Polybutylene terephthalate (PBT) PBT

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
  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
    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
  - benchmark: melting_point
    label: Melting temperature, Ultradur B 4520 uncoloured
    value: 223
    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
  - benchmark: moisture_absorption
    label: Moisture absorption, Ultradur B 4520 uncoloured
    value: 0.25
    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
  - benchmark: elastic_modulus
    label: Tensile modulus, Ultradur B 4520 uncoloured
    value: 2400
    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
  - benchmark: yield_strength
    label: Yield stress, Ultradur B 4520 uncoloured
    value: 55
    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
  - benchmark: elongation
    label: Nominal strain at break, Ultradur B 4520 uncoloured
    value: 50
    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)
  - benchmark: flexural_modulus
    label: Flexural modulus, Ultradur B 4520 uncoloured
    value: 2400
    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
  - benchmark: flexural_strength
    label: Flexural strength, Ultradur B 4520 uncoloured
    value: 85
    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
  - benchmark: heat_deflection_temperature
    label: Heat deflection temperature HDT B, Ultradur B 4520 uncoloured
    value: 165
    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
  - benchmark: heat_deflection_temperature
    label: Heat deflection temperature HDT A, Ultradur B 4520 uncoloured
    value: 55
    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
  - benchmark: max_service_temp
    label: Maximum service temperature, short-cycle operation, Ultradur B 4520
    value: 200
    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
  - benchmark: temperature_index_50pct_tensile_loss_20000h
    label: Temperature index at 50 % loss of tensile strength after 20000 h, Ultradur B 4520
    value: 135
    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
  - benchmark: cte
    label: Coefficient of linear thermal expansion, longitudinal (23 to 55 °C), Ultradur B 4520
    value: 115
    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
  - benchmark: thermal_conductivity
    label: Thermal conductivity, Ultradur B 4520 uncoloured
    value: 0.27
    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
  - benchmark: specific_heat
    label: Specific heat capacity, Ultradur B 4520 uncoloured
    value: 1250
    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
  - benchmark: dielectric_constant
    label: Relative permittivity at 1 MHz, Ultradur B 4520 uncoloured
    value: 3.3
    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
  - benchmark: dissipation_factor
    label: Dissipation factor at 1 MHz, Ultradur B 4520 uncoloured
    value: 0.02
    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
  - benchmark: electrical_resistivity
    label: Volume resistivity, Ultradur B 4520 uncoloured
    value: 100000000000000
    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
  - benchmark: dielectric_strength
    label: Electric strength K20/K20, Ultradur B 4520 uncoloured
    value: 36
    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
  - benchmark: density
    label: Specific gravity, Valox 315 (SABIC), as printed
    value: 1.31
    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
  - benchmark: yield_strength
    label: Tensile strength at yield, Valox 315 (SABIC)
    value: 51
    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
  - benchmark: elongation
    label: Elongation at break, Valox 315 (SABIC)
    value: 300
    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
  - benchmark: flexural_modulus
    label: Flexural modulus, Valox 315 (SABIC)
    value: 2.34
    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
  - benchmark: heat_deflection_temperature
    label: Deflection temperature at 0.46 MPa, Valox 315 (SABIC)
    value: 154
    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
  - benchmark: heat_deflection_temperature
    label: Deflection temperature at 1.8 MPa, Valox 315 (SABIC)
    value: 54
    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
  - benchmark: elastic_modulus
    label: Tensile modulus, Celanex 2002 (unreinforced)
    value: 2600
    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
  - benchmark: heat_deflection_temperature
    label: DTUL at 0.45 MPa, Celanex 2002
    value: 150
    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
  - benchmark: elongation
    label: Elongation at break, Celanex 2003HR (hydrolysis resistant)
    value: 60
    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
  - benchmark: atomic_oxygen_erosion_yield
    label: Atomic oxygen erosion yield, MISSE 2 PEACE PBT in LEO
    value: 9.11e-24
    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
  - benchmark: density
    label: Density, PBT as used in the NASA MISSE 2 table
    value: 1.3318
    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
  - benchmark: glass_transition_temperature
    label: Glass transition temperature, PBT (approximate)
    value: 60
    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
  - benchmark: max_service_temp
    label: Short-term heat resistance, PBT (general)
    value: 150
    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
  - benchmark: melting_point
    label: Melting point, PBT (crystalline, stated value)
    value: 230
    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
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.
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.'
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
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.
story:
  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
      level: 0
      verdict: Not classified hazardous
      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.
    - 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.
  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
      benchmark: elastic_modulus
      line: The BASF uncoloured grade has a tensile modulus of 2400 MPa and a flexural modulus of 2400 MPa at 23 °C.
    - label: Heat
      benchmark: heat_deflection_temperature
      line: The BASF grade has an HDT B of 165 °C at 0.45 MPa, and a melting temperature of 223 °C by DSC.
    - label: Vacuum
      benchmark: atomic_oxygen_erosion_yield
      line: The MISSE 2 flight value is 9.11e-24 cm3/atom in LEO (NASA Table I), which is high for an organic polymer.
  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:
    - scope: material
      label: Density
      benchmark: density
    - scope: material
      label: Melting point
      benchmark: melting_point
    - scope: material
      label: Atomic oxygen erosion yield
      benchmark: atomic_oxygen_erosion_yield
  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.