spore: profile
id: fep
spore_version: 0.2
family: fluoropolymers
name: Fluorinated ethylene propylene
abbreviation: FEP
role: melt-processible fluoropolymer for wire coating, linings and low-outgassing films
category: polymers
type: fluoropolymers
summary: FEP is a melt-processible copolymer of tetrafluoroethylene and hexafluoropropylene, sold by DuPont as Teflon FEP and by Daikin as NEOFLON FEP. It melts near 255 degC by ASTM D 3418 and is almost chemically inert. On the MISSE 2 flight it eroded under atomic oxygen at 2.00e-25 cm3/atom, and Hubble's retrieved FEP lost most of its stretch after long exposure in low Earth orbit.
best_for: A chemically inert, electrically insulating and low-outgassing fluoropolymer that can be melt-processed into thin films, coatings and tubing.
weakest_at: Mechanical strength and ductility after long orbital exposure (Hubble retrieved specimens dropped to 0 to 25 percent elongation), and releasing hydrogen fluoride when processed above 250 degC.
identity:
  formula: Copolymer of tetrafluoroethylene and hexafluoropropylene, (-CF2-CF2-)n units with -CF2-CF(CF3)- units; CAS 25067-11-2
  cas: 25067-11-2
  source: daikin-fep-stewardship
  where: Chemical Name and CAS Registry Number table; composition from Wikipedia FEP lead paragraph (copolymer of hexafluoropropylene and tetrafluoroethylene)
tags:
  environments:
    - low-earth-orbit
  stresses:
    - atomic-oxygen
    - total-radiation-dose
    - thermal-cycling
    - vacuum-and-outgassing
  applications:
    - electronics-and-chips
    - propulsion-and-tanks
properties:
  - benchmark: atomic_oxygen_erosion_yield
    label: Atomic oxygen erosion yield, MISSE 2 flight
    value: 2.e-25
    unit: cm3/atom
    scope: material
    conditions:
      environment: low Earth orbit, ISS MISSE 2 PEACE Polymers tray
      fluence: 8.43e21 atoms/cm2 (4 year exposure)
      unit_in_source: cm3/atom
    method: Value printed in NASA Table I (MISSE 2 PEACE Polymers erosion yield data) as the measured MISSE 2 erosion yield; the paper cites refs 11 and 12 for the data
    status: flight
    source: nasa-ao-tool
    where: Table I, row Fluorinated ethylene propylene (FEP), column erosion yield
  - benchmark: density
    label: Density (MISSE 2 sample, ref 12)
    value: 2.1443
    unit: g/cm3
    scope: material
    conditions:
      sample: MISSE 2 PEACE Polymers film
    method: Density listed in NASA Table II (MISSE 2 PEACE Polymers density and fractional ash content), column Density, ref. 12
    status: ground
    source: nasa-ao-tool
    where: Table II, row Fluorinated ethylene propylene (FEP), Density column
  - benchmark: density
    label: Density (semi-finished FEP, ASTM D 792)
    value: 2150
    unit: kg/m3
    scope: material
    conditions:
      test_standard: ASTM D 792
    method: Value printed in the Material Data Center property table for Teflon FEP 9495 (Chemours), Other Properties section
    status: ground
    source: mdc-fep-9495
    where: Other Properties table, row Density
  - benchmark: melting_point
    label: Melting point, Teflon FEP 9495
    value: 255
    unit: degC
    scope: material
    conditions:
      test_standard: ASTM D 3418
    method: Value printed in the Material Data Center property table for Teflon FEP 9495 (Chemours), Thermal Properties section
    status: ground
    source: mdc-fep-9495
    where: Thermal Properties table, row Melting Temperature
  - benchmark: melting_point
    label: Melting point range, NEOFLON FEP NP-40 family
    value: 245
    value_high: 275
    unit: °C
    scope: material
    conditions:
      grade: NEOFLON FEP NP-40, NP-102, NP-112, NP-1105
    method: Value printed in the Daikin safety data sheet, section 9.1, Melting point/freezing point line
    status: ground
    source: daikin-np40-sds
    where: Section 9.1, Information on basic physical and chemical properties
  - benchmark: max_service_temp
    label: Maximum operating temperature
    value: 204
    unit: degC
    scope: material
    conditions:
      basis: value in the infobox of the Wikipedia article
    method: Value printed in the infobox of the Wikipedia FEP article; it is a secondary summary, not a datasheet value
    status: ground
    source: wiki-fep
    where: Infobox, row Maximum operating temperature
  - benchmark: ultimate_tensile_strength
    label: Tensile strength at break, Teflon FEP 9495
    value: 20
    unit: MPa
    scope: material
    conditions:
      test_standard: ASTM D 638
    method: Value printed in the Material Data Center property table for Teflon FEP 9495, Mechanical Properties section
    status: ground
    source: mdc-fep-9495
    where: Mechanical Properties table, row Tensile Strength
  - benchmark: elongation
    label: Elongation at break, Teflon FEP 9495
    value: 300
    unit: '%'
    scope: material
    conditions:
      test_standard: ASTM D 638
    method: Value printed in the Material Data Center property table for Teflon FEP 9495, Mechanical Properties section
    status: ground
    source: mdc-fep-9495
    where: Mechanical Properties table, row Elongation at Break
  - benchmark: elongation
    label: Elongation at break, pristine FEP (Hubble test set)
    value: 340
    value_high: 390
    unit: '%'
    scope: material
    conditions:
      sample: pristine FEP specimens, Hubble Space Telescope test set (three specimens)
    method: Value printed in NASA Table 3 (summary of strength test results), pristine rows, elongation column
    status: ground
    source: townsend-hst-fep
    where: Table 3, pristine rows, Elongation (%) column
  - benchmark: yield_strength
    label: Yield strength, pristine FEP (Hubble test set)
    value: 13.8
    value_high: 14.3
    unit: MPa
    scope: material
    conditions:
      sample: pristine FEP specimens, Hubble Space Telescope test set
    method: Value printed in NASA Table 3, pristine rows, first (yield) strength column; the table header is garbled in the PDF text layer, so the column is read from its position
    status: ground
    source: townsend-hst-fep
    where: Table 3, pristine rows, Yield Strength (MPa) column
  - benchmark: flexural_modulus
    label: Flexural modulus, Teflon FEP 9495
    value: 520
    unit: MPa
    scope: material
    conditions:
      test_standard: ASTM D 790
    method: Value printed in the Material Data Center property table for Teflon FEP 9495, Mechanical Properties section
    status: ground
    source: mdc-fep-9495
    where: Mechanical Properties table, row Flexural Modulus
  - benchmark: dielectric_constant
    label: Dielectric constant at 1 MHz
    value: 2.03
    unit: '-'
    scope: material
    conditions:
      frequency: 1 MHz
      test_standard: ASTM D 150
    method: Value printed in the Material Data Center property table for Teflon FEP 9495, Electrical Properties section
    status: ground
    source: mdc-fep-9495
    where: Electrical Properties table, row Dielectric Constant, 1 MHz
  - benchmark: dielectric_strength
    label: Dielectric strength, short time
    value: 80
    unit: kV/mm
    scope: material
    conditions:
      test_standard: ASTM D 149
      mode: short time
    method: Value printed in the Material Data Center property table for Teflon FEP 9495, Electrical Properties section
    status: ground
    source: mdc-fep-9495
    where: Electrical Properties table, row Dielectric Strength, Short Time
  - benchmark: dissipation_factor
    label: Dissipation factor at 1 MHz
    value: 0.0006
    unit: '-'
    scope: material
    conditions:
      frequency: 1 MHz
      test_standard: ASTM D 150
    method: Value printed in the Material Data Center property table for Teflon FEP 9495, Electrical Properties section
    status: ground
    source: mdc-fep-9495
    where: Electrical Properties table, row Dissipation Factor, 1 MHz
  - benchmark: moisture_absorption
    label: Water absorption, 24 hour
    value: 0.01
    unit: '%'
    scope: material
    conditions:
      test_standard: ASTM D 570
      time: 24 hours
    method: Value printed in the Material Data Center property table for Teflon FEP 9495, Other Properties section
    status: ground
    source: mdc-fep-9495
    where: Other Properties table, row Water Absorption, 24hr
  - benchmark: limiting_oxygen_index
    label: Limiting oxygen index
    value: 95
    unit: '%'
    scope: material
    conditions:
      test_standard: ASTM D 2863
    method: Value printed in the Material Data Center property table for Teflon FEP 9495, Thermal Properties section
    status: ground
    source: mdc-fep-9495
    where: Thermal Properties table, row Limiting Oxygen Index
  - benchmark: melt_flow_index
    label: Melt flow index
    value: 30
    unit: g/10min
    scope: material
    conditions:
      temperature: 372 degC
      load: 5 kg
      test_standard: ASTM D 2116
    method: Value printed in the Material Data Center property table for Teflon FEP 9495, Processing section
    status: ground
    source: mdc-fep-9495
    where: Processing/Physical table, row Melt Flow Index, MFI
corrosion:
  - environment: Atomic oxygen in low Earth orbit (MISSE 2, about 4 years)
    headline: FEP erodes under atomic oxygen, but more slowly than most polymers on the MISSE 2 tray.
    effect: Measured erosion yield of 2.00e-25 cm3/atom, printed in the same table as the predicted values for 40 polymers.
    conditions:
      fluence: 8.43e21 atoms/cm2
    source: nasa-ao-tool
    where: Table I, FEP row
    rating: unknown
  - environment: Hubble Space Telescope, long-duration exposure in low Earth orbit (outer MLI layer)
    headline: Retrieved FEP lost most of its stretch and became brittle, with cracks through the thickness.
    effect: The retrieved specimens reached 0 percent elongation in the SM2 LS group, against 340 to 390 percent for pristine FEP; the report attributes the damage to thermal cycling and deep-layer electron and proton radiation.
    conditions:
      exposure: long-duration exposure on Hubble, retrieved on the SM2 servicing mission
    source: townsend-hst-fep
    where: Section on tensile test results, Table 3
    rating: unknown
  - environment: Reactive chemicals and high temperature
    headline: FEP is inert to most chemicals, but elemental fluorine, molten alkali metals and chlorine tetrafluoride attack it.
    effect: Daikin says FEP is completely inert to attack by most chemicals except at high temperature, and is susceptible to high-pressure elemental fluorine gas, molten alkali metals and chlorine tetrafluoride.
    conditions:
      temperature: high temperature
    source: daikin-fep-stewardship
    where: Physical and Chemical Properties paragraph
    rating: unknown
  - environment: Heating during processing or fire
    headline: Above 250 degC FEP gives off hydrogen fluoride and other toxic fluorinated compounds.
    effect: Daikin states that hydrogen fluoride and other toxic fluorinated compounds may be produced above 250 degC, and the SDS warns that toxic gases form during heating or in fire.
    conditions:
      temperature: above 250 degC
    source: daikin-fep-stewardship
    where: Exposure Effects of Decomposition Products paragraph
    rating: unknown
uses:
  - application: electronics-and-chips
    device: Wire and cable insulation
    example: Daikin lists wire and cable coating films and sheets as the main use of its FEP molding materials, together with tubes and small parts.
    source: daikin-fep-stewardship
    where: Uses paragraph
  - application: propulsion-and-tanks
    device: Pipe and valve linings and sleeves
    example: Daikin lists pipe and valve linings and sleeves among its typical FEP uses, for lining process piping that must resist aggressive chemicals.
    source: daikin-fep-stewardship
    where: Uses paragraph
risks:
  hazards:
    - text: The FEP resin is not classified under the CLP regulation and has no GHS pictograms or hazard statements in the Daikin SDS.
      ghs: []
      source: daikin-np40-sds
      where: Section 2.1 Classification, and Section 2 hazard statements Not applicable
    - text: Heating above 250 degC or fire releases hydrogen fluoride and other toxic fluorinated gases, which can cause serious lung irritation.
      ghs: []
      source: daikin-fep-stewardship
      where: Exposure Effects of Decomposition Products paragraph
  failure_risks:
    - source: townsend-hst-fep
      where: Section on tensile test results, Table 3
      mode: Long-duration exposure to space, with thermal cycling and radiation,…
      consequence: Long-duration exposure to space, with thermal cycling and radiation, embrittles the film and cracks it, as seen on Hubble.
  side_effects:
    - text: Excessive airborne powder can irritate the eyes, skin and upper airways, and smoking near the material can expose smokers to toxic gases.
      source: daikin-fep-stewardship
      where: Health and Environmental Effects paragraph
  handling:
    - text: Process ovens and equipment in well-ventilated areas, and wear proper PPE; use colorants with heat stability above 400 degC.
      source: daikin-fep-stewardship
      where: Processing Precautions paragraph
  mitigations:
    - text: Ventilate processing areas and keep processing below the temperature at which hydrogen fluoride is produced.
      source: daikin-fep-stewardship
      where: Processing Precautions and Exposure Effects paragraphs
supply:
  - subject: Fluorspar (CaF2), the mineral feedstock for fluorine chemistry
    abundance: Fluorspar is the mineral source of the hydrogen fluoride used to make fluoropolymers; USGS reports the primary feedstock for fluorine chemicals, including fluoropolymers, is aqueous HF.
    producers:
      - country: China
        production: 6,000 thousand metric tons
        year: 2025
      - country: Mexico
        production: 1,500 thousand metric tons
        year: 2025
      - country: Mongolia
        production: 1,500 thousand metric tons
        year: 2025
      - country: South Africa
        production: 410 thousand metric tons
        year: 2025
      - country: Vietnam
        production: 160 thousand metric tons
        year: 2025
    source: usgs-fluorspar-2026
    where: World Mine Production table, 2025 column; world total 10,000 thousand metric tons (rounded)
media: []
documents:
  - title: Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit (NASA/TM-2008-215490)
    type: report
    url: https://ntrs.nasa.gov/api/citations/20090011780/downloads/20090011780.pdf
    year: 2008
  - title: Teflon FEP on-orbit degradation (Townsend and Hansen, NASA GSFC)
    type: report
    url: https://ntrs.nasa.gov/api/citations/19990040483/downloads/19990040483.pdf
    year: 1999
  - title: NEOFLON FEP NP-40, NP-102, NP-112, NP-1105 safety data sheet (Daikin, revision 08.03.2023)
    type: sds
    url: https://www.daikinchemicals.com/library/pb_common/pdf/sds/Fluoropolymer/FEP_NP-series/sds-np-40-E_20260723.pdf
    year: 2023
  - title: NEOFLON FEP NF Series safety data sheet (Daikin, revision 31.03.2023)
    type: sds
    url: https://www.daikinchemicals.com/library/pb_common/pdf/sds/Fluoropolymer_Films/NEOFLON_FEP_NF_Series_DIL_EN_20260716.pdf
    year: 2023
  - title: 'Mineral Commodity Summaries 2026: Fluorspar (USGS)'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-fluorspar.pdf
    year: 2026
  - title: Teflon FEP 9495 property table (Material Data Center, Chemours)
    type: datasheet
    url: https://www.materialdatacenter.com/ms/en/Teflon/The+Chemours+Company/Teflon™+FEP+9495/6a4f05df/824
    year: 2026
gaps:
  - No ageing or ultraviolet test values for FEP were read in this run; the VUV and X-ray studies found in search were not opened for numbers.
  - No humid-air or water-vapour corrosion result for FEP found; the water absorption value is the only moisture number.
  - Atomic weights of C, F and H are not sourced in this run, so recipe parts carry no atomic_weight field.
  - Monomer share in the FEP copolymer is not read from a source with a number; Wikipedia gives about 5 percent propylene component, which is not used as a value here.
  - Erosion yield, melt flow index and limiting oxygen index use names that are not in spores/property-canon.yaml; they are listed here as new names.
  - No PubChem GHS entry was opened; the hazard data rest on the Daikin and SDS documents.
  - The Interstate Plastics FEP safety sheet returned HTTP 403 and was not read.
  - No FEP-specific critical-mineral listing; fluorspar is in USGS MCS 2026 but its critical-mineral status is not stated in the page read.
sources:
  nasa-ao-tool:
    title: Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit
    id: NASA/TM-2008-215490
    url: https://ntrs.nasa.gov/api/citations/20090011780/downloads/20090011780.pdf
    year: 2008
    kind: report
    license: public domain (NASA)
  townsend-hst-fep:
    title: On-Orbit Teflon FEP Degradation (Townsend and Hansen, NASA GSFC)
    id: NTRS 19990040483
    url: https://ntrs.nasa.gov/api/citations/19990040483/downloads/19990040483.pdf
    year: 1999
    kind: report
    license: public domain (NASA)
  daikin-np40-sds:
    title: NEOFLON FEP NP-40, NP-102, NP-112, NP-1105 safety data sheet (Daikin)
    id: Daikin SDS, revision 08.03.2023
    url: https://www.daikinchemicals.com/library/pb_common/pdf/sds/Fluoropolymer/FEP_NP-series/sds-np-40-E_20260723.pdf
    year: 2023
    kind: datasheet
    license: cited, not reproduced
  daikin-nf-sds:
    title: NEOFLON FEP NF Series safety data sheet (Daikin)
    id: Daikin SDS, revision 31.03.2023
    url: https://www.daikinchemicals.com/library/pb_common/pdf/sds/Fluoropolymer_Films/NEOFLON_FEP_NF_Series_DIL_EN_20260716.pdf
    year: 2023
    kind: datasheet
    license: cited, not reproduced
  daikin-fep-stewardship:
    title: Daikin-NEOFLON FEP product stewardship summary (env-pss-fep-001)
    id: env-pss-fep-001 Rev. 0
    url: https://www.daikinchemicals.com/library/pb_common/pdf/dai/env-pss-fep-001_Rev.0-002.pdf
    year: 2021
    kind: datasheet
    license: cited, not reproduced
  usgs-fluorspar-2026:
    title: 'Mineral Commodity Summaries 2026: Fluorspar (U.S. Geological Survey)'
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-fluorspar.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  mdc-fep-9495:
    title: Teflon FEP 9495 property data (Material Data Center, Chemours)
    id: materialdatacenter FEP 9495
    url: https://www.materialdatacenter.com/ms/en/Teflon/The+Chemours+Company/Teflon™+FEP+9495/6a4f05df/824
    year: 2026
    kind: datasheet
    license: cited, not reproduced
  wiki-fep:
    title: Fluorinated ethylene propylene (Wikipedia)
    id: Wikipedia, en
    url: https://en.wikipedia.org/wiki/Fluorinated_ethylene_propylene
    year: 2026
    kind: web
    license: CC BY-SA 4.0
license: CC-BY-4.0
updated: 2026-10-20T00:00:00.000Z
review:
  status: draft
  method: assistant
  checked_values: 17
  unreachable: 1
  caveats: 1
  note: 'Written from pages fetched in this run: 17 property values, 8 sources. Interstate Plastics sheet returned HTTP 403.'
story:
  recipe:
    line: FEP is a copolymer of tetrafluoroethylene and hexafluoropropylene. Its repeat units are CF2-CF2 from the first monomer and CF2-CF(CF3) from the second, with a small fraction of propylene-based units in the chain according to Wikipedia. Daikin and Chemours sell it as a pellet resin, and it is processed by melt extrusion or injection moulding.
    parts:
      - name: Tetrafluoroethylene
        monomer: C2F4
        role: Main backbone monomer; the -CF2-CF2- units give the chemical inertness and low friction of the chain.
      - name: Hexafluoropropylene
        monomer: C3F6
        role: Second monomer; its pendant -CF3 groups break up the crystal structure, so FEP melts about 40 degC lower than PFA according to Wikipedia.
  risk_groups:
    - title: Workers who melt, extrude or mould FEP, because processing above 250…
    - title: Firefighters and anyone handling burning FEP, because fire produces…
    - title: Mission planners using FEP outer layers, because thermal cycling and…
  why: FEP keeps the chemical inertness and insulating behaviour of PTFE but can be melt-processed into thin films, coatings and tubing. On the MISSE 2 flight its atomic oxygen erosion yield was 2.00e-25 cm3/atom, and its dielectric constant at 1 MHz is 2.03.
  uses:
    - where: Use
      line: Wire and cable insulation, where the low dielectric constant and dissipation factor matter.
    - where: Use
      line: Pipe and valve linings and sleeves in chemical plants.
    - where: Use
      line: Thin films for spacecraft thermal blankets, where the MISSE 2 erosion yield and the Hubble embrittlement set the limits.
  can_do:
    - label: Strength
      line: FEP resists most chemicals, insulates well at high frequency, and melt-processes into thin films. It has a melting point of 255 degC and a 20 MPa tensile strength in the ASTM D 638 test.
  compare: Among the MISSE 2 polymers FEP erodes slowly under atomic oxygen, at 2.00e-25 cm3/atom. It melts at about 255 degC and can be melt-processed, which PTFE cannot. Its tensile strength of 20 MPa and elongation of 300 percent are modest for a structural role.
  compare_rows:
    - label: Melting point
      benchmark: melting_point
    - label: Tensile strength
      benchmark: ultimate_tensile_strength
    - label: Dielectric constant at 1 MHz
      benchmark: dielectric_constant
  handling:
    - Ventilate ovens and extrusion lines, wear PPE, and keep processing below the temperature at which hydrogen fluoride is produced. Use colorants with heat stability above 400 degC. Keep burning or overheated FEP away from people.
  good_for:
    - Insulating wire and cable jackets, linings for chemical pipework, and low-outgassing films where chemical inertness and atomic oxygen resistance matter.
  watch_out:
    - Long orbital exposure embrittles FEP; the Hubble specimens reached 0 percent elongation. Above 250 degC it releases hydrogen fluoride, and it has low tensile strength for structural loads.
  verdict: FEP is a practical, chemically inert insulator with good atomic oxygen resistance for its class, but its ductility falls off sharply after long exposure to thermal cycling and radiation, so it should be used as a thin, protected layer rather than a structural part.