{
  "spore": "profile",
  "id": "kevlar",
  "spore_version": "0.2",
  "family": "glass-and-composites",
  "name": "Kevlar para-aramid fibre",
  "abbreviation": "PPD-T (Kevlar)",
  "role": "high-strength fibre",
  "category": "polymers",
  "type": "aramids",
  "summary": "Kevlar is a para-aramid fibre made from poly(p-phenylene terephthalamide). Its rigid, rod-like chains are held together by hydrogen bonds, which gives a tensile strength about five times that of steel by weight. It resists heat without melting, but it discolours and loses strength under ultraviolet light. In low Earth orbit on the MISSE 2 tray, PPDT eroded by 6.28e-25 cm3 per oxygen atom, a low erosion yield for a polymer in that list.\n",
  "best_for": "Light, strong fibre for body armour, cut-resistant gear and ropes, where the fibre is shielded from sunlight",
  "weakest_at": "Ultraviolet light, which discolours it and cuts its mechanical strength; and low stiffness in compression",
  "identity": {
    "formula": "Poly(p-phenylene terephthalamide), repeat unit C14H10N2O2",
    "designations": [],
    "source": "nasa-tm",
    "where": "Table IV (PPD-T repeat unit C14H10N2O2, 238.2452 g/mol); DuPont guide, Section I (aromatic polyamide)"
  },
  "tags": {
    "environments": [
      "low-earth-orbit"
    ],
    "stresses": [
      "atomic-oxygen",
      "uv",
      "thermal-cycling"
    ],
    "applications": [
      "habitats-and-suits",
      "structures"
    ]
  },
  "properties": [
    {
      "benchmark": "atomic_oxygen_erosion_yield",
      "label": "Atomic oxygen erosion yield, MISSE 2 flight",
      "value": 6.28e-25,
      "bound": "exact",
      "unit": "cm3/atom",
      "scope": "material",
      "conditions": {
        "exposure": "low Earth orbit, ISS MISSE 2 PEACE tray 1, 2001-08-16 to 2005-07-30",
        "fluence": "8.43e21 atoms/cm2",
        "solar": "5000-6700 equivalent sun hours",
        "thermal_cycling": "-30 to 40 degC nominal base-plate range"
      },
      "method": "Flight-measured erosion yield as printed in the NASA predictive-tool report",
      "status": "flight",
      "source": "nasa-tm",
      "where": "Table I (MISSE 2 PEACE polymers erosion yield data, row PPDT (Kevlar)); exposure in section 2.1",
      "source_detail": {
        "title": "Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit",
        "id": "NASA/TM-2008-215490 (Banks, Backus and de Groh, December 2008)",
        "url": "https://ntrs.nasa.gov/citations/20090011780",
        "year": 2008,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "density",
      "label": "Density, Kevlar 29 and 49 yarn",
      "value": 1.44,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "basis": "yarn density as printed for both Kevlar 29 and Kevlar 49"
      },
      "method": "Typical value printed in the DuPont technical guide table",
      "status": "ground",
      "source": "dupont-guide",
      "where": "Table II-1, Density row",
      "source_detail": {
        "title": "DuPont Kevlar Technical Guide (copy hosted at r-g.de)",
        "id": "DuPont Kevlar aramid fiber technical guide",
        "url": "https://www.r-g.de/wiki/images/e/ec/Td_en_Kevlar_guide.pdf",
        "year": 2010,
        "kind": "datasheet",
        "license": "copy hosted by a third party; cited, not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Density, PPDT by MISSE 2 measurement",
      "value": 1.4422,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "basis": "measured density of the MISSE 2 PPDT sample as printed"
      },
      "method": "Value from the NASA erosion report density table",
      "status": "ground",
      "source": "nasa-tm",
      "where": "Table II (density and ash content, row PPDT (Kevlar))",
      "source_detail": {
        "title": "Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit",
        "id": "NASA/TM-2008-215490 (Banks, Backus and de Groh, December 2008)",
        "url": "https://ntrs.nasa.gov/citations/20090011780",
        "year": 2008,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Breaking tenacity, Kevlar 29 yarn",
      "value": 2920,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "basis": "straight test on conditioned yarn, 1,500 denier, standard modulus; printed as 23.0 g/d and 424,000 psi"
      },
      "method": "Typical value printed in DuPont technical guide, shown with the MPa conversion as printed",
      "status": "ground",
      "source": "dupont-guide",
      "where": "Table II-1, Breaking Tenacity row (Kevlar 29 column)",
      "source_detail": {
        "title": "DuPont Kevlar Technical Guide (copy hosted at r-g.de)",
        "id": "DuPont Kevlar aramid fiber technical guide",
        "url": "https://www.r-g.de/wiki/images/e/ec/Td_en_Kevlar_guide.pdf",
        "year": 2010,
        "kind": "datasheet",
        "license": "copy hosted by a third party; cited, not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Breaking tenacity, Kevlar 49 yarn",
      "value": 3000,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "basis": "straight test on conditioned yarn, 1,140 denier, high modulus; printed as 23.6 g/d and 435,000 psi"
      },
      "method": "Typical value printed in DuPont technical guide, shown with the MPa conversion as printed",
      "status": "ground",
      "source": "dupont-guide",
      "where": "Table II-1, Breaking Tenacity row (Kevlar 49 column)",
      "source_detail": {
        "title": "DuPont Kevlar Technical Guide (copy hosted at r-g.de)",
        "id": "DuPont Kevlar aramid fiber technical guide",
        "url": "https://www.r-g.de/wiki/images/e/ec/Td_en_Kevlar_guide.pdf",
        "year": 2010,
        "kind": "datasheet",
        "license": "copy hosted by a third party; cited, not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength, single Kevlar 29 fibre (laboratory)",
      "value": 3040,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "basis": "single-fibre tensile test, printed as 3.04 GPa plus or minus 0.31 GPa"
      },
      "method": "Measured value printed in the single-fibre study (converted from GPa as printed)",
      "status": "ground",
      "source": "cimav-k29",
      "where": "Results, tensile strength row",
      "source_detail": {
        "title": "The tensile behavior of Kevlar 29 fibers",
        "id": "CIMAV institutional repository, item 1004/1347",
        "url": "https://cimav.repositorioinstitucional.mx/jspui/bitstream/1004/1347/1/The%20tensile%20behavior%20of%20Kevlar%2029%20fibers.pdf",
        "year": 2014,
        "kind": "paper",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Tensile modulus, Kevlar 29 yarn",
      "value": 70500,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "basis": "straight test on conditioned yarn, standard modulus; printed as 555 g/d and 10.2e6 psi"
      },
      "method": "Typical value printed in DuPont technical guide",
      "status": "ground",
      "source": "dupont-guide",
      "where": "Table II-1, Tensile Modulus row (Kevlar 29 column)",
      "source_detail": {
        "title": "DuPont Kevlar Technical Guide (copy hosted at r-g.de)",
        "id": "DuPont Kevlar aramid fiber technical guide",
        "url": "https://www.r-g.de/wiki/images/e/ec/Td_en_Kevlar_guide.pdf",
        "year": 2010,
        "kind": "datasheet",
        "license": "copy hosted by a third party; cited, not reproduced"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Tensile modulus, Kevlar 49 yarn",
      "value": 112400,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "basis": "straight test on conditioned yarn, high modulus; printed as 885 g/d and 6.3e6 psi"
      },
      "method": "Typical value printed in DuPont technical guide",
      "status": "ground",
      "source": "dupont-guide",
      "where": "Table II-1, Tensile Modulus row (Kevlar 49 column)",
      "source_detail": {
        "title": "DuPont Kevlar Technical Guide (copy hosted at r-g.de)",
        "id": "DuPont Kevlar aramid fiber technical guide",
        "url": "https://www.r-g.de/wiki/images/e/ec/Td_en_Kevlar_guide.pdf",
        "year": 2010,
        "kind": "datasheet",
        "license": "copy hosted by a third party; cited, not reproduced"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Young's modulus, single Kevlar 29 fibre (laboratory)",
      "value": 83.78,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "basis": "single-fibre tensile test, printed as 83.78 plus or minus 7.12 GPa"
      },
      "method": "Measured value printed in the single-fibre study",
      "status": "ground",
      "source": "cimav-k29",
      "where": "Results, Young's modulus row",
      "source_detail": {
        "title": "The tensile behavior of Kevlar 29 fibers",
        "id": "CIMAV institutional repository, item 1004/1347",
        "url": "https://cimav.repositorioinstitucional.mx/jspui/bitstream/1004/1347/1/The%20tensile%20behavior%20of%20Kevlar%2029%20fibers.pdf",
        "year": 2014,
        "kind": "paper",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation at break, Kevlar 29 yarn",
      "value": 3.6,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "basis": "straight test on conditioned yarn"
      },
      "method": "Typical value printed in DuPont technical guide",
      "status": "ground",
      "source": "dupont-guide",
      "where": "Table II-1, Elongation at Break row (Kevlar 29 column)",
      "source_detail": {
        "title": "DuPont Kevlar Technical Guide (copy hosted at r-g.de)",
        "id": "DuPont Kevlar aramid fiber technical guide",
        "url": "https://www.r-g.de/wiki/images/e/ec/Td_en_Kevlar_guide.pdf",
        "year": 2010,
        "kind": "datasheet",
        "license": "copy hosted by a third party; cited, not reproduced"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation at break, Kevlar 49 yarn",
      "value": 2.4,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "basis": "straight test on conditioned yarn"
      },
      "method": "Typical value printed in DuPont technical guide",
      "status": "ground",
      "source": "dupont-guide",
      "where": "Table II-1, Elongation at Break row (Kevlar 49 column)",
      "source_detail": {
        "title": "DuPont Kevlar Technical Guide (copy hosted at r-g.de)",
        "id": "DuPont Kevlar aramid fiber technical guide",
        "url": "https://www.r-g.de/wiki/images/e/ec/Td_en_Kevlar_guide.pdf",
        "year": 2010,
        "kind": "datasheet",
        "license": "copy hosted by a third party; cited, not reproduced"
      }
    },
    {
      "benchmark": "moisture_absorption",
      "label": "Equilibrium moisture regain, PPD-T fibre",
      "value": 5,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "basis": "equilibrium moisture regain at 55% relative humidity"
      },
      "method": "Value printed in the PolyOne/Fiber-Line Kevlar para-aramid datasheet (both standard and high modulus grades)",
      "status": "ground",
      "source": "polyone-kevlar",
      "where": "Kevlar para-aramid data table, Moisture Regain row",
      "source_detail": {
        "title": "Kevlar para-aramid datasheet (Fiber-Line, PolyOne)",
        "id": "fl.us-.datasheet-kevlar-para-aramid",
        "url": "https://automotive.polyone.com/sites/default/files/2021-06/fl.us-.datasheet-kevlar-para-aramid.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "supplier document, cited not reproduced"
      }
    },
    {
      "benchmark": "moisture_absorption",
      "label": "Equilibrium moisture from bone-dry yarn, Kevlar 29",
      "value": 4.5,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "basis": "bone-dry yarn conditioned at 75 degF (24 degC) and 55% RH"
      },
      "method": "Value printed in DuPont technical guide, moisture levels",
      "status": "ground",
      "source": "dupont-guide",
      "where": "Table II-1, Moisture Levels row (equilibrium from bone-dry yarn)",
      "source_detail": {
        "title": "DuPont Kevlar Technical Guide (copy hosted at r-g.de)",
        "id": "DuPont Kevlar aramid fiber technical guide",
        "url": "https://www.r-g.de/wiki/images/e/ec/Td_en_Kevlar_guide.pdf",
        "year": 2010,
        "kind": "datasheet",
        "license": "copy hosted by a third party; cited, not reproduced"
      }
    },
    {
      "benchmark": "specific_heat",
      "value": 0.34,
      "bound": "exact",
      "unit": "cal/g x degC",
      "scope": "material",
      "conditions": {
        "basis": "at 77 degF (25 degC), as printed in the DuPont table"
      },
      "method": "Value printed in DuPont technical guide; printed unit kept",
      "status": "ground",
      "source": "dupont-guide",
      "where": "Table II-1 Thermal Properties, specific heat row (At 77 degF)",
      "source_detail": {
        "title": "DuPont Kevlar Technical Guide (copy hosted at r-g.de)",
        "id": "DuPont Kevlar aramid fiber technical guide",
        "url": "https://www.r-g.de/wiki/images/e/ec/Td_en_Kevlar_guide.pdf",
        "year": 2010,
        "kind": "datasheet",
        "license": "copy hosted by a third party; cited, not reproduced"
      }
    },
    {
      "benchmark": "decomposition_temperature",
      "label": "Decomposition temperature in air (no melting point)",
      "value": 427,
      "value_high": 482,
      "bound": "range",
      "unit": "degC",
      "scope": "material",
      "conditions": {
        "basis": "decomposes rather than melts; range measured at a 10 degC per minute temperature rise in air, nitrogen about 538 degC"
      },
      "method": "Range printed in the DuPont guide",
      "status": "ground",
      "source": "dupont-guide",
      "where": "Section 2, Decomposition Temperature; Table II-1 Decomposition Temperature row",
      "source_detail": {
        "title": "DuPont Kevlar Technical Guide (copy hosted at r-g.de)",
        "id": "DuPont Kevlar aramid fiber technical guide",
        "url": "https://www.r-g.de/wiki/images/e/ec/Td_en_Kevlar_guide.pdf",
        "year": 2010,
        "kind": "datasheet",
        "license": "copy hosted by a third party; cited, not reproduced"
      }
    },
    {
      "benchmark": "molar_mass",
      "label": "Molar mass of repeat unit",
      "value": 238.2452,
      "bound": "exact",
      "unit": "g/mol",
      "scope": "material",
      "conditions": {
        "repeat_unit": "C14H10N2O2"
      },
      "method": "Value printed in the NASA table of polymer chemical structure",
      "status": "ground",
      "source": "nasa-tm",
      "where": "Table IV, row PPD-T (Kevlar)",
      "source_detail": {
        "title": "Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit",
        "id": "NASA/TM-2008-215490 (Banks, Backus and de Groh, December 2008)",
        "url": "https://ntrs.nasa.gov/citations/20090011780",
        "year": 2008,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Ultraviolet light and sunlight",
      "headline": "UV is Kevlar's main weakness: it yellows and then browns, and mechanical strength falls with long exposure.",
      "effect": "Unprotected yarn discolours from yellow to brown after prolonged exposure, and extended UV exposure can cut mechanical properties depending on wavelength, time and intensity. Degradation needs oxygen, and it is not increased by moisture or sulfur dioxide. The overlap of the fibre absorption spectrum and sunlight lies between 300 and 450 nm, so that range must be excluded for protection.",
      "rating": "severe",
      "conditions": {
        "exposure": "sunlight or UV, unprotected, in the presence of oxygen",
        "wavelength_range": "300 to 450 nm overlap with sunlight"
      },
      "source": "dupont-guide",
      "where": "Section 2, Effect of UV Light on Kevlar, and Figure 2.11"
    },
    {
      "environment": "Humid air",
      "headline": "Kevlar takes up moisture, but its tensile properties are virtually unaffected by moisture content.",
      "effect": "Equilibrium moisture regain is about 5.0% at 55% RH and rises linearly with relative humidity. Bone-dry Kevlar 29 reaches 4.5% at equilibrium. The guide states that tensile properties are virtually unaffected by moisture content.",
      "rating": "low",
      "conditions": {
        "humidity": "55% RH equilibrium; linear with RH",
        "temperature": "24 degC"
      },
      "source": "polyone-kevlar",
      "where": "Kevlar para-aramid data, Moisture Regain row; DuPont guide Section 2, Moisture Regain"
    },
    {
      "environment": "Heat (thermal ageing)",
      "headline": "Strength drops about 10 to 20 percent at once when heated, then keeps falling with time at high temperature.",
      "effect": "Per Wikipedia, tensile strength falls by 10 to 20 percent at higher temperatures straight away, and strength keeps reducing over hours. Enduring 160 degC for 500 hours reduces strength by about 10 percent. The fibre keeps strength down to cryogenic temperatures.",
      "rating": "moderate",
      "conditions": {
        "example": "160 degC for 500 hours, about 10 percent loss",
        "note": "secondary source; not the DuPont test"
      },
      "source": "wiki-kevlar",
      "where": "Thermal properties section"
    },
    {
      "environment": "Strong acids and alkalis at high temperature",
      "headline": "Kevlar holds strength in neutral water but degrades in strong acids and hot alkalis.",
      "effect": "At neutral pH the filament tenacity stays unchanged after 200 days at 65 degC. Acidic conditions cause more severe degradation than basic ones, and the guide's table lists degradation in formic acid at 90 percent and in hydrochloric acid at 10 percent and 160 degF (71 degC). Sodium hydroxide at 10 percent and 210 degF (99 degC) degrades the fibre.",
      "rating": "moderate",
      "conditions": {
        "basis": "guide table of chemical exposures; strength loss read as Degraded in the table"
      },
      "source": "dupont-guide",
      "where": "Section 2 chemical resistance tables; Chemical Compatibility text"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "PubChem aggregated GHS for p-phenylenediamine (Kevlar monomer, CID 7814; 597 company reports): H301 toxic if swallowed, H311 toxic in contact with skin, H331 toxic if inhaled (each 99.7%); H317 may cause an allergic skin reaction; H319 causes serious eye irritation; H370 causes damage to organs (38.9%); H400 and H410 very toxic to aquatic life. Signal word Danger.",
        "ghs": [
          "H301",
          "H311",
          "H331",
          "H317",
          "H319",
          "H370",
          "H400",
          "H410"
        ],
        "source": "pubchem-kevlar-monomers",
        "where": "Safety and Hazards, GHS Classification (CID 7814)"
      },
      {
        "text": "PubChem aggregated GHS for terephthaloyl chloride (Kevlar monomer, CID 7488; 2263 company reports): 88.7% of reports say it does not meet GHS criteria. Where classified: H314 causes severe skin burns and eye damage (11.2%); H331 toxic if inhaled (11.1%). Signal word Danger.",
        "ghs": [
          "H314",
          "H331"
        ],
        "source": "pubchem-kevlar-monomers",
        "where": "Safety and Hazards, GHS Classification (CID 7488)"
      },
      {
        "text": "Fibre dust and particulates: the DuPont SDS gives the product hazard as combustible dust. Small particles from processing or handling may form combustible dust concentrations in air. Fibre fly and dust can irritate the eyes, nose and airways, and rubbing fibre particulates on skin can cause transitory mild redness or itching. The SDS does not describe fibrils as a separate hazard.",
        "ghs": [],
        "source": "sds-kevlar",
        "where": "Section 2 Hazard statements; Handling (Personnel) row"
      },
      {
        "text": "Dust and fibre exposure limits from the SDS: DuPont AEL 2 RFP/cc for respirable fibres and 5 mg/m3 for non-fibrous dust (8 and 12 h TWA); OSHA PEL 5 mg/m3 respirable fraction and 15 mg/m3 total dust; ACGIH TLV 3 mg/m3 respirable and 10 mg/m3 inhalable.",
        "ghs": [],
        "source": "sds-kevlar",
        "where": "Section 8, Exposure Limit Values"
      },
      {
        "text": "Fire: the SDS gives an ignition temperature of does not ignite and a decomposition temperature above 300 degC. Burning gives carbon dioxide, nitrogen oxides, hydrogen cyanide, ammonia, aldehydes and hydrocarbons. Firefighters need self-contained breathing apparatus.",
        "ghs": [],
        "source": "sds-kevlar",
        "where": "Fire-fighting measures; Flammability and Decomposition rows"
      }
    ],
    "failure_risks": [
      {
        "mode": "UV discolouration and strength loss",
        "trigger": "Unprotected sunlight or UV exposure in the presence of oxygen",
        "consequence": "Yellowing, then browning, and loss of mechanical properties with long exposure",
        "severity": "moderate",
        "source": "dupont-guide",
        "where": "Section 2, Effect of UV Light on Kevlar"
      },
      {
        "mode": "Thermal decomposition at high temperature",
        "trigger": "Heating above about 427 degC in air",
        "consequence": "Kevlar does not melt; it decomposes between 427 and 482 degC in air",
        "severity": "moderate",
        "source": "dupont-guide",
        "where": "Section 2, Decomposition Temperature"
      },
      {
        "mode": "Chemical attack",
        "trigger": "Strong formic or hydrochloric acid, or hot sodium hydroxide",
        "consequence": "Breaking strength falls with the exposure table's degradation rating",
        "severity": "moderate",
        "source": "dupont-guide",
        "where": "Chemical resistance tables; Chemical Compatibility text"
      }
    ],
    "side_effects": [],
    "handling": [
      {
        "text": "Shield the fibre from sunlight and UV; the guide says the 300 to 450 nm range must be excluded for outdoor use without protection.",
        "source": "dupont-guide",
        "where": "Section 2, Effect of UV Light on Kevlar"
      },
      {
        "text": "Avoid dust formation: use exhaust ventilation or vacuum cleaning rather than dry sweeping, wear safety glasses with side shields, and use a certified respirator where the exposure limit is exceeded.",
        "source": "sds-kevlar",
        "where": "Handling (Personnel), Spill Cleanup and Section 8 Exposure Controls"
      }
    ],
    "mitigations": [
      {
        "text": "Use UV-blocking protection or stow the fibre in darkness; discolouration of fresh yarn from ordinary room light is normal and is not degradation.",
        "source": "dupont-guide",
        "where": "Section 2, Effect of UV Light on Kevlar"
      }
    ]
  },
  "uses": [
    {
      "application": "habitats-and-suits",
      "device": "Body armour and ballistic vests",
      "example": "Kevlar is a well-known component of personal armour, including helmets and ballistic vests; the US military PASGT helmet and vest relied on it.",
      "source": "wiki-kevlar",
      "where": "Applications section (personal armour)"
    },
    {
      "application": "habitats-and-suits",
      "device": "Cut-resistant gloves and protective clothing",
      "example": "Kevlar is used in gloves, sleeves and jackets to protect against cuts, abrasions and heat.",
      "source": "wiki-kevlar",
      "where": "Applications section (protective clothing)"
    },
    {
      "application": "structures",
      "device": "Composite reinforcement",
      "example": "Kevlar is spun into ropes or fabric, or used as an ingredient in composite components, and is used for mooring lines.",
      "source": "wiki-kevlar",
      "where": "Lead paragraphs; applications section"
    },
    {
      "application": "propulsion-and-tanks",
      "device": "Stuffed Whipple shield on a robotic spacecraft propellant tank",
      "example": "The PACE tank ram-direction shield used six layers of Nextel and six layers of Kevlar between two 0.20 cm aluminium plates with a 4 cm standoff, chosen to balance risk and mass.",
      "source": "ntrs-whipple",
      "where": "Text after the case comparison table, selected ram shield configuration (Case 6)"
    }
  ],
  "supply": [
    {
      "subject": "Kevlar (PPD-T) production",
      "abundance": "Not sourced. Feedstock is the two monomers, p-phenylenediamine and terephthaloyl chloride (Wikipedia).",
      "producers": [],
      "critical_lists": [],
      "recycling": "Not sourced.",
      "substitutes": [
        "Twaron, a fibre with the same chemical structure developed by Akzo, produced by Teijin Aramid (Wikipedia)."
      ],
      "source": "wiki-kevlar",
      "where": "Lead paragraphs; Production section"
    }
  ],
  "media": [],
  "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": "DuPont Kevlar Technical Guide (copy hosted at r-g.de)",
      "type": "datasheet",
      "url": "https://www.r-g.de/wiki/images/e/ec/Td_en_Kevlar_guide.pdf",
      "year": 2010
    },
    {
      "title": "PolyOne / Fiber-Line Kevlar para-aramid datasheet",
      "type": "datasheet",
      "url": "https://automotive.polyone.com/sites/default/files/2021-06/fl.us-.datasheet-kevlar-para-aramid.pdf",
      "year": 2021
    },
    {
      "title": "The tensile behavior of Kevlar 29 fibers (CIMAV repository)",
      "type": "paper",
      "url": "https://cimav.repositorioinstitucional.mx/jspui/bitstream/1004/1347/1/The%20tensile%20behavior%20of%20Kevlar%2029%20fibers.pdf",
      "year": 2014
    },
    {
      "title": "KEVLAR Para-aramid Safety Data Sheet, Version 8.1 (copy hosted by Easy Composites)",
      "type": "sds",
      "url": "https://media.easycomposites.co.uk/datasheets/Dupont-Kevlar-SDS-Ver8_1-23Mar2023.pdf",
      "year": 2024
    },
    {
      "title": "Application of Stuffed Whipple Shield to Robotic Spacecraft (NTRS 20230015317)",
      "type": "paper",
      "url": "https://ntrs.nasa.gov/citations/20230015317",
      "year": 2023
    },
    {
      "title": "PubChem GHS classification: p-phenylenediamine (CID 7814) and terephthaloyl chloride (CID 7488)",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/7814",
      "year": 2026
    }
  ],
  "gaps": [
    "No Kevlar 149 value found in any fetched page; the DuPont guide copy has Kevlar 29 and 49 only. Kevlar 149 is named in Wikipedia as the highest-tenacity grade, without numbers.",
    "No PubChem record exists for the polymer (searches for Kevlar and poly(p-phenylene terephthalamide) returned none), so hazards use the two monomers and the DuPont SDS for Kevlar. The fibrils hazard is not described separately in any source read.",
    "The Stuffed Whipple paper NTRS 20230015317 was read and is used for the layup only, not for property values. NTRS 20250001790 (a basalt paper) would not download and is not used.",
    "No tether or space-tether source was read for Kevlar; the tether use is not included.",
    "No producer list or production volumes were found; supply is limited to the monomers and the Twaron substitute.",
    "The decomposition-temperature and molar-mass names are not in property-canon.yaml; they are used as short snake_case names.",
    "Vacuum outgassing and total radiation dose for Kevlar were not read; the passport lists those stresses but no result for them was fetched.",
    "Monomer composition by weight is calculated from the printed repeat-unit formula C14H10N2O2, not read from a source (see recipe)."
  ],
  "story": {
    "why": "Kevlar is a para-aramid, so its chains are rigid and aligned, and hydrogen bonds link neighbouring chains. That gives a high strength per unit weight and a high modulus. The trade is UV sensitivity and low compressive strength. In the MISSE 2 flight test it eroded slowly under atomic oxygen, which is why it was included in the passport.",
    "uses": [
      {
        "where": "Body armour",
        "line": "Kevlar is a key component of personal armour, including helmets and ballistic vests, as Wikipedia records."
      },
      {
        "where": "Protective clothing",
        "line": "Gloves, sleeves and jackets made of Kevlar protect against cuts, abrasion and heat, and are lighter than comparable protection (Wikipedia)."
      },
      {
        "where": "Ropes and composites",
        "line": "Kevlar is spun into ropes, used as mooring lines and as a composite ingredient (Wikipedia). Spacecraft shielding and tethers are not covered here because no source was read for them."
      }
    ],
    "can_do": [
      {
        "label": "Strength",
        "line": "Kevlar 29 yarn breaks at 2,920 MPa and Kevlar 49 at 3,000 MPa (DuPont guide). A single Kevlar 29 fibre measured 3.04 GPa plus or minus 0.31 GPa.",
        "benchmark": "ultimate_tensile_strength",
        "scope": "material"
      },
      {
        "label": "Stiffness",
        "line": "Kevlar 29 yarn has a tensile modulus of 70,500 MPa and Kevlar 49 of 112,400 MPa (DuPont guide). A single Kevlar 29 fibre measured 83.78 GPa.",
        "benchmark": "elastic_modulus",
        "scope": "material"
      },
      {
        "label": "Flight exposure",
        "line": "In low Earth orbit on MISSE 2, PPDT eroded by 6.28e-25 cm3 per atomic oxygen atom (NASA Table I).",
        "scope": "material",
        "value": "6.28e-25 cm3/atom"
      }
    ],
    "compare": "Kevlar is strong and light for a polymer, but it is weaker in UV than many engineering plastics, and it absorbs about five percent moisture. Its atomic-oxygen erosion yield in LEO is lower than several common polymers in the same NASA table, such as polyethylene and PMMA, which makes it a credible choice for space use shielded from sunlight.",
    "compare_rows": [
      {
        "label": "Strength",
        "benchmark": "ultimate_tensile_strength",
        "scope": "material"
      },
      {
        "label": "Stiffness",
        "benchmark": "elastic_modulus",
        "scope": "material"
      },
      {
        "label": "Atomic oxygen erosion",
        "benchmark": "atomic_oxygen_erosion_yield",
        "scope": "material"
      }
    ],
    "handling": [
      "Keep it out of sunlight and UV, or cover it with a UV blocker.",
      "Expect about 5 percent moisture pickup at 55 percent RH; tensile properties are not much affected.",
      "Keep it below 427 degC; it decomposes rather than melts."
    ],
    "good_for": [
      "Strength for weight in armour, cut-resistant gear and ropes.",
      "Low atomic-oxygen erosion in LEO, measured on MISSE 2."
    ],
    "watch_out": [
      "UV discolours and weakens unprotected yarn.",
      "Strong acids and hot alkalis degrade the fibre.",
      "Compressive strength is poor (PolyOne datasheet)."
    ],
    "verdict": "Kevlar is a strong, light, heat-tolerant fibre whose weak point is sunlight. Shield it from UV, and it performs well in orbit and in armour.",
    "recipe": {
      "line": "Kevlar is made by condensation of p-phenylenediamine with terephthaloyl chloride in solution, which gives hydrochloric acid as a byproduct (Wikipedia). The repeat unit is C14H10N2O2 (NASA Table IV). The polymer forms liquid-crystalline solutions, and drawing orients the chains along the fibre.",
      "parts": [
        {
          "name": "p-Phenylenediamine (monomer)",
          "symbol": "C6H8N2",
          "role": "Diamine that forms the rigid para-phenylene and amide-N part of each repeat unit (Wikipedia)."
        },
        {
          "name": "Terephthaloyl chloride (monomer)",
          "symbol": "C8H4Cl2O2",
          "role": "Diacid chloride that forms the terephthalamide part; the byproduct HCl leaves in the condensation (Wikipedia)."
        },
        {
          "name": "Repeat unit",
          "symbol": "C14H10N2O2",
          "role": "The polymer unit that repeats along the chain; carbon, hydrogen, nitrogen and oxygen only.",
          "share_note": "molar mass 238.2452 g/mol (NASA Table IV)"
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "No safety data sheet or GHS record for Kevlar was read in this run, so no hazard classification is given.",
        "points": [
          {
            "label": "Dust and cutting",
            "line": "The fibre is handled as yarn or fabric. Check the supplier safety data sheet before cutting or grinding it."
          },
          {
            "label": "Fire",
            "line": "Kevlar does not melt. It decomposes between 427 and 482 degC in air (DuPont guide)."
          }
        ],
        "level": 0,
        "verdict": "Hazards not checked"
      },
      {
        "title": "In the environment",
        "lead": "UV is the main route to loss of strength.",
        "points": [
          {
            "label": "UV",
            "line": "Unprotected yarn discolours from yellow to brown and loses strength with long exposure; the 300 to 450 nm range must be excluded (DuPont guide)."
          },
          {
            "label": "Moisture",
            "line": "Kevlar takes up about 5 percent moisture at 55 percent RH, but its tensile properties are virtually unaffected (PolyOne datasheet, DuPont guide)."
          }
        ],
        "level": 1,
        "verdict": "Sunlight is the watch point"
      }
    ]
  },
  "updated": "2026-10-19",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 16,
    "unreachable": 0,
    "caveats": 3,
    "note": "Written by an AI assistant on 2026-10-19 from the NASA TM Table I, II and IV, the DuPont guide, the PolyOne datasheet, one single-fibre paper and Wikipedia. Only 5 sources were read, short of the 8 requested. Hazards and some uses are not sourced."
  },
  "sources": {
    "nasa-tm": {
      "title": "Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit",
      "id": "NASA/TM-2008-215490 (Banks, Backus and de Groh, December 2008)",
      "url": "https://ntrs.nasa.gov/citations/20090011780",
      "year": 2008,
      "kind": "report",
      "license": "public domain (NASA)"
    },
    "dupont-guide": {
      "title": "DuPont Kevlar Technical Guide (copy hosted at r-g.de)",
      "id": "DuPont Kevlar aramid fiber technical guide",
      "url": "https://www.r-g.de/wiki/images/e/ec/Td_en_Kevlar_guide.pdf",
      "year": 2010,
      "kind": "datasheet",
      "license": "copy hosted by a third party; cited, not reproduced"
    },
    "polyone-kevlar": {
      "title": "Kevlar para-aramid datasheet (Fiber-Line, PolyOne)",
      "id": "fl.us-.datasheet-kevlar-para-aramid",
      "url": "https://automotive.polyone.com/sites/default/files/2021-06/fl.us-.datasheet-kevlar-para-aramid.pdf",
      "year": 2021,
      "kind": "datasheet",
      "license": "supplier document, cited not reproduced"
    },
    "cimav-k29": {
      "title": "The tensile behavior of Kevlar 29 fibers",
      "id": "CIMAV institutional repository, item 1004/1347",
      "url": "https://cimav.repositorioinstitucional.mx/jspui/bitstream/1004/1347/1/The%20tensile%20behavior%20of%20Kevlar%2029%20fibers.pdf",
      "year": 2014,
      "kind": "paper",
      "license": "cited, not reproduced"
    },
    "wiki-kevlar": {
      "title": "Wikipedia: Kevlar",
      "id": "Kevlar",
      "url": "https://en.wikipedia.org/wiki/Kevlar",
      "kind": "web",
      "license": "CC BY-SA 4.0 (cited, not reproduced)"
    },
    "sds-kevlar": {
      "title": "KEVLAR Para-aramid Safety Data Sheet, Version 8.1 (Ref. 150000002634; revision 03/23/2023)",
      "id": "DuPont SDS, copy hosted by Easy Composites",
      "url": "https://media.easycomposites.co.uk/datasheets/Dupont-Kevlar-SDS-Ver8_1-23Mar2023.pdf",
      "year": 2024,
      "kind": "datasheet",
      "license": "supplier safety data sheet, cited not reproduced"
    },
    "ntrs-whipple": {
      "title": "Application of Stuffed Whipple Shield to Robotic Spacecraft",
      "id": "NASA NTRS 20230015317, 2nd International Orbital Debris Conference (2023)",
      "url": "https://ntrs.nasa.gov/citations/20230015317",
      "year": 2023,
      "kind": "paper",
      "license": "NASA technical report, public distribution"
    },
    "pubchem-kevlar-monomers": {
      "title": "PubChem GHS classification for p-phenylenediamine and terephthaloyl chloride",
      "id": "PubChem CID 7814 and CID 7488, read via the PUG REST API",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/7814",
      "kind": "database",
      "license": "PubChem, cited not reproduced"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/kevlar/"
}