Polyethylene oxide PEO

(-CH₂CH₂O-)n, poly(ethylene oxide) · CAS 25322-68-3

Polyethylene oxide (PEO) is the linear polyether (-CH2CH2O-)n.

6 sources · Updated 2026-10-20 · CC BY 4.0

Evidence level

5 of 5

Flown or field-proven

Erosion yield

1.93e-24

Density

1.147

Melting point

Recipe, share of the weight

C2H4O Repeat unit C2H4O, molar mass 44.0530 g/mol (NASA TM-2008-215490, Table I)Ethylene oxide repeat unit

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

Risk at a glance

People Low. Irritant (vendor)
If it fails Moderate. Erosion of a thin PEO film in atomic oxygen
Corrosion Severe. The commercial PEO grade dissolves in water, so water exposure is a degradation route by dissolution.

Quick facts: PEO

Key properties of PEO
Property	Value	Basis
Density	1.15 g/cm³	1 sourced value
Melting point	66 to 75 °C	1 sourced value
Maximum service temperature	65 °C	1 sourced value

What is the density of Polyethylene oxide (PEO)?

Polyethylene oxide (PEO) has a density of 1.15 g/cm³. The source and test conditions are listed in the properties table on this page.

What is the melting point of Polyethylene oxide (PEO)?

Polyethylene oxide (PEO) has a melting point of 66 to 75 °C. The source and test conditions are listed in the properties table on this page.

What is the maximum service temperature of Polyethylene oxide (PEO)?

Polyethylene oxide (PEO) has a maximum service temperature of 65 °C. The source and test conditions are listed in the properties table on this page.

What is Polyethylene oxide (PEO) used for?

Uses recorded in the sources include MISSE 2 PEACE flight test sample, outside the ISS (flight test, not a flight part); Coating and lubricant formulations (vendor-listed use).

Why it exists

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.

Where it's used

MISSE 2 PEACE flight test

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.

Coating and lubricant formulations

Polysciences lists PEO for rheology and viscosity control in aqueous formulations and for coating and lubricant formulation work.

Recipe

(-CH₂CH₂O-)n, poly(ethylene oxide); repeat unit C₂H₄O

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).

What PEO is made of
Ingredient	Share of the weight	What it does
Ethylene oxide repeat unit C2H4O	Repeat unit C2H4O, molar mass 44.0530 g/mol (NASA TM-2008-215490, Table I)	Only repeat unit; the grade is set by molecular weight, about 100,000 for Polysciences 06104

Weight shares are as printed in the sources.

What it can do

Erosion yield

1.93e-24

measured

Flown on MISSE 2, PEO eroded at 1.93e-24 cm3/atom (NASA TM-2008-215490, Table I).

Density

1.147

measured

The MISSE 2 PEACE PEO sample has a density of 1.147 g/cm3 (NASA TM-2008-215490, Table II).

Melting point

measured

The commercial PEO grade of molecular weight about 100,000 melts at 66 to 75 °C (Polysciences 06104).

How it compares

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.

The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details. Other materials are shown beside it; each was measured under its own conditions, so open its page before comparing closely. Compare every grade in the family.

Benchmarks
Measurement	PEO	PPO
Thermal behavior and safety
Melting point, commercial PEO grade MW about 100,000Vendor product specification as printed	66 °C	no data
Vacuum heat treatment before flight, PEO/Alkox	60 °C⁸	no data
Base-plate thermal cycling range, MISSE 2 flightNominal range as printed in NASA TM-2008-215490	-30 °C	no data
Physical and electrical
Density of MISSE 2 PEO sample	1.147 g/cm³⁴	1.1 g/cm³
Other measurements
Atomic oxygen erosion yield, MISSE 2 PEACE flight, low Earth orbit	1.93×10^-24 cm³/atom¹	no data
Atomic oxygen erosion yield predicted by NASA formula for PEO	7.99×10^-24 cm³/atom²	no data
Atomic oxygen erosion yield, RF plasma asher ground test	1.8×10^-23 cm³/atom³	no data
Ratio of asher to in-space erosion yield, PEORatio column printed in NASA TM-2011-216904	9.3 ratio	no data
Fractional ash content of PEO after oxidation in a plasma asher	0.00112 mass fraction⁵	no data
Refractive index, commercial PEO grade MW about 100,000	1.51 dimensionless⁶	no data
Maximum operating temperature, PEO/Alkox in MISSE PEACE	65 °C⁷	no data
Atomic oxygen fluence, MISSE 2 PEACE flight	8.43×10^21 atoms/cm²⁹	no data
Total equivalent sun hours, MISSE 2 PEACE flight	5000 ESH¹⁰	no data

Why choose it, and why not

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 for

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.

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.

Technical details

For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.

Notes

The method, full conditions and any caveat for the numbered rows above.

Notes for the numbered rows
#	Measurement	Method	Conditions	Caveat
1	Atomic oxygen erosion yield, MISSE 2 PEACE flight, low Earth orbit	Mass loss and density measured after flight, per NASA TM-2008-215490 (Banks, de Groh and Backus)	environment low Earth orbit, outside the ISS Quest airlock, MISSE 2 PEC 2 tray 1fluence 8.43e21 atoms/cm2duration about 4 years	—
2	Atomic oxygen erosion yield predicted by NASA formula for PEO	Predictive formula printed in NASA TM-2008-215490; not a measurement	basis predictive tool from chemical structure, bonding and density, before flight comparison	—
3	Atomic oxygen erosion yield, RF plasma asher ground test	Plasma asher erosion yield as printed in NASA TM-2011-216904	apparatus RF plasma asher, ground laboratory test	—
4	Density of MISSE 2 PEO sample	Density gradient column, as printed in NASA TM-2008-215490	sample MISSE 2 PEACE PEO sample, dehydrated before weighing	—
5	Fractional ash content of PEO after oxidation in a plasma asher	RF plasma asher, as printed in NASA TM-2008-215490	method fraction of the dehydrated polymer mass left as nonvolatile ash after complete oxidation	—
6	Refractive index, commercial PEO grade MW about 100,000	Vendor product specification as printed (printed as 1.510-1.540)	grade Polysciences product 06104, molecular weight about 100,000temperature not stated	—
7	Maximum operating temperature, PEO/Alkox in MISSE PEACE	Maximum operating temperature as listed for the MISSE PEACE material, from NASA TM-2001-211311	trade name Alkox E-30 powder, MISSE serial 2-E5-17	—
8	Vacuum heat treatment before flight, PEO/Alkox	Pre-flight vacuum heat treatment as listed, from NASA TM-2001-211311	duration 24 hrsatmosphere vacuum	—
9	Atomic oxygen fluence, MISSE 2 PEACE flight	Fluence from witness samples, as printed in NASA TM-2008-215490	witness average of two fluence witness samplesduration 4 yr exposure	—
10	Total equivalent sun hours, MISSE 2 PEACE flight	Estimated total as printed in NASA TM-2008-215490	includes Earth-reflected illumination of 650 to 820 ESH	—

Corrosion and compatibility

What happens when it meets other materials and environments.

Corrosion and compatibility
Environment	Concern	What happens
Atomic oxygen in low Earth orbit, MISSE 2 PEACE flight (fluence 8.43e21 atoms/cm2)	low	PEO eroded at 1.93e-24 cm3/atom in flight, which is more than three times lower than the NASA predictive formula gave.¹
Plasma asher ground test of atomic oxygen erosion, PEO	moderate	The ground asher yield for PEO is 1.8e-23 cm3/atom, about 9.3 times the flight value.²
Heat, above the PEO/Alkox maximum operating temperature	moderate	The MISSE 2 PEO/Alkox sample is rated to 65 C, and the commercial grade melts at 66 to 75 C.³
Water and aqueous solutions	severe	The commercial PEO grade dissolves in water, so water exposure is a degradation route by dissolution.⁴

Corrosion details
#	Environment	Details	Test conditions
1	Atomic oxygen in low Earth orbit, MISSE 2 PEACE flight (fluence 8.43e21 atoms/cm2)	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.	exposure ISS exterior, MISSE 2 PEC 2 tray 1, about 4 yearsbasis flight erosion yield after mass loss and density measurement
2	Plasma asher ground test of atomic oxygen erosion, PEO	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.	apparatus RF plasma ashersample MISSE 2 PEO sample with fingerprints noted
3	Heat, above the PEO/Alkox maximum operating temperature	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.	grade Polysciences 06104, molecular weight about 100,000
4	Water and aqueous solutions	Polysciences lists the grade as soluble in water, acetone, alcohol, chloroform, toluene and dichloromethane. The page gives no water-ageing or swelling data.	grade Polysciences 06104, molecular weight about 100,000

Risks and side effects

Hazards to people, what happens when a cell overheats, and how the material is handled and stored.

For people

The one hazard statement read is a vendor's irritant classification for the powder.

Handling: Polysciences 06104 says to avoid excessive dust generation during powder transfer, and to wear gloves and safety glasses when appropriate.

If it fails

The flight data show erosion, not a failure threshold.

Erosion: 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.

Handling and storage

Storage: Store at room temperature and keep the container tightly closed, per the Polysciences product page.

Test details
The original wording and numbers from the sources, for readers who want them.

Failure risks

Failure risks
Failure	Trigger and consequence
Erosion of a thin PEO film in atomic oxygenmoderate severity	Long exposure to low Earth orbit atomic oxygen, 8.43e21 atoms/cm2 in MISSE 2NASA states that the PEACE samples, in general, eroded partially or completely through at a fluence close to the full mission fluence.

Side effects on surrounding parts

Side effects on surrounding parts
Affects	Effect
Ground erosion measurements	Fingerprints on a PEO sample meant no erosion yield was recorded in the early tests, so handling skin contact can corrupt the ground result.

Handling and storage

Store at room temperature in a tightly closed container. Avoid dust formation during powder transfer.

Mitigations

Keep the service temperature below 65 C, the MISSE 2 maximum operating temperature for this material.

Documents

Datasheets, safety data sheets, papers and standards you can open.

Documents
Document	Type	Year
NASA TM-2008-215490, Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit	report	2008
NASA TM-2001-211311, MISSE PEACE Polymers experiment	report	2001
NASA TM-2011-216904, Ground-Laboratory to In-Space Atomic Oxygen Correlation for the PEACE Polymers	report	2011
Polysciences product 06104, Poly(ethylene oxide) MW 100,000	datasheet

Full record

The complete spore, as stored. Free to reuse under CC-BY-4.0. Images keep the licence shown with each one.

Show the full YAML

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

References

Every number above carries a reference number. Click one to see the source and where in it the value comes from.

References
Source	Type	Year	Used for
Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit, NASA/TM-2008-215490	report	2008	10 values
MISSE PEACE Polymers experiment, NASA/TM-2001-211311, Table 2 (vacuum heat treated MISSE PEACE polymers)	report	2001	4 values
Ground-Laboratory to In-Space Atomic Oxygen Correlation for the PEACE Polymers, NASA/TM-2011-216904	report	2011	4 values
Polysciences product 06104, Poly(ethylene oxide) MW 100,000	datasheet		7 values
Wikipedia, Polyethylene glycol (PEG and PEO naming by molecular mass)	web		0 values
Wikipedia, Atomic oxygen (definition and reactivity)	web		0 values

References
Identity
Formula	(-CH2CH2O-)n, poly(ethylene oxide); repeat unit C2H4O
CAS	25322-68-3
Role	Water-soluble polyether; flown as a MISSE 2 PEACE polymer for atomic-oxygen erosion
Benchmarks	13

References
Use this record
YAML CSV JSON CSV has one row per value, with its conditions, method, source and the place in the source.

References
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