spore: profile
id: pu
spore_version: 0.2
family: engineering-polymers
name: Polyurethane
abbreviation: PU
role: thermoplastic and cast elastomer, and rigid or flexible foam, made from a diisocyanate and a polyol
category: polymers
type: polyurethanes
summary: |
  Polyurethane (PU) is a polymer whose chains are joined by carbamate (urethane) links, made by reacting a diisocyanate or polymeric isocyanate with a polyol. As a sample on the MISSE 2 PEACE experiment in low Earth orbit it had an atomic oxygen erosion yield of 1.56e-24 cm3/atom, close to the 1.58e-24 cm3/atom predicted by NASA. Cast thermoplastic PU grades read for this profile are 1.03 g/cm3 with a tensile strength above 40 MPa and an elongation above 300 %, and a 95 Shore A elastomer from another range has a tensile strength of 10.5 MPa and an elongation of 250 %.
best_for: Flexible, tough elastomers and seals in the ground-tested grades read, and a known LEO atomic oxygen rate of 1.56e-24 cm3/atom
weakest_at: Atomic oxygen in low Earth orbit (erosion yield 1.56e-24 cm3/atom) and hydrolysis; the isocyanate precursors are strong respiratory sensitisers
identity:
  formula: 'Polyurethane: carbamate-linked polymer of a diisocyanate and a polyol; NASA TM repeat unit C6H10O4N2'
  cas: ''
  source: wikipedia-polyurethane
  where: Lead and Chemistry sections (carbamate links, diisocyanate plus polyol); repeat unit C6H10O4N2 from NASA TM-2008-215490 Table IV
tags:
  environments:
    - low-earth-orbit
  stresses:
    - atomic-oxygen
    - uv
    - vacuum-and-outgassing
  applications: []
properties:
  - benchmark: density
    label: Density, polyurethane (MISSE 2 PEACE ref. 12)
    value: 1.2345
    unit: g/cm3
    scope: material
    conditions:
      basis: density as listed in NASA Table II, column header 'Density, ref. 12, rho'
    method: Density value listed in NASA TM-2008-215490 Table II; the report gives no test temperature
    status: ground
    source: nasa-tm-2008-215490
    where: Table II (MISSE 2 PEACE polymers density and fractional ash content), row Polyurethane PU
  - benchmark: atomic_oxygen_erosion_yield
    label: Atomic oxygen erosion yield, polyurethane (MISSE 2)
    value: 1.56e-24
    unit: cm3/atom
    scope: material
    conditions:
      platform: ISS, MISSE 2 PEACE, low Earth orbit
      atomic_oxygen_fluence: 8.43×10^21 atoms/cm2 as printed in NASA TM Section 2 text
    method: Measured on MISSE 2 flight samples and listed in NASA TM-2008-215490 Table I
    status: flight
    source: nasa-tm-2008-215490
    where: Table I (MISSE 2 PEACE polymers erosion yield data), row Polyurethane PU
  - benchmark: atomic_oxygen_erosion_yield
    label: Atomic oxygen erosion yield, polyurethane (predicted)
    value: 1.58e-24
    unit: cm3/atom
    scope: material
    conditions:
      basis: NASA predictive tool, NASA TM-2008-215490
    method: Predicted by the NASA predictive tool and listed in Table VII beside the MISSE 2 value
    status: calculated
    source: nasa-tm-2008-215490
    where: Table VII (comparison of predicted and MISSE 2 measured erosion yields), row Pol yurethane PU
  - benchmark: density
    label: Density, cast thermoplastic PU (CPU-H)
    value: 1.03
    unit: g/cm3
    scope: material
    conditions:
      product: Max Spare CPU-H, thermoplastic cast polyurethane
      tolerance_as_printed: ±0.02
    method: Nominal value printed on the supplier datasheet, ASTM D 792
    status: ground
    source: maxspare-cpu-h
    where: Physical properties table, Density row
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, cast thermoplastic PU (CPU-H), 95 Shore A
    value: 40
    unit: Mpa
    scope: material
    conditions:
      product: Max Spare CPU-H
      bound_as_printed: '> 40'
    method: Nominal value printed on the supplier datasheet, ASTM D 412; printed unit is Mpa
    status: ground
    source: maxspare-cpu-h
    where: Physical properties table, Tensile strength row
  - benchmark: elongation
    label: Elongation at break, cast thermoplastic PU (CPU-H)
    value: 300
    unit: '%'
    scope: material
    conditions:
      product: Max Spare CPU-H
      bound_as_printed: '> 300'
    method: Nominal value printed on the supplier datasheet, ASTM D 412
    status: ground
    source: maxspare-cpu-h
    where: Physical properties table, Elongation at break row
  - benchmark: min_service_temp
    label: Operating temperature lower limit, CPU-H
    value: -30
    unit: °C
    scope: material
    conditions:
      product: Max Spare CPU-H
      range_as_printed: '-30 to +100 °C'
    method: Operating temperature printed on the supplier datasheet
    status: ground
    source: maxspare-cpu-h
    where: Physical properties table, Operating Temp. row
  - benchmark: max_service_temp
    label: Operating temperature upper limit, CPU-H
    value: 100
    unit: °C
    scope: material
    conditions:
      product: Max Spare CPU-H
      range_as_printed: '-30 to +100 °C'
    method: Operating temperature printed on the supplier datasheet
    status: ground
    source: maxspare-cpu-h
    where: Physical properties table, Operating Temp. row
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, PU range at 95 Shore A
    value: 10.5
    unit: MPa
    scope: material
    conditions:
      hardness: 95 Shore A
      standard_as_printed: BS EN ISO 37
      cure: full cure
    method: Typical value printed on the ARRK PU range datasheet, marked as for comparative purposes only
    status: ground
    source: arrk-pu-range
    where: Material properties table, Tensile Strength row, column 95
  - benchmark: elongation
    label: Elongation at break, PU range at 95 Shore A
    value: 250
    unit: '%'
    scope: material
    conditions:
      hardness: 95 Shore A
      standard_as_printed: BS EN ISO 37
      cure: full cure
    method: Typical value printed on the ARRK PU range datasheet, marked as for comparative purposes only
    status: ground
    source: arrk-pu-range
    where: Material properties table, Elongation at Break row, column 95
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, PU range at 35 Shore A
    value: 2.5
    unit: MPa
    scope: material
    conditions:
      hardness: 35 Shore A
      standard_as_printed: BS EN ISO 37
      cure: full cure
    method: Typical value printed on the ARRK PU range datasheet
    status: ground
    source: arrk-pu-range
    where: Material properties table, Tensile Strength row, column 35
  - benchmark: elongation
    label: Elongation at break, PU range at 35 Shore A
    value: 1000
    unit: '%'
    scope: material
    conditions:
      hardness: 35 Shore A
      standard_as_printed: BS EN ISO 37
      cure: full cure
    method: Typical value printed on the ARRK PU range datasheet
    status: ground
    source: arrk-pu-range
    where: Material properties table, Elongation at Break row, column 35
  - benchmark: flash_point
    label: Flash point, Part A of a polyurethane elastomer system
    value: 368
    unit: °F
    scope: material
    conditions:
      product: Smooth-On Crystal Clear Series Part A (isocyanate component)
      bound_as_printed: '>368°F'
    method: Value printed in the supplier SDS, Section 9
    status: ground
    source: smooth-on-480a-sds
    where: Section 9, Flash Point row
  - benchmark: max_service_temp
    label: Maximum operating temperature, PU range (35 to 65 Shore A)
    value: 100
    unit: °C
    scope: material
    conditions:
      note: Maximum operating temperature 100 °C at 35 to 65 Shore A, 120 °C at 75 to 95 Shore A, as printed
    method: Printed on the ARRK datasheet with the note that the value is application specific
    status: ground
    source: arrk-pu-range
    where: Material properties table, Max. Operating Temperature row
risks:
  hazards:
    - text: 'Isocyanate component (Part A): 4,4'' Methylenedicyclohexyl diisocyanate, CAS 5124-30-1, 35 – 85 % by weight. Signal word Danger. Causes skin irritation, may cause an allergic skin reaction, causes serious eye irritation, toxic if inhaled, may cause allergy or asthma symptoms or breathing difficulties if inhaled, may cause respiratory irritation.'
      ghs:
        - H315
        - H317
        - H319
        - H331
        - H334
        - H335
      source: smooth-on-480a-sds
      where: Section 2 (Hazard identification, H-code list) and Section 3.1 (composition)
    - text: MDI is described as an allergen and sensitiser; sensitised people may have dangerous systemic reactions to very small exposures, including respiratory failure.
      ghs:
        - H334
        - H335
      source: wikipedia-mdi
      where: Hazards section (H334 and H335 listed in the article infobox)
  failure_risks:
    - mode: Atomic oxygen erosion in low Earth orbit
      trigger: Exposure of a polyurethane part to atomic oxygen in low Earth orbit, as on the MISSE 2 flight
      consequence: Surface erosion at 1.56e-24 cm3/atom as measured on MISSE 2, and 1.58e-24 cm3/atom predicted by NASA.
      severity: moderate
      source: nasa-tm-2008-215490
      where: Table I and Table VII
    - mode: Hydrolysis
      trigger: Exposure to water over time
      consequence: Wikipedia states that polyurethanes may degrade due to hydrolysis; no test figure is given.
      source: wikipedia-polyurethane
      where: Degradation section
  side_effects: []
  handling:
    - text: Isocyanate Part A is a respiratory and skin sensitiser; the SDS requires ventilation or respiratory protection when inadequately ventilated (P285).
      source: smooth-on-480a-sds
  mitigations: []
uses:
  - application: mechanisms
    device: Cast thermoplastic polyurethane seals and rollers
    example: CPU-H, a cast thermoplastic polyurethane sold by Max Spare for seals, with a Shore A hardness of 95, density 1.03 g/cm3 and operating range -30 to +100 °C.
    source: maxspare-cpu-h
    where: Product header and Physical properties table
  - application: structures
    device: Polymer sample on a space flight experiment
    example: Polyurethane on the MISSE 2 PEACE tray, flown on the ISS in low Earth orbit, with erosion yield listed in NASA TM-2008-215490.
    source: nasa-tm-2008-215490
    where: Table I
  - application: structures
    device: Foam and elastomer products
    example: Polyurethane is made by reacting a diisocyanate with a polyol, and flexible foams began production in 1954 using TDI and polyester polyols.
    source: wikipedia-polyurethane
    where: Lead, Chemistry and History sections
supply:
  - subject: Polyurethane (global output)
    demand: Global production in 2019 was 25 million metric tonnes; foams accounted for 67 % of all polyurethane produced in 2016.
    routes: Reaction of a diisocyanate (or polymeric isocyanate) with a polyol.
    producers: []
    critical_lists: []
    substitutes: []
    source: wikipedia-polyurethane
    where: Production section
  - subject: Methylene diphenyl diisocyanate (MDI, main isocyanate for rigid PU)
    demand: Total world production of MDI and polymeric MDI was over 7.5 million tonnes per year as of 2017.
    routes: MDI reacts with polyols in the manufacture of polyurethane.
    producers: []
    critical_lists: []
    substitutes: []
    source: wikipedia-mdi
    where: Production section; Uses section
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: Smooth-On Safety Data Sheet, Crystal Clear Series Part A, SDS No. 480A (revision 25 June 2021)
    type: sds
    url: https://www.smooth-on.com/msds/files/CRYSTAL%20CLEAR%203713%20A_3_B_3%20SDS.pdf
    year: 2021
  - title: Max Spare CPU-H, Thermoplastic Cast Polyurethane datasheet
    type: datasheet
    url: https://www.maxspare.com/sealingmaterials/CPU-H.pdf
  - title: ARRK, Elastomers Polyurethane (PU) and Silicone Material Datasheet Range, December 2022
    type: datasheet
    url: https://spg.arrk.com/assets/img/arrk-spg-datasheet-pu-elastomers-materials_dec-2022.pdf
    year: 2022
  - title: NIST Atomic Weights and Isotopic Compositions for All Elements (C, H, N, O)
    type: database
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=C&all=all&ascii=html
gaps:
  - No flight or ground outgassing, total mass loss, UV or thermal-cycling result for polyurethane in space was read in this run; the NASA report gives only the erosion yield.
  - The Wikipedia page gives no numeric repeat unit; the repeat unit used here is the NASA TM model unit C6H10O4N2, not a verified structure for a commercial PU.
  - Cured-polyurethane hazard data were not found on a fetched page. The hazards recorded are from the Part A isocyanate SDS (Smooth-On), which is the reactive component, not the cured polymer.
  - Isocyanate supply (MDI and TDI) producer shares by country were not found on a primary source; no USGS or critical-mineral list applies to PU.
  - The Erlan 80 cast PU datasheet redirected to an unrelated page and could not be read.
  - Hardness values for the ARRK and CPU-H grades are not in the canonical property list and are not recorded as properties; the Shore A numbers appear in the labels and uses.
  - Atomic oxygen fluence (8.43e21 atoms/cm2) and the exposure duration (about 4 years) are printed in the NASA TM but are not recorded as properties because the name is not in the canonical list.
  - The 2019 global production (25 Mt) and the MDI figure are from Wikipedia and carry no primary citation in the article text read.
  - No PubChem record for polyurethane or MDI was read; PubChem returned a verification page.
  - The NASA TM notes erosion yield can be affected by fluence and sample state; no per-sample exposure time for the PU flight sample was read beyond the 4-year total.
sources:
  nasa-tm-2008-215490:
    title: Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit
    id: NASA/TM-2008-215490 (Banks and Backus, 2008), NTRS 20090011780
    url: https://ntrs.nasa.gov/citations/20090011780
    year: 2008
    kind: report
    license: NASA public document
  wikipedia-polyurethane:
    title: Polyurethane, Wikipedia
    id: Polyurethane article, Lead, Chemistry, History, Degradation and Production sections
    url: https://en.wikipedia.org/wiki/Polyurethane
    kind: web
    license: CC BY-SA 4.0, linked not reproduced
  wikipedia-mdi:
    title: Methylene diphenyl diisocyanate, Wikipedia
    id: MDI article, Uses, Hazards and Production sections
    url: https://en.wikipedia.org/wiki/Methylene_diphenyl_diisocyanate
    kind: web
    license: CC BY-SA 4.0, linked not reproduced
  smooth-on-480a-sds:
    title: Smooth-On Safety Data Sheet, Crystal Clear Series Part A (SDS No. 480A)
    id: SDS No. 480A, revision 25 June 2021, version 2.0
    url: https://www.smooth-on.com/msds/files/CRYSTAL%20CLEAR%203713%20A_3_B_3%20SDS.pdf
    year: 2021
    kind: datasheet
    license: supplier SDS, linked not reproduced
  maxspare-cpu-h:
    title: Max Spare CPU-H Thermoplastic Cast Polyurethane datasheet
    id: CPU-H physical properties table
    url: https://www.maxspare.com/sealingmaterials/CPU-H.pdf
    kind: datasheet
    license: manufacturer datasheet, linked not reproduced
  arrk-pu-range:
    title: ARRK Elastomers Polyurethane and Silicone Material Datasheet Range
    id: ARRK SPG datasheet, December 2022
    url: https://spg.arrk.com/assets/img/arrk-spg-datasheet-pu-elastomers-materials_dec-2022.pdf
    year: 2022
    kind: datasheet
    license: manufacturer datasheet, linked not reproduced
  nist-carbon:
    title: NIST Atomic Weights and Isotopic Compositions, carbon
    id: NIST standard atomic weight of C [12.0096, 12.0116]
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=C&all=all&ascii=html
    kind: database
    license: US government data
  nist-hydrogen:
    title: NIST Atomic Weights and Isotopic Compositions, hydrogen
    id: NIST standard atomic weight of H [1.007 84, 1.008 11]
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=H&all=all&ascii=html
    kind: database
    license: US government data
  nist-nitrogen:
    title: NIST Atomic Weights and Isotopic Compositions, nitrogen
    id: NIST standard atomic weight of N [14.006 43, 14.007 28]
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=N&all=all&ascii=html
    kind: database
    license: US government data
  nist-oxygen:
    title: NIST Atomic Weights and Isotopic Compositions, oxygen
    id: NIST standard atomic weight of O [15.999 03, 15.999 77]
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=O&all=all&ascii=html
    kind: database
    license: US government data
license: CC-BY-4.0
updated: '2026-10-20'
review:
  status: draft
  method: assistant
  checked_values: 14
  unreachable: 2
  caveats: 4
  note: Values read by an AI assistant on 2026-10-20 from the pages named. NASA Table I, II and VII were read from the NTRS PDF text. Unreachable Erlan 80 datasheet (redirect) and PubChem (verification page).
story:
  recipe:
    line: Polyurethane is made by reacting a diisocyanate with a polyol, forming carbamate (urethane) links between the two monomers. The repeat unit used for the NASA atomic oxygen model is C6H10O4N2, with the atoms listed below.
    parts:
      - name: Carbon
        symbol: C
        role: Carbon skeleton of the diisocyanate and polyol segments.
      - name: Hydrogen
        symbol: H
        role: Hydrogen on the chain and in the urethane N-H groups.
      - name: Oxygen
        symbol: O
        role: Oxygen in the carbamate C=O and C-O-C links.
      - name: Nitrogen
        symbol: 'N'
        role: Nitrogen in the carbamate N-H links formed from the isocyanate.
  risk_groups:
    - title: For people
      lead: The cured polymer is not described as hazardous in the sources read; the reactive isocyanate component is.
      level: 2
      verdict: Isocyanate component is a respiratory and skin sensitiser
      points:
        - label: Classification
          line: The Smooth-On Part A SDS prints H315, H317, H319, H331, H334 and H335, with signal word Danger, for the isocyanate component.
        - label: Composition
          line: The same SDS lists 4,4' Methylenedicyclohexyl diisocyanate, CAS 5124-30-1, at 35 to 85 % by weight.
    - title: If it fails
      lead: The failure route in these sources is erosion in orbit and hydrolysis.
      points:
        - label: Atomic oxygen
          line: On MISSE 2 the erosion yield was 1.56e-24 cm3/atom, against 1.58e-24 cm3/atom predicted by NASA.
        - label: Hydrolysis
          line: Wikipedia states that polyurethanes may degrade due to hydrolysis; no test figure is given.
  why: Polyurethane is a versatile polymer joined by carbamate links. The NASA report records a LEO atomic oxygen erosion yield of 1.56e-24 cm3/atom on MISSE 2, close to its prediction. Cast thermoplastic grades read give tensile strengths of 40 MPa or more and elongations of 300 % or more.
  can_do:
    - label: Stretch and recover
      value: 1000 % elongation
      benchmark: elongation
      line: The ARRK range gives 1000 % elongation at break at 35 Shore A, and 250 % at 95 Shore A, both as typical values.
    - label: Survive in orbit with known erosion
      value: 1.56e-24 cm3/atom
      benchmark: atomic_oxygen_erosion_yield
      line: NASA lists a MISSE 2 erosion yield for polyurethane of 1.56e-24 cm3/atom and predicts 1.58e-24 cm3/atom.
    - label: Work between -30 and 100 °C
      value: '-30 to 100 °C'
      benchmark: min_service_temp
      line: The CPU-H datasheet prints an operating range of -30 to +100 °C.
  compare: The rows compare different grades and test methods, so they are examples and not a ranking. The NASA density is for the polymer on the MISSE 2 tray, while the CPU-H and ARRK rows are supplier typical values.
  compare_rows:
    - scope: material
      label: Density
      benchmark: density
    - scope: material
      label: Erosion yield
      benchmark: atomic_oxygen_erosion_yield
    - scope: material
      label: Tensile strength at 95 Shore A
      benchmark: ultimate_tensile_strength
  handling:
    - 'Treat the isocyanate component as a respiratory and skin sensitiser: use ventilation and respiratory protection, as the SDS requires.'
    - Check the current supplier SDS for each grade, since the cured elastomer and the isocyanate part are different materials.
    - Treat the datasheet values as typical, not as specification limits.
  good_for:
    - 'Flexible elastomers: 1000 % elongation at break at 35 Shore A in the ARRK range.'
    - 'Known atomic oxygen behaviour: 1.56e-24 cm3/atom on MISSE 2, measured in low Earth orbit.'
    - Seals in a -30 to +100 °C range (CPU-H datasheet).
  watch_out:
    - Atomic oxygen erodes PU at 1.56e-24 cm3/atom in low Earth orbit, so exterior use needs protection or a rate allowance.
    - 'Isocyanate sensitisation: the Part A SDS prints H334, which can cause asthma-like symptoms on inhalation.'
    - No outgassing, UV or radiation result for PU in space was read, so only the erosion yield is recorded.
  verdict: Polyurethane has a MISSE 2 flight erosion yield of 1.56e-24 cm3/atom in low Earth orbit, a density of 1.2345 g/cm3 in the NASA table, and typical elastomer grades with tensile strengths from 2.5 to 40 MPa and elongations up to 1000 %. Its isocyanate precursors are strong sensitisers, and this profile has no sourced space outgassing or UV data.