FEP gaining popularity on high demand

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FEP gaining popularity on high demand

FEP gaining popularity on high demand

Technical Articles
Oct 01,18

Most of the properties of polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP) and and perfluoroalkoxy alkanes (PFA) vary slightly. However, FEP stands out in its range of applications, says Shrikant Dethe.

The accidental discovery of PTFE (Polytetrafluoroethylene) in 1938 by Dr Roy J Plunkett has turned out to have the lowest coefficient of friction of any known solid material. But as PTFE lacks the melt-processability, a need of other fluoropolymers was generated.

Fluorinated ethylene propylene (FEP) shares the same basic monomer and is commercially obtained by free-radical polymerisation in an aqueous media via addition of tetrafluoroethylene (TFE, CF2=CF2) and hexafluoropropylene (HFP, CF3-CF=CF2).

Properties of FEP

Structure of FEP is semi-crystalline, giving it not only a distinct and sharp melting point, but also generally better mechanical properties than those of the amorphous type of polymers. Sterilisation of the tubing can be done by gas (EtO), steam (autoclave) and gamma radiation.

It has properties such as:

FEP can operate in working temperature ranging from -240 °C to 200 °C
It has low coefficient of friction
FEP is resistant to virtually all chemicals.
It has high UV stability
FEP has excellent dielectric properties. It has low dielectric constant.
FEP is transparent and extremely non-sticky. It has low flammability and high thermal stability.

Applications of FEP

Due to its good mechanical, chemical and electrical properties, FEP find applications in wide range of industries.

Engineered fluoropolymer lining, tubing and fabricated products for aerospace industry relies on its ability to resist damage from aggressive chemical fuels and withstand wide variation in temperature.

Further its non-stickiness nature makes a top choice in food and beverage processing industry. FEP tube is also used for hot sterilizing water transfer in purification system and UV water treatment.

FEP tubing’s inability to absorb materials, high chemical inertness and full sterilisation capacity makes it ideal choice for sterile filling, diagnostic equipment, cell transfer and laboratory use.

In electrical industry, FEP has well established itself due its low dielectric constant value & high electrical breakdown voltage property.

Retractable coiled FEP tube

In the recent years, the gradual downfall of PFA retractable coil has been observed due to its incompatibility with solvents. This has increased the consumption of FEP tube which serves greatly because of its high chemical inertness, heat resistance and flexibility. Additionally, it’s used in chemical dispensers, deionised water re-circulators and even in heat exchangers.

How different is it from PTFE and PFA?

Most of the properties vary slightly among these 3 fluoropolymers.

FEP and PFA (Perfluoroalkoxy alkanes) can be extruded and thermoformed unlike PTFE.
FEP has a lower working temperature than PTFE and PFA.
PFA deforms more under load compared to FEP. This indicates better retractability for FEP.
Better abrasion resistance of FEP than PFA.

This has resulted in the fact that in the whole family of recently developed fluoropolymers, FEP stands out in its range of applications. Current research is trying on a fluoropolymer which would resist harsh chemicals and is flexible too. This would serve for a large number of the applications and would serve universally.

About the Author:

Shrikant Dethe is currently working at Ami Polymer Pvt Ltd. He is a B Tech (Chemical Engineer) from IIT Bombay. He can be contacted on shrikant@amipolymer.com

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Unique properties of FEP

Operating working temperature: -240°C to 200°C
Mechanical: Low coefficient of friction
Chemical: Resistance to virtually all chemicals
Weather: High UV stability
Electrical: Low dielectric constant
General: Transparent, low flammability, anti-sticking nature and high thermal stability