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A Complete Guide on Ethylene Tetrafluoroethylene (ETFE)

Ethylene Tetrafluoroethylene (ETFE) is a fluorine-based plastic designed to have high corrosion resistance and strength over a wide temperature range. Thanks to its special chemical and physical properties, ETFE is widely applied in the chemical, electrical/electronic, construction, architectural, and automotive industries.

Become an expert by learning some basic information about ETFE, what are the key features & properties, its popular applications and conditions to process this polymer material!

Let’s first start by understanding fluoropolymers...

What is ETFE - Ethylene Tetrafluoroethylene?


A Complete Guide on Ethylene Tetrafluoroethylene (ETFE) Fluoropolymers is the class of polymer materials which contain fluorine atoms in their chemical structure. There are two types of fluoropolymers:

  • Perfluoropolymers – In this polymer type, all the hydrogen atoms in the analogous hydrocarbon polymer structures were replaced by fluorine atoms
  • Partially Fluorinated polymers – While, in such polymers there are both hydrogen and fluorine atoms in the polymer structures

After successful development and commercialization of several fluoropolymers i.e. PTFE, PCTFE, FEP, PVDF, ECTFE… In 1973, the Ethylene Tetrafluoroethylene (ETFE) was commercialized by DuPont. ETFE is a partially fluorinated copolymer of ethylene and Tetrafluoroethylene (TFE).


TFE and ethylene have a strong tendency to alternate during polymerization, thus, ETFE resins are composed mainly of alternating sequence of the two monomers and have following structure:

Molecular Structure of Ethylene Tetrafluoroethylene
Molecular Structure of Ethylene Tetrafluoroethylene
Chemical Formula: (C4H4F4)n

The crystallinity of ETFE ranges from 40% to 60%, and it has a melting temperature of 225–300°C depending on the comonomer ratio and the processing method. Further, the ratio of the two monomers are varied to obtain several grades of ETFE with optimized properties for specific end applications.

ETFE copolymers are basically alternating copolymers, and in the molecular formula, they are isomeric with polyvinylidene fluoride (PVDF) with head-to-head, tail-to-tail structure.

ETFE has excellent electrical and chemical properties. ETFE is especially suited for applications requiring:

  • High Mechanical Strength
  • High Chemical Resistance
  • Superior thermal and electrical properties

The mechanical properties of ETFE are superior to those of PTFE and FEP (perfluoroalkoxy resins). It is also important to note that to modified ETFE copolymers are superior to PVDF with the exception of PVDF’s remarkable piezoelectric and pyroelectric properties.

The commercial ETFE products include:


» View All Commercially Available ETFE Grades & Suppliers in Omnexus Plastics Database

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Typical Characteristics and Properties of ETFE


ETFE has the best of all fluoropolymers the wear resistance, the impact toughness and radiation resistance. ETFE is melt processable. The mechanical properties of ETFE are similar to those of fully fluorinated polymers.

ETFE [poly(ethene-co-tetrafluoroethene); CAS: 25038-71-5] has:

  • Excellent resistance to extremes of temperature 
  • Excellent chemical resistance 
  • Good mechanical strength with excellent tensile strength and elongation. It has superior physical properties compared to most fluoropolymers 
  • With low smoke and flame characteristics, ETFE is rated 94V-0 by UL 
  • It is odorless and non-toxic. 
  • Exhibits outstanding resistance to weather and aging, Exception UV transmission 
  • Excellent dielectric properties. 
  • Its radiation resistance is high with the advantage of being cross-linked by high-energy radiation. The radiation cross-linked ETFE wire insulation can be continuously used at 200 °C.

ETFE is less flexible than PTFE, but has superior impact strength, abrasion and cut through resistance. Addition of a third component to the chemical structure creates a modified ETFE. For example, ETFE modified by glass fiber reinforcement is tougher and stiffer and has higher tensile strength than PTFE, PFA or FEP. ETFE has a working temperature range of -200°C to 150°C.

Let’s check out property comparison between different fluoropolymers:

Fluoropolymer Produced First in Melting Temperature
°C
Tensile Modulus
MPa
Elongation at Break
%
Dielectric Strength
kV/mm
Use Temperature
%
PTFE 1947 317-337 550 300-550 19.7 260
PCTFE 1953 210-215 60-100 100-250 19.7 200
FEP 1960 260-282 345 ~300 19.7 200
PVF 1961 190-200 2000 90-250 12-14 110
PVDF 1961 155-192 1040-2070 50-250 63-67 150
ECTFE 1970 235-245 240 250-300 80 150
ETFE 1973 254-279 827 150-300 14.6 150
THV 1996 145-155 82-207 500-600 48-62 93

» Learn More About Other ETFE Properties and Related Values in Detail

Although, ETFE has some limitations:

  • High cost 
  • Maximum use temperature lower than other fluoropolymers (150°C) 
  • Attacked by oxidizing acids, amines and sulfonic acids 
  • High density 
  • Toxic smoke emission 
  • Limited number of grades available

Applications of ETFE


ETFEs are only used for relatively high-performance applications related to heat, low temperature, chemical internes, and electrical insulation.

Because ETFE is a semi-transparent material, it can also be used as a viable replacement for glass or traditional plastic. ETFE is an attractive replacement for glass because it maintains 1% the weight of glass, yet transmits 25% more light and is less expensive to install.

ETFE is extremely suitable for use in architectural structures. The superior transmission of UV and long wave radiation also leads to it being used extensively in outdoor constructions.

There are several well-known buildings that have used ETFE in their construction, including:
Popular Uses of ETFE Around You

More applications of ETFE include:

Application Description
ETFE Automotive Applications Automotive:

O-rings, gaskets valve stem seals, shaft seals, lining of fuel hoses, power steering and transmission

ETFE has good resistance to petroleum and fuel permeation, which resulted in a significant growth of ETFE as fuel tubing.


ETFE in Electrical and Electronic Applications Electrical & Electronic:

Electrical sleeving, wire and cable insulation and jacketing, appliance wires, motor lead wires, compact wire and coatings
Battery components
Coil forms
Other electrical components: sockets, connectors, switches, insulators...

Use of ETFE in Engineering Applications Engineering:

Seats and plugs, bearing, non-stick surfaces, coatings for pipes, fittings and gears, injection and blow-molded articles Pump housings, compressor linings and components...

As a tube, ETFE is very much more flexible than FEP and PFA. An ETFE tube will not develop kinks like FEP. ETFE is also suitable for pump impellers or moving parts of equipment that are operating in chemically aggressive environments.

Medical Applications of ETFE Medical:

Oxygen respirator components
Blood analyzer valves
Evaporating dishes
Centrifuge tubes

Applications of ETFE Films Films:

Food packaging
Pharmaceutical packaging
Heat shrinkable films
Electroluminescent display panels



How is ETFE Made?


ETFE is a partially fluorinated straight-chain polymer with very high molecular weight. It is produced by free-radical polymerization mechanism in a solvent or a hybrid (a solvent/aqueous mixture) media, using an organic peroxide initiator. Copolymerization of TFE and ethylene proceeds by an addition mechanism. It normally includes an additional termonomer to increase the flexibility required in commercial applications.
Free Radical Polymerization for ETFE Production
Free Radical Polymerization for ETFE Production

Due to the risk of explosive decomposition reaction, the copolymerization of ethylene and TFE must be conducted in special vessels at low pressure.

Suspension polymerization is generally carried out in an inert chlorofluorocarbon solvent using fluorinated peroxides as initiator and methanol as a chain transfer agent.


Methods to Process ETFE


ETFE can be easily processed by all standard thermoplastic processing methods such as injection molding, compression molding, blow molding, rotational molding, extrusion, and wire coating.

Process equipment for fluoropolymers must be made from corrosion-resistant alloys because of the corrosive compound that may be produced when they are heated above melting points.

  • Processing temperature: 290 to 340°C 
  • Drying is recommended but not necessary 
  • Injection Molding: A mold temperature of 65-150°C is recommended 
  • Extrusion: Extruder barrels should be long, relative to diameter, to provide residence time for heating the resin to approximately 345°C


Injection Molding / Extrusion: How to Avoid Plastic Quality Crashes

Commercially Available ETFE (Ethylene Tetrafluoroethylene) Compounds





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Polymer Properties Explore ETFE Properties in Detail Polymer Application Check Latest News About Fluoropolymers

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