spore: profile
id: ep
spore_version: 0.2
family: engineering-polymers
name: Epoxy (epoxide)
abbreviation: EP
role: thermosetting resin for coatings, adhesives and composite matrices
category: polymers
type: epoxies-and-resins
summary: Epoxies are reactive prepolymers that cure into a cross-linked thermoset network. The most common resin is bisphenol A diglycidyl ether (BADGE, DGEBA), made from bisphenol A and epichlorohydrin. In the NASA MISSE 2 flight tray, an epoxy sample eroded at 4.21e-24 cm3/atom under atomic oxygen in low Earth orbit, close to the 4.02e-24 cm3/atom predicted by NASA's erosion-yield tool.
best_for: Structural bonding and matrix resin where a rigid, chemically resistant cured network is needed (EPON 828 cures to tensile values above 69 MPa when unfilled)
weakest_at: 'Atomic oxygen and ultraviolet exposure in orbit: an erosion yield of 4.21e-24 cm3/atom, and UV ageing that cracks the surface and lowers hardness'
identity:
  formula: Cross-linked epoxy network; repeat unit C20H19O3 (molar mass 307.3683 g/mol) as printed in the NASA TM polymer table
  source: nasa-tm-2008-215490
  where: Table IV (repeat unit formula and molar mass)
tags:
  environments:
    - low-earth-orbit
  stresses:
    - atomic-oxygen
    - uv
    - vacuum-and-outgassing
  applications:
    - structures
properties:
  - benchmark: atomic_oxygen_erosion_yield
    label: Atomic oxygen erosion yield, MISSE 2 flight tray
    value: 4.21e-24
    unit: cm3/atom
    scope: material
    conditions:
      exposure: MISSE 2 PEACE, ISS outside Quest airlock, 2001-08-16 to 2005-07-30
      fluence: 8.43e21 atoms/cm2
    method: Measured on flown samples; density and ash corrected by the NASA tool authors
    status: flight
    source: nasa-tm-2008-215490
    where: Table I, row Epoxide or epoxy, MISSE 2 erosion yield column
  - benchmark: atomic_oxygen_erosion_yield
    label: Predicted atomic oxygen erosion yield (NASA tool)
    value: 4.02e-24
    unit: cm3/atom
    scope: material
    conditions:
      model: NASA predictive tool, fitted to the MISSE 2 data
    method: Predicted by the NASA erosion-yield tool, compared with the measured value
    status: calculated
    source: nasa-tm-2008-215490
    where: Table VII, row Epoxide or epoxy, predicted erosion yield column
  - benchmark: density
    label: Density, epoxy (NASA MISSE 2 polymer table)
    value: 1.115
    unit: g/cm3
    scope: material
    conditions:
      basis: density used by the NASA tool, from supplier data (ref. 12 in the paper)
    method: Supplier information cited by the NASA paper; not a new measurement
    status: ground
    source: nasa-tm-2008-215490
    where: Table II, row Epoxide or epoxy, Density column
  - benchmark: ash_mass_fraction
    label: Mass fraction that is ash (Na), epoxy
    value: 0.0334
    unit: fraction
    scope: material
    conditions:
      basis: mass fraction of the polymer that is ash, measured for the NASA tool
    method: Measured by the NASA paper authors
    status: ground
    source: nasa-tm-2008-215490
    where: Table II, row Epoxide or epoxy, mass fraction of ash column (printed 3.34e-2)
  - benchmark: molar_mass
    label: Repeat unit molar mass, epoxy
    value: 307.3683
    unit: g/mol
    scope: material
    conditions:
      formula: C20H19O3
    method: Printed in the NASA paper table of repeat-unit structures
    status: ground
    source: nasa-tm-2008-215490
    where: Table IV, row Epoxide or epoxy, atomic mass column
  - benchmark: molar_mass
    label: Molar mass, bisphenol A diglycidyl ether (BADGE)
    value: 340.4
    unit: g/mol
    scope: material
    conditions:
      formula: C21H24O4
    method: Computed by PubChem from the molecular formula
    status: calculated
    source: pubchem-badge
    where: Compound summary, Molecular Weight (CID 2286)
  - benchmark: epoxide_equivalent_weight
    label: Epoxide equivalent weight, EPON Resin 828
    value: 185
    value_high: 192
    unit: g/eq
    scope: material
    conditions:
      grade: EPON Resin 828 (uncured liquid resin)
    method: ASTM D1652, as printed on the manufacturer bulletin
    status: ground
    source: epon828-bulletin
    where: Typical properties table, Epoxide Equivalent Weight row
  - benchmark: viscosity
    label: Viscosity at 25 degC, EPON Resin 828
    value: 110
    value_high: 150
    unit: P
    scope: material
    conditions:
      temperature: 25 °C
      grade: EPON Resin 828 (uncured liquid resin)
    method: ASTM D445, as printed on the manufacturer bulletin
    status: ground
    source: epon828-bulletin
    where: Typical properties table, Viscosity @ 25 °C row
  - benchmark: density
    label: Density at 25 degC, EPON Resin 828
    value: 1.16
    unit: g/ml
    scope: material
    conditions:
      temperature: 25 °C
      grade: EPON Resin 828 (uncured liquid resin)
    method: Printed on the manufacturer bulletin
    status: ground
    source: epon828-bulletin
    where: Typical properties table, Density @ 25 °C row
  - benchmark: refractive_index
    label: Refractive index at 25 degC, EPON Resin 828
    value: 1.573
    unit: dimensionless
    scope: material
    conditions:
      temperature: 25 °C
      grade: EPON Resin 828 (uncured liquid resin)
    method: Printed on the manufacturer bulletin
    status: ground
    source: epon828-bulletin
    where: Typical properties table, Refractive index @ 25 °C row
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, unfilled cured EPON 828 systems
    value: 69
    unit: MPa
    scope: material
    conditions:
      basis: printed as greater than 10,000 psi (69 MPa); a floor across curing agents, not a single result
      cure: varies with curing agent
    method: Manufacturer statement on the bulletin
    status: ground
    source: epon828-bulletin
    where: General information, curing section (Tensile values row)
  - benchmark: elastic_modulus
    label: Modulus, unfilled cured EPON 828 systems
    value: 2750
    unit: MPa
    scope: material
    conditions:
      basis: printed as greater than 400,000 psi (2750 MPa); a floor across curing agents
    method: Manufacturer statement on the bulletin
    status: ground
    source: epon828-bulletin
    where: General information, curing section (modulus values sentence)
  - benchmark: shear_strength
    label: Shear strength, EPON 828 bonded systems
    value: 41
    unit: MPa
    scope: material
    conditions:
      basis: printed as up to 6,000 psi (41 MPa)
    method: Manufacturer statement on the bulletin
    status: ground
    source: epon828-bulletin
    where: General information, adhesion sentence
  - benchmark: hardness
    label: Leeb hardness, unaged epoxy resin (UV study)
    value: 860
    unit: HLD
    scope: material
    conditions:
      basis: non-aged reference for the UV ageing series
    method: Leeb hardness as printed in the UV ageing study
    status: ground
    source: pmc11821137
    where: Results, hardness section (non-aged value)
  - benchmark: hardness
    label: Leeb hardness, epoxy resin after 792 h UV ageing
    value: 838
    unit: HLD
    scope: material
    conditions:
      exposure: UV-340 fluorescent lamp, 792 h
    method: Leeb hardness as printed in the UV ageing study
    status: ground
    source: pmc11821137
    where: Results, hardness section (838 HLD at 792 h)
  - benchmark: percent_strength_loss
    label: Bending strength decrease, epoxy composite after UV ageing
    value: 6
    unit: percent
    scope: material
    conditions:
      basis: CFRP pultruded composite with epoxy resin, not the neat resin; printed change from initial value
      exposure: UV ageing, overhead-wire composite study
    method: Measured in the UV ageing study
    status: ground
    source: pmc11821137
    where: Abstract, final sentence
corrosion:
  - environment: Ultraviolet radiation with oxygen and water (lab UV ageing, UV-340 lamp)
    headline: UV ageing cracks the surface of epoxy resin and lowers hardness; the resin fails first at the surface.
    effect: Photo-oxidation and chain scission cause weight change, colour deepening, microcracks and a loss of hardness. The study says UV aging predominantly affected the surface layer resin.
    rating: moderate
    conditions:
      exposure: UV-340 fluorescent lamp, up to 1080 h
      hardness_series: 860 HLD unaged, 838 HLD at 792 h
    source: pmc11821137
    where: Abstract; Results, hardness section
  - environment: Atomic oxygen in low Earth orbit (MISSE 2, ISS, about 3.95 years)
    headline: Epoxy eroded at 4.21e-24 cm3/atom, a moderate yield compared with other MISSE 2 polymers.
    effect: A 4.21e-24 cm3/atom erosion yield after a fluence of 8.43e21 atoms/cm2. The 2.68e-24 polypropylene and 9.14e-24 POM values in the same table give the range.
    rating: moderate
    conditions:
      fluence: 8.43e21 atoms/cm2
      exposure: MISSE 2 PEACE, ISS, 2001 to 2005
    source: nasa-tm-2008-215490
    where: Table I, row Epoxide or epoxy
risks:
  hazards:
    - text: 'PubChem GHS summary for bisphenol A diglycidyl ether: causes skin irritation (H315), may cause an allergic skin reaction (H317) and causes serious eye irritation (H319), in more than 99.9% of notifications.'
      ghs:
        - H315
        - H317
        - H319
      source: pubchem-badge
      where: GHS Classification (CID 2286)
    - text: PubChem also lists toxic to aquatic life with long lasting effects (H411) in 50.9% of reports.
      ghs:
        - H411
      source: pubchem-badge
      where: GHS Classification (CID 2286)
  failure_risks:
    - source: pmc11821137
      where: Results, hardness section
      mode: Photo-oxidation under ultraviolet light cracks the surface and…
      consequence: Photo-oxidation under ultraviolet light cracks the surface and reduces hardness.
    - source: nasa-tm-2008-215490
      where: Table I
      mode: Atomic oxygen erodes the surface in low Earth orbit at 4.21e-24…
      consequence: Atomic oxygen erodes the surface in low Earth orbit at 4.21e-24 cm3/atom.
  side_effects: []
  handling:
    - text: Wear gloves and eye protection; the GHS statements list skin irritation, sensitisation and eye irritation.
      source: pubchem-badge
      where: GHS Classification (CID 2286)
  mitigations: []
uses:
  - application: structures
    device: Structural adhesives and bonded joints
    example: EPON 828 is cured with a range of hardeners to bond a broad range of substrates; cured systems show shear strength of up to 6,000 psi (41 MPa).
    source: epon828-bulletin
    where: General information and adhesion sentences
  - application: structures
    device: Carbon fibre epoxy composite for overhead wires
    example: A pultruded carbon fibre epoxy composite used in overhead wires lost 6.0% of its bending strength after UV ageing.
    source: pmc11821137
    where: Abstract
story:
  recipe:
    line: Most commercial epoxies are made by reacting bisphenol A with epichlorohydrin, then forming the glycidyl ether groups with sodium hydroxide, which removes the chlorine as sodium chloride. The liquid resin is then cured by a hardener that opens the epoxide rings and cross-links the network.
    parts:
      - name: Bisphenol A
        symbol: BPA
        role: The diphenol that forms the backbone of the resin, from the reaction with epichlorohydrin.
      - name: Epichlorohydrin
        symbol: ECH
        role: Supplies the epoxide (glycidyl) end groups, after dehydrochlorination with sodium hydroxide.
  risk_groups:
    - title: For people
      level: 0
      verdict: Irritant and sensitiser
      lead: The uncured resin is classified as an irritant and a sensitiser by most reporters to PubChem.
      points:
        - label: Skin and eyes
          line: Causes skin irritation, may cause an allergic skin reaction and causes serious eye irritation, per PubChem's GHS summary.
    - title: In orbit
      lead: Epoxy is used in orbit only as a test material here.
      points:
        - label: Atomic oxygen
          line: Eroded at 4.21e-24 cm3/atom during about 3.95 years on the ISS, with a predicted value of 4.02e-24 cm3/atom.
  why: Epoxies are used where a rigid, chemically resistant thermoset is needed. They cure into a cross-linked network that bonds well to many substrates. In the NASA MISSE 2 flight tray, the epoxy eroded at a moderate rate under atomic oxygen, and it cracks under UV ageing in the laboratory.
  uses:
    - where: Structural bonding
      line: EPON 828 bonds a broad range of substrates. Unfilled cured systems exceed 69 MPa in tensile strength and 2,750 MPa in modulus, as printed by the manufacturer.
    - where: Composite overhead-wire component
      line: A carbon fibre epoxy composite used in overhead wires was studied under UV ageing. The composite lost 6.0% of its bending strength.
  can_do:
    - label: Erosion in orbit
      value: 4.21e-24 cm3/atom
      line: The epoxy eroded at 4.21e-24 cm3/atom in the MISSE 2 flight tray, close to the 4.02e-24 cm3/atom predicted by NASA's erosion-yield tool.
    - label: Density
      value: 1.115 g/cm3
      line: The NASA table gives a density of 1.115 g/cm3 for the epoxy used in the erosion model.
  compare: The epoxy sits in the middle of the MISSE 2 polymer set on erosion yield. The table compares it with polypropylene, polystyrene and polyoxymethylene using the same NASA data. Tensile and modulus values are manufacturer floors for unfilled cured EPON 828 and should not be read as a single test result.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Atomic oxygen erosion yield
      benchmark: atomic_oxygen_erosion_yield
    - label: Modulus
      benchmark: elastic_modulus
  handling:
    - Use gloves and eye protection; the uncured resin is an irritant and a sensitiser.
    - Keep out of direct UV light, which cracks the cured surface.
  good_for:
    - Structural bonding where the cured network must resist chemicals and heat.
    - Composite matrices for structural parts, as in the overhead-wire study.
  watch_out:
    - Atomic oxygen erodes epoxy in low Earth orbit at 4.21e-24 cm3/atom.
    - UV ageing reduces surface hardness and cracks the resin.
  verdict: Epoxy is a rigid, well-bonding thermoset. It resists atomic oxygen better than some polymers in the MISSE 2 set, but it needs UV protection and handling care.
gaps:
  - No epoxy supply data (producers, shares, critical-mineral status) was read in this run; bisphenol A and epichlorohydrin production shares were not fetched.
  - No epoxy-specific ageing data beyond UV and atomic oxygen, such as thermal ageing, humidity and chemical resistance, was read in this run.
  - Only four sources were reached in this run; the lithium standard asks for 8 or more.
  - Glass transition temperature and cure schedule for EPON 828 were not read from a fetched page; the search snippets were not used as values.
  - Ash mass fraction and repeat-unit molar mass use non-canonical benchmark names (ash_mass_fraction, molar_mass).
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, December 2008)
    url: https://ntrs.nasa.gov/citations/20090011780
    year: 2008
    kind: report
    license: CC-BY-4.0
  epon828-bulletin:
    title: Technical Data Bulletin, EPON Resin 828 RP 3075
    id: Hexion, reissued September 2005
    url: https://www.spacematdb.com/spacemat/manudatasheets/Epon828.pdf
    year: 2005
    kind: datasheet
    license: manufacturer bulletin, cited
  pmc11821137:
    title: Effect of Ultraviolet Aging on Properties of Epoxy Resin and Its Pultruded Fiber-Reinforced Composite
    id: doi:10.3390/polym (Polymers, MDPI, 2025), PMC11821137
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC11821137/
    year: 2025
    kind: paper
    license: CC BY 4.0
  pubchem-badge:
    title: Bisphenol A diglycidyl ether, PubChem compound summary
    id: PubChem CID 2286
    url: https://pubchem.ncbi.nlm.nih.gov/compound/2286
    year: 2026
    kind: database
    license: PubChem, public domain
documents:
  - type: datasheet
    title: EPON Resin 828 technical data bulletin
    url: https://www.spacematdb.com/spacemat/manudatasheets/Epon828.pdf
review:
  status: draft
  method: assistant
  checked_values: 16
  caveats: 4
  note: Written by an AI assistant from pages read in this run; 16 values, 4 sources. Supply, thermal ageing and the glass transition temperature were not found.
updated: '2026-10-20'
license: CC-BY-4.0