{
  "spore": "profile",
  "id": "pbt",
  "spore_version": "0.2",
  "family": "polyesters",
  "name": "Polybutylene terephthalate (PBT)",
  "abbreviation": "PBT",
  "role": "Injection-moulding polyester for electrical housings, plug connectors and keycaps; one sample flew on MISSE 2 in low Earth orbit",
  "category": "polymers",
  "type": "polyesters",
  "summary": "PBT is a semicrystalline polyester made from 1,4-butanediol and terephthalic acid. The BASF Ultradur B 4520 uncoloured grade is listed with a DSC melting temperature of 223 °C, a tensile yield stress of 55 MPa and a heat deflection temperature of 165 °C at 0.45 MPa. A PBT sample on the MISSE 2 tray in low Earth orbit had an atomic oxygen erosion yield of 9.11e-24 cm3/atom in NASA's Table I, a higher value than the one NASA lists for PET (Mylar) on the same tray. Its weak points are hot water and long heat, where the ester links hydrolyse, and the material embrittles with thermal ageing.",
  "best_for": "Stiff, dimensionally stable moulded parts for electrical housings and plug connectors that stay dry and below about 150 °C",
  "weakest_at": "Hot water and long heat: PBT is sensitive to hot water above 60 °C, and atomic oxygen in low Earth orbit erodes it at 9.11e-24 cm3/atom (MISSE 2)",
  "identity": {
    "formula": "(C12H12O4)n, repeat unit C12H12O4 (polybutylene terephthalate, from 1,4-butanediol and terephthalic acid)",
    "cas": "24968-12-5",
    "designations": [],
    "source": "nasa-tm2008",
    "where": "Table IV (repeat unit C12H12O4, molar mass 220.2244) and Table V of NASA/TM-2008-215490; CAS number and monomers from the Wikipedia article on polybutylene terephthalate"
  },
  "tags": {
    "environments": [
      "low-earth-orbit"
    ],
    "stresses": [
      "atomic-oxygen",
      "thermal-cycling"
    ],
    "applications": [
      "electronics-and-chips"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Density, Ultradur B 4520 uncoloured",
      "value": 1300,
      "bound": "exact",
      "unit": "kg/m³",
      "scope": "material",
      "conditions": {
        "grade": "Ultradur B 4520 uncoloured",
        "temperature": "23 °C"
      },
      "method": "ISO 1183, typical value printed in the BASF product information",
      "status": "ground",
      "source": "basf-b4520-pds",
      "where": "Typical values for uncoloured product at 23 °C, Properties block, Density row",
      "source_detail": {
        "title": "BASF SE, Ultradur B 4520 product information, typical values for uncoloured product",
        "id": "Ultradur B 4520 product information, 09/2026",
        "url": "https://download.basf.com/p1/8a8081c57fd4b609017fd62e21255407/en/ULTRADUR%3Csup%3E%C2%AE%3Csup%3E_B4520_Product_Data_Sheet_Asia_PacificEurope_English.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting temperature, Ultradur B 4520 uncoloured",
      "value": 223,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "grade": "Ultradur B 4520 uncoloured",
        "heating": "DSC, as printed"
      },
      "method": "ISO 11357-1/-3 (DSC), typical value printed in the BASF product information",
      "status": "ground",
      "source": "basf-b4520-pds",
      "where": "Processing block, Melting Temperature DSC row",
      "source_detail": {
        "title": "BASF SE, Ultradur B 4520 product information, typical values for uncoloured product",
        "id": "Ultradur B 4520 product information, 09/2026",
        "url": "https://download.basf.com/p1/8a8081c57fd4b609017fd62e21255407/en/ULTRADUR%3Csup%3E%C2%AE%3Csup%3E_B4520_Product_Data_Sheet_Asia_PacificEurope_English.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "moisture_absorption",
      "label": "Moisture absorption, Ultradur B 4520 uncoloured",
      "value": 0.25,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "humidity": "50 % r.h.",
        "temperature": "23 °C"
      },
      "method": "Similar to ISO 62, equilibrium at 23 °C/50 % r.h., typical value printed in the BASF product information",
      "status": "ground",
      "source": "basf-b4520-pds",
      "where": "Properties block, Moisture absorption, equilibrium 23°C/50% r.h. row",
      "source_detail": {
        "title": "BASF SE, Ultradur B 4520 product information, typical values for uncoloured product",
        "id": "Ultradur B 4520 product information, 09/2026",
        "url": "https://download.basf.com/p1/8a8081c57fd4b609017fd62e21255407/en/ULTRADUR%3Csup%3E%C2%AE%3Csup%3E_B4520_Product_Data_Sheet_Asia_PacificEurope_English.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Tensile modulus, Ultradur B 4520 uncoloured",
      "value": 2400,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "Ultradur B 4520 uncoloured",
        "temperature": "23 °C"
      },
      "method": "ISO 527-1/-2, typical value printed in the BASF product information",
      "status": "ground",
      "source": "basf-b4520-pds",
      "where": "Mechanical properties block, Tensile modulus row",
      "source_detail": {
        "title": "BASF SE, Ultradur B 4520 product information, typical values for uncoloured product",
        "id": "Ultradur B 4520 product information, 09/2026",
        "url": "https://download.basf.com/p1/8a8081c57fd4b609017fd62e21255407/en/ULTRADUR%3Csup%3E%C2%AE%3Csup%3E_B4520_Product_Data_Sheet_Asia_PacificEurope_English.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield stress, Ultradur B 4520 uncoloured",
      "value": 55,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "Ultradur B 4520 uncoloured",
        "strain_rate": "50 mm/min",
        "temperature": "23 °C"
      },
      "method": "ISO 527-1/-2, typical value printed in the BASF product information",
      "status": "ground",
      "source": "basf-b4520-pds",
      "where": "Mechanical properties block, Yield stress, 50 mm/min row",
      "source_detail": {
        "title": "BASF SE, Ultradur B 4520 product information, typical values for uncoloured product",
        "id": "Ultradur B 4520 product information, 09/2026",
        "url": "https://download.basf.com/p1/8a8081c57fd4b609017fd62e21255407/en/ULTRADUR%3Csup%3E%C2%AE%3Csup%3E_B4520_Product_Data_Sheet_Asia_PacificEurope_English.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Nominal strain at break, Ultradur B 4520 uncoloured",
      "value": 50,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "grade": "Ultradur B 4520 uncoloured",
        "strain_rate": "50 mm/min",
        "lower_bound": "true"
      },
      "method": "ISO 527-1/-2; the datasheet prints the value as greater than 50 %",
      "status": "ground",
      "source": "basf-b4520-pds",
      "where": "Mechanical properties block, Nominal strain at break, 50 mm/min row (printed as >50)",
      "source_detail": {
        "title": "BASF SE, Ultradur B 4520 product information, typical values for uncoloured product",
        "id": "Ultradur B 4520 product information, 09/2026",
        "url": "https://download.basf.com/p1/8a8081c57fd4b609017fd62e21255407/en/ULTRADUR%3Csup%3E%C2%AE%3Csup%3E_B4520_Product_Data_Sheet_Asia_PacificEurope_English.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "flexural_modulus",
      "label": "Flexural modulus, Ultradur B 4520 uncoloured",
      "value": 2400,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "Ultradur B 4520 uncoloured",
        "temperature": "23 °C"
      },
      "method": "ISO 178, typical value printed in the BASF product information",
      "status": "ground",
      "source": "basf-b4520-pds",
      "where": "Mechanical properties block, Flexural modulus row",
      "source_detail": {
        "title": "BASF SE, Ultradur B 4520 product information, typical values for uncoloured product",
        "id": "Ultradur B 4520 product information, 09/2026",
        "url": "https://download.basf.com/p1/8a8081c57fd4b609017fd62e21255407/en/ULTRADUR%3Csup%3E%C2%AE%3Csup%3E_B4520_Product_Data_Sheet_Asia_PacificEurope_English.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "flexural_strength",
      "label": "Flexural strength, Ultradur B 4520 uncoloured",
      "value": 85,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "Ultradur B 4520 uncoloured",
        "temperature": "23 °C"
      },
      "method": "ISO 178, typical value printed in the BASF product information",
      "status": "ground",
      "source": "basf-b4520-pds",
      "where": "Mechanical properties block, Flexural strength row",
      "source_detail": {
        "title": "BASF SE, Ultradur B 4520 product information, typical values for uncoloured product",
        "id": "Ultradur B 4520 product information, 09/2026",
        "url": "https://download.basf.com/p1/8a8081c57fd4b609017fd62e21255407/en/ULTRADUR%3Csup%3E%C2%AE%3Csup%3E_B4520_Product_Data_Sheet_Asia_PacificEurope_English.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "heat_deflection_temperature",
      "label": "Heat deflection temperature HDT B, Ultradur B 4520 uncoloured",
      "value": 165,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "load": "0.45 MPa",
        "grade": "Ultradur B 4520 uncoloured"
      },
      "method": "ISO 75-1/-2 (HDT B), typical value printed in the BASF product information",
      "status": "ground",
      "source": "basf-b4520-pds",
      "where": "Thermal properties block, HDT B (0.45 MPa) row",
      "source_detail": {
        "title": "BASF SE, Ultradur B 4520 product information, typical values for uncoloured product",
        "id": "Ultradur B 4520 product information, 09/2026",
        "url": "https://download.basf.com/p1/8a8081c57fd4b609017fd62e21255407/en/ULTRADUR%3Csup%3E%C2%AE%3Csup%3E_B4520_Product_Data_Sheet_Asia_PacificEurope_English.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "heat_deflection_temperature",
      "label": "Heat deflection temperature HDT A, Ultradur B 4520 uncoloured",
      "value": 55,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "load": "1.80 MPa",
        "grade": "Ultradur B 4520 uncoloured"
      },
      "method": "ISO 75-1/-2 (HDT A), typical value printed in the BASF product information",
      "status": "ground",
      "source": "basf-b4520-pds",
      "where": "Thermal properties block, HDT A (1.80 MPa) row",
      "source_detail": {
        "title": "BASF SE, Ultradur B 4520 product information, typical values for uncoloured product",
        "id": "Ultradur B 4520 product information, 09/2026",
        "url": "https://download.basf.com/p1/8a8081c57fd4b609017fd62e21255407/en/ULTRADUR%3Csup%3E%C2%AE%3Csup%3E_B4520_Product_Data_Sheet_Asia_PacificEurope_English.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "max_service_temp",
      "label": "Maximum service temperature, short-cycle operation, Ultradur B 4520",
      "value": 200,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "duty": "short-cycle operation",
        "grade": "Ultradur B 4520 uncoloured"
      },
      "method": "Typical value printed in the BASF product information; no test standard printed",
      "status": "ground",
      "source": "basf-b4520-pds",
      "where": "Thermal properties block, Max. service temperature (short cycle operation) row",
      "source_detail": {
        "title": "BASF SE, Ultradur B 4520 product information, typical values for uncoloured product",
        "id": "Ultradur B 4520 product information, 09/2026",
        "url": "https://download.basf.com/p1/8a8081c57fd4b609017fd62e21255407/en/ULTRADUR%3Csup%3E%C2%AE%3Csup%3E_B4520_Product_Data_Sheet_Asia_PacificEurope_English.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "temperature_index_50pct_tensile_loss_20000h",
      "label": "Temperature index at 50 % loss of tensile strength after 20000 h, Ultradur B 4520",
      "value": 135,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "time": "20000 h",
        "criterion": "50 % loss of tensile strength"
      },
      "method": "IEC 60216 temperature index, typical value printed in the BASF product information. Not a canonical property name; snake_case used",
      "status": "ground",
      "source": "basf-b4520-pds",
      "where": "Thermal properties block, Temperature index at 50% loss of tensile strength after 20000 h row",
      "source_detail": {
        "title": "BASF SE, Ultradur B 4520 product information, typical values for uncoloured product",
        "id": "Ultradur B 4520 product information, 09/2026",
        "url": "https://download.basf.com/p1/8a8081c57fd4b609017fd62e21255407/en/ULTRADUR%3Csup%3E%C2%AE%3Csup%3E_B4520_Product_Data_Sheet_Asia_PacificEurope_English.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of linear thermal expansion, longitudinal (23 to 55 °C), Ultradur B 4520",
      "value": 115,
      "bound": "exact",
      "unit": "E-6/K",
      "scope": "material",
      "conditions": {
        "range": "23 to 55 °C",
        "direction": "longitudinal"
      },
      "method": "ISO 11359-1/-2, typical value printed in the BASF product information",
      "status": "ground",
      "source": "basf-b4520-pds",
      "where": "Thermal properties block, Coefficient of linear thermal expansion, longitudinal row",
      "source_detail": {
        "title": "BASF SE, Ultradur B 4520 product information, typical values for uncoloured product",
        "id": "Ultradur B 4520 product information, 09/2026",
        "url": "https://download.basf.com/p1/8a8081c57fd4b609017fd62e21255407/en/ULTRADUR%3Csup%3E%C2%AE%3Csup%3E_B4520_Product_Data_Sheet_Asia_PacificEurope_English.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, Ultradur B 4520 uncoloured",
      "value": 0.27,
      "bound": "exact",
      "unit": "W/(m K)",
      "scope": "material",
      "conditions": {
        "grade": "Ultradur B 4520 uncoloured",
        "temperature": "23 °C"
      },
      "method": "DIN 52612-1, typical value printed in the BASF product information",
      "status": "ground",
      "source": "basf-b4520-pds",
      "where": "Thermal properties block, Thermal conductivity row",
      "source_detail": {
        "title": "BASF SE, Ultradur B 4520 product information, typical values for uncoloured product",
        "id": "Ultradur B 4520 product information, 09/2026",
        "url": "https://download.basf.com/p1/8a8081c57fd4b609017fd62e21255407/en/ULTRADUR%3Csup%3E%C2%AE%3Csup%3E_B4520_Product_Data_Sheet_Asia_PacificEurope_English.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "specific_heat",
      "label": "Specific heat capacity, Ultradur B 4520 uncoloured",
      "value": 1250,
      "bound": "exact",
      "unit": "J/(kg*K)",
      "scope": "material",
      "conditions": {
        "grade": "Ultradur B 4520 uncoloured",
        "temperature": "23 °C"
      },
      "method": "Typical value printed in the BASF product information; no test standard printed",
      "status": "ground",
      "source": "basf-b4520-pds",
      "where": "Thermal properties block, Specific heat capacity row",
      "source_detail": {
        "title": "BASF SE, Ultradur B 4520 product information, typical values for uncoloured product",
        "id": "Ultradur B 4520 product information, 09/2026",
        "url": "https://download.basf.com/p1/8a8081c57fd4b609017fd62e21255407/en/ULTRADUR%3Csup%3E%C2%AE%3Csup%3E_B4520_Product_Data_Sheet_Asia_PacificEurope_English.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "dielectric_constant",
      "label": "Relative permittivity at 1 MHz, Ultradur B 4520 uncoloured",
      "value": 3.3,
      "bound": "exact",
      "unit": "dimensionless",
      "scope": "material",
      "conditions": {
        "frequency": "1 MHz",
        "grade": "Ultradur B 4520 uncoloured"
      },
      "method": "IEC 62631-2-1, typical value printed in the BASF product information",
      "status": "ground",
      "source": "basf-b4520-pds",
      "where": "Electrical properties block, Relative permittivity (1 MHz) row",
      "source_detail": {
        "title": "BASF SE, Ultradur B 4520 product information, typical values for uncoloured product",
        "id": "Ultradur B 4520 product information, 09/2026",
        "url": "https://download.basf.com/p1/8a8081c57fd4b609017fd62e21255407/en/ULTRADUR%3Csup%3E%C2%AE%3Csup%3E_B4520_Product_Data_Sheet_Asia_PacificEurope_English.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "dissipation_factor",
      "label": "Dissipation factor at 1 MHz, Ultradur B 4520 uncoloured",
      "value": 0.02,
      "bound": "exact",
      "unit": "dimensionless",
      "scope": "material",
      "conditions": {
        "frequency": "1 MHz",
        "grade": "Ultradur B 4520 uncoloured",
        "unit_in_source": "E-4 (printed as 200 E-4)"
      },
      "method": "IEC 62631-2-1. The datasheet prints 200 E-4, converted here to 0.02 (200 x 10^-4)",
      "status": "ground",
      "source": "basf-b4520-pds",
      "where": "Electrical properties block, Dissipation factor (1 MHz) row",
      "source_detail": {
        "title": "BASF SE, Ultradur B 4520 product information, typical values for uncoloured product",
        "id": "Ultradur B 4520 product information, 09/2026",
        "url": "https://download.basf.com/p1/8a8081c57fd4b609017fd62e21255407/en/ULTRADUR%3Csup%3E%C2%AE%3Csup%3E_B4520_Product_Data_Sheet_Asia_PacificEurope_English.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "electrical_resistivity",
      "label": "Volume resistivity, Ultradur B 4520 uncoloured",
      "value": 100000000000000,
      "bound": "exact",
      "unit": "Ohm*m",
      "scope": "material",
      "conditions": {
        "grade": "Ultradur B 4520 uncoloured"
      },
      "method": "IEC 62631-3-1, typical value printed as 1E14 Ohm*m in the BASF product information",
      "status": "ground",
      "source": "basf-b4520-pds",
      "where": "Electrical properties block, Volume resistivity row",
      "source_detail": {
        "title": "BASF SE, Ultradur B 4520 product information, typical values for uncoloured product",
        "id": "Ultradur B 4520 product information, 09/2026",
        "url": "https://download.basf.com/p1/8a8081c57fd4b609017fd62e21255407/en/ULTRADUR%3Csup%3E%C2%AE%3Csup%3E_B4520_Product_Data_Sheet_Asia_PacificEurope_English.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "dielectric_strength",
      "label": "Electric strength K20/K20, Ultradur B 4520 uncoloured",
      "value": 36,
      "bound": "exact",
      "unit": "kV/mm",
      "scope": "material",
      "conditions": {
        "specimen": "60 x 60 x 1 mm",
        "grade": "Ultradur B 4520 uncoloured"
      },
      "method": "IEC 60243-1, typical value printed in the BASF product information",
      "status": "ground",
      "source": "basf-b4520-pds",
      "where": "Electrical properties block, Electric strength K20/K20 row",
      "source_detail": {
        "title": "BASF SE, Ultradur B 4520 product information, typical values for uncoloured product",
        "id": "Ultradur B 4520 product information, 09/2026",
        "url": "https://download.basf.com/p1/8a8081c57fd4b609017fd62e21255407/en/ULTRADUR%3Csup%3E%C2%AE%3Csup%3E_B4520_Product_Data_Sheet_Asia_PacificEurope_English.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "density",
      "label": "Specific gravity, Valox 315 (SABIC), as printed",
      "value": 1.31,
      "bound": "exact",
      "unit": "g/cc",
      "scope": "material",
      "conditions": {
        "grade": "Valox 315",
        "temperature": "not printed on the page"
      },
      "method": "ASTM D792; the page prints specific gravity, read here as density in g/cc",
      "status": "ground",
      "source": "lookpolymers-valox315",
      "where": "Physical section, Specific Gravity row",
      "source_detail": {
        "title": "SABIC Valox 315 PBT datasheet, as listed on LookPolymers",
        "id": "lookpolymers.com polymer page, SABIC Valox 315",
        "url": "https://www.lookpolymers.com/polymer_SABIC-Innovative-Plastics-Valox-315-PBT.php",
        "kind": "database",
        "license": "Database listing (cited, not reproduced)"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Tensile strength at yield, Valox 315 (SABIC)",
      "value": 51,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "Valox 315",
        "specimen": "Type I, 50 mm/min"
      },
      "method": "ASTM D638, value printed on the LookPolymers page for SABIC Valox 315",
      "status": "ground",
      "source": "lookpolymers-valox315",
      "where": "Mechanical section, Tensile Strength, Yield row",
      "source_detail": {
        "title": "SABIC Valox 315 PBT datasheet, as listed on LookPolymers",
        "id": "lookpolymers.com polymer page, SABIC Valox 315",
        "url": "https://www.lookpolymers.com/polymer_SABIC-Innovative-Plastics-Valox-315-PBT.php",
        "kind": "database",
        "license": "Database listing (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation at break, Valox 315 (SABIC)",
      "value": 300,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "grade": "Valox 315",
        "specimen": "Type I, 50 mm/min"
      },
      "method": "ASTM D638, value printed on the LookPolymers page for SABIC Valox 315",
      "status": "ground",
      "source": "lookpolymers-valox315",
      "where": "Mechanical section, Elongation at Break row",
      "source_detail": {
        "title": "SABIC Valox 315 PBT datasheet, as listed on LookPolymers",
        "id": "lookpolymers.com polymer page, SABIC Valox 315",
        "url": "https://www.lookpolymers.com/polymer_SABIC-Innovative-Plastics-Valox-315-PBT.php",
        "kind": "database",
        "license": "Database listing (cited, not reproduced)"
      }
    },
    {
      "benchmark": "flexural_modulus",
      "label": "Flexural modulus, Valox 315 (SABIC)",
      "value": 2.34,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "grade": "Valox 315",
        "speed": "1.3 mm/min",
        "span": "50 mm"
      },
      "method": "ASTM D790, value printed on the LookPolymers page for SABIC Valox 315",
      "status": "ground",
      "source": "lookpolymers-valox315",
      "where": "Mechanical section, Flexural Modulus row",
      "source_detail": {
        "title": "SABIC Valox 315 PBT datasheet, as listed on LookPolymers",
        "id": "lookpolymers.com polymer page, SABIC Valox 315",
        "url": "https://www.lookpolymers.com/polymer_SABIC-Innovative-Plastics-Valox-315-PBT.php",
        "kind": "database",
        "license": "Database listing (cited, not reproduced)"
      }
    },
    {
      "benchmark": "heat_deflection_temperature",
      "label": "Deflection temperature at 0.46 MPa, Valox 315 (SABIC)",
      "value": 154,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "grade": "Valox 315",
        "load": "0.46 MPa",
        "thickness": "6.40 mm",
        "state": "unannealed"
      },
      "method": "ASTM D648, value printed on the LookPolymers page for SABIC Valox 315",
      "status": "ground",
      "source": "lookpolymers-valox315",
      "where": "Thermal section, Deflection Temperature at 0.46 MPa row",
      "source_detail": {
        "title": "SABIC Valox 315 PBT datasheet, as listed on LookPolymers",
        "id": "lookpolymers.com polymer page, SABIC Valox 315",
        "url": "https://www.lookpolymers.com/polymer_SABIC-Innovative-Plastics-Valox-315-PBT.php",
        "kind": "database",
        "license": "Database listing (cited, not reproduced)"
      }
    },
    {
      "benchmark": "heat_deflection_temperature",
      "label": "Deflection temperature at 1.8 MPa, Valox 315 (SABIC)",
      "value": 54,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "grade": "Valox 315",
        "load": "1.8 MPa",
        "thickness": "6.40 mm",
        "state": "unannealed"
      },
      "method": "ASTM D648, value printed on the LookPolymers page for SABIC Valox 315",
      "status": "ground",
      "source": "lookpolymers-valox315",
      "where": "Thermal section, Deflection Temperature at 1.8 MPa row",
      "source_detail": {
        "title": "SABIC Valox 315 PBT datasheet, as listed on LookPolymers",
        "id": "lookpolymers.com polymer page, SABIC Valox 315",
        "url": "https://www.lookpolymers.com/polymer_SABIC-Innovative-Plastics-Valox-315-PBT.php",
        "kind": "database",
        "license": "Database listing (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Tensile modulus, Celanex 2002 (unreinforced)",
      "value": 2600,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "Celanex 2002",
        "standard_condition": "as printed in the Celanese short-term properties guide"
      },
      "method": "ISO 527, value printed in the Celanese short-term properties guide, column 2002",
      "status": "ground",
      "source": "celanese-short-term",
      "where": "ISO test method table, Tensile Modulus row, column 2002",
      "source_detail": {
        "title": "Celanese, Celanex PBT Short-Term Properties Guide (ISO and ASTM data)",
        "id": "PBT-023_CelanexPBTShortTermPropTG_AM_0613",
        "url": "https://s3.amazonaws.com/entecpolymers.com/v3/uploads/pdfs/Celanex%C2%AE-Short-Term-Properties-Guide-Contains-ISO-ASTM-Data_190430_170500.pdf",
        "year": 2013,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "heat_deflection_temperature",
      "label": "DTUL at 0.45 MPa, Celanex 2002",
      "value": 150,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "grade": "Celanex 2002",
        "load": "0.45 MPa"
      },
      "method": "ISO 75, value printed in the Celanese short-term properties guide, column 2002",
      "status": "ground",
      "source": "celanese-short-term",
      "where": "ISO test method table, DTUL at 0.45 MPa row, column 2002",
      "source_detail": {
        "title": "Celanese, Celanex PBT Short-Term Properties Guide (ISO and ASTM data)",
        "id": "PBT-023_CelanexPBTShortTermPropTG_AM_0613",
        "url": "https://s3.amazonaws.com/entecpolymers.com/v3/uploads/pdfs/Celanex%C2%AE-Short-Term-Properties-Guide-Contains-ISO-ASTM-Data_190430_170500.pdf",
        "year": 2013,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation at break, Celanex 2003HR (hydrolysis resistant)",
      "value": 60,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "grade": "Celanex 2003HR"
      },
      "method": "ASTM D638, value printed in the Celanese short-term properties guide, column 2003HR",
      "status": "ground",
      "source": "celanese-short-term",
      "where": "ASTM test method table, Elongation at Break row, column 2003HR",
      "source_detail": {
        "title": "Celanese, Celanex PBT Short-Term Properties Guide (ISO and ASTM data)",
        "id": "PBT-023_CelanexPBTShortTermPropTG_AM_0613",
        "url": "https://s3.amazonaws.com/entecpolymers.com/v3/uploads/pdfs/Celanex%C2%AE-Short-Term-Properties-Guide-Contains-ISO-ASTM-Data_190430_170500.pdf",
        "year": 2013,
        "kind": "datasheet",
        "license": "Manufacturer product information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "atomic_oxygen_erosion_yield",
      "label": "Atomic oxygen erosion yield, MISSE 2 PEACE PBT in LEO",
      "value": 9.11e-24,
      "bound": "exact",
      "unit": "cm3/atom",
      "scope": "material",
      "conditions": {
        "platform": "ISS, MISSE 2 PEACE tray, outside the Quest airlock",
        "fluence": "8.43e21 atoms/cm2",
        "exposure": "16 August 2001 to 30 July 2005 (3.95 years)"
      },
      "method": "Flight erosion yield as printed in NASA Table I. Table VII prints a different MISSE 2 value (9.11e-25); see gaps. The name atomic_oxygen_erosion_yield is not in property-canon.yaml",
      "status": "flight",
      "source": "nasa-tm2008",
      "where": "Table I, Polybutylene terephthalate row (PBT); exposure details in section 2.1",
      "source_detail": {
        "title": "Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit, NASA/TM-2008-215490",
        "id": "NASA/TM-2008-215490 (Banks and Backus, December 2008)",
        "url": "https://ntrs.nasa.gov/citations/20090011780",
        "year": 2008,
        "kind": "report",
        "license": "NASA public document"
      }
    },
    {
      "benchmark": "density",
      "label": "Density, PBT as used in the NASA MISSE 2 table",
      "value": 1.3318,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "reference": "ref. 12 in NASA/TM-2008-215490"
      },
      "method": "Density value printed in NASA Table II for the MISSE 2 PEACE polymer sample",
      "status": "ground",
      "source": "nasa-tm2008",
      "where": "Table II, Density column, Polybutylene terephthalate row",
      "source_detail": {
        "title": "Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit, NASA/TM-2008-215490",
        "id": "NASA/TM-2008-215490 (Banks and Backus, December 2008)",
        "url": "https://ntrs.nasa.gov/citations/20090011780",
        "year": 2008,
        "kind": "report",
        "license": "NASA public document"
      }
    },
    {
      "benchmark": "glass_transition_temperature",
      "label": "Glass transition temperature, PBT (approximate)",
      "value": 60,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "precision": "approximately, as printed"
      },
      "method": "Value printed as approximately 60 °C on the Kdfeddersen PBT page; no test method printed",
      "status": "ground",
      "source": "kdfeddersen-pbt",
      "where": "Table of PBT thermal values, Glass transition temperature row",
      "source_detail": {
        "title": "Polybutylene terephthalate (PBT): properties, applications and processing, K.D. Feddersen",
        "id": "kdfeddersen.com products page, PBT",
        "url": "https://www.kdfeddersen.com/en/products/polymers/polybutylenterephthalate",
        "kind": "web",
        "license": "Supplier information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "max_service_temp",
      "label": "Short-term heat resistance, PBT (general)",
      "value": 150,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "duty": "short periods only"
      },
      "method": "Value printed on the Kdfeddersen PBT page as up to 150 °C for short periods; no test standard printed",
      "status": "ground",
      "source": "kdfeddersen-pbt",
      "where": "Table of PBT thermal values, Short-term heat resistance row",
      "source_detail": {
        "title": "Polybutylene terephthalate (PBT): properties, applications and processing, K.D. Feddersen",
        "id": "kdfeddersen.com products page, PBT",
        "url": "https://www.kdfeddersen.com/en/products/polymers/polybutylenterephthalate",
        "kind": "web",
        "license": "Supplier information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point, PBT (crystalline, stated value)",
      "value": 230,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "note": "stated in the text; differs from the DSC value of 223 °C"
      },
      "method": "Value stated in the text of the Asahi Kasei PBT column; no test method printed",
      "status": "ground",
      "source": "asahi-kasei-pbt",
      "where": "Text stating PBT is a crystalline material with a melting point of 230°C",
      "source_detail": {
        "title": "What is Polybutylene Terephthalate (PBT)?, Asahi Kasei Plastics column",
        "id": "asahi-kasei-plastics.com column 10",
        "url": "https://www.asahi-kasei-plastics.com/en/column/10/",
        "kind": "web",
        "license": "Manufacturer information (cited, not reproduced)"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Atomic oxygen in low Earth orbit (MISSE 2 PEACE, ISS, about four years)",
      "headline": "Erosion yield of 9.11e-24 cm3/atom at a fluence of 8.43e21 atoms/cm2, one of the higher values in NASA's MISSE 2 table",
      "effect": "PBT erodes at a high rate in LEO. In NASA's table only a few polymers (for example POM at 9.14e-24 cm3/atom) show a comparable erosion yield, so thin PBT parts need protection in LEO.",
      "rating": "severe",
      "conditions": {
        "fluence": "8.43e21 atoms/cm2",
        "environment": "LEO flight, MISSE 2 PEACE"
      },
      "source": "nasa-tm2008",
      "where": "Table I; exposure details in section 2.1"
    },
    {
      "environment": "Thermal ageing in air at elevated temperature (typical rated limits)",
      "headline": "Temperature index of 135 °C at 50 % loss of tensile strength after 20000 h, and 145 °C after 5000 h (IEC 60216)",
      "effect": "A long-term service limit of about 135 °C is the figure BASF gives for the tensile-strength criterion. Above that, tensile strength falls by half within the rated time.",
      "rating": "moderate",
      "conditions": {
        "criterion": "50 % loss of tensile strength",
        "time": "20000 h and 5000 h"
      },
      "source": "basf-b4520-pds",
      "where": "Thermal properties block, Temperature index rows (20000 h and 5000 h)"
    },
    {
      "environment": "Thermo-oxidative ageing of a long glass-fibre PBT composite in an air oven at 120 °C for up to 60 days",
      "headline": "Tensile strength of the glass-fibre composite fell by 38.24 % after 20 days, and flexural strength by 24.19 % after 50 days",
      "effect": "The mechanical properties drop early in ageing, then embrittlement follows, and crosslinking and chain degradation both act. This is a glass-fibre DOPO composite, not neat PBT, so the numbers are for that composite.",
      "rating": "moderate",
      "conditions": {
        "temperature": "120 °C",
        "time": "0 to 60 days in an air oven",
        "material": "long glass-fibre PBT with DOPO flame retardant"
      },
      "source": "dopo-2017",
      "where": "Abstract and results section on mechanical properties after ageing"
    },
    {
      "environment": "Hot water and warm humid air",
      "headline": "PBT is vulnerable to hydrolysis in warm, humid environments, and is sensitive to hot water above 60 °C",
      "effect": "Ester links break under hydrolysis, which makes the film or moulding brittle. A 2025 study found that PBT hydrolyses faster at 120 °C when PA6 is blended in, because the amine end groups released by PA6 catalyse PBT hydrolysis.",
      "rating": "severe",
      "conditions": {
        "temperature": "warm to hot, humid"
      },
      "source": "asahi-kasei-pbt",
      "where": "Text on hydrolysis of PBT; Wikipedia states the 60 °C sensitivity for PBT and PET"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "Supplier SDS for ULTRADUR B 4520 uncoloured PBT: no need for classification according to GHS criteria, and no hazard warning label is required for the product.",
        "ghs": [],
        "source": "basf-b4520-sds",
        "where": "Section 2, Classification of the product and Label elements"
      },
      {
        "text": "Under hot-melt processing conditions the SDS says to wear personal protective equipment to prevent thermal burns, because contact with molten product may cause thermal burns.",
        "ghs": [],
        "source": "basf-b4520-sds",
        "where": "Section 2, Labeling of special preparations; section 11, acute toxicity"
      },
      {
        "text": "Product dust can form an explosive mixture with air, so dust formation should be avoided.",
        "ghs": [],
        "source": "basf-b4520-sds",
        "where": "Section 7, Handling and storage"
      }
    ],
    "failure_risks": [
      {
        "mode": "Overheating and thermal decomposition",
        "trigger": "Temperatures above about 290 °C (TGA onset as printed), or prolonged overheating",
        "consequence": "Decomposition releases carbon monoxide, tetrahydrofuran and terephthalic acid; the BASF datasheet says to avoid overheating",
        "severity": "moderate",
        "source": "basf-b4520-sds",
        "where": "Section 10, Thermal decomposition and Hazardous decomposition products"
      },
      {
        "mode": "Hydrolytic embrittlement",
        "trigger": "Warm to hot, humid conditions, or hot water above 60 °C",
        "consequence": "The ester links break, so the part loses toughness and becomes brittle",
        "severity": "moderate",
        "source": "asahi-kasei-pbt",
        "where": "Text on hydrolysis of PBT"
      },
      {
        "mode": "Thermal ageing embrittlement",
        "trigger": "Long exposure at elevated temperature in air; the IEC 60216 index is 135 °C at 50 % tensile loss after 20000 h",
        "consequence": "Tensile strength falls, and the glass-fibre composite embrittles after its first ageing stage",
        "severity": "moderate",
        "source": "dopo-2017",
        "where": "Abstract and results on mechanical properties after ageing"
      },
      {
        "mode": "Atomic oxygen erosion in low Earth orbit",
        "trigger": "LEO exposure, fluence of 8.43e21 atoms/cm2 over the MISSE 2 flight",
        "consequence": "The surface erodes at 9.11e-24 cm3/atom",
        "severity": "high",
        "source": "nasa-tm2008",
        "where": "Table I and section 2.1"
      }
    ],
    "side_effects": [
      {
        "text": "Decomposition products include carbon monoxide, tetrahydrofuran, terephthalic acid, carbon dioxide and water, and gaseous products of degradation if the product is greatly overheated.",
        "affects": "People near an overheated part or fire, and nearby hardware",
        "source": "basf-b4520-sds",
        "where": "Section 10, Possible decomposition products"
      },
      {
        "text": "Molten resin causes thermal burns on contact, so operators need hand and eye protection during hot-melt work.",
        "affects": "Operators during moulding or hot-melt handling",
        "source": "basf-b4520-sds",
        "where": "Sections 2 and 8"
      }
    ],
    "handling": [
      {
        "text": "Dry the resin before processing: 120 °C to 140 °C for 2 to 4 hours, to a residual moisture below 0.02 %. The Asahi Kasei page gives 3 hours or more at 130 °C, with water below 0.03 %.",
        "source": "kdfeddersen-pbt",
        "where": "Table of PBT processing values (drying temperature, drying time, residual moisture)"
      },
      {
        "text": "Keep the resin dry before processing. The BASF datasheet says moisture should generally be below 0.04 % when processing, and pre-drying should be the rule.",
        "source": "basf-b4520-pds",
        "where": "Physical form and storage block"
      },
      {
        "text": "Keep processing temperatures between 230 °C and 260 °C for injection moulding, and do not overheat the melt.",
        "source": "kdfeddersen-pbt",
        "where": "Table of PBT processing values, Cylinder temperature row"
      },
      {
        "text": "Avoid dust formation and use local exhaust ventilation where dust forms.",
        "source": "basf-b4520-sds",
        "where": "Section 7 and section 8"
      }
    ],
    "mitigations": [
      {
        "text": "Use a hydrolysis-resistant grade where the part sees hot water or humidity. Celanese lists Celanex 2003HR as hydrolysis resistant.",
        "source": "celanese-short-term",
        "where": "Grade overview table, row 2003HR"
      },
      {
        "text": "Keep the part dry and out of hot, humid conditions, and treat thermal ageing as a limit on service life at 135 °C and above.",
        "source": "basf-b4520-pds",
        "where": "Thermal properties block"
      },
      {
        "text": "Expect erosion in LEO: the MISSE 2 PBT sample eroded at 9.11e-24 cm3/atom, so flight parts need a protective layer or extra thickness.",
        "source": "nasa-tm2008",
        "where": "Table I"
      }
    ]
  },
  "uses": [
    {
      "application": "electronics-and-chips",
      "device": "Housings and plug connectors in electrical engineering, and plug connectors in automotive construction",
      "example": "PBT is used for housings in electrical engineering and as plug connectors in automotive construction.",
      "source": "wikipedia-pbt",
      "where": "Applications paragraph"
    },
    {
      "application": "electronics-and-chips",
      "device": "Keycaps of high-end computer keyboards",
      "example": "PBT is used in the keycaps of some high-end computer keyboards.",
      "source": "wikipedia-pbt",
      "where": "Applications paragraph"
    }
  ],
  "supply": [
    {
      "subject": "1,4-butanediol (BDO), the main PBT feedstock",
      "abundance": "Global BDO capacity was about 4,000 kilotons in 2025 (market-research estimate). Asia Pacific holds around 80 % of that capacity, and China is the largest contributor within it at an estimated 62 %.",
      "producers": [
        {
          "country": "China",
          "share_percent": 62,
          "year": 2025
        }
      ],
      "critical_lists": [],
      "recycling": "Not read in a source for this run.",
      "substitutes": [],
      "source": "expert-market-bdo",
      "where": "Market summary, 2025 capacity and regional shares. The 62 % is a share of Asia Pacific capacity, not of global capacity. The full report is paywalled."
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "BASF SE, Ultradur B 4520 product information (typical values for uncoloured product, 09/2026)",
      "type": "datasheet",
      "url": "https://download.basf.com/p1/8a8081c57fd4b609017fd62e21255407/en/ULTRADUR%3Csup%3E%C2%AE%3Csup%3E_B4520_Product_Data_Sheet_Asia_PacificEurope_English.pdf",
      "year": 2026
    },
    {
      "title": "BASF SE, Safety Data Sheet ULTRADUR B 4520 UNCOLOURED (version 2.0, revised 2024/10/07)",
      "type": "sds",
      "url": "https://download.basf.com/p1/000000000030604480_SDS_GEN_US/en_US/ULD.B4520_UN_30604480_SDS_GEN_US_en_2-0.pdf",
      "year": 2024
    },
    {
      "title": "Celanese, Celanex PBT short-term properties guide (copy hosted at entecpolymers.com)",
      "type": "datasheet",
      "url": "https://s3.amazonaws.com/entecpolymers.com/v3/uploads/pdfs/Celanex%C2%AE-Short-Term-Properties-Guide-Contains-ISO-ASTM-Data_190430_170500.pdf",
      "year": 2013
    },
    {
      "title": "Valox 315 PBT (SABIC), datasheet listing on LookPolymers",
      "type": "database",
      "url": "https://www.lookpolymers.com/polymer_SABIC-Innovative-Plastics-Valox-315-PBT.php"
    },
    {
      "title": "Influence of Thermo-Oxidative Ageing on the Thermal and Dynamical Mechanical Properties of Long Glass Fibre-Reinforced PBT Composites Filled with DOPO, Materials 10(5):500",
      "type": "paper",
      "url": "https://doi.org/10.3390/ma10050500",
      "year": 2017
    },
    {
      "title": "Study on Hydrolytic Degradation of Polyester and Polyamide in Basic Solutions at High Temperatures, Polymers 17(23):3090",
      "type": "paper",
      "url": "https://doi.org/10.3390/polym17233090",
      "year": 2025
    },
    {
      "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
    }
  ],
  "gaps": [
    "PubChem could not be opened for PBT in this run (a reCAPTCHA page was returned), so the PubChem GHS record is not read. The hazard entries come from the BASF SDS instead.",
    "NASA Table VII prints the MISSE 2 erosion yield for PBT as 9.11e-25 cm3/atom, while Table I prints 9.11e-24 cm3/atom. The Table I value is used here. The conflict is not resolved in the source.",
    "NASA Table VII also prints a predicted erosion yield of 2.68e-24 cm3/atom for PBT. It is not recorded as a property, because the same table gives the measured value in conflict.",
    "No UV data for PBT was found in an opened source.",
    "No outgassing data (total mass loss, CVCM) for PBT was found in an opened source. The NASA RP-1124 outgassing table was not read for this profile.",
    "No PBT flight hardware use was found in an opened source. The uses come from a general encyclopedia article.",
    "The ScienceDirect PBT plasticity-loss paper (Polymer Degradation and Stability) returned HTTP 403 and could not be read. The PMC version of the glass-fibre ageing paper was not read either; the Materials 2017 full text was read from Europe PMC instead.",
    "Supply: no USGS, BGS or EU critical-mineral entry covers PBT or its monomers. The only supply figures are a paywalled market-research estimate for BDO, which is also not a government source. Terephthalic acid supply was not read.",
    "Recycling status of PBT was not found in an opened source.",
    "Property names not in property-canon.yaml and used here: atomic_oxygen_erosion_yield, temperature_index_50pct_tensile_loss_20000h."
  ],
  "story": {
    "why": "Polybutylene terephthalate (PBT) is a polyester made from 1,4-butanediol and terephthalic acid. It is stiff, holds its shape and resists heat better than many moulding polymers. Its weaknesses are hot water and long heat, where the ester links hydrolyse, and atomic oxygen in low Earth orbit, which erodes it.",
    "uses": [
      {
        "where": "Electrical housings and plug connectors",
        "line": "Wikipedia says PBT is used for housings in electrical engineering and as plug connectors in automotive construction."
      },
      {
        "where": "Keyboard keycaps",
        "line": "Wikipedia says PBT is used in the keycaps of some high-end computer keyboards."
      }
    ],
    "can_do": [
      {
        "label": "Stiffness",
        "line": "The BASF uncoloured grade has a tensile modulus of 2400 MPa and a flexural modulus of 2400 MPa at 23 °C.",
        "benchmark": "elastic_modulus",
        "scope": "material"
      },
      {
        "label": "Heat",
        "line": "The BASF grade has an HDT B of 165 °C at 0.45 MPa, and a melting temperature of 223 °C by DSC.",
        "benchmark": "heat_deflection_temperature",
        "scope": "material"
      },
      {
        "label": "Vacuum",
        "line": "The MISSE 2 flight value is 9.11e-24 cm3/atom in LEO (NASA Table I), which is high for an organic polymer.",
        "benchmark": "atomic_oxygen_erosion_yield",
        "scope": "material"
      }
    ],
    "compare": "PBT is a stiff, heat-resistant polyester for moulded electrical parts, with a melting temperature of 223 °C and a heat deflection temperature of 165 °C at 0.45 MPa. In LEO it erodes at 9.11e-24 cm3/atom, which is among the highest values NASA lists for MISSE 2 polymers. The compare table sets PBT against density, melting point and atomic-oxygen erosion.",
    "compare_rows": [
      {
        "label": "Density",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Melting point",
        "benchmark": "melting_point",
        "scope": "material"
      },
      {
        "label": "Atomic oxygen erosion yield",
        "benchmark": "atomic_oxygen_erosion_yield",
        "scope": "material"
      }
    ],
    "handling": [
      "Dry the resin at 120 °C to 140 °C for 2 to 4 hours before processing, to a residual moisture below 0.02 %.",
      "Keep the melt between 230 °C and 260 °C for injection moulding, and do not overheat it above 290 °C.",
      "Wear protection during hot-melt work and avoid dust formation. The uncoloured grade is not classified under GHS."
    ],
    "good_for": [
      "Electrical housings and plug connectors that need a stiff, heat-resistant moulded part, kept dry and below about 150 °C.",
      "Keycaps and other small moulded parts where the part sits in dry air at room temperature."
    ],
    "watch_out": [
      "Hot water and humidity. PBT hydrolyses above about 60 °C, and a hydrolysis-resistant grade such as Celanex 2003HR should be used where moisture is present.",
      "Atomic oxygen in LEO. The MISSE 2 PBT sample eroded at 9.11e-24 cm3/atom over the flight.",
      "Long heat. The IEC 60216 index is 135 °C at 50 % tensile loss after 20000 h."
    ],
    "verdict": "PBT is a stiff, heat-resistant moulding polyester that is easy to process and suits electrical housings. It is a weak choice for LEO exposure, because its atomic-oxygen erosion yield of 9.11e-24 cm3/atom is high, and it must be kept dry.",
    "recipe": {
      "line": "PBT is a polyester made by polymerising 1,4-butanediol with terephthalic acid. Each repeat unit (C12H12O4) joins one terephthalate group to one butylene group through ester links.",
      "parts": [
        {
          "name": "Carbon",
          "symbol": "C",
          "role": "Six carbons in the benzene ring, two carbonyl carbons and four butylene carbons."
        },
        {
          "name": "Hydrogen",
          "symbol": "H",
          "role": "Four hydrogens on the benzene ring and eight on the butylene chain."
        },
        {
          "name": "Oxygen",
          "symbol": "O",
          "role": "Two ester groups, each with a carbonyl oxygen and an ether oxygen."
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "The BASF SDS for the uncoloured grade says no GHS classification is needed. The hazards come from hot melt and dust.",
        "points": [
          {
            "label": "The resin",
            "line": "No hazard warning label is required for the uncoloured product under GHS criteria."
          },
          {
            "label": "Molten resin",
            "line": "Contact with molten product may cause thermal burns, so wear protective equipment during hot-melt work."
          },
          {
            "label": "Dust",
            "line": "Product dust can form an explosive mixture with air, so avoid dust formation."
          }
        ],
        "level": 0,
        "verdict": "Not classified hazardous"
      },
      {
        "title": "If it overheats",
        "lead": "The BASF datasheet gives the decomposition limit. Above it the resin breaks down and gives off gases.",
        "points": [
          {
            "label": "Decomposition",
            "line": "Thermal decomposition is above 290 °C (TGA), and carbon monoxide and tetrahydrofuran are emitted at that point."
          },
          {
            "label": "Service limit",
            "line": "The short-cycle maximum service temperature is 200 °C, and the IEC 60216 index is 135 °C at 50 % tensile loss after 20000 h."
          }
        ]
      },
      {
        "title": "Handling and storage",
        "points": [
          {
            "label": "Water",
            "line": "PBT hydrolyses in warm, humid conditions. Dry the resin at 120 °C to 140 °C for 2 to 4 hours, to a residual moisture below 0.02 %."
          },
          {
            "label": "Space",
            "line": "In LEO, the MISSE 2 PBT sample eroded at 9.11e-24 cm3/atom, so flight parts need protection."
          }
        ]
      }
    ]
  },
  "updated": "2026-10-20",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 33,
    "unreachable": 3,
    "caveats": 5,
    "note": "Read by an AI assistant on 2026-10-20 from fetched BASF, NASA, Celanese, SABIC (via LookPolymers), Wikipedia, Europe PMC, Kdfeddersen and Asahi Kasei pages. PubChem returned a reCAPTCHA page, ScienceDirect and MatWeb returned HTTP 403, and PMC returned a verification page. The NASA Table I and Table VII PBT values conflict and are recorded in gaps."
  },
  "sources": {
    "nasa-tm2008": {
      "title": "Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit, NASA/TM-2008-215490",
      "id": "NASA/TM-2008-215490 (Banks and Backus, December 2008)",
      "url": "https://ntrs.nasa.gov/citations/20090011780",
      "year": 2008,
      "kind": "report",
      "license": "NASA public document"
    },
    "basf-b4520-pds": {
      "title": "BASF SE, Ultradur B 4520 product information, typical values for uncoloured product",
      "id": "Ultradur B 4520 product information, 09/2026",
      "url": "https://download.basf.com/p1/8a8081c57fd4b609017fd62e21255407/en/ULTRADUR%3Csup%3E%C2%AE%3Csup%3E_B4520_Product_Data_Sheet_Asia_PacificEurope_English.pdf",
      "year": 2026,
      "kind": "datasheet",
      "license": "Manufacturer product information (cited, not reproduced)"
    },
    "basf-b4520-sds": {
      "title": "BASF SE, Safety Data Sheet ULTRADUR B 4520 UNCOLOURED POLYBUTYLENE TEREPHTHALATE",
      "id": "30604480/SDS_GEN_US, version 2.0",
      "url": "https://download.basf.com/p1/000000000030604480_SDS_GEN_US/en_US/ULD.B4520_UN_30604480_SDS_GEN_US_en_2-0.pdf",
      "year": 2024,
      "kind": "datasheet",
      "license": "Manufacturer safety data sheet (cited, not reproduced)"
    },
    "celanese-short-term": {
      "title": "Celanese, Celanex PBT Short-Term Properties Guide (ISO and ASTM data)",
      "id": "PBT-023_CelanexPBTShortTermPropTG_AM_0613",
      "url": "https://s3.amazonaws.com/entecpolymers.com/v3/uploads/pdfs/Celanex%C2%AE-Short-Term-Properties-Guide-Contains-ISO-ASTM-Data_190430_170500.pdf",
      "year": 2013,
      "kind": "datasheet",
      "license": "Manufacturer product information (cited, not reproduced)"
    },
    "lookpolymers-valox315": {
      "title": "SABIC Valox 315 PBT datasheet, as listed on LookPolymers",
      "id": "lookpolymers.com polymer page, SABIC Valox 315",
      "url": "https://www.lookpolymers.com/polymer_SABIC-Innovative-Plastics-Valox-315-PBT.php",
      "kind": "database",
      "license": "Database listing (cited, not reproduced)"
    },
    "dopo-2017": {
      "title": "Influence of Thermo-Oxidative Ageing on the Thermal and Dynamical Mechanical Properties of Long Glass Fibre-Reinforced Poly(Butylene Terephthalate) Composites Filled with DOPO",
      "id": "Materials 2017, 10(5), 500, doi:10.3390/ma10050500",
      "url": "https://doi.org/10.3390/ma10050500",
      "year": 2017,
      "kind": "paper",
      "license": "CC-BY-4.0"
    },
    "hydrolysis-2025": {
      "title": "Study on Hydrolytic Degradation of Polyester and Polyamide in Basic Solutions at High Temperatures",
      "id": "Polymers 2025, 17(23), 3090, doi:10.3390/polym17233090",
      "url": "https://doi.org/10.3390/polym17233090",
      "year": 2025,
      "kind": "paper",
      "license": "open access"
    },
    "wikipedia-pbt": {
      "title": "Polybutylene terephthalate, Wikipedia",
      "id": "en.wikipedia.org/wiki/Polybutylene_terephthalate",
      "url": "https://en.wikipedia.org/wiki/Polybutylene_terephthalate",
      "kind": "web",
      "license": "CC-BY-SA-4.0"
    },
    "kdfeddersen-pbt": {
      "title": "Polybutylene terephthalate (PBT): properties, applications and processing, K.D. Feddersen",
      "id": "kdfeddersen.com products page, PBT",
      "url": "https://www.kdfeddersen.com/en/products/polymers/polybutylenterephthalate",
      "kind": "web",
      "license": "Supplier information (cited, not reproduced)"
    },
    "asahi-kasei-pbt": {
      "title": "What is Polybutylene Terephthalate (PBT)?, Asahi Kasei Plastics column",
      "id": "asahi-kasei-plastics.com column 10",
      "url": "https://www.asahi-kasei-plastics.com/en/column/10/",
      "kind": "web",
      "license": "Manufacturer information (cited, not reproduced)"
    },
    "expert-market-bdo": {
      "title": "1,4-Butanediol Supply and Demand Analysis, Market Outlook 2026-2035, Expert Market Research",
      "id": "expertmarketresearch.com industry statistics, 1,4-butanediol",
      "url": "https://www.expertmarketresearch.com/industry-statistics/1-4-butanediol-market",
      "kind": "web",
      "license": "Market research summary (cited, not reproduced)"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/pbt/"
}