Engineering / Materials / PTFE/Teflon

PTFE/Teflon

PTFE/Teflon®

Description:

Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene, and is a fluorocarbon solid. It has a high-molecular-weight, and consists only of carbon and fluorine. PTFE is best known by the brand name Teflon® by Chemours. PTFE was discovered by DuPont in 1938.

PTFE is hydrophobic, meaning that liquids do not adhere to or absorb into it, and it has one of the lowest coefficients of friction of any solid.

Common Uses:

PTFE is found in:

  • Non-stick coating for pans and other cookware
  • Containers and pipes for reactive and corrosive chemicals
  • Machinery lubricants for reduction of friction and wear
  • Medical industry inventions as a grafting material
  • Seals requiring functionality at wide temperature ranges

Properties:

Standard Compound: -184°C (-300°F) to 232°C (450°F)

Hardness: 98 Shore A

ASTM D1418 Designation: FEP

ASTM D2000 Designation: N/A

Standard Colors:White

Production:

PTFE can be produced in a number of ways, depending on the particular traits desired for the end product. A few of the methods of producing PTFE are suspension polymerization, emulsion polymerization, dispersion polymerization, and direct substitution of hydrgen atoms on polyethylene with fluorine. In suspension polymerization, the TFE is polymerized in water, resulting in grains of PTFE. These grains can be molded after they have been processed into pellets. In the emulsion method PTFE is produced under pressure using free-radical catalysts. In the dispersion method, the PTFE is produced as a paste, which can then be processed into a fine powder. Both the paste and powder are used for coating applications. PTFE comes in virgin and mechanical grade forms, with Virgin PTFE being specified for medical or electrical applications. Mechanical grade PTFE has reprocessed PTFE added.

Advantages:

PTFE properties include:

  • Inert to most chemicals
  • Wide working temperature range
  • High molecular weight
  • Low friction coefficient
  • Good dielectric properties
  • High electonnegativity
  • Hydrophobility
  • Excellent electical insulation properties
  • Weather resistant
  • Extremely low flammability

Limitations:

PTFE limitation include:

  • Poor elastic memory at low temperatures
  • Low resistance to wear and tear
  • Higher tendency to cold flow
  • Low resistance to energy charged radiation
  • Does not work well for processing in injection moulding
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