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Polytetrafluoroethylene (PTFE): Everything You Need to Know

Polytetrafluoroethylene (PTFE): Everything You Need to Know

Undoubtedly, fluoropolymer is a class of plastics offering a varied range of properties. And, the discovery of PTFE revolutionized the emergence of fluoropolymers and their benefit in several applications. Today, PTFE applications range from low-tech non-stick frying pan surfaces (yes! it is the slippery coating in your cookware you use in your kitchen) to high-tech exotic medical and hospital uses including implants, surgical instruments and test equipment, and dramatic uses in firefighting equipment, etc.

Find out what properties make PTFE a versatile polymer offering various advantages in these applications.


What is PTFE?

What is PTFE?

Polytetrafluoroethylene or PTFE is the commonly used versatile, high-performance fluoropolymer made up of carbon and fluorine atoms. One of the common applications of this polymer is non-stick coating in kitchen cookware (pans, baking trays etc.), hence, you can easily find this in your kitchen.

Apart from being used in the kitchen, PTFE is used as a cost-effective solution for industries ranging from oil & gas, chemical processing, industrial to electrical/electronic and construction sector, etc.

The basic properties of PTFE which make it an interesting material with high commercial value are:

  • Exception chemical resistance
  • Good resistance to heat and low temperature
  • Good electrical insulating power in hot and wet environments
  • Good resistance to light, UV and weathering
  • Low coefficient of friction
  • Low dielectric constant/dissipation factor
  • Strong anti-adhesion properties
  • Flexibility
  • Good fatigue resistance under low stress
  • Availability of food, medical and high-purity grades
  • Low water absorption

PTFE is a linear polymer of tetrafluoroethylene (TFE). It is manufactured by a free-radical polymerization mechanism in an aqueous media via the addition polymerization of TFE in a batch process.

The chemical structure of PTFE [CF2-CF2]n is like that of polyethylene (PE), except that the hydrogen atoms are completely replaced by fluorine (hence it is referred as perfluoro polymer). However, it is important to note that in practice PTFE and PE are prepared and used in totally different ways.

Molecular Structure of PTFE
Molecular Structure of PTFE

It is the size of a fluorine atom which forms a uniform and continuous sheath around carbon-carbon-bonds and hence imparts good chemical resistance and stability to the molecule. This uniform fluorine sheath also provides electrical inertness to the molecule.

The fluorine content in PTFE is theoretically 76% and it has 95% crystallinity.

PTFE was first discovered “accidentally” in 1938 by Dr. Plunkett at DuPont. After that PTFE was made commercially available in 1947 with the trademark “Teflon™” from Chemours. It was the discovery of PTFE that accelerated the development of the other fluoropolymers.

Typical Characteristics and Properties of PTFE

Typical Characteristics and Properties of PTFE

PTFE is available in granular, fine powder and water-based dispersion forms.

  • The granular PTFE resin is produced by suspension polymerization in an aqueous medium with little or no dispersing agent. Granular PTFE resins are mainly used for molding (compression and isostatic) and ram extrusion.
  • The fine PTFE powder is prepared by controlled emulsion polymerization, and the products are white, small-sized particles. Fine PTFE powders can be processed into thin sections by paste extrusion or used as additives to increase wear resistance or frictional property of other materials.
  • PTFE dispersions are prepared by the aqueous polymerization using more dispersing agents with agitation. Dispersions are used for coatings and film casting.

As discussed above, PTFE has excellent properties such as chemical inertness, heat resistance (both high and low), electrical insulation properties, low coefficient of friction (static 0.08 and dynamic 0.01), and nonstick property over a wide temperature range (260 to 260°C) - thus making it suitable for a wide range of applications.

Applications of Polytetrafluoroethylene (PTFE)
Applications of Polytetrafluoroethylene (PTFE)

  • It has a density in the range of 2.1 - 2.3 g/cm3 and melt viscosity in the range of 1 -10 GPa per second

  • PTFE is among the most chemically resistant polymer. The exceptions include molten alkali metals, gaseous fluorine at high temperatures and pressures, and a few organic halogenated compounds such as chlorine trifluoride (ClF3) and oxygen difluoride (OF2)...View PTFE Grades With Good Chemical Resistance

  • Mechanical properties of PTFE are generally inferior to engineering plastics at room temperature. Compounding with fillers has been the strategy to overcome this shortage. PTFE has useful mechanical properties in its use temperature range.

    The mechanical properties of PTFE are also affected by processing variables such a preform pressure, sintering temperature, cooling rate, etc. Polymer variable such as molar mass, particle size, particle size distribution poses a significant impact on mechanical properties.

  • PTFE has excellent electrical properties such as high insulation resistance, low dielectric constant. has an extremely low dielectric constant (2.0) due to the highly symmetric structure of the macromolecules.

  • PTFE exhibits high thermal stability without obvious degradation below 440 °C

  • PTFE materials can be continuously used below 260°C.

  • PTFE is attacked by radiation, and degradation in the air begins at a dose of 0.02 Mrad.

These properties come from the special electronic structure of the fluorine atom, the stable carbon-fluorine covalent bonding, and the unique intramolecular and intermolecular interactions between the fluorinated polymer segments and the main chains.

Property Value
Melting Temperature (°C) 317-337
Tensile Modulus (MPa) 550
Elongation at Break (%) 300-550
Dielectric strength (kV/mm) 19.7
Dielectric Constant 2.0
Dynamic Co-efficient of Friction 0.04
Surface Energy (Dynes/g) 18
Appl. Temperature (°C) 260
Refractive Index 1.35

Limitation of PTFE

Limitation of PTFE

The conventional PTFE has some limitations in its applications, such as:

  • Impossibility of using conventional molten-state processing methods and difficulty and cost of the suitable specific methods
  • Sensitivity to creep and abrasion
  • Significant dimensional variation around glass transition temperature (19°C)
  • Difficulties of joining
  • Corrosive and prone to toxic fumes
  • Low radiation resistance

Impact of Fillers and Additives on PTFE Properties

Impact of Fillers and Additives on PTFE Properties

Mechanical properties of PTFE can be enhanced with the addition of fillers, particularly creep and wear rate. Glass fiber, bronze, steel, carbon, carbon fiber, graphite, etc. are among the common fillers used.

Glass fiber has a positive impact on the creep performance of PTFE by reducing its low and high temperatures. Glass filled compounds perform well in oxidizing environments. Further, PTFE’s wear characteristics are improved.

Carbon reduces creep, increases hardness and elevates the thermal conductivity of PTFE. When combined with graphite, the wear resistance of carbon-filled compounds can be improved further. These compounds are well suited for non-lubricated applications such as piston rings in compressor cylinders. Further, graphite imparts excellent wear properties to PTFE and graphite-filled PTFE has an extremely low coefficient of friction.

Carbon fiber lowers creep, increases flex and compressive modulus and raises hardness. Unlike glass fibers, carbon fibers are inert to hydrofluoric acid and strong bases. Carbon fiber PTFE compounds have a lower coefficient of thermal expansion and high thermal conductivity. These parts are ideal for automotive parts in shock absorbers, water pumps etc.

Bronze-filled PTFE compounds have high thermal and electrical conductivity which is, in turn, makes these compounds well fit for application where a part is subjected to load in extreme temperatures.

Other fillers which are incorporated in PTFE to produce specialty compounds include Calcium fluoride, Alumina, Mica, polymeric fillers.

In general:

  • Fillers result in excellent properties of PTFE at low and high temperatures.
  • Fillers/additives increase the porosity of PTFE compounds and hence impact electrical properties – dielectric strength decreases while dielectric constant and dissipation factor increases
  • Chemical properties well depend on the type of filler used. In general, the chemical properties of filled PTFE compounds are not as good as those of unfilled resin.
  • Filler impart change in electrical and thermal conductivity of PTFE

Up to 40% by volume of filler can be added to the PTFE without complete loss of physical properties
The impact of fillers below 5% is low.

Popular Techniques Used to Process PTFE

Popular Techniques Used to Process PTFE

PTFE has a very high-melt viscosity and a high-melting temperature due to rigid polymer chain structure that makes processing difficult by the normal methods of extrusion and injection molding. Processing technologies have more similarity to those of powder metallurgy than those of traditional plastics processing.

  • Sintering, pressing, ram or paste extrusion, compression molding or isotactic molding, machining, hot stamping and extrusion of presintered powders on special machines.
  • Paste extrusion in which PTFE is blended with a hydrocarbon, prior to molding a preform, is used to continuously fabricate PTFE into tubes, tapes, and wire insulation. The hydrocarbon is vaporized before the part is sintered
  • Dispersion – metal coatings, coatings, pulverization, impregnation, cast for thin films and fiber spinning.
  • [Operating range (-270°C) -200°C to 260°C (280°C)]

The properties of the PTFE products are strongly dependent on the processing procedure, such as polymer particle size, sintering temperature and processing pressure. Therefore, other fluoropolymers are still needed for some specific applications where PTFE is not completely suitable.

This led to a search for melt-processable fluoropolymers and the development of other members of the family.

Find Suitable Polytetrafluoroethylene (PTFE) Grade

View a wide range of polytetrafluoroethylene (PTFE) grades available in the market today, analyze technical data of each product, get technical assistance or request samples.

Key Applications



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1 Comments on "Polytetrafluoroethylene (PTFE): Everything You Need to Know "
Tuan Nguyen H Oct 3, 2021
Thanks for Sharing. QTE TECHNOLOGIES offers everything you need in: Laboratory, Industrial, Development, Quality control, General affairs, Factory MRO, Hospital & Nursing care - https://qtetech.com/

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