spore: profile id: peo spore_version: 0.2 family: engineering-polymers name: Polyethylene oxide abbreviation: PEO role: Water-soluble polyether; flown as a MISSE 2 PEACE polymer for atomic-oxygen erosion category: polymers type: polyethers summary: | Polyethylene oxide (PEO) is the linear polyether (-CH2CH2O-)n. It was one of the 40 polymers flown on the outside of the International Space Station in the MISSE 2 PEACE experiment, exposed for about 4 years (8.43e21 atoms/cm2 atomic-oxygen fluence). NASA measured an in-space atomic-oxygen erosion yield of 1.93e-24 cm3/atom, which was more than three times lower than the predictive formula gave. A commercial PEO grade (Polysciences 06104, molecular weight about 100,000) melts at 66 to 75 C and is soluble in water. best_for: Water-soluble, flexible polymer for aqueous formulations; the flown erosion yield is low enough to make it a candidate where atomic-oxygen erosion is the main concern weakest_at: 'Heat and water: the MISSE 2 table gives a maximum operating temperature of 65 C, the grade melts at 66 to 75 C, and the polymer is soluble in water' identity: formula: (-CH2CH2O-)n, poly(ethylene oxide); repeat unit C2H4O cas: 25322-68-3 source: polysciences-06104 where: 'Product 06104 page: CAS Number 25322-68-3 and Linear Formula (-CH2CH2O-)n. The repeat unit C2H4O, molar mass 44.0530 g/mol, is printed in Table I of nasa-tm-2008-215490.' tags: environments: - low-earth-orbit stresses: - atomic-oxygen - thermal-cycling - vacuum-and-outgassing applications: - structures - mechanisms properties: - benchmark: atomic_oxygen_erosion_yield label: Atomic oxygen erosion yield, MISSE 2 PEACE flight, low Earth orbit value: 1.93e-24 unit: cm3/atom scope: material conditions: environment: low Earth orbit, outside the ISS Quest airlock, MISSE 2 PEC 2 tray 1 fluence: 8.43e21 atoms/cm2 duration: about 4 years method: Mass loss and density measured after flight, per NASA TM-2008-215490 (Banks, de Groh and Backus) status: flight source: nasa-tm-2008-215490 where: Table I, row Polyethylene oxide (PEO), MISSE 2 erosion yield column - benchmark: atomic_oxygen_erosion_yield label: Atomic oxygen erosion yield predicted by NASA formula for PEO value: 7.99e-24 unit: cm3/atom scope: material conditions: basis: predictive tool from chemical structure, bonding and density, before flight comparison method: Predictive formula printed in NASA TM-2008-215490; not a measurement status: calculated source: nasa-tm-2008-215490 where: Table VII, row Polyethylene oxide (PEO), predicted erosion yield column - benchmark: atomic_oxygen_erosion_yield label: Atomic oxygen erosion yield, RF plasma asher ground test value: 1.8e-23 unit: cm3/atom scope: material conditions: apparatus: RF plasma asher, ground laboratory test method: Plasma asher erosion yield as printed in NASA TM-2011-216904 status: ground source: nasa-tm-2011-216904 where: Erosion yield comparison table, row 2-E5-17 Polyethylene oxide (PEO), asher erosion yield column - benchmark: erosion_yield_ratio label: Ratio of asher to in-space erosion yield, PEO value: 9.3 unit: ratio scope: material conditions: basis: asher erosion yield divided by MISSE 2 in-space erosion yield, as printed method: Ratio column printed in NASA TM-2011-216904 status: ground source: nasa-tm-2011-216904 where: Erosion yield comparison table, row 2-E5-17 Polyethylene oxide (PEO), ratio column - benchmark: density label: Density of MISSE 2 PEO sample value: 1.147 unit: g/cm3 scope: material conditions: sample: MISSE 2 PEACE PEO sample, dehydrated before weighing method: Density gradient column, as printed in NASA TM-2008-215490 status: ground source: nasa-tm-2008-215490 where: Table II, row Polyethylene oxide (PEO), density column (ref. 12) - benchmark: fractional_ash_content label: Fractional ash content of PEO after oxidation in a plasma asher value: 0.00112 unit: mass fraction scope: material conditions: method: fraction of the dehydrated polymer mass left as nonvolatile ash after complete oxidation method: RF plasma asher, as printed in NASA TM-2008-215490 status: ground source: nasa-tm-2008-215490 where: Table II, row Polyethylene oxide (PEO), mass fraction of polymer that is ash column (Na) - benchmark: melting_point label: Melting point, commercial PEO grade MW about 100,000 value: 66 value_high: 75 unit: °C scope: material conditions: grade: Polysciences product 06104, molecular weight about 100,000, CAS 25322-68-3 method: Vendor product specification as printed status: ground source: polysciences-06104 where: Product specification table, row Melting Point (printed as 66-75°) and product text (printed as 66-75°C) - benchmark: refractive_index label: Refractive index, commercial PEO grade MW about 100,000 value: 1.51 value_high: 1.54 unit: dimensionless scope: material conditions: grade: Polysciences product 06104, molecular weight about 100,000 temperature: not stated method: Vendor product specification as printed (printed as 1.510-1.540) status: ground source: polysciences-06104 where: Product specification table, row Refractive Index - benchmark: max_service_temp label: Maximum operating temperature, PEO/Alkox in MISSE PEACE value: 65 unit: C scope: material conditions: trade_name: Alkox E-30 powder, MISSE serial 2-E5-17 method: Maximum operating temperature as listed for the MISSE PEACE material, from NASA TM-2001-211311 status: ground source: nasa-tm-2001-211311 where: Table 2, List of Vacuum Heat Treated MISSE PEACE Polymers, row -2 -E5 -17 Polyethylene oxide PEO/Alkox, Max. Operating Temperature column - benchmark: heat_treatment_temperature label: Vacuum heat treatment before flight, PEO/Alkox value: 60 unit: C scope: material conditions: duration: 24 hrs atmosphere: vacuum method: Pre-flight vacuum heat treatment as listed, from NASA TM-2001-211311 status: ground source: nasa-tm-2001-211311 where: Table 2, row -2 -E5 -17 Polyethylene oxide PEO/Alkox, Vacuum Heat Treatment column - benchmark: atomic_oxygen_fluence label: Atomic oxygen fluence, MISSE 2 PEACE flight value: 8.43e+21 unit: atoms/cm2 scope: material conditions: witness: average of two fluence witness samples duration: 4 yr exposure method: Fluence from witness samples, as printed in NASA TM-2008-215490 status: flight source: nasa-tm-2008-215490 where: Section 2.1 (Flight exposure), and Section Introduction - benchmark: solar_exposure label: Total equivalent sun hours, MISSE 2 PEACE flight value: 5000 value_high: 6700 unit: ESH scope: material conditions: includes: Earth-reflected illumination of 650 to 820 ESH method: Estimated total as printed in NASA TM-2008-215490 status: flight source: nasa-tm-2008-215490 where: Section 2.1 (Flight exposure) - benchmark: thermal_cycle_range label: Base-plate thermal cycling range, MISSE 2 flight value: -30 value_high: 40 unit: C scope: material conditions: note: Nominal base-plate range, with occasional short-term excursions method: Nominal range as printed in NASA TM-2008-215490 status: flight source: nasa-tm-2008-215490 where: Section 2.1 (Flight exposure) gaps: - No supply, production or critical-mineral data for PEO were read in this run; the supply section is empty. - PubChem (CID lookup and compound page) could not be opened in this run; no PubChem GHS classification was read. - Sigma-Aldrich product pages timed out in this run, so no second vendor datasheet was read for density, glass transition or melting point. - No PEO glass transition temperature, density or thermal decomposition value was read from a fetched page in this run. - Wikipedia polyethylene glycol gives a density of 1.125 with no unit, so it was not used as a value. - 'Non-canonical property names used: atomic_oxygen_erosion_yield, erosion_yield_ratio, fractional_ash_content, heat_treatment_temperature, atomic_oxygen_fluence, solar_exposure, thermal_cycle_range.' - Only one MISSE 2 PEO row was read per source; the ground asher value comes from one NASA paper and no second ground test was found. - Hazard data rest on the Polysciences product page (irritant); no SDS for PEO was read in this run. - 'Uses: no source in this run names a space application beyond the MISSE 2 flight test; the second use is a vendor-listed formulation use.' sources: nasa-tm-2008-215490: title: Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit, NASA/TM-2008-215490 url: https://ntrs.nasa.gov/citations/20090011780 kind: report year: 2008 license: NASA public document nasa-tm-2001-211311: title: MISSE PEACE Polymers experiment, NASA/TM-2001-211311, Table 2 (vacuum heat treated MISSE PEACE polymers) url: https://misse1.larc.nasa.gov/misseone/TM-2001-211311.pdf kind: report year: 2001 license: NASA public document nasa-tm-2011-216904: title: Ground-Laboratory to In-Space Atomic Oxygen Correlation for the PEACE Polymers, NASA/TM-2011-216904 url: https://ntrs.nasa.gov/api/citations/20110006367/downloads/20110006367.pdf kind: report year: 2011 license: NASA public document polysciences-06104: title: Polysciences product 06104, Poly(ethylene oxide) MW 100,000 url: https://www.polysciences.com/default/polyethylene-oxide-mw-100000 kind: datasheet license: Manufacturer product page (cited, not reproduced) wiki-peg: title: Wikipedia, Polyethylene glycol (PEG and PEO naming by molecular mass) url: https://en.wikipedia.org/wiki/Polyethylene_glycol kind: web license: CC BY-SA (Wikipedia) wiki-atomic-oxygen: title: Wikipedia, Atomic oxygen (definition and reactivity) url: https://en.wikipedia.org/wiki/Atomic_oxygen kind: web license: CC BY-SA (Wikipedia) story: recipe: line: Poly(ethylene oxide) is made from the repeat unit -CH2CH2O-, with formula (C2H4O)n (Polysciences 06104, linear formula; NASA TM-2008-215490, Table I). The repeat-unit molar mass printed in NASA Table I is 44.0530 g/mol. The vendor grade has a molecular weight of about 100,000 (Polysciences 06104). Wikipedia distinguishes PEO (higher molecular mass) from PEG (lower molecular mass) (wiki-peg). parts: - name: Ethylene oxide repeat unit symbol: C2H4O share_note: Repeat unit C2H4O, molar mass 44.0530 g/mol (NASA TM-2008-215490, Table I) role: Only repeat unit; the grade is set by molecular weight, about 100,000 for Polysciences 06104 risk_groups: - title: For people lead: The one hazard statement read is a vendor's irritant classification for the powder. level: 1 verdict: Irritant (vendor) points: - label: Handling line: Polysciences 06104 says to avoid excessive dust generation during powder transfer, and to wear gloves and safety glasses when appropriate. - title: If it fails lead: The flight data show erosion, not a failure threshold. points: - label: Erosion line: The NASA paper says the PEO erosion yield was anomalously low by more than a factor of three against the predictive formula, and the predicted value was 7.99e-24 cm3/atom. - title: Handling and storage points: - label: Storage line: Store at room temperature and keep the container tightly closed, per the Polysciences product page. why: Polyethylene oxide is the linear polyether (-CH2CH2O-)n. As a MISSE 2 PEACE polymer it spent about 4 years outside the ISS, and NASA measured an atomic-oxygen erosion yield of 1.93e-24 cm3/atom. That value was more than three times lower than its predictive formula, which NASA said is why PEO was left out of the formula's data set. Its melting point and water solubility, from a vendor grade of molecular weight about 100,000, limit its use where heat or water is present. uses: - where: MISSE 2 PEACE flight test line: PEO was one of the 40 polymers in the MISSE 2 PEACE experiment on the ISS, flown with a total fluence of 8.43e21 atoms/cm2. - where: Coating and lubricant formulations line: Polysciences lists PEO for rheology and viscosity control in aqueous formulations and for coating and lubricant formulation work. can_do: - label: Erosion yield value: '1.93e-24' unit: cm3/atom benchmark: atomic_oxygen_erosion_yield line: Flown on MISSE 2, PEO eroded at 1.93e-24 cm3/atom (NASA TM-2008-215490, Table I). - label: Density value: '1.147' unit: g/cm3 benchmark: density line: The MISSE 2 PEACE PEO sample has a density of 1.147 g/cm3 (NASA TM-2008-215490, Table II). - label: Melting point value: '66' unit: °C benchmark: melting_point line: The commercial PEO grade of molecular weight about 100,000 melts at 66 to 75 °C (Polysciences 06104). compare: Within this profile, the in-space erosion yield of PEO is 1.93e-24 cm3/atom, and the ground plasma asher erosion yield is 1.8e-23 cm3/atom, a ratio of 9.3. NASA reports that the PEO ground yield runs about nine times the flight yield, so ground asher data should not be read as a flight value. compare_rows: - scope: material label: Erosion yield in flight benchmark: atomic_oxygen_erosion_yield - scope: material label: Density benchmark: density - scope: material label: Melting point benchmark: melting_point handling: - Store at room temperature in a tightly closed container (Polysciences 06104). - Avoid excessive dust generation during powder transfer, and use clean equipment to reduce contamination (Polysciences 06104). - Fingerprints on PEO and Upilex-S samples meant no early erosion value was recorded, so handle flight samples with gloves (NASA TM-2011-216904). good_for: - 'Low atomic-oxygen erosion in orbit: 1.93e-24 cm3/atom in MISSE 2.' - 'Aqueous formulations: the product page lists PEO as soluble in water, acetone, alcohol, chloroform, toluene and dichloromethane.' watch_out: - 'Heat: the MISSE 2 PEO/Alkox sample has a maximum operating temperature of 65 C, and the commercial grade melts at 66 to 75 C.' - 'Water: the commercial grade is soluble in water, so it is not a candidate for wet or humid service without a barrier.' - 'Data gaps: no PEO glass transition, decomposition or UV value was read in this run.' verdict: PEO is a water-soluble polyether whose one flight measurement, 1.93e-24 cm3/atom in MISSE 2, is low for a polymer in orbit. Its heat limit of 65 C and its water solubility are the main limits, and the supply and hazard records are thin. review: status: draft method: assistant checked_values: 13 caveats: 2 note: Written by an AI assistant from pages fetched in this run. PubChem and Sigma-Aldrich could not be opened. Flight values were re-read from NASA TM-2008-215490 and cross-checked with NASA TM-2011-216904. updated: '2026-10-20' license: CC-BY-4.0 corrosion: - environment: Atomic oxygen in low Earth orbit, MISSE 2 PEACE flight (fluence 8.43e21 atoms/cm2) headline: PEO eroded at 1.93e-24 cm3/atom in flight, which is more than three times lower than the NASA predictive formula gave. effect: NASA reports that PEO was significantly off the linear fit of the predictive tool, with a measured in-space yield lower than predicted by a factor of greater than three, so NASA excluded PEO from the formula's data base. rating: low conditions: exposure: ISS exterior, MISSE 2 PEC 2 tray 1, about 4 years basis: flight erosion yield after mass loss and density measurement source: nasa-tm-2008-215490 where: Section 4 (Results, PEO discussion) and Table I, row Polyethylene oxide (PEO) - environment: Plasma asher ground test of atomic oxygen erosion, PEO headline: The ground asher yield for PEO is 1.8e-23 cm3/atom, about 9.3 times the flight value. effect: NASA compares asher and in-space yields and reports PEO among the materials whose ratio is noticeably high (9.3), with fingerprints on the PEO sample so that no early erosion value was recorded. rating: moderate conditions: apparatus: RF plasma asher sample: MISSE 2 PEO sample with fingerprints noted source: nasa-tm-2011-216904 where: Erosion yield comparison table, row 2-E5-17; discussion of ratios and fingerprints - environment: Heat, above the PEO/Alkox maximum operating temperature headline: The MISSE 2 PEO/Alkox sample is rated to 65 C, and the commercial grade melts at 66 to 75 C. effect: PEO softens and melts close to 65 C, so it is not a high-temperature polymer. The MISSE 2 sample was vacuum heat treated at 60 C for 24 hrs before flight. rating: moderate conditions: grade: Polysciences 06104, molecular weight about 100,000 source: nasa-tm-2001-211311 where: Table 2 (Max. Operating Temperature and Vacuum Heat Treatment for PEO/Alkox) - environment: Water and aqueous solutions headline: The commercial PEO grade dissolves in water, so water exposure is a degradation route by dissolution. effect: Polysciences lists the grade as soluble in water, acetone, alcohol, chloroform, toluene and dichloromethane. The page gives no water-ageing or swelling data. rating: severe conditions: grade: Polysciences 06104, molecular weight about 100,000 source: polysciences-06104 where: Product specification table, row Soluble In risks: hazards: - text: Polysciences 06104 is classified as an irritant. Its product page says to refer to the SDS for hazard information. ghs: [] source: polysciences-06104 where: Hazards row, Hazard Code row, and Safety and Documentation section failure_risks: - mode: Erosion of a thin PEO film in atomic oxygen trigger: Long exposure to low Earth orbit atomic oxygen, 8.43e21 atoms/cm2 in MISSE 2 consequence: NASA states that the PEACE samples, in general, eroded partially or completely through at a fluence close to the full mission fluence. severity: moderate source: nasa-tm-2008-215490 where: Section 2 (Results), paragraph on samples eroding through side_effects: - text: Fingerprints on a PEO sample meant no erosion yield was recorded in the early tests, so handling skin contact can corrupt the ground result. affects: Ground erosion measurements source: nasa-tm-2011-216904 where: Discussion of samples with fingerprints handling: - text: Store at room temperature in a tightly closed container. Avoid dust formation during powder transfer. source: polysciences-06104 where: Handling and Storage section mitigations: - text: Keep the service temperature below 65 C, the MISSE 2 maximum operating temperature for this material. source: nasa-tm-2001-211311 where: Table 2, row PEO/Alkox uses: - application: structures device: MISSE 2 PEACE flight test sample, outside the ISS (flight test, not a flight part) example: PEO was one of the 40 polymers flown on MISSE 2 PEACE with an atomic-oxygen fluence of 8.43e21 atoms/cm2 over about 4 years. source: nasa-tm-2008-215490 where: Section 2.1 (Flight exposure) and Table I - application: mechanisms device: Coating and lubricant formulations (vendor-listed use) example: Polysciences lists PEO for coating and lubricant formulation work where water solubility and lubricity matter. source: polysciences-06104 where: Applications, Coatings and Lubricants 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: NASA TM-2001-211311, MISSE PEACE Polymers experiment type: report url: https://misse1.larc.nasa.gov/misseone/TM-2001-211311.pdf year: 2001 - title: NASA TM-2011-216904, Ground-Laboratory to In-Space Atomic Oxygen Correlation for the PEACE Polymers type: report url: https://ntrs.nasa.gov/api/citations/20110006367/downloads/20110006367.pdf year: 2011 - title: Polysciences product 06104, Poly(ethylene oxide) MW 100,000 type: datasheet url: https://www.polysciences.com/default/polyethylene-oxide-mw-100000