spore: profile
id: flax-fibre
spore_version: 0.2
family: flax
name: Flax fibre (natural bast fibre)
role: Plant-based reinforcement fibre for composites
category: composites
type: glass-fiber-reinforced
summary: Flax fibre is the bast fibre from the stem of the flax plant (Linum usitatissimum L.), used to reinforce composites as a plant-based alternative to glass fibre. Elementary flax fibres reached 1500 to 1800 MPa in tension and around 1200 MPa in a loop compression test (Bos et al. 2002), although a review quotes a lower tensile figure of 976 MPa. Density, ageing and supply data were not found in the two sources read for this profile.
best_for: Plant-based reinforcement for composites, where the review says flax can substitute for glass fibres
weakest_at: Strength depends on the isolation and decortication process; no density, ageing or supply data found yet
identity:
  formula: Cellulose-based bast fibre from the flax stem (Linum usitatissimum L.); a natural fibre bundle, not one chemical compound, so no single formula
  source: goudenhooft2019
  where: Introduction and cell-wall layers section (cellulose-rich G-layer)
properties:
  - benchmark: ultimate_tensile_strength
    label: Tensile strength of elementary flax fibres, range by isolation procedure
    value: 1500
    value_high: 1800
    bound: range
    unit: MPa
    scope: material
    conditions:
      form: elementary (single) flax fibres, decorticated and hand-isolated
      test: tension
      range_basis: depending on the isolation procedure
    method: Tensile tests by the authors (Bos et al. 2002), range as printed in the abstract
    status: ground
    source: bos2002
    where: Abstract, tensile strength sentence
  - benchmark: compressive_strength
    label: Compressive strength of elementary flax fibres, loop test
    value: 1200
    unit: MPa
    scope: material
    conditions:
      form: elementary flax fibres
      test: loop test
      qualifier: printed as around 1200 MPa
    method: Loop-test compression measurement by the authors (Bos et al. 2002); value as printed in the abstract
    status: ground
    note: The same abstract says standard decortication can lower the compressive strength severely, so this figure is for hand-isolated fibres.
    source: bos2002
    where: Abstract, compressive strength sentence
  - benchmark: ultimate_tensile_strength
    label: Strength at break of flax fibre, as quoted in a review
    value: 976
    unit: MPa
    scope: material
    conditions:
      form: flax fibre (form and test not stated in the review)
      basis: figure quoted from earlier work the review cites
    method: Quoted in an open-access review from earlier work; not measured by the review's authors
    status: ground
    note: Lower than the 1500 to 1800 MPa range measured by Bos et al. (2002). The review does not say which isolation or test gave 976 MPa, so the two are not directly comparable.
    source: goudenhooft2019
    where: Introduction, paragraph comparing flax fibres with glass fibres
  - benchmark: elastic_modulus
    label: Average elastic modulus of flax fibre, as quoted in a review
    value: 52.4
    unit: GPa
    scope: material
    conditions:
      form: flax fibre (form not stated in the review)
      basis: figure quoted from earlier work the review cites
    method: Quoted in an open-access review from earlier work; not measured by the review's authors
    status: ground
    source: goudenhooft2019
    where: Introduction, paragraph comparing flax fibres with glass fibres
  - benchmark: elongation
    label: Strain at break of flax fibre, as quoted in a review
    value: 2.15
    unit: '%'
    scope: material
    conditions:
      form: flax fibre (form not stated in the review)
      basis: figure quoted from earlier work the review cites
    method: Quoted in an open-access review from earlier work; not measured by the review's authors
    status: ground
    source: goudenhooft2019
    where: Introduction, paragraph comparing flax fibres with glass fibres
  - benchmark: fibre_diameter
    label: Average diameter of flax fibre
    value: 20
    unit: μm
    scope: material
    conditions:
      form: flax fibre
      basis: average diameter for a fibre length of 25 mm, as quoted in the review
    method: Quoted in an open-access review from earlier work (van Dam and Gorshkova); not measured by the review's authors
    status: ground
    source: goudenhooft2019
    where: Introduction, paragraph on flax fibre applications
  - benchmark: fibre_cell_wall_thickness
    label: Cell-wall thickness of flax fibre, lower bound
    value: 10
    bound: lower
    unit: μm
    scope: material
    conditions:
      form: flax fibre cell wall
      qualifier: printed as more than 10 μm
    method: Stated in an open-access review; the review does not name a measurement method for this figure
    status: ground
    source: goudenhooft2019
    where: Cell wall thickening section
  - benchmark: cellulose_content
    label: Cellulose content of the G-layer in flax fibre cell walls
    value: 90
    bound: upper
    unit: '%'
    scope: material
    conditions:
      layer: G-layer, the fibre-specific cell-wall layer (not the whole fibre)
      qualifier: printed as up to 90%
    method: Stated in an open-access review; the review does not name a measurement method for this figure
    status: ground
    source: goudenhooft2019
    where: Cell wall layers section (G-layer description)
  - benchmark: microfibril_angle
    label: Cellulose microfibril angle in the G-layer
    value: 8
    value_high: 10
    bound: range
    unit: °
    scope: material
    conditions:
      layer: G-layer, the fibre-specific cell-wall layer
      note: microfibrils almost parallel to the fibre axis
    method: Stated in an open-access review; the review does not name a measurement method for this figure
    status: ground
    source: goudenhooft2019
    where: Cell wall layers section (G-layer description)
corrosion: []
risks:
  hazards:
    - text: The review says plant fibres have a 'low hazard manufacturing process for human health' compared with glass fibres, citing earlier work. No safety data sheet or PubChem hazard record for flax fibre was read in this run, so this is the only hazard statement held.
      ghs: []
      source: goudenhooft2019
      where: Introduction, paragraph comparing plant fibres with glass fibres
  failure_risks:
    - mode: Kink bands from the standard decortication process
      trigger: Standard decortication process, as described by Bos et al. 2002
      consequence: Kink bands form in the fibres and contain cracks bridged by microfibrils; the abstract says decortication can lower compressive strength severely.
      severity: high
      source: bos2002
      where: Abstract, compressive strength and kink band sentences
  side_effects: []
  handling: []
  mitigations: []
uses:
  - application: structures
    device: Flax fibre composite reinforcement (technical fibres or short fibres in a polymer matrix)
    example: The review states that flax fibres are used as reinforcement in composite materials, either as technical fibre bundles or as short fibres impregnated with a polymer matrix.
    source: goudenhooft2019
    where: Introduction, paragraph on composite reinforcement
supply: []
media: []
documents:
  - title: 'Flax (Linum usitatissimum L.) Fibers for Composite Reinforcement: Exploring the Link Between Plant Growth, Cell Walls Development, and Fiber Properties (open access review)'
    type: paper
    url: https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2019.00411/full
    year: 2019
  - title: Tensile and compressive properties of flax fibres for natural fibre reinforced composites (Journal of Materials Science, 2002)
    type: paper
    url: https://research.wur.nl/en/publications/tensile-and-compressive-properties-of-flax-fibres-for-natural-fib/
    year: 2002
gaps:
  - 'Density not recorded: the review quotes a fibre density of 1.53 with no unit printed, so the value was left out rather than assumed to be g/cm3.'
  - Only two sources were read in this run. The site bar asks for 8 sources and 12 properties; this profile has 2 sources and 9 properties.
  - Supply (producing countries with shares, abundance, critical-mineral lists) not found in any source read. The review covers plant growth and fibre structure, not production statistics.
  - No corrosion, ageing, moisture absorption, UV or hygrothermal degradation data for flax fibre found in the two sources read.
  - No vacuum, radiation, thermal-cycling, outgassing or flight data for flax fibre found. No space application source was found; the only use listed is terrestrial composite reinforcement.
  - No safety data sheet, PubChem GHS record or occupational dust-exposure data for flax fibre were read. The hazard entry only quotes the review.
  - Glass-fibre comparison values were not read. The review says flax and glass fibres have a similar range of specific properties, without a glass figure in the text read.
  - 'Conflict held side by side: 976 MPa strength at break (quoted in the review) against 1500 to 1800 MPa tensile strength (Bos et al. 2002). The isolation and test behind 976 MPa is not stated.'
  - 'Handling and storage of flax fibre: not found in the sources read.'
  - 'Property names not in the canonical list: compressive_strength, fibre_diameter, fibre_cell_wall_thickness, cellulose_content, microfibril_angle.'
  - Taxonomy has no natural-fibre composite type. Type set to glass-fiber-reinforced as the closest fibre-reinforced composite type.
  - 'Source papers behind the review''s quoted figures (Lefeuvre and van Dam and Gorshkova) were not opened: the publisher links returned redirect pages with no text.'
sources:
  goudenhooft2019:
    title: 'Flax (Linum usitatissimum L.) Fibers for Composite Reinforcement: Exploring the Link Between Plant Growth, Cell Walls Development, and Fiber Properties'
    id: doi:10.3389/fpls.2019.00411 (Front. Plant Sci. 10, 411); authors C. Goudenhooft, A. Bourmaud, C. Baley
    url: https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2019.00411/full
    year: 2019
    kind: paper
    license: open access, Frontiers in Plant Science
  bos2002:
    title: Tensile and compressive properties of flax fibres for natural fibre reinforced composites
    id: doi:10.1023/A:1014925621252 (J. Mater. Sci. 37(8), 1683-1692); authors H.L. Bos, M.J.A. van den Oever, O.C.J.J. Peters
    url: https://research.wur.nl/en/publications/tensile-and-compressive-properties-of-flax-fibres-for-natural-fib/
    year: 2002
    kind: paper
license: CC-BY-4.0
updated: '2026-11-01'
review:
  status: draft
  method: assistant
  checked_values: 9
  unreachable: 0
  caveats: 1
  note: 'Read by an AI assistant on 2026-11-01 from the Frontiers review and the WUR abstract page only. Below the site bar: 2 sources, 9 properties, no supply, no ageing data. The 976 MPa row is a second-hand quote and conflicts with the 1500 to 1800 MPa range from Bos et al. 2002.'
story:
  recipe:
    line: Flax fibre is a bundle of elongated plant cells. The thick cell walls are mostly cellulose in the G-layer, the fibre-specific layer, where the cellulose microfibrils run almost along the fibre axis.
    parts:
      - name: Cellulose
        role: Main load-bearing polymer. In the G-layer it is highly crystalline and its microfibrils lie at a small angle to the fibre axis.
        share_note: Up to 90% of the G-layer; the whole-fibre share was not found in the sources read
        source: goudenhooft2019
        where: Cell wall layers section (G-layer description)
      - name: Lignin and xylan
        role: Absent from the G-layer, according to the review. Their share in the rest of the cell wall was not found.
        share_note: Absent from the G-layer; other layers not covered
        source: goudenhooft2019
        where: Cell wall layers section (G-layer description)
  risk_groups:
    - title: For people
      lead: The review describes plant fibre manufacturing as a low hazard process for human health, but no safety data sheet was read for flax fibre.
      points:
        - label: Decortication
          line: Bos et al. 2002 report that the standard decortication process induces kink bands in the fibres, and that these lower compressive strength severely.
      gap: No safety data sheet, PubChem record or dust exposure data for flax fibre was read in this run.
      verdict: No safety data read
  why: Flax fibre is the bast fibre from the stem of the flax plant, used in composites as a plant-based alternative to glass fibre. Its cell walls are thick, and the review describes the G-layer, the fibre-specific cell-wall layer, as rich in cellulose. The review describes flax as a renewable reinforcement with mechanical properties in a similar range to glass fibres, but this profile records the figures the two sources actually give.
  uses:
    - where: Composite reinforcement
      line: The review states that flax fibres reinforce composite materials, as technical fibre bundles or as short fibres impregnated with a polymer matrix. No space application was found in the sources read.
  can_do:
    - label: Tensile strength
      benchmark: ultimate_tensile_strength
      line: Elementary flax fibres reached 1500 to 1800 MPa in tension, depending on the isolation procedure (Bos et al. 2002).
    - label: Compressive strength
      benchmark: compressive_strength
      line: Elementary flax fibres reached around 1200 MPa in a loop test, but the same paper says standard decortication can lower compressive strength severely.
    - label: Stiffness
      benchmark: elastic_modulus
      line: The review quotes an average elastic modulus of 52.4 GPa for flax fibre. The review quotes this figure from earlier work and does not measure it.
    - label: Stretch before break
      benchmark: elongation
      line: The review quotes a strain at break of 2.15% for flax fibre, again from earlier work.
  compare: The review says flax fibres have a similar range of specific mechanical properties to glass fibres, which is why it presents them as a substitute. The sources read for this profile do not give a glass-fibre figure to set beside the flax values, so no side-by-side number is shown. The compare rows below list the three flax benchmarks that have a value in the record.
  compare_rows:
    - label: Tensile strength of elementary fibres
      benchmark: ultimate_tensile_strength
    - label: Elastic modulus
      benchmark: elastic_modulus
    - label: Strain at break
      benchmark: elongation
  good_for:
    - Plant-based reinforcement for composites. The review says flax can substitute for glass fibres in this role.
    - High tensile strength for a plant fibre. Elementary fibres reached 1500 to 1800 MPa (Bos et al. 2002).
  watch_out:
    - Strength depends on how the fibre is isolated. The review quotes 976 MPa, and Bos et al. 2002 measured 1500 to 1800 MPa, and the two are not the same test.
    - Standard decortication can lower compressive strength severely (Bos et al. 2002), so compression values apply to hand-isolated fibres.
  verdict: 'Strong and stiff for a plant fibre on the two sources read, but the record is thin: no density, supply or ageing data yet.'