Polytetrafluoroethylene PTFE

spore: profile
id: ptfe
spore_version: 0.2
family: fluoropolymers
name: Polytetrafluoroethylene
abbreviation: PTFE
role: low-friction insulating and chemically inert polymer
category: polymers
type: fluoropolymers
summary: |
  PTFE (Teflon) is a soft, slippery fluoropolymer that is an excellent electrical insulator and works from -200 degC to +260 degC according to a vendor sheet. On the MISSE 2 flight it eroded under atomic oxygen at 1.42e-25 cm3/atom, about twenty times slower than Kapton H. Its weakness is radiation: NASA wire-insulation guidance from 1968 says PTFE irradiated in air becomes useless after one or two megarads, and a NASA Glenn study calls it much more radiation-sensitive than FEP.
best_for: A low-friction, electrically insulating, low-outgassing plastic that resists atomic oxygen far better than Kapton, PEEK or most hydrocarbon polymers
weakest_at: Ionizing radiation (it loses strength and stretch at megarad doses), low strength (23 to 27 MPa at room temperature) and heating above 300 degC, where it gives off toxic fumes
identity:
  formula: (-CF2-CF2-)n
  cas: 9002-84-0
  source: utd-sds
  where: Section 1.1 (polytetrafluoroethylene, CAS 9002-84-0); formula written out by Space Mushroom from the name and from the NASA tables, which list the repeat unit as C2F4
tags:
  environments:
    - low-earth-orbit
  stresses:
    - atomic-oxygen
    - total-radiation-dose
    - thermal-cycling
    - extreme-cold
    - vacuum-and-outgassing
  applications:
    - electronics-and-chips
    - cryogenic-fuel
properties:
  - benchmark: density
    label: Density (semi-finished PTFE)
    value: 2.17
    unit: g/cm3
    scope: material
    conditions:
      form: solid tubing, semi-finished PTFE product
      manufacturer: GAPI s.r.l., Italy
      sheet_date: emission date 12/02/2007
    method: Value printed in a manufacturer safety data sheet (the sheet shows 2,17 gr/cm3 with a decimal comma)
    status: ground
    note: A Proto Labs sheet gives 2.14-2.18 g/cm3 (ASTM D792) and a Plastics International sheet gives a specific gravity of 2.13-2.22 (ASTM D792). The NASA MISSE 2 report uses 2.1503 g/cm3 for the flown PTFE film.
    source: utd-sds
    where: Section 9 (Physical and chemical properties)
  - benchmark: density
    label: Density range (machined PTFE stock)
    value: 2.14
    value_high: 2.18
    unit: g/cm3
    scope: material
    conditions:
      test_standard: ASTM D792
      form: CNC machining stock, supplier typical values
    method: Typical-value range from a supplier material data sheet
    status: ground
    note: The sheet shows 2.14-2.18 g/cm3 in both its imperial and metric columns.
    source: protolabs
    where: Properties table (Density)
  - benchmark: density
    label: Density used by NASA for the flown PTFE film
    value: 2.1503
    unit: g/cm3
    scope: material
    conditions:
      sample: PTFE film flown on MISSE 2 PEACE Polymers
      ash_fraction: '2.98e-4'
    method: Density value listed in the NASA report for the erosion-yield calculation
    status: ground
    source: banks2008
    where: Table II (polymer physical properties)
  - benchmark: tensile_strength_room_temperature
    label: Tensile strength (room temperature, supplier typical)
    value: 23
    value_high: 27
    unit: MPa
    scope: material
    conditions:
      test_standard: ISO 12086 / ISO 527 / ASTM D4894
      temperature: room temperature, not stated on the sheet
      form: CNC machining stock
    method: Typical-value range from a supplier material data sheet (also printed as 3,335-3,917 psi)
    status: ground
    note: A Plastics International sheet gives 3,000-5,000 psi (ASTM D1457, D1708, D638) at 73 degF (23 degC). In the Southampton cryogenic tests the PTFE sheet gave a lower figure, 18.15 MPa at 2 mm/min.
    source: protolabs
    where: Properties table (Tensile Strength)
  - benchmark: elongation_at_break_supplier_typical
    label: Elongation at break (supplier typical)
    value: 230
    unit: '%'
    bound: lower
    scope: material
    conditions:
      test_standard: ISO 12086 / ISO 527 / ASTM D4894
      form: CNC machining stock
    method: Minimum value printed in a supplier material data sheet (listed as 230% or more)
    status: ground
    note: A Plastics International sheet gives 300-500 percent (ASTM D1457, D1708, D638) at 73 degF (23 degC). The Southampton sheet specimen stretched about 303 percent at 2 mm/min.
    source: protolabs
    where: Properties table (Elongation at Break)
  - benchmark: tensile_strength_at_room_temperature
    label: Tensile strength at room temperature (Southampton test)
    value: 18.15
    unit: MPa
    scope: material
    conditions:
      temperature: room temperature (295 K)
      crosshead_speed: 2 mm/min (0.00159 /s)
      specimen: dumbbell cut by waterjet from flat sheet, ISO 37 Type I profile, PTFE grade not stated
    method: Tensile test in a cryogenic test rig (mean of repeats)
    status: ground
    uncertainty: standard deviation 0.49 MPa
    note: Young's modulus 0.82 GPa and strain at break 302.96 percent in the same row. At 250 mm/min the strength was 19.23 MPa. In the same table at 2 mm/min PEEK gave 99.55 MPa and UHMWPE 31.99 MPa; in Table 2 at 77 K PEEK gave 198.14 MPa. This is a prefinal preprint.
    source: wang2024
    where: Table 1 (strain rate effects at room temperature)
  - benchmark: min_service_temp
    label: Lowest service temperature (supplier)
    value: -200
    unit: degC
    scope: material
    conditions:
      basis: supplier-stated service range (printed as -328 degF)
      form: CNC machining stock
    method: Value printed in a supplier material data sheet; no test method is listed for it
    status: ground
    note: This is a stated limit, not a measured one. The Southampton tests found PTFE much stronger but far less stretchy at 77 K and 20 K (see the cryogenic strength entries).
    source: protolabs
    where: Properties table (Service Temperature min-max)
  - benchmark: max_service_temp
    label: Highest service temperature (supplier)
    value: 260
    unit: degC
    scope: material
    conditions:
      basis: supplier-stated service range (printed as +500 degF)
      form: CNC machining stock
    method: Value printed in a supplier material data sheet; no test method is listed for it
    status: ground
    note: A Plastics International sheet gives an upper service temperature of 500 degF for 20,000 h (UL746B). NASA TN D-4553 (1968) lists 260 degC as the maximum recommended continuous service temperature for Teflon TFE wire insulation.
    source: protolabs
    where: Properties table (Service Temperature min-max)
  - benchmark: max_service_temp
    label: Highest continuous service temperature of Teflon TFE wire insulation (NASA, 1968)
    value: 260
    unit: degC
    scope: material
    conditions:
      use: hook-up wire insulation for spacecraft
      basis: maximum recommended continuous duty service temperature
    method: Value stated in a NASA guide for selecting wire insulation (the same list gives 205 degC for Teflon FEP)
    status: ground
    source: nasa-tnd4553
    where: Section on temperature characteristics (page 12)
  - benchmark: melting_point_semi_finished_ptfe
    label: Melting point (semi-finished PTFE)
    value: 327
    value_high: 335
    unit: degC
    scope: material
    conditions:
      form: semi-finished PTFE product
      note: the sheet prints 327/335 degC
    method: Value printed in a manufacturer safety data sheet
    status: ground
    note: The Plastics International sheet gives 621 degF (ASTM D3418), which converts to 327 degC (Space Mushroom conversion).
    source: utd-sds
    where: Section 9 (Melting Point)
  - benchmark: glass_transition_temperature
    label: Glass transition temperature
    value: 170
    unit: K
    scope: material
    conditions:
      basis: value quoted by the authors from other papers, not measured in the study
      comparison: PEEK 416 K, UHMWPE 123 K
    method: Quoted literature value in a discussion section
    status: ground
    note: The authors use it to explain why PTFE is ductile at room temperature but brittle at 77 K and 20 K, both below this temperature.
    source: wang2024
    where: Section 4 (Discussion)
  - benchmark: cte
    label: Coefficient of linear thermal expansion (supplier typical, near room temperature)
    value: 12
    value_high: 13
    unit: x 10^-5 per degC
    scope: material
    conditions:
      test_standard: ASTM D696
      temperature_range: not stated on the sheet
      form: CNC machining stock
    method: Typical-value range from a supplier material data sheet (equal to 120-130 ppm/K)
    status: ground
    note: Measured on a sheet in the Southampton study, expansion is strongly temperature dependent, from 8.28e-6 per K (20-50 K) to 103.06e-6 per K (200-295 K).
    source: protolabs
    where: Properties table (Coefficient of Linear Thermal Expansion)
  - benchmark: cte
    label: Mean coefficient of linear thermal expansion, 200 to 295 K
    value: 103.06
    unit: x 10^-6 per K
    scope: material
    conditions:
      temperature_range: 200 to 295 K
      specimen: PTFE sheet, grade not stated
      method_detail: contraction measured between 20 K and 295 K
    method: Linear CTE calculated from a measured contraction curve
    status: ground
    uncertainty: standard deviation 0.04
    note: 'Other ranges in the same table: 8.28 (20-50 K), 25.28 (50-123 K) and 62.31 (123-200 K) x 10^-6 per K. Between 295 K and 20 K the PTFE contracted by about 1.7 percent, against 0.9 percent for PEEK (Section 3.2).'
    source: wang2024
    where: Table 4; Section 3.2
  - benchmark: ultimate_tensile_strength_at_77_k
    label: Ultimate tensile strength at 77 K
    value: 86.22
    unit: MPa
    scope: material
    conditions:
      temperature: 77 K
      crosshead_speed: 2 mm/min
      specimen: dumbbell cut from flat sheet by waterjet (ISO 37 Type I profile), PTFE grade not stated
    method: Tensile test in a cryogenic test rig (mean of repeats)
    status: ground
    uncertainty: standard deviation 0.23 MPa
    note: Young's modulus 5.71 GPa and strain at break 4.44 percent in the same row. This is a prefinal preprint.
    source: wang2024
    where: Table 2 (77 K)
  - benchmark: ultimate_tensile_strength_at_20_k
    label: Ultimate tensile strength at 20 K
    value: 82.32
    unit: MPa
    scope: material
    conditions:
      temperature: 20 K
      crosshead_speed: 2 mm/min
      specimen: dumbbell cut from flat sheet by waterjet (ISO 37 Type I profile), PTFE grade not stated
    method: Tensile test in a cryogenic test rig (mean of repeats)
    status: ground
    uncertainty: standard deviation 0.59 MPa
    note: Strain at break was 2.51 percent, against 302.96 percent at room temperature. At 250 mm/min the 20 K strength was 92.78 MPa.
    source: wang2024
    where: Table 3 (20 K)
  - benchmark: atomic_oxygen_erosion_yield
    value: 1.42e-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 in the same table
    method: Mass-loss erosion yield from the MISSE 2 flight samples, as compiled in the NASA report
    status: flight
    note: The report's predictive tool gave 1.58e-25 cm3/atom for PTFE (Table VII). Density used was 2.1503 g/cm3 and ash fraction 2.98e-4 (Table II). The report says some stacked thin-film samples eroded through, so some listed yields are lower bounds; PTFE is listed without a greater-than sign.
    source: banks2008
    where: Table I (MISSE 2 PEACE polymers erosion yield data); Table VII; Section 2.1 for exposure
  - benchmark: outgassing_tml
    label: Total mass loss, PTFE tubing (GSFC data reference GSC17398)
    value: 0
    unit: '% mass'
    scope: material
    conditions:
      specimen: PTFE TUBING AS 20-065-1, manufacturer code ZEU
      test_standard: NASA GSFC screening test, ASTM E595 type
      temperature: 398 K (125 degC), 24 h in vacuum
      acceptance: TML at most 1.0 percent and CVCM at most 0.10 percent
    method: Value printed in the NASA outgassing compilation; a finished commercial product, not a bulk resin
    status: ground
    note: Water vapour regained (WVR) was 0.00 percent in the same row. A second PTFE entry, TFE wire insulation (GSFC6086, manufacturer MSY), has TML 0.01, CVCM 0.00 and WVR 0.00 percent. Note that GSFC10661, which a Gund Company bulletin labels PTFE/FEP at 0.01/0.00/0.02, is listed in RP-1124 as TEFLON FEP TYPE A 5 MIL FILM, so it is not used here as PTFE.
    source: rp1124
    where: Section B alphabetical listing, entry PTFE TUBING AS 20-065-1; test method on page 2 of the introduction
  - benchmark: outgassing_cvcm
    label: Collected volatile condensable material, PTFE tubing (GSFC data reference GSC17398)
    value: 0
    unit: '% mass'
    scope: material
    conditions:
      specimen: PTFE TUBING AS 20-065-1, manufacturer code ZEU
      test_standard: NASA GSFC screening test, ASTM E595 type
      temperature: 398 K (125 degC), 24 h in vacuum
    method: Value printed in the NASA outgassing compilation
    status: ground
    note: The TFE wire insulation entry (GSFC6086) also shows CVCM 0.00 percent.
    source: rp1124
    where: Section B alphabetical listing, entry PTFE TUBING AS 20-065-1
  - benchmark: weight_loss_of_teflon_tfe_insulated
    label: Weight loss of Teflon TFE insulated wire in high vacuum, 100 h
    value: 0.04
    unit: '% mass'
    scope: material
    conditions:
      specimen: Teflon TFE insulated wire, sample weight 2.0 g
      temperature: 212 degF (100 degC)
      time_in_vacuum: 100 hours
    method: Weight loss in high vacuum, reported in NASA TN D-4553 from earlier work (its references 3 and 4)
    status: ground
    note: A second row gives 0.29 percent after 168 hours at 300 degF (149 degC). The report says gross weight losses of the insulations are small and acceptable, and mainly due to entrapped gases such as carbon dioxide and water.
    source: nasa-tnd4553
    where: Table 1
  - benchmark: elongation_lost_after_irradiation_in
    label: Elongation lost after irradiation in high vacuum
    value: 88
    unit: '% of original elongation'
    scope: material
    conditions:
      dose: 8 megarads (Mrad)
      atmosphere: high vacuum
      material: Teflon TFE
      radiation: ionizing radiation, type not stated in this passage
    method: Statement in a NASA guide for selecting wire insulation (a literature summary)
    status: ground
    note: The same passage says that irradiated in air, Teflon TFE is quickly degraded and becomes useless after absorbing one or two megarads. 8 megarads equals 80 kGy. A dose tested, not a limit.
    source: nasa-tnd4553
    where: Section on radiation resistance
  - benchmark: dose_at_which_radiation_damage
    label: Dose at which radiation damage becomes detectable (vendor summary)
    value: 20000
    value_high: 70000
    unit: rad
    scope: material
    conditions:
      atmosphere: in air
      threshold: first detectable mechanical damage
      vacuum_equivalent: 2-7 x 10^5 rad or more in vacuum
    method: Summary table in a Rogers Corporation technical article, compiled from literature references dated 1951 to 1969
    status: ground
    note: 2 to 7 x 10^4 rad is 200 to 700 Gy. In the same table 50 percent of tensile strength is retained at 10^6 rad in air and 10^7 rad or more in vacuum, and 100 percent elongation is retained to 2-5 x 10^5 rad in air and 2-5 x 10^6 rad in vacuum. The article says damage is smaller in vacuum because oxygen takes part in the damaging reactions. The source is a vendor article about PTFE-filled laminates; the table layout in the PDF is partly ambiguous, so only the clear rows are quoted.
    source: rogers-radiation
    where: Page 1, summary table of radiation doses related to damage levels
  - benchmark: dielectric_constant
    label: Dielectric constant
    value: 2.1
    unit: dimensionless
    scope: material
    conditions:
      basis: typical value in a supplier sheet
      temperature: 73 degF (23 degC)
      test_method: not listed for this row
    method: Typical value printed in a supplier material data sheet
    status: ground
    note: The sheet says the dielectric constant and loss factor are low and stable across a wide temperature and frequency range.
    source: plasticsintl
    where: Introductory text
  - benchmark: dielectric_strength
    label: Dielectric strength
    value: 30
    value_high: 45
    unit: kV/mm
    scope: material
    conditions:
      test_standard: ASTM D149
      specimen_thickness: 0.5 mm
    method: Typical-value range from a supplier material data sheet (printed as 762-1,143 V/mil)
    status: ground
    note: Dielectric strength depends strongly on specimen thickness.
    source: protolabs
    where: Properties table (Dielectric Strength)
  - benchmark: volume_resistivity
    label: Volume resistivity
    value: 100000000000000000
    value_high: 1000000000000000000
    unit: ohm cm
    scope: material
    conditions:
      test_standard: ASTM D257
      form: CNC machining stock
    method: Typical-value range from a supplier material data sheet (printed as 10^17-10^18 ohm-cm)
    status: ground
    note: Surface resistivity is listed as 10^16-10^17 ohm.
    source: protolabs
    where: Properties table (Volume Resistivity)
  - benchmark: dynamic_coefficient_of_friction
    label: Dynamic coefficient of friction (supplier typical, in air)
    value: 0.05
    value_high: 0.06
    unit: dimensionless
    scope: material
    conditions:
      test_standard: ASTM D1894 / ASTM D3702
      atmosphere: air, not vacuum
    method: Typical-value range from a supplier material data sheet
    status: ground
    note: A Plastics International sheet gives 0.1 (ASTM D1894, below 10 ft/min). No vacuum friction value was found.
    source: protolabs
    where: Properties table (Dynamic Coefficient of Friction)
  - benchmark: limiting_oxygen_index
    label: Limiting oxygen index
    value: 95
    unit: '% oxygen'
    bound: lower
    scope: material
    conditions:
      test_standard: ASTM D2863
      sheet_note: printed as greater than 95 percent
    method: Typical value printed in a supplier material data sheet
    status: ground
    note: The same sheet lists a UL94 flame rating of V-0 and a heat of combustion of 2,200 Btu/lb. This is a ground flammability screen in air, not the NASA-STD-6001 crew-safety test.
    source: plasticsintl
    where: 'Property table (Thermal section: Limiting Oxygen Index, Flame Rating)'
corrosion:
  - environment: Atomic oxygen in low Earth orbit
    headline: Atomic oxygen eroded PTFE about twenty times more slowly than Kapton H on the ISS.
    effect: 'On the MISSE 2 flight PTFE had an erosion yield of 1.42e-25 cm3/atom, against 3.00e-24 for Kapton H and 2.99e-24 for PEEK in the same table. Other fluoropolymers were similar: FEP 2.00e-25 and PFA 1.73e-25.'
    rating: low
    conditions:
      flight: MISSE 2, 3.95 yr, fluence 8.43e21 atoms/cm2
    source: banks2008
    where: Table I
  - environment: Heat above 300 degC (decomposition)
    headline: Overheated PTFE gives off toxic fumes.
    effect: A PTFE safety data sheet says heating above 300 degC may release a fine particulate fume and, above 400 degC, decomposition products that can cause pulmonary inflammation, haemorrhage or oedema. Combustion or thermal decomposition gives very toxic and corrosive vapours such as hydrogen fluoride (HF) and carbonyl fluoride (COF2).
    rating: severe
    conditions:
      trigger: overheating or burning
      worst_case: poor ventilation or confined spaces
    source: utd-sds
    where: Sections 3.1 to 3.6, 5.2 and 5.3
  - environment: Chemicals and water
    headline: The sheet says PTFE does not dissolve in water or organic solvents, but no corrosion test was opened.
    effect: The semi-finished PTFE safety data sheet lists solubility as 'Not in water or in organic solvent' and the product as stable at normal temperatures and storage conditions. Suppliers describe PTFE as chemically resistant, but no quantitative chemical-resistance table was opened for this profile.
    rating: unknown
    conditions:
      basis: manufacturer safety data sheet, semi-finished PTFE products
    source: utd-sds
    where: Sections 9 and 10.1
risks:
  hazards:
    - text: 'Manufacturer safety data sheet (GAPI s.r.l., semi-finished PTFE, emission date 12/02/2007): the main hazard is inhaling fumes from overheating or burning. Heating above 300 degC may liberate a fine particulate fume that causes polymer fume fever, a flu-like illness with fever, chills, nausea and chest tightness. Symptoms are often delayed 4 to 24 hours and last 24 to 48 hours.'
      ghs: []
      source: utd-sds
      where: Sections 3.1 to 3.3
    - text: Above 400 degC, decomposition products may cause pulmonary inflammation, haemorrhage or oedema, particularly in poor ventilation or confined spaces. The sheet gives exposure limits for hydrofluoric acid (TLV 2.6 mg/m3) and carbonyl fluoride (TLV 5.4 mg/m3) during thermal decomposition.
      ghs: []
      source: utd-sds
      where: Sections 3.4, 3.5 and 8.1
    - text: The solid is not classified as hazardous for transport, is described as not carcinogenic and as not toxic if swallowed. If a flame is applied it ignites but combustion stops when the flame is removed. Hydrogen fluoride fumes from a fire can react with water to form hydrofluoric acid.
      ghs: []
      source: utd-sds
      where: Sections 4.4, 5.2, 5.3, 11.2 and 14.1
  failure_risks:
    - mode: Loss of strength and ductility under ionizing radiation
      trigger: Absorbed doses of one to two megarads in air, or 8 megarads in high vacuum
      consequence: In air Teflon TFE is quickly degraded and becomes useless after one or two megarads; in vacuum it loses 88 percent of its original elongation at 8 megarads. The primary effect is chain breaking, which lowers molecular weight and makes the plastic brittle.
      severity: high
      source: nasa-tnd4553
      where: Section on radiation resistance
    - mode: Surface cracking of ePTFE cable insulation on the ISS (predicted)
      trigger: 10-year mission with thermal cycling from -100 to 130 degC and ionizing radiation
      consequence: A NASA Glenn analysis predicts an extremely embrittled front surface with cracks under any given strain, and microscopic cracks starting very early in the mission to a depth of about 0.030 cm after 10 years. This is a ground-based prediction, not a flight failure.
      severity: moderate
      source: degroh2005
      where: Research summary, last paragraphs
    - mode: Brittleness at hydrogen temperature
      trigger: Cooling from room temperature to 20 K
      consequence: At 2 mm/min strain at break fell from 302.96 percent at room temperature to 2.51 percent at 20 K, and the sheet contracted by about 1.7 percent between 295 K and 20 K.
      severity: moderate
      source: wang2024
      where: Tables 1 and 3; Section 3.2
  side_effects:
    - text: Irradiated polymers, almost without exception, release gaseous substances that may corrode spacecraft parts. In the report's mirror tests, vacuum-deposited copper and aluminium mirrors were sealed in ampoules with irradiated insulation, including Teflon TFE, and examined for corrosion.
      affects: Nearby optics and metal surfaces
      source: nasa-tnd4553
      where: Section on corrosion of mirrors by evolved gases; Figures 1 and 2 (captions not read in detail, so no result for the Teflon TFE ampoules is stated)
    - text: NASA Glenn describes PTFE as known to be significantly more susceptible to radiation degradation than FEP.
      affects: Choice between PTFE and FEP for exposed insulation
      source: degroh2005
      where: Research summary, paragraph on the mobile transporter cable
  handling:
    - text: Use usual protective clothing; avoid using the material at high temperature (the sheet says 280 degC) and take care to prevent inhalation of fume. No smoking while handling. Prevent burns from contact with hot material, hot surfaces and flames.
      source: utd-sds
      where: Sections 7.1, 7.2 and 10.2
    - text: Store at normal temperatures; the product is stable under normal storage conditions. Treatment and disposal must follow local regulations, and recycling is suggested if possible.
      source: utd-sds
      where: Sections 10.1 and 13
  mitigations:
    - text: Use local exhaust ventilation to remove vapours and fumes. Wear safety glasses, heat-resistant clothing and footwear, and a face shield if molten polymer might splash. In a fire, use self-contained breathing apparatus and full protective equipment.
      source: utd-sds
      where: Sections 5.2, 8.2 and 8.3
uses:
  - application: electronics-and-chips
    device: Trailing umbilical cable insulation of the ISS Mobile Transporter (railcar), made of expanded PTFE
    example: The cable outer jacket is six layers of expanded PTFE, about 43 mils thick after fabrication, with an inner core 7 to 10 mils thick; it has a 10-year mission life and was installed on the S0 truss during STS-110 in April 2002.
    source: degroh2005
    where: Research summary, paragraph on the mobile transporter
  - application: electronics-and-chips
    device: Spacecraft hook-up wire insulation (Teflon TFE and FEP)
    example: NASA's 1968 selection guide compares Teflon TFE and FEP against polyolefin insulations for spacecraft wire, rating outgassing, radiation resistance and weight as the most important criteria.
    source: nasa-tnd4553
    where: Abstract; Table 1
  - application: cryogenic-fuel
    device: Candidate seal or liner material for liquid-hydrogen systems (ground tensile tests only)
    example: Tensile and thermal-contraction tests at room temperature, 77 K and 20 K were run on PTFE, PEEK and UHMWPE to judge thermoplastics as alternatives to metal seals in cryogenic fuel systems.
    source: wang2024
    where: Abstract and Section 1
  - application: electronics-and-chips
    device: PTFE film flight sample on the exterior of the ISS (MISSE 2 PEACE Polymers experiment)
    example: PTFE was one of 40 polymers flown to measure atomic oxygen erosion; the passport misse2-ptfe records the same exposure.
    source: banks2008
    where: Abstract and Table I
supply:
  - subject: Fluorine feedstock (fluorspar, calcium fluoride)
    producers:
      - {country: China, share_percent: 60.0, year: 2025}
      - {country: Mexico, share_percent: 15.0, year: 2025}
      - {country: Mongolia, share_percent: 15.0, year: 2025}
      - {country: South Africa, share_percent: 4.1, year: 2025}
    recycling: "USGS: synthetic fluorspar may be produced from neutralization of waste in uranium enrichment, petroleum alkylation and stainless-steel pickling, though impurities constrain its use. Primary aluminum producers recycle HF and fluorides from smelting."
    substitutes: ["USGS: fluosilicic acid from phosphate rock has been used as an alternative to fluorspar in making AlF3 and HF (about 73,000 tons of fluorspar equivalent was recovered in 2025)."]
    source: usgs-mcs2026-fluorspar
    where: "World Mine Production and Reserves table, 2025e. Shares are calculated by Space Mushroom against the printed world total of 10,000 thousand t; the listed rows sum to 10,235, so shares are approximate. Recycling and Substitutes sections. Context: acid-grade fluorspar is mostly used to make anhydrous HF, the primary feedstock for fluoropolymers. US imports 2021-24 came from Mexico 64 percent, Vietnam 12 percent, China 10 percent, South Africa 9 percent; US net import reliance was 100 percent in 2025e."
  - subject: PTFE resin producers
    producers: []
    source: wiki-ptfe
    where: "Wikipedia PTFE page: Chemours is named as the maker of the PTFE-based Teflon brand. Daikin (Neoflon) and AGC (Fluon) were named in the brief, but their fetched Wikipedia pages do not state that they make PTFE, so they are not listed. No country shares for PTFE resin makers were found."
documents:
  - title: 'Mineral Commodity Summaries 2026: Fluorspar (USGS)'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-fluorspar.pdf
    year: 2026
  - 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: 'NASA TN D-4553: Criteria for Selection of Wire Insulations for Use in Space Applications'
    type: report
    url: https://ntrs.nasa.gov/citations/19680018792
    year: 1968
  - title: 'NASA RP-1124 Rev. 3: Outgassing Data for Selecting Spacecraft Materials'
    type: report
    url: https://ntrs.nasa.gov/citations/19940017416
    year: 1993
  - title: Hubble Space Telescope Degradation Data Used for Ground-Based Durability Projection of Insulation on the International Space Station (NASA Glenn research summary)
    type: report
    url: https://ntrs.nasa.gov/citations/20050192335
    year: 2005
  - title: Evaluating the potential of thermoplastic polymers for cryogenic sealing applications (arXiv preprint)
    type: paper
    url: https://arxiv.org/abs/2406.01165
    year: 2024
  - title: 'Safety data sheet: semi-finished PTFE products (GAPI s.r.l.)'
    type: sds
    url: https://cores.research.utdallas.edu/files/2023/04/PTFE-MSDS.pdf
    year: 2007
  - title: The Effect of Nuclear Radiation Exposure to RT/duroid PTFE-Based Composites (Rogers Corporation)
    type: datasheet
    url: https://www.RogersCorp.com/-/media/project/rogerscorp/documents/advanced-electronics-solutions/english/properties---detailed-characteristics/the-effect-of-exposure-of-rt-duroid-ptfe-based-composites-to-nuclear-radiation.pdf
    year: 2023
gaps:
  - No thermal conductivity value for PTFE was opened and read; search snippets mentioned 0.20 and 0.34 W/(m K) from other datasheets but those pages were not read, so none is entered.
  - No NASA outgassing database (outgassing.nasa.gov) entry was queried. The outgassing values come from NASA RP-1124 Revision 3 (1993), which lists finished PTFE products (tubing, wire insulation), not a bulk virgin-resin specimen. The database's current value for bulk PTFE was not read.
  - No PTFE ultraviolet or vacuum-ultraviolet exposure result was found with a number. The NASA Goddard EOIM-III comparison report that was opened covers silvered Teflon (FEP-type) and not PTFE.
  - No flown PTFE mechanical-property result (strength or elongation after orbital exposure) was found; the ISS mobile transporter cable result is a ground-based prediction in a short NASA research summary.
  - No gamma or proton dose-versus-property curve for PTFE from a primary paper was opened; radiation numbers come from a 1968 NASA guide and a vendor summary of older literature, and the type of radiation behind the 8 Mrad figure is not stated in the NASA passage.
  - No friction or wear value in vacuum was found; the friction values are in air.
  - No PubChem compound record or ECHA/GHS classification for PTFE was opened, so hazards rest on one manufacturer safety data sheet from 2007 and carry no GHS codes. Other PTFE safety data sheets seen only in search snippets were not entered.
  - 'Not entered: a quantitative chemical-resistance table, water absorption, the USGS critical-mineral status of fluorspar, and the trade-name or filled-PTFE grades.'
  - "Daikin and AGC were named in the brief, but their fetched Wikipedia pages do not state that they make PTFE, so they are not listed as PTFE producers."
  - The grade and manufacturer of the PTFE sheet in the Southampton preprint is not stated, and the Proto Labs, Plastics International and GAPI figures are supplier typical values, not certified grade data.
sources:
  usgs-mcs2026-fluorspar:
    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)
  wiki-ptfe:
    title: Polytetrafluoroethylene (Wikipedia)
    id: Wikipedia article, accessed 2026-10-19; synthesis and manufacturer sections
    url: https://en.wikipedia.org/wiki/Polytetrafluoroethylene
    year: 2026
    kind: web
    license: CC BY-SA 4.0
  nist-atomic-weights:
    title: Atomic Weights and Isotopic Compositions for All Elements (NIST)
    id: NIST composition tables, accessed 2026-10-19
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=&all=all&ascii=html
    year: 2026
    kind: database
    license: public domain (NIST)
  utd-sds:
    title: 'Safety Data Sheet: Semifinished PTFE Products (GAPI s.r.l.; copy hosted by UT Dallas core facilities)'
    id: PTFE Rev. 01, emission date 12/02/2007
    url: https://cores.research.utdallas.edu/files/2023/04/PTFE-MSDS.pdf
    year: 2007
    kind: datasheet
    license: manufacturer document, linked not reproduced
  protolabs:
    title: 'Material data sheet: PTFE (Teflon), CNC machining (Proto Labs)'
    id: Proto Labs document 2026-026
    url: https://www.protolabs.com/media/nrknfrcm/2026-026-cnc-material-data-sheet_ptfe-teflon.pdf
    year: 2026
    kind: datasheet
    license: supplier document, linked not reproduced
  plasticsintl:
    title: Teflon PTFE (Polytetrafluoroethylene) data sheet (Plastics International)
    id: Plastics International PTFE data sheet
    url: https://www.plasticsintl.com/media/trshlm53/ptfe-data-sheet.pdf
    year: 2023
    kind: datasheet
    license: supplier document, linked not reproduced
  banks2008:
    title: Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit
    id: NASA/TM-2008-215490, NTRS 20090011780
    url: https://ntrs.nasa.gov/citations/20090011780
    year: 2008
    kind: report
    license: public domain (NASA)
  nasa-tnd4553:
    title: Criteria for Selection of Wire Insulations for Use in Space Applications (V. Krueger)
    id: NASA TN D-4553, NTRS 19680018792
    url: https://ntrs.nasa.gov/citations/19680018792
    year: 1968
    kind: report
    license: public domain (NASA)
  rp1124:
    title: Outgassing Data for Selecting Spacecraft Materials (Campbell and Scialdone)
    id: NASA Reference Publication 1124, Revision 3, NTRS 19940017416
    url: https://ntrs.nasa.gov/citations/19940017416
    year: 1993
    kind: database
    license: public domain (NASA)
  degroh2005:
    title: Hubble Space Telescope Degradation Data Used for Ground-Based Durability Projection of Insulation on the International Space Station
    id: NASA Glenn research summary, NTRS 20050192335 (de Groh, Banks, Dever, Hodermarsky)
    url: https://ntrs.nasa.gov/citations/20050192335
    year: 2005
    kind: report
    license: public domain (NASA)
  wang2024:
    title: 'Evaluating the potential of thermoplastic polymers for cryogenic sealing applications: strain rate and temperature effects'
    id: arXiv:2406.01165 (pre-final version)
    url: https://arxiv.org/abs/2406.01165
    year: 2024
    kind: paper
    license: CC BY-NC-ND 4.0
  rogers-radiation:
    title: The Effect of Nuclear Radiation Exposure to RT/duroid PTFE-Based Composites
    id: Rogers Corporation publication 92-293, revised 081123
    url: https://www.RogersCorp.com/-/media/project/rogerscorp/documents/advanced-electronics-solutions/english/properties---detailed-characteristics/the-effect-of-exposure-of-rt-duroid-ptfe-based-composites-to-nuclear-radiation.pdf
    year: 2023
    kind: web
    license: manufacturer document, linked not reproduced
license: CC-BY-4.0
updated: '2026-10-17'
review:
  status: draft
  method: assistant
  checked_values: 26
  unreachable: 2
  caveats: 8
  note: Written by an AI assistant on 2026-10-17. All values were read in text extracted from the downloaded source PDFs (NASA TM, TN D-4553 and RP-1124, the Southampton preprint, the Proto Labs, Plastics International, GAPI and Rogers documents). RP-1124 is an OCR scan, so its PTFE rows were read from OCR text. 2 sources were not usable (the NASA outgassing database search page and a PubChem PTFE record). 8 values carry caveats noted in the file. No values were taken from memory.
story:
  recipe:
    line: "PTFE is made by free-radical polymerization of one monomer, tetrafluoroethylene (TFE, C2F4), initiated with persulfate such as potassium or ammonium persulfate (Wikipedia). Granular PTFE is made by suspension polymerization in water with agitation and often a surfactant; PTFE is also made by emulsion polymerization, where a surfactant keeps the polymer dispersed in water. TFE can explosively decompose to tetrafluoromethane and carbon, so the reaction needs special apparatus to prevent hot spots."
    parts:
      - {name: Carbon, symbol: C, atoms: 2, atomic_weight: 12.011, role: "The two backbone carbons of each repeat unit, bonded to each other."}
      - {name: Fluorine, symbol: F, atoms: 4, atomic_weight: 18.998, role: "Two fluorines on each backbone carbon."}
  risk_groups:
    - title: For people
      level: 2
      verdict: Safe as a solid; toxic fumes if overheated
      lead: The solid is described as not toxic, but heating PTFE above 300 °C can make you ill and above 400 °C can injure the lungs.
      points:
        - label: The solid
          line: A manufacturer safety data sheet (emission date 12/02/2007) says the solid is not classified as hazardous for transport, is not carcinogenic and is not toxic if swallowed. It ignites if a flame is applied, but combustion stops when the flame is removed.
        - label: Polymer fume fever
          line: Heating PTFE above 300 °C may release a fine fume that causes polymer fume fever, a flu-like illness with fever, chills, nausea and chest tightness. Symptoms are often delayed 4 to 24 hours and last 24 to 48 hours.
        - label: Hotter than 400 °C
          line: Above 400 °C the decomposition products may cause pulmonary inflammation, haemorrhage or oedema, especially in poor ventilation or confined spaces. Combustion gives very toxic and corrosive vapours such as hydrogen fluoride and carbonyl fluoride.
    - title: If it fails
      lead: These results come from a 1968 NASA guide, a NASA Glenn prediction and laboratory tests, not from a reported failure of a flown PTFE part.
      points:
        - label: Under radiation
          line: NASA TN D-4553 says Teflon TFE irradiated in air becomes useless after one or two megarads, and in high vacuum loses 88 percent of its elongation at 8 megarads. Radiation breaks the long molecular chains, so the plastic turns brittle.
        - label: In orbit
          line: A NASA Glenn study of the expanded PTFE cable on the ISS predicts a badly embrittled front surface, with cracks starting early and reaching about 0.030 cm deep after a 10-year mission. This is a ground-based prediction.
        - label: At hydrogen temperature
          line: In tensile tests at 2 mm/min, PTFE strain at break fell from 302.96 percent at room temperature to 2.51 percent at 20 K, so the sheet went from stretchy to brittle.
    - title: Handling and storage
      points:
        - label: Keep it cool
          line: The safety data sheet advises against using the material at high temperature (it says 280 °C), taking care to prevent inhaling fume, and not smoking while handling it.
        - label: Ventilate
          line: Use local exhaust ventilation to remove fumes. In a fire wear self-contained breathing apparatus, because hydrogen fluoride fumes can react with water to form hydrofluoric acid.
        - label: Waste
          line: The sheet says the solid is stable in normal storage and suggests recycling where possible, and disposal must follow local regulations.
  why: Polytetrafluoroethylene (PTFE) is a polymer, a material made of very long chains of repeating units. Each unit is two carbon atoms each holding two fluorine atoms, written (-CF2-CF2-). Fluorine bonds very tightly to carbon and the fluorine coats the chain like a smooth sheath, which is why PTFE is famously slippery, chemically inert and a very good electrical insulator. A supplier sheet gives a density of about 2.17 g/cm3 (dense for a plastic), a dielectric constant of 2.1 and a volume resistivity of 10^17 to 10^18 ohm cm. PTFE melts at about 327 °C and a supplier lists a working range from -200 °C to +260 °C. The price of that tight bonding is that the chain is held together only weakly from one chain to the next, so PTFE is soft (23 to 27 MPa tensile strength) and, unlike most polymers, it is sensitive to ionizing radiation. In low Earth orbit it survives atomic oxygen well, but radiation snips the chains and leaves it brittle.
  uses:
    - where: ISS railcar cable
      line: The trailing umbilical cables of the ISS Mobile Transporter use an outer jacket of six layers of expanded PTFE, about 43 mils thick, with an inner core of 7 to 10 mils. The cable has a 10-year mission life and was installed in April 2002.
    - where: Spacecraft wire insulation
      line: NASA's 1968 selection guide compared Teflon TFE and FEP with polyolefin insulations for spacecraft wire, ranking outgassing, radiation resistance and weight as the most important criteria.
    - where: Tested on the ground for hydrogen systems
      line: Researchers at Southampton tested PTFE in tension at room temperature, 77 K and 20 K to judge it as an alternative to metal seals in cryogenic fuel systems. These were laboratory tests, not a seal in service.
    - where: Flown on the ISS as film
      line: PTFE film was one of 40 polymers flown on the exterior of the ISS in the MISSE 2 experiment to measure atomic oxygen erosion over 3.95 years.
  can_do:
    - label: Atomic oxygen
      value: 1.42e-25 cm3/atom
      line: On the MISSE 2 flight PTFE eroded at 1.42 × 10⁻²⁵ cm³/atom, at a fluence of 8.43e21 atoms/cm², against 3.00 × 10⁻²⁴ for Kapton H in the same table.
    - label: Outgassing
      value: 0.00% in the NASA listing
      line: Outgassing is the release of trapped gases and volatile compounds in vacuum, which can then condense on optics and sensors. NASA's outgassing compilation lists a PTFE tubing product at 0.00% total mass loss (TML) and 0.00% condensable material (CVCM) after 24 hours at 125 °C in vacuum, and a PTFE wire insulation at 0.01% and 0.00%. These are finished products, not bulk resin.
    - label: Heat
      value: Melts at 327 °C
      line: A safety data sheet gives a melting point of 327 to 335 °C, and a supplier lists a service range of -200 °C to +260 °C. NASA's 1968 guide lists 260 °C as the maximum continuous service temperature of Teflon TFE wire insulation.
    - label: Electrical insulation
      value: 10^17 to 10^18 ohm cm
      line: A supplier sheet gives a volume resistivity of 10^17 to 10^18 ohm cm, a dielectric strength of 30 to 45 kV/mm (0.5 mm specimen, ASTM D149) and a dielectric constant of 2.1.
    - label: Low temperature
      value: 86.22 MPa at 77 K
      line: In tensile tests at 2 mm/min PTFE reached 18.15 MPa at room temperature, 86.22 MPa at 77 K and 82.32 MPa at 20 K. Strain at break fell to 4.44 percent at 77 K and 2.51 percent at 20 K, so it is much stronger but brittle when cold.
  compare: In low Earth orbit PTFE eroded at 1.42 × 10⁻²⁵ cm³/atom, against 2.99 × 10⁻²⁴ for PEEK and 3.00 × 10⁻²⁴ for Kapton H in the same flight table; FEP measured 2.00 × 10⁻²⁵. In a room-temperature tension test at 2 mm/min PTFE reached 18.15 MPa, against 99.55 MPa for PEEK and 31.99 MPa for UHMWPE in the same study, and at 77 K it reached 86.22 MPa against 198.14 MPa for PEEK. For radiation, NASA Glenn describes PTFE as significantly more susceptible to radiation degradation than FEP.
  handling:
    - The solid is not classified as hazardous for transport, but never heat it above 300 °C without ventilation.
    - Fumes from overheated PTFE cause polymer fume fever; above 400 °C they can injure the lungs.
    - Do not smoke while handling it, and use local exhaust ventilation where it is heated.
    - Fire gives hydrogen fluoride fumes, so use self-contained breathing apparatus.
  good_for:
    - Atomic oxygen resistance. The MISSE 2 erosion yield was 1.42 × 10⁻²⁵ cm³/atom, far below Kapton H at 3.00 × 10⁻²⁴.
    - Electrical insulation. A supplier sheet gives a dielectric constant of 2.1 and a volume resistivity of 10^17 to 10^18 ohm cm.
    - Low outgassing. NASA's listing shows PTFE tubing at 0.00% total mass loss and 0.00% condensable material after 24 hours at 125 °C.
    - A very wide temperature range. A supplier lists -200 °C to +260 °C.
  watch_out:
    - Radiation. NASA TN D-4553 says Teflon TFE becomes useless after one or two megarads in air, and loses 88 percent of its elongation at 8 megarads in vacuum.
    - Softness. Tensile strength is only 23 to 27 MPa at room temperature.
    - Brittle when cold. Strain at break fell from 302.96 percent at room temperature to 2.51 percent at 20 K.
    - Overheating. Heating above 300 °C releases fumes, and above 400 °C toxic gases including hydrogen fluoride.
  verdict: PTFE is a slippery, low-outgassing, electrically excellent plastic that resists atomic oxygen far better than most polymers, but it is soft and ionizing radiation breaks it down at doses of a few megarads. It suits shielded or short-exposure uses such as cable insulation, not a long-lived exposed surface. Only the MISSE 2 erosion yield here is a flight result; the radiation and cold figures are ground tests or literature summaries.
  compare_rows:
    - label: Density
      benchmark: density
      scope: material
    - label: Max service temp
      benchmark: max_service_temp
      scope: material
    - label: Glass transition temperature
      benchmark: glass_transition_temperature
      scope: material