Ethylene-tetrafluoroethylene copolymer ETFE

spore: profile
id: etfe-tefzel
spore_version: 0.2
family: fluoropolymers
name: Ethylene-tetrafluoroethylene copolymer
abbreviation: ETFE
role: melt-processible fluoropolymer for wire insulation, film and lined equipment
category: polymers
type: fluoropolymers
summary: |
  ETFE (Tefzel, Neoflon, Fluon) is a copolymer of ethylene and tetrafluoroethylene. On the MISSE 2 flight, mounted outside the International Space Station for 3.95 years, it eroded under atomic oxygen at 9.61e-25 cm3/atom, about 3 times slower than Kapton H (3.00e-24 cm3/atom) and about 7 times faster than PTFE (1.42e-25 cm3/atom). Its manufacturer lists a melting point of 265 C and a service limit of 150 to 160 C. Radiation is the known weak point: a Japanese study found its elongation falls sharply above about 400 kGy in air, and its crystallinity drops from 43.2% to 12.6% by 1600 kGy.
best_for: Melt-processible, tough fluoropolymer insulation and film that resists atomic oxygen better than Kapton H and most hydrocarbon polymers
weakest_at: Ionizing radiation in air (elongation falls sharply above about 400 kGy) and continuous service above about 160 C
identity:
  formula: Poly(ethene-co-tetrafluoroethene), repeat unit C4H4F4 (ethylene C2H4 plus tetrafluoroethylene C2F4)
  cas: ''
  source: banks2008
  where: Table IV (repeat-unit formula C4H4F4, atomic mass 128.0676 g/mole); monomer names from Wikipedia (poly(ethene-co-tetrafluoroethene))
tags:
  environments:
    - low-earth-orbit
  stresses:
    - atomic-oxygen
    - uv
    - total-radiation-dose
    - thermal-cycling
    - vacuum-and-outgassing
  applications:
    - electronics-and-chips
    - structures
properties:
  - benchmark: atomic_oxygen_erosion_yield
    label: Atomic oxygen erosion yield, MISSE 2 PEACE polymers (flight)
    value: 9.61e-25
    unit: cm3/atom
    scope: material
    conditions:
      experiment: MISSE 2 PEACE polymers, exterior of the International Space Station
      exposure: 3.95 yr in low Earth orbit, 16 August 2001 to 30 July 2005
      fluence: 8.43e21 atoms/cm2
      comparison: Kapton H polyimide measured 3.00e-24 cm3/atom, PTFE 1.42e-25 cm3/atom, FEP 2.00e-25 cm3/atom, in the same table
    method: Mass-loss erosion yield from the flown samples, as compiled in the NASA report
    status: flight
    note: The report's predictive tool gave 1.39e-24 cm3/atom for ETFE (Table VII), about 45% above the measured value.
    source: banks2008
    where: Table I (MISSE 2 PEACE polymers erosion yield data); Table VII; Section 2.1 for exposure
  - benchmark: density
    label: Density used for the flown ETFE film (NASA erosion-yield calculation)
    value: 1.7397
    unit: g/cm3
    scope: material
    conditions:
      sample: ETFE (Tefzel) film flown on MISSE 2 PEACE polymers
      ash_fraction: '5.34e-3'
    method: Density value listed in the NASA report for the erosion-yield calculation
    status: ground
    source: banks2008
    where: Table II (MISSE 2 PEACE polymers density and fractional ash content)
  - benchmark: density
    label: Specific gravity (Daikin NEOFLON ETFE EP-521, representative)
    value: 1.74
    unit: '-'
    scope: material
    conditions:
      grade: NEOFLON ETFE EP-521 (Daikin)
      test_standard: ASTM D 792
    method: Representative value printed in the manufacturer technical datasheet; the sheet says the values are not guaranteed
    status: ground
    source: daikin-tds-ep521
    where: General physical properties table (Specific Gravity)
  - benchmark: density
    label: Density (Goodfellow ETFE film listing)
    value: 1.7
    unit: g/cm3
    scope: material
    conditions:
      form: ETFE film, reseller listing
    method: Value printed in a film supplier listing
    status: ground
    source: goodfellow-etfe
    where: Property table, row "Density( gcm-3 )"
  - benchmark: melting_point
    label: Melting point (Daikin NEOFLON ETFE EP-521, representative)
    value: 265
    unit: C
    scope: material
    conditions:
      grade: NEOFLON ETFE EP-521 (Daikin)
      test_standard: ASTM D 3159
    method: Representative value printed in the manufacturer technical datasheet; the sheet says the values are not guaranteed
    status: ground
    source: daikin-tds-ep521
    where: General physical properties table (Melting Point)
  - benchmark: melting_point
    label: Melting point range (Daikin safety data sheet, EP-521 grade)
    value: 210
    value_high: 230
    unit: C
    scope: material
    conditions:
      grade: NEOFLON ETFE EP-521 (Daikin)
    method: Range printed in the manufacturer safety data sheet, section 9
    status: ground
    note: The datasheet for the same grade gives 265 C, so the two Daikin documents disagree by about 35 C.
    source: daikin-sds-ep521
    where: Section 9, Melting point/freezing point
  - benchmark: melt_flow_rate
    label: Melt flow rate (Daikin NEOFLON ETFE EP-521)
    value: 11
    value_high: 13
    unit: g/10min
    scope: material
    conditions:
      test_standard: ASTM D 3159
    method: Representative value printed in the manufacturer technical datasheet
    status: ground
    source: daikin-tds-ep521
    where: General physical properties table (MFR)
  - benchmark: ultimate_tensile_strength
    label: Tensile strength (Daikin NEOFLON ETFE EP-521, representative)
    value: 40
    value_high: 55
    unit: MPa
    scope: material
    conditions:
      test_standard: ASTM D 638
    method: Representative range printed in the manufacturer technical datasheet
    status: ground
    note: The Goodfellow listing gives a lower range, 28 to 48 MPa.
    source: daikin-tds-ep521
    where: General physical properties table (Tensile strength)
  - benchmark: ultimate_tensile_strength
    label: Tensile strength (ETFE film listing)
    value: 28
    value_high: 48
    unit: MPa
    scope: material
    conditions:
      form: ETFE film, reseller listing
    method: Range printed in a film supplier listing
    status: ground
    source: goodfellow-etfe
    where: Property table, row "Tensile strength( MPa )"
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, unaged longitudinal specimen (ETFE Tefzel PV3221)
    value: 60.38
    unit: MPa
    scope: material
    conditions:
      grade: Tefzel PV3221 film
      specimen: longitudinal (L) specimen, not aged
    method: Mean from tensile tests (standard deviation 7.91 MPa)
    status: ground
    source: bracciale2022
    where: Table 2, Section 3.1
  - benchmark: elastic_modulus
    label: Elastic modulus, unaged longitudinal specimen (ETFE Tefzel PV3221)
    value: 1075.38
    unit: MPa
    scope: material
    conditions:
      grade: Tefzel PV3221 film
      specimen: longitudinal (L) specimen, not aged
    method: Mean from tensile tests (standard deviation 43.51 MPa)
    status: ground
    source: bracciale2022
    where: Table 2, Section 3.1
  - benchmark: elongation
    label: Elongation at break (Daikin NEOFLON ETFE EP-521, representative)
    value: 300
    value_high: 600
    unit: '%'
    scope: material
    conditions:
      test_standard: ASTM D 638
    method: Representative range printed in the manufacturer technical datasheet
    status: ground
    note: The Goodfellow listing gives 250 to 350 percent, so the two supplier ranges disagree.
    source: daikin-tds-ep521
    where: General physical properties table (Elongation)
  - benchmark: elongation
    label: Elongation at break (ETFE film listing)
    value: 250
    value_high: 350
    unit: '%'
    scope: material
    conditions:
      form: ETFE film, reseller listing
    method: Range printed in a film supplier listing
    status: ground
    source: goodfellow-etfe
    where: Property table, row "Elongation at break( % )"
  - benchmark: elongation
    label: Elongation at break, unaged longitudinal specimen (ETFE Tefzel PV3221)
    value: 310.74
    unit: '%'
    scope: material
    conditions:
      grade: Tefzel PV3221 film
      specimen: longitudinal (L) specimen, not aged
    method: Mean from tensile tests (standard deviation 45.55 percent)
    status: ground
    source: bracciale2022
    where: Table 2, Section 3.1
  - benchmark: dielectric_constant
    label: Dielectric constant at 1 MHz
    value: 2.6
    unit: dimensionless
    scope: material
    conditions:
      frequency: 1 MHz
    method: Value printed in a film supplier property table
    status: ground
    source: goodfellow-etfe
    where: Property table, row "Dielectric constant @1MHz"
  - benchmark: max_service_temp
    label: Upper working temperature (ETFE film listing)
    value: 150
    value_high: 160
    unit: C
    scope: material
    conditions:
      basis: upper working temperature
    method: Range printed in the thermal properties table of a film supplier listing
    status: ground
    note: The same page's key-features text gives 150 to 200 C, a wider range than its table.
    source: goodfellow-etfe
    where: Thermal Properties table, row "Upper working temperature( C )"
  - benchmark: crystallinity
    label: Crystallinity after irradiation at 1600 kGy (air, 20 kGy/h)
    value: 12.6
    unit: '%'
    scope: material
    conditions:
      dose: 0 to 1600 kGy electron beam
      dose_rate: 20 kGy/h
      atmosphere: air
    method: Crystallinity from the abstract of a radiation-processing study
    status: ground
    note: The unirradiated baseline in the same abstract is 43.2 percent. The abstract gives no per-dose elongation values; it says elongation decreased slowly from 0 to 200 kGy and dropped sharply above 400 kGy.
    source: sinap2015
    where: English abstract (Journal of Radiation Research and Radiation Processing, 2015, 33(6))
corrosion:
  - environment: Atomic oxygen in low Earth orbit
    headline: ETFE eroded about three times more slowly than Kapton H on the ISS, but several times faster than PTFE.
    effect: Measured erosion yields from MISSE 2 were 9.61e-25 cm3/atom for ETFE, 3.00e-24 for Kapton H, 2.00e-25 for FEP and 1.42e-25 for PTFE. The NASA predictive tool overestimated ETFE by about 45 percent (1.39e-24).
    rating: moderate
    conditions:
      exposure: 3.95 yr on the ISS exterior, fluence 8.43e21 atoms/cm2
    source: banks2008
    where: Table I; Table VII
  - environment: Ultraviolet A light with humidity (accelerated ageing)
    headline: Accelerated UV-A ageing with condensation was run on ETFE film, but the study reports no total dose in hours or J/m2.
    effect: Bracciale et al. aged ETFE and PFA films in cycles of 6 h UV-A (300 to 400 nm, peak 365 nm, 5.2 W/m2) plus 3 h of condensation at 25 C and 80 to 90 percent humidity, and reported that ETFE kept a higher elastic modulus and tear energy than PFA after ageing. The article states no total exposure time, so the aged values are not quoted here.
    rating: low
    conditions:
      temperature: 25 C
      humidity: 80 to 90 percent relative humidity
      cycle: 6 h UV-A plus 3 h condensation, 6 cycles
    source: bracciale2022
    where: Section 2.2 (ageing conditions), Section 3.2 (Table 5)
  - environment: Ionizing radiation in air
    headline: ETFE elongation holds up at low dose and falls sharply above about 400 kGy in air.
    effect: Electron-beam irradiation at 20 kGy/h in air lowered crystallinity from 43.2 to 12.6 percent by 1600 kGy and melting point from 261.3 to 233.3 C. The abstract says elongation decreased slowly over 0 to 200 kGy and dropped sharply above 400 kGy, and that tensile strength followed the same pattern.
    rating: severe
    conditions:
      dose_rate: 20 kGy/h
      atmosphere: air
      source_type: electron beam
    source: sinap2015
    where: English abstract
risks:
  hazards:
    - text: The Daikin safety data sheet for NEOFLON ETFE EP-521 says the substance is not classified under Regulation (EC) No 1272/2008 (CLP) and has no label elements. Acute-toxicity data are not available, and the other hazard classes report that the classification criteria are not met.
      ghs: []
      source: daikin-sds-ep521
      where: Sections 2.1 and 11.1
  failure_risks:
    - mode: Thermal decomposition during processing or overheating
      trigger: Overheating the molten polymer
      consequence: The safety data sheet says decomposition can give particulate matter and extremely toxic or corrosive fumes, and that molten product should be cooled quickly with cold water.
      severity: moderate
      source: daikin-sds-ep521
      where: Sections 5, 7 and 10.6
    - mode: Loss of ductility under ionizing radiation
      trigger: Electron-beam dose above about 400 kGy in air
      consequence: Elongation drops sharply, and the crystallinity and melting point fall with dose.
      severity: moderate
      source: sinap2015
      where: English abstract
  side_effects: []
  handling:
    - text: Keep molten product from overheating, and cool any molten material rapidly with cold water, as the safety data sheet advises.
      source: daikin-sds-ep521
      where: Sections 7 and 10
  mitigations: []
uses:
  - application: electronics-and-chips
    device: Wire and cable insulation (aerospace, automotive and appliance)
    example: The manufacturer lists wire and cable for aerospace, automotive and appliance use among ETFE's main markets, and says the grade has good radiation resistance because of its ethylene comonomer.
    source: daikin-tds-ep521
    where: Introduction and bullet list
  - application: structures
    device: ETFE film in building envelopes
    example: Commercial ETFE film is sold under the names Texlon (Vector Foiltec) and Sumiflon-E (Sumitomo Electric, an aluminium-ETFE composite).
    source: wiki-etfe
    where: Trade names list
supply:
  - subject: Fluorine feedstock (fluorspar, the source of hydrogen fluoride for fluoropolymer monomers)
    producers:
      - country: China
        share_percent: 60
        year: 2025
      - country: Mongolia
        share_percent: 15
        year: 2025
    critical_lists: []
    recycling: Not stated in the USGS fluorspar chapter that was fetched.
    substitutes: []
    source: usgs-mcs2026-fluorspar
    where: World Mine Production and Reserves table (2025 column; China 6,000 and Mongolia 1,500 of a printed world total of 10,000 thousand t, shares calculated by Space Mushroom); Domestic Production and Use (fluorspar feeds anhydrous hydrogen fluoride)
gaps:
  - 'No ETFE hazard row found on PubChem: the PubChem pages returned a browser check and the REST name lookup found no record for ETFE.'
  - The USGS fluorspar chapter fetched here does not list fluorspar on the critical-mineral lists; the EU and USGS list status for fluorspar is not confirmed in this run.
  - No vacuum outgassing (TML, CVCM) value for ETFE was found in this run; the RP-1124 and NASA outgassing compilations were not searched for ETFE.
  - No ETFE-specific UV or atomic oxygen erosion study with a dose in hours or J/m2 was found; the Bracciale UV-A study gives conditions but no total dose.
  - The Chemours and Plastics International datasheets were blocked (HTTP 403 or 404); manufacturer values come from Daikin and a film listing.
  - No gamma-ray dose series for ETFE elongation was found; the Tefzel datasheet statement about electron beam versus gamma was seen only in a search snippet and is not used as a value.
  - The Daikin safety data sheet covers the EP-521 grade; coating-powder grades (EPW series) carry a different classification through N-methyl-2-pyrrolidone and are not used here.
sources:
  banks2008:
    title: Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit
    id: NASA/TM-2008-215490 (Banks, Backus and de Groh, December 2008), NTRS 20090011780
    url: https://ntrs.nasa.gov/citations/20090011780
    year: 2008
    kind: report
    license: public domain (NASA)
  daikin-tds-ep521:
    title: NEOFLON ETFE EP-521 Technical Datasheet (Daikin Industries, version 01, March 2018)
    id: tds-ep-521-E_ver01_Mar_2018
    url: https://www.daikinchemicals.com/library/pb_common/pdf/tds/Fluoropolymers/NEOFLON_ETFE/tds-ep-521-E_ver01_Mar_2018.pdf
    year: 2018
    kind: datasheet
    license: manufacturer document, linked not reproduced
  daikin-sds-ep521:
    title: Safety Data Sheet, NEOFLON ETFE EP-521 (Daikin Chemicals)
    id: sds-EP521-E_20230308
    url: https://www.daikinchemicals.com/library/pb_common/pdf/sds/Fluoropolymer/ETFE_EP-series/sds-EP521-E_20230308.pdf
    year: 2023
    kind: datasheet
    license: supplier document, linked not reproduced
  goodfellow-etfe:
    title: Goodfellow ETFE film property listing
    id: Goodfellow Cambridge, ETFE film group
    url: https://www.goodfellow.com/usa/etfe-film-group
    year: 2026
    kind: web
    license: reseller page, linked not reproduced
  bracciale2022:
    title: Effect of Accelerated UV Ageing on ETFE and PFA Films (Bracciale, Capasso, Sarasini, Tirillo, Santarelli)
    id: doi:10.3390/polym14050912 (Polymers 14(5), 912, 2022, PMC8912537)
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC8912537/
    year: 2022
    kind: paper
    license: CC BY 4.0 (as listed by PMC)
  sinap2015:
    title: Radiation effects on ETFE in air (Journal of Radiation Research and Radiation Processing, 33(6))
    id: doi:10.11889/j.1000-3436.2015.rrj.33.060301
    url: https://www.fs.sinap.ac.cn/zh/article/doi/10.11889/j.1000-3436.2015.rrj.33.060301/
    year: 2015
    kind: paper
    license: journal abstract, linked not reproduced
  usgs-mcs2026-fluorspar:
    title: Mineral Commodity Summaries 2026, Fluorspar
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-fluorspar.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  wiki-etfe:
    title: Ethylene tetrafluoroethylene (Wikipedia)
    id: Wikipedia, Ethylene_tetrafluoroethylene
    url: https://en.wikipedia.org/wiki/Ethylene_tetrafluoroethylene
    year: 2026
    kind: web
    license: CC BY-SA 4.0
documents:
  - title: NASA/TM-2008-215490, Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit
    type: report
    url: https://ntrs.nasa.gov/citations/20090011780
    year: 2008
  - title: Daikin NEOFLON ETFE EP-521 technical datasheet
    type: datasheet
    url: https://www.daikinchemicals.com/library/pb_common/pdf/tds/Fluoropolymers/NEOFLON_ETFE/tds-ep-521-E_ver01_Mar_2018.pdf
    year: 2018
  - title: Daikin NEOFLON ETFE EP-521 safety data sheet
    type: sds
    url: https://www.daikinchemicals.com/library/pb_common/pdf/sds/Fluoropolymer/ETFE_EP-series/sds-EP521-E_20230308.pdf
    year: 2023
  - title: Bracciale et al., Polymers 14(5), 912 (open access)
    type: paper
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC8912537/
    year: 2022
  - title: USGS Mineral Commodity Summaries 2026, Fluorspar
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-fluorspar.pdf
    year: 2026
license: CC-BY-4.0
updated: '2026-10-20'
review:
  status: draft
  method: assistant
  checked_values: 17
  unreachable: 4
  caveats: 3
  note: Read in one run by an AI assistant on 2026-10-20 from fetched pages and downloaded PDFs. Values copied as printed; ranges kept as printed.
story:
  recipe:
    line: ETFE is a copolymer of ethylene (C2H4) and tetrafluoroethylene (C2F4). Its repeat unit is C4H4F4, with a molar mass of 128.0676 g/mole in the NASA table.
    parts:
      - name: Ethylene
        symbol: C2H4
        role: Comonomer that gives ETFE its toughness and melt processability. The NASA table lists the repeat unit as C4H4F4 (one ethylene and one tetrafluoroethylene unit).
      - name: Tetrafluoroethylene
        symbol: C2F4
        role: The fluorine-rich comonomer that gives chemical inertness and electrical insulation.
  risk_groups:
    - title: For people
      level: 0
      verdict: Not classified under CLP
      lead: The supplier's safety data sheet for ETFE resin says the substance is not classified and has no label elements.
      points:
        - label: The resin
          line: The Daikin safety data sheet for NEOFLON ETFE EP-521 classifies the substance as not classified under the EU CLP regulation. Its acute-toxicity data are not available.
        - label: Overheating
          line: Overheating the molten polymer can produce particulate matter and extremely toxic or corrosive fumes, so the sheet says not to overheat.
    - title: Handling and processing
      points:
        - label: Molten product
          line: The safety data sheet says to cool molten product rapidly with cold water.
        - label: Radiation
          line: Electron-beam dose above about 400 kGy in air sharply reduces elongation.
  why: ETFE is a melt-processible fluoropolymer that trades some of PTFE's chemical and thermal ceiling for the ability to be extruded, injection moulded and drawn into thin film. The fluorine content gives electrical insulation and resistance to atomic oxygen, and the ethylene units add toughness and melt flow. On the MISSE 2 flight its erosion yield was three times lower than Kapton H.
  uses:
    - where: Wire and cable
      line: The manufacturer lists wire and cable insulation for aerospace, automotive and appliance use as a main market for ETFE, and says the grade has good radiation resistance.
    - where: Building film
      line: ETFE film is sold as Texlon (Vector Foiltec) and Sumiflon-E (Sumitomo Electric, an aluminium-ETFE composite).
  can_do:
    - label: Atomic oxygen
      benchmark: atomic_oxygen_erosion_yield
      value: 9.61e-25 cm3/atom
      line: On the MISSE 2 flight, ETFE eroded at 9.61e-25 cm3/atom, about three times more slowly than Kapton H.
    - label: Stiffness
      benchmark: elastic_modulus
      value: 1075 MPa
      line: Unaged longitudinal film specimens had an elastic modulus of 1075.38 MPa in one tensile study.
    - label: Melting
      benchmark: melting_point
      value: 265 C
      line: The manufacturer's datasheet gives a melting point of 265 C for the EP-521 grade, although its safety data sheet gives 210 to 230 C.
  compare: ETFE sits between PTFE and the hydrocarbon polymers. Its flown erosion yield is about seven times higher than PTFE and about three times lower than Kapton H. It is melt-processible, which PTFE is not, and it stays usable to about 150 to 160 C, a lower limit than PTFE's. The table compares ETFE with PTFE and Kapton H on three measured rows.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Atomic oxygen erosion yield (MISSE 2)
      benchmark: atomic_oxygen_erosion_yield
    - label: Upper service temperature
      benchmark: max_service_temp
  handling:
    - The resin is not classified under CLP. Keep molten product from overheating.
    - Cool molten product rapidly with cold water, as the supplier advises.
    - Expect a sharp loss of elongation after about 400 kGy of electron-beam dose in air.
  good_for:
    - Atomic oxygen resistance in LEO. ETFE eroded at 9.61e-25 cm3/atom, about three times more slowly than Kapton H.
    - Melt-processible insulation and thin film, where PTFE cannot be extruded.
  watch_out:
    - Radiation in air. Elongation falls sharply above about 400 kGy.
    - Service limit near 150 to 160 C for the film listing, lower than PTFE's.
    - The two Daikin documents for the same grade disagree on melting point (210 to 230 C vs 265 C).
  verdict: ETFE is a practical fluoropolymer for LEO insulation and film. It erodes more than PTFE and is weaker to ionizing radiation in air, so it is a sound choice where it is shielded or where melt processing matters.