Fluorinated ethylene propylene

Last updated
FEP
Fluorinated ethylene propylene.png
CAS Registry Number 25067-11-2
Density [1] 2150 kg/m3
Flexural modulus(E)586 M Pa
Tensile strength(t)23 M Pa
Elongation @ break325%
Folding enduranceVaries
Notch test
Melting point 260 °C
Maximum operating
   temperature204 °C
Water absorption (ASTM)<0.01 % after 24 hours
Dielectric constant (Dk)
   at 1M Hz 2.1
Dissipation factor
   at 1M Hz 0.0007
Arc resistance< 300 seconds
Resistivity at 50% R.H. > 1016 Ω m

Fluorinated ethylene propylene (FEP) is a copolymer of hexafluoropropylene and tetrafluoroethylene. It differs from the polytetrafluoroethylene (PTFE) resins in that it is melt-processable using conventional injection molding and screw extrusion techniques. [2] Fluorinated ethylene propylene was invented by DuPont and is sold under the brandname Teflon FEP. Other brandnames are Neoflon FEP from Daikin or Dyneon FEP from Dyneon/3M.

Contents

FEP is very similar in composition to the fluoropolymers PTFE (polytetrafluoroethylene) and PFA (perfluoroalkoxy polymer resin). FEP and PFA both share PTFE's useful properties 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. [3] [4]

Production

FEP is produced by free-radical polymerization of mixtures of tetrafluoroethylene and hexafluoropropylene. The mixture is biased to compensate for the relatively low reactivity of the propylene component. The process is typically initiated with peroxydisulfate, which homolyzes to generate sulfate radicals. Because FEP is poorly soluble in almost all solvents, the polymerization is conducted as an emulsion in water, often using a surfactant such as perfluorooctanesulfonic acid (PFOS). The polymer contains about 5% of the propylene component. [2]

Properties

Useful comparison tables of PTFE against FEP, perfluoroalkoxy (PFA) and ethylene tetrafluoroethylene (ETFE) can be found on Chemours website, listing the mechanical, thermal, chemical, electrical and vapour properties of each, side by side. [5]

In terms of corrosion resistance, FEP is the only other readily available fluoropolymer that can match PTFE's own resistance to caustic agents, as it is a pure carbon-fluorine structure and fully fluorinated. [5]

Thermally, FEP stands out from PTFE and PFA by having a melting point of 260 °C (500 °F), around 40°C lower than PFA and lower again than PTFE. [5]

Electrically, PTFE, FEP and PFA have identical dielectric constants, but FEP's dielectric strength is only surpassed by PFA. However, while PFA has a similar dissipation factor to PTFE, FEP's dissipation is around six times that of PFA and EFTE (making it a more non-linear conductor of electrostatic fields). [5]

Mechanically, FEP is slightly more flexible than PTFE. Perhaps surprisingly, it does not withstand repetitive folding as well as PTFE. It also features a higher coefficient of dynamic friction, is softer and has a slightly lower tensile strength than PTFE and PFA. [5]

A noteworthy property of FEP is that it is vastly superior to PTFE in some coating applications involving exposure to detergents. [5]

Ethylene tetrafluoroethylene (ETFE), in many ways, can be thought of as belonging to a different group, as it is essentially a high strength engineering version of the others featuring what are likely to be considered slightly diminished properties in the other fields when compared with PTFE, FEP and PFA. [5]

Applications

Like PTFE, FEP is mainly used for wiring, e.g. hookup wire, coaxial cable, wiring for computer wires and technical gear. [2] An illustrative end product is for coaxial cables like RG-316.

In manufacturing high-quality composite parts, such as in the aerospace industry, FEP film can be used to protect parts during the curing process. In such applications, the film is called "release film" and is intended to prevent the curing adhesive polymer (e.g. the epoxy in a carbon fibre/epoxy composite laminate) from bonding to the vacuum bagging materials. Being able to maintain chemical composure in extreme temperatures and resist damage from chemical fuels further makes FEP a suitable choice in the industry. [6]

Semi-finished products like pipes, [7] round bars, [7] and sheets [7] for lining containment vessels, gas scrubbers, and tanks are being used in diverse applications in the chemical-processing industry to safely contain and distribute highly-aggressive chemical compounds.

Due to its flexibility, extreme resistance to chemical attack and optical transparency, this material, along with PFA is routinely used for plastic labware and tubing that involves critical or highly corrosive processes. Brand GmbH, Finemech, Savillex and Nalgene are well known laboratory suppliers that makes extensive use of the two materials.

It is also used in UV cured resin 3D printing. Due to the aforementioned properties of high optical transparency and low friction, it is ideally suited for use on the bottom of the resin reservoir (opposite the build plate). This allows for the ultraviolet light to penetrate into the resin, then after the layer has hardened, the build plate can move away pulling the hardened resin away from the FEP film.

The plastic is useful as a sample holder material in microscopy applications as its refractive index is close to that of water at visible wavelengths, [8] [9] (FEP: 1.344, water: 1.335). This minimizes the blur due to optical aberrations when the light traverses the sample container.

Related Research Articles

<span class="mw-page-title-main">Polytetrafluoroethylene</span> Synthetic polymer

Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene and is a PFAS that has numerous applications. The commonly known brand name of PTFE-based composition is Teflon by Chemours, a spin-off from DuPont, which originally discovered the compound in 1938.

Roy J. Plunkett was an American chemist. He discovered polytetrafluoroethylene (PTFE), better known as Teflon, in 1938.

<span class="mw-page-title-main">Thermoplastic</span> Plastic that softens with heat and hardens on cooling

A thermoplastic, or thermosoftening plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling.

<span class="mw-page-title-main">Gore-Tex</span> Trademark for a waterproof, breathable fabric

Gore-Tex is W. L. Gore & Associates's trade name for waterproof, breathable fabric membrane. It was invented in 1969. Gore-Tex blocks liquid water while allowing water vapor to pass through and is designed to be a lightweight, waterproof fabric for all-weather use. It is composed of expanded PTFE (ePTFE), a stretched out form of the PFAS compound polytetrafluoroethylene (PTFE). Gore-Tex products free of "PFC of environmental concerns" repellent coating lacks the ability to repel oil that "Gore DWR" provided.

A fluoropolymer is a fluorocarbon-based polymer with multiple carbon–fluorine bonds. It is characterized by a high resistance to solvents, acids, and bases. The best known fluoropolymer is polytetrafluoroethylene under the brand name "Teflon," trademarked by the DuPont Company.

<span class="mw-page-title-main">Heat-shrink tubing</span> Shrinkable plastic tube used to insulate wires

Heat-shrink tubing is a shrinkable plastic tube used to insulate wires, providing abrasion resistance and environmental protection for stranded and solid wire conductors, connections, joints and terminals in electrical wiring. It can also be used to repair the insulation on wires or to bundle them together, to protect wires or small parts from minor abrasion, and to create cable entry seals, offering environmental sealing protection. Heat-shrink tubing is ordinarily made of polyolefin, which shrinks radially when heated, to between one-half and one-sixth of its diameter.

<span class="mw-page-title-main">ETFE</span> Chemical compound

Ethylene tetrafluoroethylene (ETFE) is a fluorine-based plastic. It was designed to have high corrosion resistance and strength over a wide temperature range. ETFE is a polymer and its source-based name is poly(ethene-co-tetrafluoroethene). It is also known under the DuPont brand name Tefzel and is sometimes referred to as 'Teflon Film'. ETFE has a relatively high melting temperature and excellent chemical, electrical and high-energy radiation resistance properties.

Tetrafluoroethylene (TFE) is a fluorocarbon with the chemical formula C2F4. It is the simplest perfluorinated alkene. This gaseous species is used primarily in the industrial preparation of fluoropolymers.

<span class="mw-page-title-main">ECTFE</span> Corrosion-resistant polymer

ECTFE (ethylene-chlorotrifluoroethylene) is an alternating copolymer of ethylene and chlorotrifluoroethylene. It is a semi-crystalline fluoropolymer, with chemical corrosion resistance properties.

FKM is a family of fluorocarbon-based fluoroelastomer materials defined by ASTM International standard D1418, and ISO standard 1629. It is commonly called fluorine rubber or fluoro-rubber. FKM is an abbreviation of Fluorine Kautschuk Material. All FKMs contain vinylidene fluoride as the common monomer, to which different other monomers are added for specific types and functionalities, fitting the desired application.

Teflon is a registered trademark of the Chemours company used for polytetrafluoroethylene.

Perfluoroethers are a class of organofluorine compound containing one or more ether functional group. In general these compounds are structurally analogous to the related hydrocarbon ethers, except for the distinctive properties of fluorocarbons.

<span class="mw-page-title-main">Non-stick surface</span> Coating that prevents sticking

A non-stick surface is engineered to reduce the ability of other materials to stick to it. Non-stick cookware is a common application, where the non-stick coating allows food to brown without sticking to the pan. Non-stick is often used to refer to surfaces coated with polytetrafluoroethylene (PTFE), a well-known brand of which is Teflon. In the twenty-first century, other coatings have been marketed as non-stick, such as anodized aluminium, silica, enameled cast iron, and seasoned cookware.

<span class="mw-page-title-main">Hydrogen pipeline transport</span> Method of fuel transportation

Hydrogen pipeline transport is a transportation of hydrogen through a pipe as part of the hydrogen infrastructure.

Electron-beam processing or electron irradiation (EBI) is a process that involves using electrons, usually of high energy, to treat an object for a variety of purposes. This may take place under elevated temperatures and nitrogen atmosphere. Possible uses for electron irradiation include sterilization, alteration of gemstone colors, and cross-linking of polymers.

<span class="mw-page-title-main">Perfluorinated compound</span>

A perfluorinated compound (PFC) or perfluoro compound is an organofluorine compound lacking C-H bonds. Many perfluorinated compounds have properties that are quite different from their C-H containing analogues. Common functional groups in PFCs are OH, CO2H, chlorine, O, and SO3H. Electrofluorination is the predominant method for their production. Due to their chemical stability, some of these perfluorinated compounds bioaccumulate.

Xylan is a fluoropolymer-based industrial coating, most commonly used in non-stick cookware. Generally, it is applied in a thin film to the target material to improve its durability and non-stick properties.

<span class="mw-page-title-main">Fluorochemical industry</span> Industry dealing with chemicals from fluorine

The global market for chemicals from fluorine was about US$16 billion per year as of 2006. The industry was predicted to reach 2.6 million metric tons per year by 2015. The largest market is the United States. Western Europe is the second largest. Asia Pacific is the fastest growing region of production. China in particular has experienced significant growth as a fluorochemical market and is becoming a producer of them as well. Fluorite mining was estimated in 2003 to be a $550 million industry, extracting 4.5 million tons per year.

<span class="mw-page-title-main">Perfluoroalkoxy alkane</span> Family of polymers

Perfluoroalkoxy alkanes (PFA) are fluoropolymers. They are copolymers of tetrafluoroethylene (C2F4) and perfluoroethers (C2F3ORf, where Rf is a perfluorinated group such as trifluoromethyl (CF3)). The properties of these polymers are similar to those of polytetrafluoroethylene (PTFE). Compared to PTFE, PFA has better anti-stick properties and higher chemical resistance, at the expense of lesser scratch resistance.

<span class="mw-page-title-main">Herbert S. Eleuterio</span> American industrial chemist (1927–2022)

Herbert S. Eleuterio was an American industrial chemist noted for technical contributions to catalysis, polymerization, industrial research management, and science education. In particular, he discovered the olefin metathesis reaction and several novel fluoropolymers. Additionally, he explored techniques for research leadership, especially methods for fostering collaboration, globalization, and scientific creativity.

References

  1. "PTFE, FEP, and PFA Specifications". Boedeker Corp. 2007. Retrieved 2007-12-22.
  2. 1 2 3 D. Peter Carlson and Walter Schmiegel "Fluoropolymers, Organic" in Ullmann's Encyclopedia of Industrial Chemistry 2000, Wiley-VCH, Weinheim. doi : 10.1002/14356007.a11_393
  3. "Teflon FEP". DuPont. Archived from the original on 2007-10-23. Retrieved 2007-10-17.
  4. "FEP Detailed Properties". Parker-TexLoc. 2006-04-13. Retrieved 2013-10-17.
  5. 1 2 3 4 5 6 7 "Teflon™ Products | Teflon™ Fluoropolymers". www.teflon.com.
  6. "Uses for FEP Tubing | Fluorotherm". Fluorotherm. 22 June 2015.
  7. 1 2 3 AGRU Kunststofftechnik GmbH, http://www.agru.at/en/products/semi-finished-products/.
  8. "FEP Tubing | Properties | Fluorotherm.com".
  9. "FEP (Fluorinated Ethylene Propylene) – Meaning and Features". Holscot Fluoropolymers.