PBT · reinforced grade
PBT-GF40
Properties of the GF40 condition, compared with the other PBT grades.
Maximum stiffness/strength PBT for metal-replacement structural parts; accept higher warpage, brittleness and tool wear.
What is PBT-GF40?
PBT-GF40 is PBT in the GF40 grade — maximum stiffness/strength PBT for metal-replacement structural parts; accept higher warpage, brittleness and tool wear. PBT-GF40 has a yield strength of 55 MPa (7.98 ksi) and a tensile strength of 155 MPa (22.5 ksi) — stronger than 59% of polymer grades. Elongation at break is 2.3% and the elastic modulus is 13 GPa (1.89 Msi). PBT-GF40 has a density of 1.63 g/cm³ (0.0589 lb/in³), heavier than 93% of polymer grades. Its glass-transition temperature is 55°C (131 °F). Unfilled is the default condition FabDigit quotes; GF40 is available on request or by drawing note.
Advantages
- Stiff — 13 GPa (1.89 Msi), better than 98% of polymer grades
- Low, predictable mold shrinkage — 0.3%, better than 91% of polymer grades
- Low moisture uptake — 0.09%, better than 79% of polymer grades
- High service temperature — 145°C (293 °F), better than 76% of polymer grades
Limitations
- Heavy — 1.63 g/cm³ (0.0589 lb/in³), worse than 93% of polymer grades
- Limited ductility — 2.3%, worse than 91% of polymer grades
- Difficult to machine — 33/100, worse than 85% of polymer grades
PBT-GF40 properties
Typical room-temperature values for PBT-GF40 — 12 properties are specific to this condition; the rest are grade-level values shared by every PBT grade. Each bar shows where the value sits among the polymer grades in FabDigit's library — further right is higher.
Physical5
PBT-GF40 has a density of 1.63 g/cm³ (0.0589 lb/in³), heavier than 93% of polymer grades. Its glass-transition temperature is 55°C (131 °F).
Mechanical17
PBT-GF40 has a yield strength of 55 MPa (7.98 ksi) and a tensile strength of 155 MPa (22.5 ksi) — stronger than 59% of polymer grades. Elongation at break is 2.3% and the elastic modulus is 13 GPa (1.89 Msi).
Thermal11
PBT-GF40 is rated for continuous service to 145°C (293 °F). It conducts heat at 0.25 W/m·K (0.144 BTU/hr·ft·°F), better than 71% of polymer grades. Thermal expansion is 20 µm/m·K (11.1 µin/in·°F).
Electrical7
PBT-GF40 is an electrical insulator with a dielectric strength of 23 kV/mm (584.2 V/mil) and a resistivity of 1×10¹⁴ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (82/100), better than 54% of polymer grades. UV resistance is fair.
Sustainability4
Producing a kilogram of PBT-GF40 takes about 105 MJ of energy and emits 5 kg of CO₂ — more than 54% of polymer grades. Typical recycled content is 5%.
Manufacturability8
PBT-GF40's machinability is poor (33/100, worse than 85% of polymer grades); weldability very good (70/100); formability poor (20/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other PBT grades and fills
PBT is also supplied in 12 other conditions. The full side-by-side table is on the PBT overview.
- UnfilledDefaultPick for tough, low-friction, dimensionally stable parts where high stiffness and 1.8 MPa heat resistance are not required.55 MPa tensile
- GF40Maximum stiffness/strength PBT for metal-replacement structural parts; accept higher warpage, brittleness and tool wear.155 MPa tensile
- GF30The workhorse structural PBT: choose for stiff, creep-resistant, heat-resistant parts (connectors, housings, brackets) where warpage can be managed by gating.135 MPa tensile
- GF30 FR V-0Standard for connectors, coil bobbins and switchgear needing both V-0 and >200 °C HDT with high stiffness.125 MPa tensile
- GF15Mid-way grade when you need roughly double the stiffness and 200 °C HDT but want lower warpage and better surface than GF30.95 MPa tensile
- MINChoose for flat, dimensionally accurate covers and lids where isotropic shrinkage and good surface beat maximum strength.85 MPa tensile
- FR V-0Choose for electrical housings, relay bases and connectors that must carry a UL 94 V-0 listing at 0.8–1.5 mm wall.52 MPa tensile
- IMUse where notch sensitivity or cold (-30 °C) impact is the failure mode — snap fits, exterior clips, mirror housings.42 MPa tensile
Working with PBT-GF40
Is PBT easy to machine?
Machines cleanly with sharp, positive-rake carbide tools and air cooling; glass-filled grades are abrasive and need diamond or coated tooling, and sharp internal corners must be avoided due to notch sensitivity.
Can PBT be welded?
Excellent for ultrasonic, hot-plate, vibration, spin and laser welding (with laser-transparent/absorbing pairs); no solvent bonding — use cyanoacrylate/epoxy on abraded, primed surfaces.
Can PBT be formed, bent or molded?
Dry to <0.02% moisture (120 °C, 3–4 h) to prevent hydrolytic MW loss; mold at 240–260 °C melt and 60–90 °C tool, fast fill, and expect anisotropic shrinkage in GF grades — gate to control warp.
What surface finishes work on PBT?
Takes pad printing and laser marking well; painting/metallizing needs plasma or primer pretreatment because of the low-energy, solvent-resistant surface; molded-in texture is usually preferred over polishing.
PBT chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| 1,4-butanediol (BDO) unitdiol comonomer of the polyester backbone | ≈ 40 | 40 |
| glass fiber0 for unfilled default; 15/30/40 wt% in GF variants | 0 – 40 | 0 |
| flame retardant + synergistbrominated or halogen-free P-based system + Sb2O3 in FR V-0 grades | 0 – 20 | 0 |
| stabilizers / nucleant / pigmentantioxidant, hydrolysis stabilizer, mold release, carbon black | 0.2 – 2 | 0.8 |
| terephthalic acid / DMT unitdiacid comonomer; balance of resin | balance | — |
PBT-GF40 — frequently asked
What is PBT-GF40 used for?
PBT-GF40 is typically used for automotive electrical connectors, relay and switch housings, coil bobbins and formers, automotive electronic control unit housings, appliance structural components and sensor bodies. In short: stronger precise PBT.
What is the yield strength of PBT-GF40?
PBT-GF40 has a typical yield strength of 55 MPa (7.98 ksi) and a tensile strength of 155 MPa (22.5 ksi) — stronger than 59% of polymer grades. Strength varies by condition: see the 13 listed tempers.
Is PBT-GF40 easy to machine?
Not especially — machinability is rated poor (33/100, worse than 85% of polymer grades). Machines cleanly with sharp, positive-rake carbide tools and air cooling; glass-filled grades are abrasive and need diamond or coated tooling, and sharp internal corners must be avoided due to notch sensitivity.
Can PBT-GF40 be welded?
Yes — weldability is rated very good (70/100). Excellent for ultrasonic, hot-plate, vibration, spin and laser welding (with laser-transparent/absorbing pairs); no solvent bonding — use cyanoacrylate/epoxy on abraded, primed surfaces.
What surface finishes work on PBT-GF40?
Takes pad printing and laser marking well; painting/metallizing needs plasma or primer pretreatment because of the low-energy, solvent-resistant surface; molded-in texture is usually preferred over polishing.
Can PBT-GF40 be formed, bent or molded?
Dry to <0.02% moisture (120 °C, 3–4 h) to prevent hydrolytic MW loss; mold at 240–260 °C melt and 60–90 °C tool, fast fill, and expect anisotropic shrinkage in GF grades — gate to control warp.
What is the maximum service temperature of PBT-GF40?
PBT-GF40 is rated for continuous use to about 145°C (293 °F), and briefly to 160°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in PBT-GF40?
Yes — PBT-GF40 is available for injection molding with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ISO 7792-1/-2 Plastics — Thermoplastic polyester (TP) moulding and extrusion materials — ISO (2012)
- ASTM D5927 Standard Specification for Thermoplastic Polyester (TPES) Injection and Extrusion Materials — ASTM (2020)
- Ultradur (PBT) product range brochure and CAMPUS data — BASF (2023)
- Crastin PBT thermoplastic polyester resin product guide — Celanese (DuPont Performance Materials) (2023)
- Valox resin product data / processing guide — SABIC (2022)
- Pocan PBT technical information — LANXESS (2023)
- CAMPUS plastics database — PBT ISO 10350 single-point data — CWFG (2024)
- Engineered Materials Handbook Vol. 2: Engineering Plastics — ASM International (1988)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.