PBT
also Crastin, Pocan
PBT (Valox, Pocan) is a fast-crystallising thermoplastic polyester with good flow for thin-wall, high-output injection moulding; unfilled it is 1.31 g/cm³ with 55 MPa tensile strength, 100 % elongation, 2.6 GPa modulus, about 0.1 % water absorption and good electrical insulation, solvent, oil and automotive-fluid resistance.
PBT grades and fills
PBT is supplied in 10 conditions, soft to hard.
Compare all 10 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Impact modified | Use where notch sensitivity or cold (-30 °C) impact is the failure mode — snap fits, exterior clips, mirror housings. | 42 | 200 | ||
PTFE/silicone lubricated bearing grade | Choose for sliding gears, cams and bushings needing low friction and wear without external lubrication. | 48 | 48 | 20 | 78 Shore D |
Flame retardant, UL 94 V-0 | Choose for electrical housings, relay bases and connectors that must carry a UL 94 V-0 listing at 0.8–1.5 mm wall. | 52 | 8 | ||
Heat stabilized | Pick for automotive electrical parts that must survive thousands of hours at 130–150 °C without embrittlement. | 55 | 55 | 80 | 82 Shore D |
ESD / conductive | Use for static-dissipative fixtures, fuel-system and electronics handling parts requiring 10^4–10^9 Ω surface resistivity. | 60 | 60 | 5 | 84 Shore D |
Mineral / glass-mineral filled, low warpage | Choose for flat, dimensionally accurate covers and lids where isotropic shrinkage and good surface beat maximum strength. | 85 | 3 | ||
15% short glass fiber reinforced | Mid-way grade when you need roughly double the stiffness and 200 °C HDT but want lower warpage and better surface than GF30. | 95 | 3.5 | 85 HRM | |
30% glass fiber, UL 94 V-0 | Standard for connectors, coil bobbins and switchgear needing both V-0 and >200 °C HDT with high stiffness. | 125 | 2.2 | ||
30% short glass fiber reinforced | The workhorse structural PBT: choose for stiff, creep-resistant, heat-resistant parts (connectors, housings, brackets) where warpage can be managed by gating. | 135 | 2.8 | 90 HRM | |
40% short glass fiber reinforced | Maximum stiffness/strength PBT for metal-replacement structural parts; accept higher warpage, brittleness and tool wear. | 155 | 2.3 |
Supply forms, finishes and certifications
Ways PBT is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
FDA | FDA / food-contact compliant grade | Certification |
UV | UV / weather stabilized | Grade option |
UnfilledDefault | Natural/uncoloured injection grade | Standard supply |
What is PBT?
PBT (Valox, Pocan) is a fast-crystallising thermoplastic polyester with good flow for thin-wall, high-output injection moulding; unfilled it is 1.31 g/cm³ with 55 MPa tensile strength, 100 % elongation, 2.6 GPa modulus, about 0.1 % water absorption and good electrical insulation, solvent, oil and automotive-fluid resistance. Glass reinforcement raises stiffness and lifts the 1.8 MPa HDT from about 60 °C to over 200 °C; GF15–GF40, FR V-0, UV, ESD, PTFE-lubricated and FDA grades are available. Limits are notch sensitivity, low heat deflection under 1.8 MPa load when unreinforced, hydrolysis in hot water or alkali, and moderate UV resistance without stabiliser. PBT has a density of 1.31 g/cm³ (0.0473 lb/in³), heavier than 71% of polymer grades. Its glass-transition temperature is 55°C (131 °F). PBT has a yield strength of 55 MPa (7.98 ksi) and a tensile strength of 55 MPa (7.98 ksi) — stronger than 62% of polymer grades. Elongation at break is 100% and the elastic modulus is 2.6 GPa (0.377 Msi).
What is PBT used for?
- Automotive electrical connectors
- Relay and switch housings
- Coil bobbins and formers
- Automotive electronic control unit housings
- Appliance structural components
- Sensor bodies
- Circuit breaker parts
Advantages
- Low moisture uptake — 0.09%, better than 79% of polymer grades
PBT properties
Typical room-temperature values in the Unfilled condition; bars are the position among polymer grades.
Physical5
PBT has a density of 1.31 g/cm³ (0.0473 lb/in³), heavier than 71% of polymer grades. Its glass-transition temperature is 55°C (131 °F).
Mechanical17
PBT has a yield strength of 55 MPa (7.98 ksi) and a tensile strength of 55 MPa (7.98 ksi) — stronger than 62% of polymer grades. Elongation at break is 100% and the elastic modulus is 2.6 GPa (0.377 Msi).
Thermal11
PBT is rated for continuous service to 110°C (230 °F). It conducts heat at 0.25 W/m·K (0.144 BTU/hr·ft·°F), better than 72% of polymer grades. Thermal expansion is 80 µm/m·K (44.4 µin/in·°F).
Electrical7
PBT 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 56% of polymer grades. UV resistance is fair.
Sustainability4
Producing a kilogram of PBT 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's machinability is good (68/100, better than 71% of polymer grades); weldability very good (70/100); formability poor (20/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the polymer family
Yield strength against density for every polymer grade FabDigit runs. PBT is highlighted; hover a dot for its name, or open the interactive family chart.
Working with PBT
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.
Manufacturability
The process limits FabDigit's quote engine applies to PBT. Design inside these and the part quotes instantly; outside them it routes to an engineer.
Injection molding
| Mold shrinkage | — |
|---|---|
| Wall thickness | — – — |
| Recommended draft | — |
| Pre-drying | — |
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 |
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.
Surface treatments FabDigit runs on polymer parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Injection Molding Coating
Metallization / Functional
Equivalent designations
Standards and trade names that resolve to PBT in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Trade names
- CrastinPocanUltradurValox
- Also called
- Polybutylene TerephthalatePTMT
How much does PBT cost?
PBT is a standard-cost polymer ($$), cheaper than about 62% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
PBT — frequently asked
What is PBT used for?
PBT 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?
PBT has a typical yield strength of 55 MPa (7.98 ksi) and a tensile strength of 55 MPa (7.98 ksi) — stronger than 62% of polymer grades. Strength varies by condition: see the 10 listed tempers.
Is PBT easy to machine?
Reasonably — machinability is rated good (68/100, better than 71% 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 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?
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 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?
PBT is rated for continuous use to about 110°C (230 °F), and briefly to 160°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does PBT cost?
PBT is a standard-cost polymer ($$), cheaper than about 62% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in PBT?
Yes — PBT 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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.