Differences between PTFE (Teflon), FEP, and PFA

The name, “Teflon” is Dupont’s trademark name for its family of fluoropolymers.  At times, it is mistaken that DuPont’s trademark name is meant only to refer to the fluoropolymer, PTFE, when FEP and PFA also can be used under the appellation.

Industry experts also use other names to refer to the fluoropolymers.  FEP, PFA, and PTFE are also known under names such as THV, PVDF, ETFE, ECTFE, and CTFE.

Though all of the fluoropolymers can be cataloged in the same family, they vary slightly in regards to thermal and mechanical properties.

PTFE and PFA have a raised temperature tolerance in comparison to FEP.

FEP and PFA are clear, yet PTFE is translucent.  FEP and PFA have better mechanical properties in comparision to PTFE.

The main differences are in regards to chemical inertness, corrosion resistance ,permeability, and FDA approval.

For more information, visit our Overview of Fluoropolymers
and Typical properties of fluoropolymers.

Fluorotherm’s Chemically Resistant PTFE, FEP and PFA Products are the Materials of Choice

To Our Valued Customers,

Beginning this month, we would like to selectively pick one of the unique characteristics of fluoropolymers and briefly elaborate on the reasons why they are the materials of choice over other polymers for applications that require specific performance criteria.

 

Some of these criteria may require electrical, chemical inertness, non-shedding, optical, thermal (both high temperature and cryogenic conditions), ultraviolet light transparency, lubricity, weathering and corrosion resistance characteristics, among others. Fluoropolymers such as PTFE, FEP and PFA uniquely meet one or a combination of these criteria.

 

Chemical Resistance

 

Specifically perfluorinated fluoropolymer materials such as PTFE, FEP and PFA contain only carbon and fluorine with single chemical bonds in the chemical structure. Their hydrocarbon counterparts, such as polyethylene and polypropylene; contain carbon and hydrogen. The morphology or structural shape of the fluoropolymer molecule containing strong C-F single bonds is uniquely tailored to prevent chemical attack of the carbon-carbon backbone by most common chemicals. Think Caesar’s Roman army with rectangular shields that received better protection against flying spears than the round shields of opposing armies.

 

PTFE (polytetrafluoroethylene) is highly resistant to attack by most highly corrosive chemicals. For example, Fluorotherm has many instances of heat exchangers and other products that continue to operate in hot sulfuric, nitric and hydrochloric acids. Our heat exchanger designs were originally introduced to the market in the mid-1960′s., and new combinations of increasingly robust design and materials have evolved ever since.  An example of our heat exchanger frame initially installed in 1982 is shown below. The tubing material has been replaced but the frame is relatively clean considering its exposure to hot nitric and hydrofluoric acids for  26 years.

FLUOROTHERM TEFLON® IMMERSION HEAT EXCHANGER – 1982 INSTALLATION – AND STILL OPERATING !

 

FEP (polytetrafluoroethylene-co-hexfluoropropylene) and PFA (polytetrafluoroethylene-co-perfluoro alkoxyvinyl ether) have similar chemical resistance to PTFE. Tubing made of these materials have a long life in aggressive environments in the simultaneous presence of harsh chemicals and high temperatures compared to other plastics and materials where failure may occur due to either structural or thermal degradation.

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Extreme chemical inertness of perfluorinated polymers serves well in a broad range of industries and applications. Some of these include the oil well and oil services industries; refinery and petrochemicals, pharmaceutical applications; the chemical process industry (CPI); pulp and paper mills, environmental sampling and laboratory environments among others.

 

The list of chemicals that are compatible with our tubing materials is too numerous to mention. In fact, it is easier to list the few materials that do not work with our fluoropolymers. For additional information please click on the following link:http://www.fluorotherm.com/chemical_resistance.html

 

 

For additional information on chemical resistance of PTFE, FEP, PFA and PVDF please contact us at sales@fluorotherm.com. We will be happy to discuss the suitability of our products in your particular application and suggest alternatives if necessary.

PTFE and FEP Plastic Tubing: What you need to know!

PTFE

PTFE(Poly tetra-fluoro ethylene) is a fully fluorinated polymer available in various unmodified and modified grades. PTFE is processed by compacting the powder under pressure at ambient or slightly higher than ambient temperatures. Methods of forming products include paste extrusion, ram extrusion, molding and calendaring between rolls. Many formed PTFE products are consolidated by sintering in an oven or used in unsintered form ( eg: thread sealant tape). Paste extrusion and calendaring methods are used with fine powder PTFE resins while granular PTFE resins are processed by ram extrusion and molding.

Fluorotherm manufactures PTFE paste extruded tubing with the following features:

·    Extremely high lubricity, thus low coefficient of friction compared to other materials
·    Non-stick and non-wetting (hydrophobic), low surface tension with water
·    Excellent dielectric and electrical insulation characteristics
·    Exceptional chemical inertness
·    Upper temperature use limit for PTFE is 500°F (260°C) under non-stress conditions
·    Suitable for cryogenic conditions: -320°F (-96°C) the boiling point of liquid nitrogen
·    PTFE has UL 94 VO rating for flame resistance, does not burn
·    Autoclave and ETO sterilizable
·    PTFE tubing is easily purged and cleaned

Visit our PTFE detailed properties page to discover why PTFE is the right choice for your industry.

 

FEP Tubing

 

FEP (Fluorinated ethylene propylene) is a fully fluorinated copolymer. FEP is established for its excellent chemical resistance, outstanding electrical properties and a wide service temperature range extending up to 400 deg F. A list of its key properties is shown in the table below. FEP is UV light transparent – a property that is effectively utilized in water disinfecting by ultra violet light of the appropriate wavelength. FDA regulation 21 CFR 177.1550 is applicable to FEP for use as article or components of articles intended to contact food. FEP is classified as USP Class VI and applies to tubing products.

To see the comparisons of all our Teflon ® products including PFA, MFA, ETFE, PCTFE, and PVDF please visit our product comparison chart.