it can withstand intrinsically without breaking down, , without experiencing failure of its insulating properties. ...

Applications

The roof of the Hubert H. Humphrey Metrodome 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, bushings, gears, slide plates, 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 lubricants in its matrix are being manufactured. Image File history File linksMetadata Size of this preview: 800 × 600 pixelsFull resolution (2560 × 1920 pixel, file size: 1. ... Image File history File linksMetadata Size of this preview: 800 × 600 pixelsFull resolution (2560 × 1920 pixel, file size: 1. ... The entrance The Hubert H. Humphrey Metrodome, usually simply called The Metrodome or The Dome, and often nicknamed the Homerdome (even though in reality it is no friendlier to the long ball than average[3]), is a domed sports stadium in downtown Minneapolis, Minnesota. ... A bearing is a device to permit constrained relative motion between two parts, typically rotation or linear movement. ... This article or section does not adequately cite its references or sources. ... Spur gears found on a piece of farm equipment A gear is a wheel with teeth around its circumference, the purpose of the teeth being to mesh with similar teeth on another mechanical device -- possibly another gear wheel -- so that force can be transmitted between the two devices in a... For other uses of this word, see nylon (disambiguation). ... It has been suggested that Delrin be merged into this article or section. ... Ultra high molecular weight polyethylene (UHMWPE), also known as high modulus polyethylene (HMPE) or high performance polyethylene (HPPE), is a thermoplastic. ... Molybdenum disulfide, also called molybdenum sulfide or molybdenum(IV) sulfide, with the formula MoS2, is a black crystalline sulfide of molybdenum. ... A lubricant (colloquially, lube) is a substance (often a liquid) introduced between two moving surfaces to reduce the friction and wear between them. ...


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 acres (about 8 hectares) 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. Gore-Tex membrane, electron microphotograph Gore-Tex (abbreviated GTX) is a registered trademark of W.L. Gore & Associates best known for its use in relation to waterproof/breathable fabrics. ... The entrance The Hubert H. Humphrey Metrodome, usually simply called The Metrodome or The Dome, and often nicknamed the Homerdome (even though in reality it is no friendlier to the long ball than average[3]), is a domed sports stadium in downtown Minneapolis, Minnesota. ... This article is about the city in Minnesota. ... An acre is the name of a unit of area in a number of different systems, including Imperial units and United States customary units. ... A hectare (symbol ha) is a unit of area, equal to 10 000 square metres, commonly used for measuring land area. ... The O2 redirects here. ... This article is about the capital of England and the United Kingdom. ...


Powdered PTFE is used in pyrotechnic compositions 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 flares and igniters for solid-fuel rocket propellants.[6] A pyrotechnic composition is a substance or mixture of substances designed to produce an effect by heat, light, sound, gas or smoke or a combination of these, as a result of non detonative self-sustaining exothermic chemical reactions. ... An oxidizing agent is a substance that oxidizes another substance in electrochemistry or redox chemical reactions in general. ... Aluminum is a soft and lightweight metal with a dull silvery appearance, due to a thin layer of oxidation that forms quickly when it is exposed to air. ... General Name, symbol, number magnesium, Mg, 12 Chemical series alkaline earth metals Group, period, block 2, 3, s Appearance silvery white solid at room temp Standard atomic weight 24. ... Soot, also called lampblack, Pigment Black 7, carbon black or black carbon, is a dark powdery deposit of unburned fuel residues, usually composed mainly of amorphous carbon, that accumulates in chimneys, automobile mufflers and other surfaces exposed to smoke—especially from the combustion of carbon-rich organic fuels in the... Fluoride is the ionic form of fluorine. ... A Lockheed MC-130 releasing 2x1 Inch MTV decoy flares A (decoy) flare is an aerial infrared countermeasure to counter an infrared homing (heat seeking) surface-to-air missile (SAM) or air-to-air missile (AAM). ... A pyrotechnic initiator (also initiator or igniter) is a device containing a pyrotechnic composition used primarily to ignite other, more difficult to ignite materials, e. ... The Space Shuttle Columbia is initially launched with the help of solid-fuel boosters A solid rocket or a solid fuel rocket is a rocket with a motor that uses solid propellants (fuel/oxidizer). ... A propellant is a material that is used to move an object by applying a motive force. ...


PTFE is also used in body piercing, such as a sub-clavicle piercing, due to its flexibility and bio-compatibility. This article does not cite any references or sources. ...


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. In telecommunication and physics, radiometry is the science of radiation measurement. ... Illuminance is the total luminous flux incident per unit area. ... Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. ... A radiometer is a device used to measure the radiant flux or power in electromagnetic radiation. ... For other uses, see Infrared (disambiguation). ... In optics a diffuser is any device that diffuses or spreads out or scatters light in some maner. ... Lamberts cosine law says that the total radiant power observed from a Lambertian surface is directly proportional to the cosine of the angle θ between the observers line of sight and the surface normal. ... Irradiance, radiant emittance, and radiant exitance are radiometry terms for the power of electromagnetic radiation at a surface, per unit area. ...


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. Soviet ammunition BM 15 of 125mm French anti-tank round with its sabot APFSDS at point of separation of sabot. ... This article includes a list of works cited or a list of external links, but its sources remain unclear because it lacks in-text citations. ... ...


PTFE's low frictional properties have also been utilized as computer mice feet such as the Logitech G5 and Logitech G7 computer mice series from Logitech. The low-friction provided by PTFE allows the mice to be moved and glide across surfaces smoothly and with less effort. Operating a mechanical 1: Pulling the mouse turns the ball. ... A Logitech G5, showing the orange weight caddy. ... Logitech G7 The Logitech G7 is a cordless laser mouse produced by Logitech targeted at the gamer market. ... This article or section does not cite any references or sources. ...


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.[7] Image File history File links Free_radical_polymerization_of_tetrafluoroethylene. ... Image File history File links Free_radical_polymerization_of_tetrafluoroethylene. ... Image File history File links Fluorination_of_polyethylene. ... Image File history File links Fluorination_of_polyethylene. ... Emulsion polymerization is a type of polymerization that takes place in an emulsion typically incorporating water, monomer, and surfactant. ... Tetrafluoroethylene, or tetrafluoroethene, C2F4, is a compound of carbon and fluorine. ... This article does not cite any references or sources. ... Distinguished from fluorene and fluorone. ...


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).[citation needed] These degradation products can be lethal to birds, and can cause flu-like symptoms in humans. For other uses, see Bird (disambiguation). ...


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.


A 1959 study, (conducted before the Food and Drug Administration approved the material for use in food processing equipment) showed that the toxicity of fumes given off by the coated pan on dry heating was less than that of fumes given off by ordinary cooking oils.[8] “FDA” redirects here. ...


Carcinogens in production

The United States Environmental Protection Agency's scientific advisory board found in 2005 that perfluorooctanoic acid (PFOA), a chemical compound used to make Teflon, is a "likely carcinogen." This finding was part of a draft report that has yet to be made final.[9] DuPont settled for $300 million in a 2004 lawsuit filed by residents near its manufacturing plant in Ohio and West Virginia based on groundwater pollution from this chemical. Currently this chemical is not regulated by the EPA. EPA redirects here. ... Perfluorooctanoic acid (PFOA), also known as C8, is an artificial acid that has many industrial uses. ... The hazard symbol for carcinogenic chemicals in the Globally Harmonized System. ...


In January 2006, DuPont, the only company that manufactures PFOA in the US, agreed to eliminate releases of the chemical from its manufacturing plants by 2015,[10] but did not commit to completely phasing out its use of the chemical. This agreement is said to apply to not only PTFE used in cookware but also other products such as food packaging, clothing, and carpeting. DuPont also stated that it cannot produce PTFE without the use of the chemical PFOA, although it is looking for a substitute.


PFOA is used only during the manufacture of the product—only a trace amount of PFOA remains after the curing process. DuPont maintains that there should be no measurable amount of PFOA on a finished pan, provided that it has been properly cured.[11]


Similar polymers

Teflon is also used as the trade name for a polymer with similar properties, perfluoroalkoxy polymer resin (PFA).

Other polymers with similar composition are also known by the Teflon name: Image File history File links PFA_structure. ... Image File history File links PFA_structure. ... Teflon is polytetrafluoroethylene (PTFE), a polymer of fluorinated ethylene. ...

They retain the useful properties of PTFE of low friction and non-reactivity, but are more easily formable. FEP is softer than PTFE and melts at 260°C; it is highly transparent and resistant to sunlight.[12] PFA tubing is very common in chemical handling applications Perfluoroalkoxy (PFA) is a type of fluoropolymer with properties similar to polytetrafluoroethylene (PTFE). ... Teflon is polytetrafluoroethylene (PTFE), a polymer of fluorinated ethylene. ...


See also

// MTV is an acronym for pyrolants based on magnesium/Teflon®/Viton®. Teflon and Viton are trademarks of DuPont for polytetrafluoroethylene, C2F4, and vinylidenfluoride-hexafluoroisopropene-copolymer, (CH2CF2)n(CF(CF3)CF2)n. ... This article needs to be cleaned up to conform to a higher standard of quality. ...

Notes

  1. ^ Roy J. Plunkett Chemical Heritage Foundation. Retrieved 10 September 2006.
  2. ^ The story of Teflon
  3. ^ a b http://www2.dupont.com/Teflon_Industrial/en_US/tech_info/techinfo_compare.html Fluoropolymer Comparison - Typical Properties] www2.dupont.com. Retrieved 10 September 2006.
  4. ^ Coefficient of Friction (COF) Testing of Plastics MatWeb Material Property Data Retrieved 1 January 2007.
  5. ^ http://socrates.berkeley.edu/~peattiea/research_main.html
  6. ^ E.-C. Koch "Metal-Fluorocarbon Pyrolants:III. Development and Application of Magnesium/Teflon/Viton" Propellants Explosives Pyrotechnics (2002),27(5),pp. 262-266.
  7. ^ Mike Orthner, Polytetrafluoroethylene/"Teflon" Synthesis, accessed on 02 Oct 2006.
  8. ^ Dale Blumenthal. Is That Newfangled Cookware Safe?. Food and Drug Administration. Retrieved on 2006-05-20.
  9. ^ Perfluorooctanoic Acid Human Health Risk Assessment Review Panel. Environmental Protection Agency. Retrieved on 2005-05-20.
  10. ^ Juliet Eilperin. "Harmful PTFE Chemical To Be Eliminated by 2015", Washington Post, 2006-01-26. Retrieved on 2006-09-10. 
  11. ^ About Teflon. DuPont. Retrieved on 2006-05-20.
  12. ^ FEP Detailed Properties Parker-TexLoc, 13 April 2006. Retrieved 10 September 2006.

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References

  • Ellis, D.A.; Mabury, S.A.; Martin, J.W.; Muir, D.C.G. "Thermolysis of fluoropolymers as a potential source of halogenated organic acids in the environment." Nature 2001, 412 (6844), pp. 321-324.

External links


  Results from FactBites:
 
Polytetrafluoroethylene molded product in block form and method for production thereof - Patent 6899932 (3887 words)
After a polytetrafluoroethylene powder is compression-molded to form a preform, the resultant preform is baked while being rotated, thereby to produce a polytetrafluoroethylene molded article.
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