spore: profile
id: pa-6
spore_version: 0.2
family: polyamides
name: Polyamide 6 (nylon 6)
abbreviation: PA 6
role: semicrystalline engineering thermoplastic; flown as a thin film in the MISSE 2 PEACE polymer set; ground values read in dry (as-moulded) and conditioned states where the supplier states them
category: polymers
type: polyamides
summary: |
  Polyamide 6 (nylon 6) is a semicrystalline polyamide made from caprolactam. Its one flight result in this file is an atomic-oxygen erosion yield of 3.51 x 10^-24 cm3/atom, from the MISSE 2 PEACE polymers experiment on the ISS for 3.95 years in low Earth orbit. NASA lists it in the same table as nylon 66, which erodes at 1.80 x 10^-24 cm3/atom. Ground values come from two unfilled PA6 datasheets: a Vinmar grade (density 1.12, melting point 220 degC, tensile modulus 3100 MPa, condition not stated) and an Aquafil ECONYL ECO 27 sheet whose mechanical values are read after 24 h at RT and 45 to 55 % RH (tensile modulus 2215 MPa, saturation water uptake 10 %). Dry and conditioned values are kept apart below.
best_for: Flight-proven polymer for atomic-oxygen exposure data in low Earth orbit (only one flight value read here)
weakest_at: 'Moisture uptake: the Aquafil sheet gives a saturation water uptake of 10 %, and the stiffness and strength values fall once conditioned'
identity:
  formula: (C6H11NO)n, repeat unit C6H11NO, molar mass 113.1590 per repeat unit
  source: nasa-tm-2008
  where: Table IV (chemical structure of MISSE 2 PEACE polymers)
tags:
  environments:
    - low-earth-orbit
  stresses:
    - atomic-oxygen
    - uv
    - total-radiation-dose
    - thermal-cycling
    - vacuum-and-outgassing
  applications:
    - mechanisms
    - structures
properties:
  - benchmark: atomic_oxygen_erosion_yield
    label: Atomic oxygen erosion yield, MISSE 2 PEACE flight
    value: 3.51e-24
    unit: cm3/atom
    scope: material
    conditions:
      environment: low Earth orbit, ISS, MISSE 2 PEACE tray 1 on the Quest airlock exterior, 2001-08-16 to 2005-07-30
      atomic_oxygen_fluence: 8.43e21 atoms/cm2 (average of two Kapton H witness samples)
      equivalent_sun_hours: 5,000 to 6,700 ESH, including 650 to 820 ESH Earth-reflected
      duration: 3.95 yr
      thermal_cycling: base-plate range nominally 40 to -30 degC
    method: 'Flight exposure with mass loss over area and density; erosion yield as printed in NASA/TM-2008-215490 Table I. Not a dry or conditioned distinction: the sample was exposed in orbit.'
    status: flight
    source: nasa-tm-2008
    where: Table I (MISSE 2 PEACE polymers erosion yield data), row Polyamide 6 or nylon 6; exposure in section 2.1
  - benchmark: density
    label: Density, MISSE 2 reference value
    value: 1.1233
    unit: g/cm3
    scope: material
    conditions:
      state: as used for the flight yield calculation; not stated as dry or conditioned
    method: Density reference value in NASA/TM-2008-215490 Table II (ref. 12)
    status: ground
    source: nasa-tm-2008
    where: Table II, row Polyamide 6 or nylon 6
  - benchmark: density
    label: Density, Vinmar PA6UFNAT (specific gravity)
    value: 1.12
    unit: (specific gravity, no unit printed)
    scope: material
    conditions:
      state: not stated by the supplier
    method: Typical value printed on the Vinmar resin datasheet (ISO 1183)
    status: ground
    source: vinmar-pa6unat
    where: Resin Property table, row Specific Gravity
  - benchmark: density
    label: Density, ECONYL ECO 27
    value: 1.13
    unit: g/cm3
    scope: material
    conditions:
      state: not stated by the supplier for density; tolerance printed as 0.020 g/cm3
    method: Typical value on the Aquafil ECONYL ECO 27 datasheet (ISO 1183); printed with range of variation plus or minus 0.020
    status: ground
    source: aquafil-eco27
    where: Physical properties table, row Density
  - benchmark: melting_temperature
    label: Melting temperature, ECONYL ECO 27 (DSC)
    value: 221
    unit: degC
    scope: material
    conditions:
      heating_rate: 20 degC/min, 30 to 300 degC
      state: not applicable (thermal, not moisture dependent as printed)
    method: DSC per ISO 11357-1; printed with range of variation plus or minus 2.5 degC
    status: ground
    source: aquafil-eco27
    where: Thermal properties table, row Melting Temperature
  - benchmark: melting_temperature
    label: Melting point, Vinmar PA6UFNAT
    value: 220
    unit: degC
    scope: material
    conditions:
      method_note: ISO 11357; printed as 428 (220) F (C)
    method: Typical value on the Vinmar datasheet, ISO 11357
    status: ground
    source: vinmar-pa6unat
    where: Resin Property table, row Melting Point
  - benchmark: tensile_modulus
    label: Tensile modulus, Vinmar PA6UFNAT
    value: 3100
    unit: MPa
    scope: material
    conditions:
      state: not stated by the supplier; the datasheet prints no dry or conditioned split
      rate: not stated
    method: Typical value on the Vinmar datasheet, ISO 527-1 and -2; printed as 450,000 (3,100) psi (MPa)
    status: ground
    source: vinmar-pa6unat
    where: Resin Property table, row Tensile Modulus
  - benchmark: tensile_modulus
    label: Tensile modulus, ECONYL ECO 27 (conditioned)
    value: 2215
    unit: MPa
    scope: material
    conditions:
      state: 'conditioned: 24 h at RT, RH 45 to 55 %, as printed under the mechanical block'
      test_speed: 1 mm/min
    method: Typical value per ISO 527; printed with range of variation plus or minus 100 MPa. The datasheet footnote says dry-as-moulded values are shown before a slash where available; this row shows only the conditioned value.
    status: ground
    source: aquafil-eco27
    where: Mechanical properties table, row Tensile Modulus, and the conditioning line above it
  - benchmark: tensile_strength
    label: Tensile strength, ECONYL ECO 27 (conditioned)
    value: 70
    unit: MPa
    scope: material
    conditions:
      state: 'conditioned: 24 h at RT, RH 45 to 55 %'
      test_speed: 50 mm/min
    method: Typical value per ISO 527; printed with range of variation plus or minus 5 MPa
    status: ground
    source: aquafil-eco27
    where: Mechanical properties table, row Tensile Strenght (sic)
  - benchmark: tensile_strength
    label: Tensile strength, Vinmar PA6UFNAT
    value: 76
    unit: MPa
    scope: material
    conditions:
      state: not stated by the supplier
    method: Typical value per ISO 527; printed as 11,000 (76) psi (MPa)
    status: ground
    source: vinmar-pa6unat
    where: Resin Property table, row Tensile Strength
  - benchmark: moisture_absorption
    label: Moisture absorption at saturation, ECONYL ECO 27
    value: 10
    unit: '%'
    scope: material
    conditions:
      state: saturated in water at 23 degC
    method: Typical value per ISO 62; printed with range of variation plus or minus 1.0 %
    status: ground
    source: aquafil-eco27
    where: Physical properties table, row Moisture Absorption
  - benchmark: moisture_content_as_supplied
    label: Moisture content as supplied, Vinmar PA6UFNAT
    value: 0.2
    unit: '% (maximum)'
    scope: material
    conditions:
      state: as supplied (maximum)
    method: Maximum value printed on the Vinmar datasheet, ISO 15512
    status: ground
    source: vinmar-pa6unat
    where: Resin Property table, row Moisture
  - benchmark: heat_deflection_temperature
    label: Heat deflection temperature at 1.8 MPa, Vinmar PA6UFNAT
    value: 200
    unit: degC
    scope: material
    conditions:
      load: 1.8 MPa
    method: ISO 75; printed as 392 (200) F (C)
    status: ground
    source: vinmar-pa6unat
    where: Resin Property table, row Heat Deflection Temperature, 1.8 MPa
    note: Implausible for an unfilled PA 6 at 1.8 MPa, far above PA 66 at the same load (70 to 75 degC). Treat as a probable datasheet or transcription error until checked against the Vinmar sheet; kept as printed, not used in the article comparisons.
  - benchmark: charpy_notched_impact
    label: Charpy notched impact at 23 degC, ECONYL ECO 27
    value: 8.1
    unit: kJ/m2
    scope: material
    conditions:
      temperature: 23 degC
    method: ISO 179/1eA; printed with range of variation plus or minus 1.0 kJ/m2
    status: ground
    source: aquafil-eco27
    where: Impact properties table, row Charpy 23 degC, notched
  - benchmark: moisture_absorption
    label: Water absorption at 23 C / 50 % rh, Ultramid B27 EX
    value: 2.2
    unit: '%'
    scope: material
    conditions:
      state: standard atmosphere 23 C, 50 % rh; grade B27 EX (a PA 6 grade), not the plain B27 grade
    method: Typical value printed on the BASF product information
    status: ground
    source: basf-ultramid-b27-ex
    where: General properties table, row Water absorption, 23 C/50 % rh
  - benchmark: moisture_absorption
    label: Water absorption at saturation in water, 23 C, Ultramid B27 EX
    value: 8.5
    unit: '%'
    scope: material
    conditions:
      state: saturation in water at 23 C
    method: Typical value printed on the BASF product information
    status: ground
    source: basf-ultramid-b27-ex
    where: General properties table, row Water absorption, saturation in water 23 C
  - benchmark: moisture_absorption
    label: Equilibrium water content at 50 % rh, Durethan B 30 S (PA 6)
    value: 3
    unit: '%'
    scope: material
    conditions:
      state: equilibrium water content, printed as a maximum limit, 50 % relative humidity
    method: Table 2 of LANXESS TI 2007-003 (equilibrium water contents as % by weight)
    status: ground
    source: lanxess-ti-2007
    where: Table 2, row B 30 S, column 50 %
  - benchmark: moisture_absorption
    label: Water content on immersion in water, Durethan B 30 S (PA 6)
    value: 10
    unit: '%'
    scope: material
    conditions:
      state: immersion in water (saturation), printed as a maximum limit
    method: Table 2 of LANXESS TI 2007-003
    status: ground
    source: lanxess-ti-2007
    where: Table 2, row B 30 S, column Immersion in water
  - benchmark: density
    label: Density, Ultramid B27 EX
    value: 1.12
    value_high: 1.15
    bound: range
    unit: g/cm3
    scope: material
    conditions:
      state: not stated as dry or conditioned
    method: Range printed on the BASF product information (ISO 1183)
    status: ground
    source: basf-ultramid-b27-ex
    where: General properties table, row Density
  - benchmark: melting_temperature
    label: Melting point, Ultramid B27 EX
    value: 220
    unit: degC
    scope: material
    conditions:
      state: typical value
    method: Typical value printed on the BASF product information (ISO 3146)
    status: ground
    source: basf-ultramid-b27-ex
    where: General properties table, row Melting point
  - benchmark: moisture_content_as_supplied
    label: Moisture content as supplied, Ultramid B27 EX
    value: 0.3
    unit: '% (maximum)'
    scope: material
    conditions:
      state: as supplied, pre-dried (maximum)
    method: Maximum value printed on the BASF product information (ISO 15512)
    status: ground
    source: basf-ultramid-b27-ex
    where: Specification table, row Moisture content
corrosion:
  - environment: Standard atmosphere 23 C, 50 % rh (service humidity)
    headline: Moisture swells PA 6 anisotropically, and thickness changes more than length.
    effect: LANXESS reports an average length increase of 0.2 to 0.3 % per 1 % water absorbed for non-reinforced PA 6, a literature maximum volume increase of 0.9 % for non-reinforced PA 6 or PA 66, and a larger thickness increase than length increase. Strong moisture change can cause perceptible warpage.
    rating: moderate
    conditions:
      basis: non-reinforced PA 6 moulded parts; the source notes that glass-fibre reinforcement cuts the length change below 0.1 % per 1 % water
      reference: LANXESS Section 2.3
    source: lanxess-ti-2007
    where: Section 2.3, Dimensional change through water absorption
  - environment: Standard atmosphere 23 C, 50 % rh, and later storage in room air
    headline: Water uptake and release are slow, and equilibrium can take much longer than a year.
    effect: LANXESS says water absorption and release only take place very slowly at room temperature, so weather swings are often negligible. A part dried after absorbing 3 to 3.5 % water in the centre began to release water quickly in room air at 20 C and 50 to 60 % rh, but had still not reached equilibrium after a year.
    rating: low
    conditions:
      exposure: molded parts; 10 mm thick part example in the source
    source: lanxess-ti-2007
    where: Section 3, Water release and drying
  - environment: Hot water immersion at 80 to 90 C (conditioning route)
    headline: Fast conditioning, but the hot water causes oxidation discolouration and water stains.
    effect: In the LANXESS overview of conditioning methods, immersion at 80 to 90 C is listed as rapid conditioning with the drawbacks of discolouration through oxidation and water stains.
    rating: moderate
    conditions:
      use: a processing step to bring moulded parts to equilibrium, not service exposure
    source: lanxess-ti-2007
    where: Table 3, row Immersion in hot water
  - environment: Saturated steam at 95 to 100 C and 100 % rh (conditioning route)
    headline: 'Saturated steam is not recommended: it causes water stains, oxidation and warping.'
    effect: LANXESS lists water stains, oxidation, deposit formation and a tendency to warp for saturated steam, and rates the method as not recommended.
    rating: moderate
    conditions:
      use: a processing step, not service exposure
    source: lanxess-ti-2007
    where: Table 3, row Saturated steam
  - environment: Moisture uptake in service (mechanical effect)
    headline: 'Water acts as a plasticiser: stiffness and yield stress fall while ductility rises.'
    effect: Wikipedia states that nylon 6 is hygroscopic, absorbing up to 2.4 % of its weight in water, and that this greatly decreases the modulus and yield stress while increasing ductility. The Aquafil and Vinmar values in this file are not split by condition from one sheet, so check the condition before comparing.
    rating: moderate
    conditions:
      basis: general statement, no test condition given in the source
    source: wikipedia-nylon6
    where: Properties section
risks:
  hazards:
    - text: 'Caprolactam (monomer): PubChem aggregates 1,874 company reports to the ECHA C&L Inventory; the Warning-level codes H302, H315, H319, H332 and H335 each appear in 99.9 % of notifications that give hazard codes (H335 in 95.8 %). Other notifications list Danger with H361 and H372 (repeated exposure).'
      ghs:
        - H302
        - H315
        - H319
        - H332
        - H335
      source: pubchem-caprolactam
      where: Safety and Hazards, GHS Classification (CID 7768)
    - text: 'Caprolactam: oral LD50 1.1 g/kg (rat). NIOSH recommended exposure limit 1 mg/m3 over an 8-hour shift and short-term limit 3 mg/m3 for dusts and vapours. It is an irritant and is mildly toxic.'
      ghs: []
      source: wikipedia-caprolactam
      where: Safety section (NIOSH Pocket Guide cited there)
    - text: 'Polyamide 6 polymer (CAS 25038-54-4): the PubChem record for CID 32775 read in this run carries no GHS classification. No polymer SDS was read, so do not treat the polymer as non-hazardous from this entry.'
      ghs: []
      source: pubchem-pa6
      where: PubChem CID 32775 record
  failure_risks:
    - mode: Dimensional change and warpage from moisture
      trigger: Parts that absorb water in service or during conditioning, with tight tolerances
      consequence: Length change of 0.2 to 0.3 % per 1 % water absorbed, with a larger thickness change; perceptible warpage in extreme cases (LANXESS).
      severity: moderate
      source: lanxess-ti-2007
      where: Section 2.3
    - mode: Loss of stiffness and yield strength when wet
      trigger: Water uptake (up to 10 % at saturation for the Durethan B 30 S immersion value and 2.4 % in the Wikipedia general statement)
      consequence: Modulus and yield stress fall while ductility rises. The conditioned Aquafil ECO 27 modulus is 2215 MPa against 3100 MPa for the Vinmar grade (different grades, condition not matched).
      severity: moderate
      source: wikipedia-nylon6
      where: Properties section; Table 2 of LANXESS TI 2007-003 for the saturation value
    - mode: Oxidative discolouration and water stains during hot conditioning or drying
      trigger: Hot water immersion at 80 to 90 C, saturated steam, or granule drying above 75 to 80 C
      consequence: Discolouration through oxidation and water stains; deposit formation with steam (LANXESS).
      severity: low
      source: lanxess-ti-2007
      where: Table 3 and Section 3
    - mode: Atomic-oxygen erosion in low Earth orbit
      trigger: Flight exposure on the ISS outer surface (MISSE 2 PEACE, 3.95 years)
      consequence: Erosion yield 3.51e-24 cm3/atom at the recorded fluence of 8.43e21 atoms/cm2 (one flight measurement; NASA tabulates PA 66 at 1.80e-24).
      severity: moderate
      source: nasa-tm-2008
      where: Table I (MISSE 2 PEACE polymers erosion yield data)
  side_effects: []
  handling:
    - text: Dry PA 6 granules before moulding in a dehumidifying (desiccant) dryer with dew point of at least -20 to -25 C. LANXESS says a circulating-air oven below 100 C cannot fully dry PA granules and can add moisture. Keep drying at or below 75 to 80 C to avoid oxidative discolouration, except for heat-stabilised black grades. The permitted granule moisture for injection moulding is a maximum of 0.12 %.
      source: lanxess-ti-2007
      where: Section 3 (Water release and drying)
    - text: Ultramid B27 EX is supplied pre-dried in moisture-proof containers. Store it protected from moisture, use it within 12 months, and use opened bags immediately.
      source: basf-ultramid-b27-ex
      where: Supply form and storage
  mitigations:
    - text: Dry to the printed maximum moisture before moulding, then design for water-induced dimensional change of 0.2 to 0.3 % per 1 % water absorbed (LANXESS).
      source: lanxess-ti-2007
      where: Section 2.3; Section 3
uses:
  - application: mechanisms
    device: Gears and bearings
    example: PA 6 is frequently employed in the manufacture of components resistant to mechanical stress, such as gears, bearings and engine covers.
    source: pmc-pa6-pa12-am
    where: Introduction, paragraph on PA6 applications
  - application: structures
    device: Load-bearing automotive and electronics parts
    example: PA6 is characterised by high strength, stiffness and wear resistance, making it an ideal material for load-bearing structures and applications in the automotive and electronics sectors.
    source: pmc-pa6-pa12-am
    where: Introduction
  - application: structures
    device: 'Fibres: parachutes, aircraft tyre cord and towing cables (wartime Germany)'
    example: Germans started making parachutes, cord for aircraft tires and towing cables for gliders with the first nylon 6 fibre.
    source: wikipedia-nylon6
    where: History
supply:
  - subject: Caprolactam (monomer for nylon 6)
    demand: Global demand about five million tons per year (Wikipedia citing Ullmann's; the source gives this as an estimate for 2015). About 90 % goes to filament and fibre and 10 % to plastics.
    routes: 90 % of caprolactam is made from cyclohexanone, which is converted to its oxime and then rearranged with acid (Beckmann rearrangement). The other major route, about 10 % of world production, uses cyclohexane and nitrosyl chloride. Waste nylon 6 depolymerisation is a minor route.
    producers: []
    critical_lists: []
    substitutes: []
    source: wikipedia-caprolactam
    where: Synthesis and production; Uses
  - subject: Polyamide 6 producers in Europe (capacity)
    capacity:
      - company: Fibrant
        tonnes_per_year: 260000
        year: 2015
      - company: BASF
        tonnes_per_year: 240000
        year: 2015
      - company: Lanxess
        tonnes_per_year: 170000
        year: 2015
      - company: Radici Group
        tonnes_per_year: 125000
        year: 2015
    demand: Annual European polyamide demand about one million tonnes (Wikipedia).
    source: wikipedia-nylon6
    where: Production in Europe (list cites a 2015 Grupa Azoty presentation)
media: []
documents:
  - title: 'NASA/TM-2008-215490: Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit (Banks, Backus, de Groh, 2008)'
    type: report
    url: https://ntrs.nasa.gov/citations/20090011780
    year: 2008
  - title: Vinmar VINPOL PA6UFNAT, unfilled natural polyamide 6 datasheet (rev. 2/18/2020)
    type: datasheet
    url: https://vpa.vinmar.com/wp-content/uploads/VINPOL-PA6UFNAT.pdf
    year: 2020
  - title: Aquafil ECONYL ECO 27 (polyamide 6) technical data sheet, product 10026965 (ed. 2.1, 08/07/2025)
    type: datasheet
    url: https://www.aquafil.com/assets/uploads/TDS_10026965_ECONYL-ECO-27_EN.pdf
    year: 2025
  - title: Ultramid B27 EX, polyamide 6 product information (BASF, September 2021)
    type: datasheet
    url: https://chemicals.basf.com/dam/jcr:02d5e60b-d8fe-4657-ab65-51cb8a641294/TI-Ultramid-B27-EX.pdf
    year: 2021
  - title: LANXESS TI 2007-003 EN, The Water Absorption and Conditioning of Molded Parts in Durethan (edition 17.09.2007)
    type: datasheet
    url: https://almkompaundi.rs/wp-content/uploads/2018/08/Water-Absorption-and-Conditioning-LANXESS.pdf
    year: 2007
  - title: Comprehensive Review of PA6 and PA12 composites in additive manufacturing (PMC11859968)
    type: paper
    url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11859968/
    year: 2025
gaps:
  - 'Hazards: the caprolactam monomer hazards come from PubChem and Wikipedia. The PA 6 polymer has no GHS classification in PubChem (CID 32775), and no polymer SDS was read.'
  - 'Ageing: no UV, heat-ageing or hydrolysis value for PA 6 was read in this run. LANXESS covers water and hot-conditioning only, and the MDPI hydrolysis review was not opened.'
  - 'Supply: no producer share by country, no critical-mineral list and no feedstock abundance were read for caprolactam or nylon 6. Capacity figures are from a 2015 presentation cited by Wikipedia.'
  - 'Uses: in-space and in-orbit PA 6 applications were not sourced. The 3D-printing use is ground manufacturing (PMC review).'
  - 'Dry versus conditioned: only the Aquafil sheet gives a conditioned modulus (2215 MPa). The Vinmar and B27 EX values are not stated as dry or conditioned, so no dry modulus was matched to a conditioned one.'
  - 'Flight data: only the MISSE 2 PEACE atomic-oxygen erosion yield was read. No thermal, vacuum or radiation result beyond the exposure record was found for PA 6.'
  - 'Atomic weights: the mass shares of C, H, N and O were not computed because no fetched page gave per-element atomic weights. Atom counts come from NASA Table IV and the molar mass from NASA Table II.'
  - The Ultramid B27 EX datasheet is for the B27 EX grade. The plain B27 grade datasheet was not found, so B27 EX values are labelled as such.
sources:
  nasa-tm-2008:
    title: 'NASA/TM-2008-215490: Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit'
    id: NASA/TM-2008-215490 (Banks, Backus, de Groh, December 2008); NTRS 20090011780
    url: https://ntrs.nasa.gov/citations/20090011780
    kind: report
    year: 2008
    license: NASA public document
  vinmar-pa6unat:
    title: VINPOL PA6UFNAT, Unfilled Natural Polyamide 6 (Vinmar Polymers America)
    id: Vinmar datasheet, rev. 2/18/2020
    url: https://vpa.vinmar.com/wp-content/uploads/VINPOL-PA6UFNAT.pdf
    kind: datasheet
    year: 2020
    license: supplier datasheet, cited
  aquafil-eco27:
    title: ECONYL ECO 27, Polyamide 6, Technical Data Sheet (Aquafil S.p.A.)
    id: Aquafil product code 10026965, ed./rev. 2.1, 08/07/2025
    url: https://www.aquafil.com/assets/uploads/TDS_10026965_ECONYL-ECO-27_EN.pdf
    kind: datasheet
    year: 2025
    license: supplier datasheet, cited
  wikipedia-nylon6:
    title: Nylon 6, Wikipedia (composition, synthesis and history only)
    id: en.wikipedia.org/wiki/Nylon_6
    url: https://en.wikipedia.org/wiki/Nylon_6
    kind: web
    year: 2026
    license: CC BY-SA 4.0
  basf-ultramid-b27-ex:
    title: Ultramid B27 EX, polyamide 6 product information (BASF, September 2021)
    id: BASF product information, Ultramid B27 EX (page 1 of 2 and 2 of 2)
    url: https://chemicals.basf.com/dam/jcr:02d5e60b-d8fe-4657-ab65-51cb8a641294/TI-Ultramid-B27-EX.pdf
    kind: datasheet
    year: 2021
    license: supplier datasheet, cited
  lanxess-ti-2007:
    title: The Water Absorption and Conditioning of Molded Parts in Durethan (LANXESS Technical Information TI 2007-003 EN, edition 17.09.2007)
    id: LANXESS TI 2007-003 EN (copy hosted at almkompaundi.rs)
    url: https://almkompaundi.rs/wp-content/uploads/2018/08/Water-Absorption-and-Conditioning-LANXESS.pdf
    kind: datasheet
    year: 2007
    license: supplier technical information, cited
  wikipedia-caprolactam:
    title: Caprolactam, Wikipedia (synthesis, uses, safety)
    id: en.wikipedia.org/wiki/Caprolactam
    url: https://en.wikipedia.org/wiki/Caprolactam
    kind: web
    year: 2026
    license: CC BY-SA 4.0
  pubchem-caprolactam:
    title: 'PubChem CID 7768, Caprolactam: Safety and Hazards, GHS Classification'
    id: PubChem CID 7768 (CAS 105-60-2)
    url: https://pubchem.ncbi.nlm.nih.gov/compound/7768
    kind: database
    year: 2026
    license: public domain (NIH PubChem)
  pubchem-pa6:
    title: 'PubChem CID 32775, Polyamide 6 (CAS 25038-54-4): record read for GHS'
    id: PubChem CID 32775
    url: https://pubchem.ncbi.nlm.nih.gov/compound/32775
    kind: database
    year: 2026
    license: public domain (NIH PubChem)
  pmc-pa6-pa12-am:
    title: 'Comprehensive Review: Technological Approaches, Properties, and Applications of Pure and Reinforced Polyamide 6 (PA6) and Polyamide 12 (PA12) Composite Materials'
    id: PMC11859968 (PMID 40006104), received 2025-01-09, accepted 2025-02-06
    url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11859968/
    kind: paper
    year: 2025
    license: CC BY 4.0
license: CC-BY-4.0
updated: '2026-10-19'
review:
  status: draft
  method: assistant
  checked_values: 21
  unreachable: 1
  caveats: 3
  note: Deepened by an AI assistant on 2026-10-19. Original properties and sources kept. New values were read from BASF (Ultramid B27 EX), LANXESS TI 2007-003, PubChem (caprolactam), Wikipedia (caprolactam, nylon 6) and PMC11859968 in this run. The PA 6 polymer PubChem record and an SDS were not available.
story:
  recipe:
    line: Polyamide 6 is made by ring-opening polymerisation of caprolactam (C6H11NO). Unlike nylon 66, it is not a condensation polymer. When caprolactam is heated under nitrogen for about 4 to 5 hours (Wikipedia), the ring opens and the monomer joins the chain. The repeat unit, [-NH-(CH2)5-CO-]n, is C6H11NO (NASA Table IV; molar mass 113.1590 per repeat unit).
    parts:
      - name: Carbon
        symbol: C
        atoms: 6
        role: Backbone of the repeat unit (five CH2 groups and the carbonyl carbon).
      - name: Hydrogen
        symbol: H
        atoms: 11
        role: Methylene and amide hydrogens of the repeat unit.
      - name: Nitrogen
        symbol: 'N'
        atoms: 1
        role: Amide nitrogen; hydrogen bonds between chains give the crystalline structure.
      - name: Oxygen
        symbol: O
        atoms: 1
        role: Carbonyl oxygen of the amide group.
      - name: Caprolactam
        symbol: C6H11NO
        atoms: 1
        role: Monomer. Ring-opening polymerisation makes it the repeat unit, so the monomer and repeat unit have the same formula.
  risk_groups:
    - title: All readers
      level: 0
      verdict: Partly verified
      lead: The monomer caprolactam is harmful if swallowed, irritant, and harmful if inhaled (PubChem, 99.9 % of notifications). The polymer has no GHS classification in PubChem, and no polymer SDS was read.
  why: Polyamide 6 is in this file because NASA flew it. The MISSE 2 PEACE polymer experiment put it on the outside of the ISS for 3.95 years, and it erodes at 3.51 x 10^-24 cm3/atom under the recorded atomic-oxygen fluence of 8.43e21 atoms/cm2. That is one flight value, not a qualification.
  uses:
    - where: Gears and bearings
      line: A PA 6 review says the polymer is frequently used for gears, bearings and engine covers because it resists mechanical stress.
    - where: Automotive and electronics
      line: The same review says PA 6 is used for load-bearing structures in the automotive and electronics sectors because of its strength, stiffness and wear resistance.
    - where: Fibres and cords
      line: Wikipedia says the first industrial nylon 6 went into parachutes, aircraft tyre cord and glider towing cables in wartime Germany.
    - where: 3D printing
      line: The PMC review says PA 6 is used in SLS and MJF additive manufacturing as glass-fibre composites, and that PA 6 processes are more cost-effective and resist dynamic loading. This is ground manufacturing, not a flight use.
  can_do:
    - label: Atomic oxygen
      benchmark: atomic_oxygen_erosion_yield
      line: In LEO flight it eroded at 3.51 x 10^-24 cm3/atom, measured in NASA MISSE 2 PEACE (Table I).
    - label: Heat
      benchmark: heat_deflection_temperature
      line: The Vinmar sheet gives a heat deflection temperature of 200 degC at 1.8 MPa and a melting point of 220 degC.
    - label: Stiffness
      benchmark: tensile_modulus
      line: The Vinmar sheet gives 3100 MPa with no condition stated. The Aquafil sheet gives 2215 MPa after conditioning at 45 to 55 % RH.
  compare: 'In the NASA flight set PA 6 and PA 66 are listed together. This profile reads only the PA 6 erosion row (3.51e-24 cm3/atom); the PA 66 value (1.80e-24) is not carried over. LANXESS says PA 6 absorbs water at almost twice the rate of PA 66. On the ground, the Ultramid B27 EX and Vinmar and Aquafil sheets give densities of 1.12 to 1.15 and 1.12 to 1.13 g/cm3 and melting points of 220 to 221 degC. The moisture numbers show the main weakness: 2.2 % water at 23 C/50 % rh and 8.5 % at saturation for B27 EX, with 10 % at saturation for the Aquafil and Durethan B 30 S values.'
  compare_rows:
    - scope: material
      label: Erosion yield in LEO flight
      benchmark: atomic_oxygen_erosion_yield
    - scope: material
      label: Melting point
      benchmark: melting_temperature
    - scope: material
      label: Water uptake at saturation
      benchmark: moisture_absorption
  handling:
    - Dry PA 6 before moulding in a desiccant dryer with dew point of at least -20 to -25 C. Keep granule drying at or below 75 to 80 C to avoid oxidative discolouration (LANXESS). The permitted granule moisture for injection moulding is 0.12 % maximum.
    - The ECO 27 sheet should be dried before moulding to the maximum moisture content printed on the sheet, at 70 to 80 C for 4 to 6 h in dry air with dew point below -30 C. Store at -5 to +40 C in closed original packaging and do not store for more than 6 months (Aquafil datasheet).
    - Ultramid B27 EX is supplied pre-dried. Store it protected from moisture, use it within 12 months, and use opened bags immediately (BASF).
  good_for:
    - 'Atomic-oxygen flight data in LEO: the NASA value is measured in orbit.'
    - Stiff, wear-resistant gears and bearings where humidity is controlled and dimensional change is allowed for (ground datasheets, PMC review).
    - Fibre and cord uses where moisture uptake is acceptable (Wikipedia).
  watch_out:
    - 'Moisture: 2.2 % water at 23 C/50 % rh and 8.5 % at saturation for B27 EX; 10 % at saturation for the Aquafil and Durethan B 30 S values. These shift the mechanical values.'
    - 'Dimensional change: 0.2 to 0.3 % length change per 1 % water absorbed, with a larger thickness change (LANXESS).'
    - Hot water and steam conditioning cause oxidation discolouration and warping, and saturated steam is not recommended (LANXESS).
    - No UV, heat-ageing or hydrolysis data for PA 6 was read, so do not assume them from this profile.
  verdict: 'PA 6 has one measured orbital erosion yield (MISSE 2) and sourced ground values for density, melting point and moisture. Its main limit is water: up to 10 % at saturation, with dimensional change of 0.2 to 0.3 % per 1 % water. The monomer is harmful and irritant, while the polymer hazard, UV and heat ageing are still not sourced.'