{
  "spore": "profile",
  "id": "pbi",
  "spore_version": "0.2",
  "family": "high-performance-polymers",
  "name": "Polybenzimidazole",
  "abbreviation": "PBI",
  "role": "High-temperature aromatic polymer used as flame-resistant fibre and moulded resin, and in NASA space textiles",
  "category": "polymers",
  "type": "high-performance",
  "summary": "Polybenzimidazole (PBI) is an all-aromatic heterocyclic polymer, first developed in 1961 by Vogel and Marvel. It has no melting point and is usually yellow to brown. Goodfellow lists a density of 1.3 g/cm3, a heat deflection temperature of 435 degC at 0.45 MPa, a tensile strength of 160 MPa, a tensile modulus of 5.9 GPa and a limiting oxygen index of 58 percent. TotalMateria gives a glass transition of 425 degC. As a sample on the MISSE 2 PEACE experiment in low Earth orbit it had an atomic oxygen erosion yield of more than 2.21e-24 cm3/atom, which NASA prints as a lower bound (greater-than sign).\n",
  "best_for": "Flame-resistant protective fabrics and high-temperature parts that must keep stiffness, with a glass transition of 425 degC",
  "weakest_at": "Atomic oxygen in low Earth orbit (erosion yield of at least 2.21e-24 cm3/atom on MISSE 2); fine dust is flammable and explosive when suspended in air",
  "identity": {
    "formula": "Polybenzimidazole, repeat unit C20H12N4 (molar mass 308.34 g/mol), poly[2,2'-(m-phenylene)-5,5'-bibenzimidazole]",
    "cas": "32075-68-6",
    "designations": [],
    "source": "wiki-pbi",
    "where": "Wikipedia Polybenzimidazole page (infobox: repeat-unit formula and molar mass; chemical name). CAS 32075-68-6 is also printed on the Goodfellow PBI film page. The MCAM SDS gives CAS 25928-81-8 for polybenzimidazole, so both numbers are recorded and the difference is listed in gaps."
  },
  "tags": {
    "environments": [
      "low-earth-orbit"
    ],
    "stresses": [
      "atomic-oxygen"
    ],
    "applications": [
      "habitats-and-suits"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "value": 1.2758,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "basis": "polymer density from the MISSE 2 PEACE polymer table, supplier information or density gradient"
      },
      "method": "Table II density column, reported with the mass fraction of sodium ash",
      "status": "ground",
      "source": "nasa-misse2-pbi",
      "where": "Table II (MISSE 2 PEACE polymers density and fractional ash content), row Polybenzimidazole PBI",
      "source_detail": {
        "title": "NASA/TM-2008-215490: Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit (Banks, Backus and de Groh, 2008)",
        "url": "https://ntrs.nasa.gov/api/citations/20090011780/downloads/20090011780.pdf",
        "year": 2008,
        "kind": "report"
      }
    },
    {
      "benchmark": "density",
      "value": 1.3,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "basis": "polybenzimidazole film product listing, form not stated on the page beyond film"
      },
      "method": "Density value printed on the Goodfellow product page",
      "status": "ground",
      "source": "goodfellow-pbi",
      "where": "Mechanical and Physical Properties table, Density( gcm-3 ) row",
      "source_detail": {
        "title": "Goodfellow: Polybenzimidazole Film, PBI, CAS 32075-68-6 (product page)",
        "url": "https://www.goodfellow.com/usa/polybenzimidazole-film-group",
        "kind": "datasheet"
      }
    },
    {
      "benchmark": "glass_transition_temperature",
      "value": 425,
      "bound": "exact",
      "unit": "degC",
      "scope": "material",
      "conditions": {
        "basis": "single glass transition value printed in the material data table for the PBI entry"
      },
      "method": "Value printed on the TotalMateria material data page (page lists temperature bands with the value)",
      "status": "ground",
      "source": "totalmateria-pbi",
      "where": "Physical properties, row Glass Transition Temperature, Tg",
      "source_detail": {
        "title": "TotalMateria: PBI material data page (material 5094597)",
        "url": "https://www.totalmateria.com/en-us/material/5094597",
        "kind": "datasheet"
      }
    },
    {
      "benchmark": "heat_deflection_temperature",
      "value": 435,
      "bound": "exact",
      "unit": "degC",
      "scope": "material",
      "conditions": {
        "stress": "0.45 MPa"
      },
      "method": "Heat-deflection temperature printed in the thermal properties table",
      "status": "ground",
      "source": "goodfellow-pbi",
      "where": "Thermal Properties table, row Heat-deflection temperature - 0.45MPa( C )",
      "source_detail": {
        "title": "Goodfellow: Polybenzimidazole Film, PBI, CAS 32075-68-6 (product page)",
        "url": "https://www.goodfellow.com/usa/polybenzimidazole-film-group",
        "kind": "datasheet"
      }
    },
    {
      "benchmark": "max_service_temp",
      "value": 260,
      "value_high": 400,
      "bound": "exact",
      "unit": "degC",
      "scope": "material",
      "conditions": {
        "basis": "upper working temperature range printed on the product page"
      },
      "method": "Range printed on the Goodfellow product page as 260-400",
      "status": "ground",
      "source": "goodfellow-pbi",
      "where": "Thermal Properties table, row Upper working temperature( C ) 260-400",
      "source_detail": {
        "title": "Goodfellow: Polybenzimidazole Film, PBI, CAS 32075-68-6 (product page)",
        "url": "https://www.goodfellow.com/usa/polybenzimidazole-film-group",
        "kind": "datasheet"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "value": 0.41,
      "bound": "exact",
      "unit": "W m-1 K-1",
      "scope": "material",
      "conditions": {
        "temperature": "23 degC"
      },
      "method": "Value printed as 0.41@23 degC on the product page",
      "status": "ground",
      "source": "goodfellow-pbi",
      "where": "Thermal Properties table, row Thermal conductivity",
      "source_detail": {
        "title": "Goodfellow: Polybenzimidazole Film, PBI, CAS 32075-68-6 (product page)",
        "url": "https://www.goodfellow.com/usa/polybenzimidazole-film-group",
        "kind": "datasheet"
      }
    },
    {
      "benchmark": "cte",
      "value": 23,
      "bound": "exact",
      "unit": "10-6 K-1",
      "scope": "material",
      "conditions": {
        "basis": "coefficient of thermal expansion as printed on the product page, temperature not stated"
      },
      "method": "Value printed as x10-6 K-1 on the product page",
      "status": "ground",
      "source": "goodfellow-pbi",
      "where": "Thermal Properties table, row Coefficient of thermal expansion",
      "source_detail": {
        "title": "Goodfellow: Polybenzimidazole Film, PBI, CAS 32075-68-6 (product page)",
        "url": "https://www.goodfellow.com/usa/polybenzimidazole-film-group",
        "kind": "datasheet"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "value": 5.9,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "basis": "tensile modulus printed on the product page"
      },
      "method": "Value printed on the Goodfellow product page",
      "status": "ground",
      "source": "goodfellow-pbi",
      "where": "Mechanical Properties table, row Tensile modulus( GPa )",
      "source_detail": {
        "title": "Goodfellow: Polybenzimidazole Film, PBI, CAS 32075-68-6 (product page)",
        "url": "https://www.goodfellow.com/usa/polybenzimidazole-film-group",
        "kind": "datasheet"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "value": 160,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "basis": "tensile strength printed on the product page (unnotched)"
      },
      "method": "Value printed on the Goodfellow product page; Wikipedia infobox gives the same 160 MPa",
      "status": "ground",
      "source": "goodfellow-pbi",
      "where": "Mechanical Properties table, row Tensile strength( MPa )",
      "source_detail": {
        "title": "Goodfellow: Polybenzimidazole Film, PBI, CAS 32075-68-6 (product page)",
        "url": "https://www.goodfellow.com/usa/polybenzimidazole-film-group",
        "kind": "datasheet"
      }
    },
    {
      "benchmark": "elongation",
      "value": 3,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "basis": "elongation at break printed on the product page"
      },
      "method": "Value printed on the Goodfellow product page",
      "status": "ground",
      "source": "goodfellow-pbi",
      "where": "Mechanical Properties table, row Elongation at break( % )",
      "source_detail": {
        "title": "Goodfellow: Polybenzimidazole Film, PBI, CAS 32075-68-6 (product page)",
        "url": "https://www.goodfellow.com/usa/polybenzimidazole-film-group",
        "kind": "datasheet"
      }
    },
    {
      "benchmark": "limiting_oxygen_index",
      "value": 58,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "basis": "oxygen concentration at which the sample burns, printed on the product page"
      },
      "method": "Value printed on the Goodfellow product page; the page also says Does not burn in its flammability row",
      "status": "ground",
      "source": "goodfellow-pbi",
      "where": "Physical Properties table, row Limiting oxygen index( % )",
      "source_detail": {
        "title": "Goodfellow: Polybenzimidazole Film, PBI, CAS 32075-68-6 (product page)",
        "url": "https://www.goodfellow.com/usa/polybenzimidazole-film-group",
        "kind": "datasheet"
      }
    },
    {
      "benchmark": "moisture_absorption",
      "value": 0.4,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "time": "over 24 hours"
      },
      "method": "Value printed as water absorption over 24 hours on the product page",
      "status": "ground",
      "source": "goodfellow-pbi",
      "where": "Physical Properties table, row Water absorption - over 24 hours( % )",
      "source_detail": {
        "title": "Goodfellow: Polybenzimidazole Film, PBI, CAS 32075-68-6 (product page)",
        "url": "https://www.goodfellow.com/usa/polybenzimidazole-film-group",
        "kind": "datasheet"
      }
    },
    {
      "benchmark": "dielectric_constant",
      "value": 3.2,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "frequency": "1 MHz"
      },
      "method": "Value printed on the Goodfellow product page at 1 MHz",
      "status": "ground",
      "source": "goodfellow-pbi",
      "where": "Electrical Properties table, row Dielectric constant @1MHz",
      "source_detail": {
        "title": "Goodfellow: Polybenzimidazole Film, PBI, CAS 32075-68-6 (product page)",
        "url": "https://www.goodfellow.com/usa/polybenzimidazole-film-group",
        "kind": "datasheet"
      }
    },
    {
      "benchmark": "dielectric_strength",
      "value": 21,
      "bound": "exact",
      "unit": "kV/mm",
      "scope": "material",
      "conditions": {
        "basis": "dielectric strength printed on the product page"
      },
      "method": "Value printed on the Goodfellow product page",
      "status": "ground",
      "source": "goodfellow-pbi",
      "where": "Electrical Properties table, row Dielectric strength( kV mm-1 )",
      "source_detail": {
        "title": "Goodfellow: Polybenzimidazole Film, PBI, CAS 32075-68-6 (product page)",
        "url": "https://www.goodfellow.com/usa/polybenzimidazole-film-group",
        "kind": "datasheet"
      }
    },
    {
      "benchmark": "electrical_resistivity",
      "value": 800000000000000,
      "bound": "exact",
      "unit": "Ohm cm",
      "scope": "material",
      "conditions": {
        "basis": "volume resistivity printed on the product page"
      },
      "method": "Printed as 8x10 to the power 14 Ohmcm on the Goodfellow product page",
      "status": "ground",
      "source": "goodfellow-pbi",
      "where": "Electrical Properties table, row Volume resistivity( Ohmcm )",
      "source_detail": {
        "title": "Goodfellow: Polybenzimidazole Film, PBI, CAS 32075-68-6 (product page)",
        "url": "https://www.goodfellow.com/usa/polybenzimidazole-film-group",
        "kind": "datasheet"
      }
    },
    {
      "benchmark": "atomic_oxygen_erosion_yield",
      "value": 2.21e-24,
      "bound": "lower",
      "unit": "cm3/atom",
      "scope": "material",
      "conditions": {
        "environment": "low Earth orbit, ISS outside Quest airlock, MISSE 2 PEACE tray, 3.95 years",
        "bound": "lower bound, printed as greater than 2.21e-24"
      },
      "method": "Measured erosion yield from the MISSE 2 flight sample, read from NASA Table I; NASA prints it as a lower bound",
      "status": "flight",
      "source": "nasa-misse2-pbi",
      "where": "Table I (MISSE 2 PEACE polymers erosion yield data), row Polybenzimidazole PBI",
      "source_detail": {
        "title": "NASA/TM-2008-215490: Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit (Banks, Backus and de Groh, 2008)",
        "url": "https://ntrs.nasa.gov/api/citations/20090011780/downloads/20090011780.pdf",
        "year": 2008,
        "kind": "report"
      }
    },
    {
      "benchmark": "glass_transition_temperature",
      "value": 415,
      "bound": "exact",
      "unit": "degC",
      "scope": "material",
      "conditions": {
        "standard": "ISO 11357-1,-2"
      },
      "method": "Value printed on the APSOplast PBI technical data sheet (compound PBI 00.004-00)",
      "status": "ground",
      "source": "apso-pbi",
      "where": "Thermal attributes, row Glass transition temperature (ISO 11357-1,-2)",
      "source_detail": {
        "title": "APSOplast PBI technical data sheet (compound PBI 00.004-00)",
        "url": "https://www.apsoparts.com/media/downloads/asset//std.lang.all/0_/en/PBI_00_004-00_EN.pdf",
        "kind": "datasheet"
      }
    },
    {
      "benchmark": "max_service_temp",
      "value": 310,
      "bound": "exact",
      "unit": "degC",
      "scope": "material",
      "conditions": {
        "basis": "maximum operating temperature, long term"
      },
      "method": "Value printed on the APSOplast PBI technical data sheet",
      "status": "ground",
      "source": "apso-pbi",
      "where": "Thermal attributes, row Max. operating temperature long term",
      "source_detail": {
        "title": "APSOplast PBI technical data sheet (compound PBI 00.004-00)",
        "url": "https://www.apsoparts.com/media/downloads/asset//std.lang.all/0_/en/PBI_00_004-00_EN.pdf",
        "kind": "datasheet"
      }
    },
    {
      "benchmark": "min_service_temp",
      "value": -50,
      "bound": "exact",
      "unit": "degC",
      "scope": "material",
      "conditions": {
        "basis": "minimum operating temperature"
      },
      "method": "Value printed on the APSOplast PBI technical data sheet",
      "status": "ground",
      "source": "apso-pbi",
      "where": "Thermal attributes, row Min. operating temperature",
      "source_detail": {
        "title": "APSOplast PBI technical data sheet (compound PBI 00.004-00)",
        "url": "https://www.apsoparts.com/media/downloads/asset//std.lang.all/0_/en/PBI_00_004-00_EN.pdf",
        "kind": "datasheet"
      }
    },
    {
      "benchmark": "moisture_absorption",
      "value": 7.5,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "basis": "at saturation in air of 23 degC and 50 percent relative humidity"
      },
      "method": "Value printed on the APSOplast PBI technical data sheet",
      "status": "ground",
      "source": "apso-pbi",
      "where": "Other attributes, row Moisture absorption",
      "source_detail": {
        "title": "APSOplast PBI technical data sheet (compound PBI 00.004-00)",
        "url": "https://www.apsoparts.com/media/downloads/asset//std.lang.all/0_/en/PBI_00_004-00_EN.pdf",
        "kind": "datasheet"
      }
    },
    {
      "benchmark": "atomic_oxygen_erosion_yield",
      "value": 2.27e-24,
      "bound": "exact",
      "unit": "cm3/atom",
      "scope": "material",
      "conditions": {
        "environment": "low Earth orbit prediction, MISSE 2 exposure"
      },
      "method": "Predicted erosion yield from the NASA atomic oxygen predictive tool, compared with the measured value in Table VII",
      "status": "calculated",
      "source": "nasa-misse2-pbi",
      "where": "Table VII (comparison of the predicted and actual erosion yields), row Polybenzimidazole PBI, predicted column",
      "source_detail": {
        "title": "NASA/TM-2008-215490: Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit (Banks, Backus and de Groh, 2008)",
        "url": "https://ntrs.nasa.gov/api/citations/20090011780/downloads/20090011780.pdf",
        "year": 2008,
        "kind": "report"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Low Earth orbit, atomic oxygen (MISSE 2, ISS outside the Quest airlock, 3.95 years)",
      "headline": "PBI erodes under atomic oxygen, and the MISSE 2 flight value is only a lower bound.",
      "effect": "The flight erosion yield was greater than 2.21e-24 cm3/atom. NASA gives a predicted value of 2.27e-24 cm3/atom for the same exposure, so the prediction and flight value are close.",
      "rating": "moderate",
      "conditions": {
        "fluence": "not printed on the PBI row of Table I",
        "duration": "3.95 years"
      },
      "source": "nasa-misse2-pbi",
      "where": "Table I and Table VII (NASA/TM-2008-215490)"
    },
    {
      "environment": "Elevated temperature in air",
      "headline": "PBI keeps its service range to about 400 degC.",
      "effect": "The product page gives an upper working temperature of 260 to 400 degC and a heat-deflection temperature of 435 degC at 0.45 MPa. Wikipedia says PBI is stable above 400 degC and does not melt.",
      "rating": "low",
      "conditions": {
        "basis": "upper working temperature range from the product page"
      },
      "source": "goodfellow-pbi",
      "where": "Thermal Properties table"
    },
    {
      "environment": "Humid air and water",
      "headline": "Water uptake is low.",
      "effect": "Water absorption over 24 hours is 0.4 percent. Wikipedia gives a moisture regain of 13 percent, close to cotton at 16 percent.",
      "rating": "low",
      "conditions": {
        "time": "24 hours"
      },
      "source": "goodfellow-pbi",
      "where": "Physical Properties table, Water absorption row"
    },
    {
      "environment": "Phosphoric acid in fuel-cell membranes",
      "headline": "Phosphoric acid-doped PBI leaches out of the membrane.",
      "effect": "Leaching and condensation on the phosphate groups limited phosphoric acid-doped PBI membranes. A higher acid loading degrades mechanical properties.",
      "rating": "moderate",
      "conditions": {
        "basis": "doped membranes, not the neat polymer"
      },
      "source": "pmc-pa-pbi-review",
      "where": "Introduction and PBI membrane sections"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "The MCAM safety data sheet gives no GHS classification for polybenzimidazole: classification none, no signal word, no hazard statements.",
        "ghs": [],
        "source": "mcam-sds-pbi",
        "where": "Section 2 (GHS classifications)"
      },
      {
        "text": "Dust is flammable and explosive when finely divided and suspended in air, so dust control and grounding apply during handling.",
        "ghs": [],
        "source": "mcam-sds-pbi",
        "where": "Section 5 (fire-fighting measures) and Section 7 (dust handling)"
      }
    ],
    "failure_risks": [
      {
        "mode": "Atomic oxygen erosion in low Earth orbit",
        "trigger": "Atomic oxygen fluence in LEO (MISSE 2, 3.95 years)",
        "consequence": "Surface erosion, with a flight erosion yield greater than 2.21e-24 cm3/atom",
        "source": "nasa-misse2-pbi",
        "where": "Table I"
      },
      {
        "mode": "Acid leaching in phosphoric acid-doped membranes",
        "trigger": "Phosphoric acid doping in fuel-cell electrolytes",
        "consequence": "Loss of acid and conductivity; higher acid loading degrades mechanical properties",
        "source": "pmc-pa-pbi-review",
        "where": "PBI membrane section"
      }
    ],
    "side_effects": [
      {
        "text": "Processing can release dust; the primary route of entry is inhalation of particulates.",
        "source": "mcam-sds-pbi",
        "where": "Section 11 (toxicological information), primary route of entry"
      }
    ],
    "handling": [
      {
        "text": "Keep particulate exposure under the limits in the SDS: ACGIH TLV 10 mg/m3, OSHA PEL 15 mg/m3 total and 5 mg/m3 respirable.",
        "source": "mcam-sds-pbi",
        "where": "Section 8 (exposure controls), particulates table"
      },
      {
        "text": "Use local exhaust ventilation and ground transfer equipment where dust can form, and remove ignition sources.",
        "source": "mcam-sds-pbi",
        "where": "Section 7 (handling and storage)"
      }
    ],
    "mitigations": [
      {
        "text": "Use local exhaust ventilation and dust control as the SDS directs.",
        "source": "mcam-sds-pbi",
        "where": "Section 8 (exposure controls)"
      }
    ]
  },
  "uses": [
    {
      "application": "habitats-and-suits",
      "device": "Apollo-era tethers, belts and restraints",
      "example": "NASA reports that PBI multifilament yarns were used in tethers, belts and restraints in the Apollo program.",
      "source": "ntrs-flame-fibers-2017",
      "where": "Section on the development of polybenzimidazole fibers"
    },
    {
      "application": "habitats-and-suits",
      "device": "Space Shuttle stowage partitions and Skylab apparel",
      "example": "NASA reports that PBI staple fibre was used in apparel fabrics for Skylab and in stowage partitions for the Space Shuttle programme.",
      "source": "ntrs-flame-fibers-2017",
      "where": "Section on the development of polybenzimidazole fibers"
    },
    {
      "application": "habitats-and-suits",
      "device": "Protective apparel and flame-resistant clothing",
      "example": "Wikipedia lists protective apparel as the first application of PBI fibre, and the Goodfellow page lists flammability as Does not burn.",
      "source": "wiki-pbi",
      "where": "Applications, 4.1 Protective apparel; Goodfellow Physical Properties table"
    }
  ],
  "supply": [
    {
      "subject": "Producer",
      "abundance": "PBI fibre and filament were developed by Hoechst Celanese under US government contracts from the Department of Defense and NASA. The company dedicated a facility to PBI filaments. No current production volume or country share was found in a source read in this run.",
      "producers": [
        {
          "country": "United States"
        }
      ],
      "critical_lists": [],
      "recycling": "Not sourced.",
      "substitutes": [
        "Wikipedia names phosphoric acid-doped PBI as one of the most mature membrane options for high-temperature PEM fuel cells."
      ],
      "source": "ntrs-flame-fibers-2017",
      "where": "Section on the development of polybenzimidazole fibers and the closing section on the Hoechst-Celanese facility"
    },
    {
      "subject": "Feedstock",
      "abundance": "PBI is made by condensing diphenyl isophthalate with 3,3',4,4'-tetraaminodiphenyl, then the intermediate cyclises (Wikipedia, Synthesis). No feedstock tonnage or price was found.",
      "producers": [],
      "critical_lists": [],
      "recycling": "Not sourced.",
      "substitutes": [],
      "source": "wiki-pbi",
      "where": "Synthesis section"
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "APSOplast PBI technical data sheet (compound PBI 00.004-00)",
      "type": "datasheet",
      "url": "https://www.apsoparts.com/media/downloads/asset//std.lang.all/0_/en/PBI_00_004-00_EN.pdf"
    },
    {
      "title": "MCAM Duratron CU60 PBI safety data sheet (SDS-2700)",
      "type": "sds",
      "url": "https://www.boedeker.com/Portals/0/Safety Data Sheets SDS/MCAM/MCAM-Duratron-CU60-PBI-EN-SDS-2700-191023.pdf",
      "year": 2019
    },
    {
      "title": "NASA/TM-2008-215490 (MISSE 2 PEACE polymers erosion yield and density tables)",
      "type": "report",
      "url": "https://ntrs.nasa.gov/api/citations/20090011780/downloads/20090011780.pdf",
      "year": 2008
    }
  ],
  "gaps": [
    "No PBI composition or CAS number was read from PubChem; the PubChem lookup by name and by CAS 25928-81-8 returned no CID in this run.",
    "No flight result beyond the MISSE 2 erosion yield; no UV, radiation or thermal-cycling result for PBI was found in a fetched page.",
    "Two CAS numbers are printed for PBI: 32075-68-6 (Wikipedia, Goodfellow) and 25928-81-8 (MCAM SDS). The source of each is recorded.",
    "No production volume or country share was found in a fetched source; the only producer named is Hoechst Celanese from the NASA report.",
    "Limiting oxygen index, compressive modulus and atomic oxygen erosion yield are not in the canonical property list; they use short names (limiting_oxygen_index, atomic_oxygen_erosion_yield).",
    "Hazard data rest on one MCAM SDS for the polymer. The Newtex sulfonated PBI SDS was not fetched.",
    "Glass transition in Wikipedia is given as about 430 degC; only the TotalMateria value (425 degC) is recorded as a property."
  ],
  "story": {
    "why": "PBI keeps its shape and stiffness at high temperature and does not burn easily. Its glass transition is 425 degC (TotalMateria), and its limiting oxygen index is 58 percent (Goodfellow). NASA used it for Apollo tethers and Shuttle-era textiles.",
    "uses": [
      {
        "where": "Space textiles",
        "line": "NASA reports that PBI staple and multifilament fibres were used in Apollo tethers and restraints, Skylab apparel and Space Shuttle stowage partitions."
      },
      {
        "where": "Protective clothing",
        "line": "Wikipedia lists protective apparel as the main use of PBI fibre."
      }
    ],
    "can_do": [
      {
        "label": "Hold a heat",
        "line": "Holds a heat-deflection temperature of 435 degC at 0.45 MPa (Goodfellow).",
        "scope": "material",
        "value": "435 degC"
      },
      {
        "label": "Resist a flame",
        "line": "Limiting oxygen index of 58 percent (Goodfellow); the page says the material does not burn.",
        "scope": "material",
        "value": "58 percent"
      },
      {
        "label": "Survive orbit",
        "line": "Atomic oxygen erosion yield on MISSE 2 is greater than 2.21e-24 cm3/atom, a lower bound (NASA Table I).",
        "scope": "material",
        "value": "2.21e-24 cm3/atom"
      }
    ],
    "compare": "The Goodfellow PBI product page gives a density of 1.3 g/cm3 and a tensile strength of 160 MPa, with a tensile modulus of 5.9 GPa, a glass transition of 425 degC on TotalMateria and a limiting oxygen index of 58 percent. Its density in the NASA polymer table is 1.2758 g/cm3. The APSO datasheet gives a glass transition of 415 degC and a long-term maximum service temperature of 310 degC.",
    "compare_rows": [
      {
        "label": "Density",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Glass transition",
        "benchmark": "glass_transition_temperature",
        "scope": "material"
      },
      {
        "label": "Atomic oxygen erosion yield in LEO",
        "benchmark": "atomic_oxygen_erosion_yield",
        "scope": "material"
      }
    ],
    "handling": [
      "Keep dust levels within the SDS limits: 10 mg/m3 ACGIH TLV, 15 mg/m3 OSHA PEL total and 5 mg/m3 respirable.",
      "Use local exhaust ventilation and grounding where dust forms, and keep ignition sources away from processing areas."
    ],
    "good_for": [
      "High-temperature parts that must keep stiffness near 400 degC, such as flame-resistant textiles and space stowage.",
      "Space textiles where flame resistance matters more than atomic oxygen resistance."
    ],
    "watch_out": [
      "The atomic oxygen erosion yield is a lower bound. The true erosion is higher than 2.21e-24 cm3/atom.",
      "Values come from different grades and forms (film, rod, fibre, bulk). Check the grade named on each row.",
      "The two CAS numbers (32075-68-6 and 25928-81-8) appear in different sources."
    ],
    "verdict": "PBI is a high-temperature, flame-resistant aromatic polymer with a glass transition near 425 degC and a limiting oxygen index of 58 percent. Its weakness in low Earth orbit is atomic oxygen erosion, where NASA gives a flight lower bound of 2.21e-24 cm3/atom.",
    "recipe": {
      "line": "PBI is an all-aromatic polymer. Its repeat unit is C20H12N4, with a molar mass of 308.34 g/mol, built from benzimidazole rings linked through a meta-phenylene group (Wikipedia). It is made by condensing diphenyl isophthalate with 3,3',4,4'-tetraaminodiphenyl, and the intermediate cyclises spontaneously (Wikipedia, Synthesis).",
      "parts": [
        {
          "name": "Carbon",
          "symbol": "C",
          "role": "Forms the aromatic benzimidazole rings and the meta-phenylene link of the backbone."
        },
        {
          "name": "Hydrogen",
          "symbol": "H",
          "role": "Sits on the aromatic rings; the all-aromatic backbone gives the high thermal stability."
        },
        {
          "name": "Nitrogen",
          "symbol": "N",
          "role": "Forms the imidazole rings. Their hydrogen-bond network helps the polymer stay stiff and oxidation resistant."
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "The MCAM SDS gives no GHS hazard classification, but it warns that fine dust is flammable and explosive, and that inhalation of particulates is the main route of entry.",
        "points": [],
        "level": 1,
        "verdict": "Dust is the watch point"
      },
      {
        "title": "For the mission",
        "lead": "The MISSE 2 flight sample shows an erosion yield greater than 2.21e-24 cm3/atom, a lower bound from NASA Table I.",
        "points": [],
        "level": 2,
        "verdict": "Atomic oxygen erodes it"
      }
    ]
  },
  "updated": "2026-10-20",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 0,
    "unreachable": 0,
    "caveats": 0
  },
  "sources": {
    "nasa-misse2-pbi": {
      "title": "NASA/TM-2008-215490: Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit (Banks, Backus and de Groh, 2008)",
      "url": "https://ntrs.nasa.gov/api/citations/20090011780/downloads/20090011780.pdf",
      "year": 2008,
      "kind": "report"
    },
    "wiki-pbi": {
      "title": "Polybenzimidazole (Wikipedia)",
      "url": "https://en.wikipedia.org/wiki/Polybenzimidazole",
      "year": 2026,
      "kind": "web"
    },
    "goodfellow-pbi": {
      "title": "Goodfellow: Polybenzimidazole Film, PBI, CAS 32075-68-6 (product page)",
      "url": "https://www.goodfellow.com/usa/polybenzimidazole-film-group",
      "kind": "datasheet"
    },
    "totalmateria-pbi": {
      "title": "TotalMateria: PBI material data page (material 5094597)",
      "url": "https://www.totalmateria.com/en-us/material/5094597",
      "kind": "datasheet"
    },
    "mcam-sds-pbi": {
      "title": "Mitsubishi Chemical Advanced Materials: Duratron CU60 PBI safety data sheet (SDS-2700, revised 23 October 2019)",
      "url": "https://www.boedeker.com/Portals/0/Safety Data Sheets SDS/MCAM/MCAM-Duratron-CU60-PBI-EN-SDS-2700-191023.pdf",
      "kind": "datasheet"
    },
    "ntrs-flame-fibers-2017": {
      "title": "Flame Retardant Fibers for Human Space Exploration: Past, Present, and Future (NASA NTRS 20170008542)",
      "url": "https://ntrs.nasa.gov/api/citations/20170008542/downloads/20170008542.pdf",
      "year": 2017,
      "kind": "report"
    },
    "apso-pbi": {
      "title": "APSOplast PBI technical data sheet (compound PBI 00.004-00)",
      "url": "https://www.apsoparts.com/media/downloads/asset//std.lang.all/0_/en/PBI_00_004-00_EN.pdf",
      "kind": "datasheet"
    },
    "pmc-pa-pbi-review": {
      "title": "Ionic Liquid in Phosphoric Acid-Doped Polybenzimidazole (PA-PBI) as Electrolyte Membranes for PEM Fuel Cells: A Review (PMC8541579)",
      "url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8541579/",
      "kind": "paper"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/pbi/"
}