PBI · grade · default condition
PBI Unfilled
Properties of the Unfilled condition, compared with the other PBI grades.
Pick for maximum temperature capability, compressive strength and stiffness — semiconductor test sockets, insulator bushings, hot-gas seats.
What is PBI Unfilled?
PBI Unfilled is PBI in the Unfilled grade — pick for maximum temperature capability, compressive strength and stiffness — semiconductor test sockets, insulator bushings, hot-gas seats. PBI Unfilled has a tensile strength of 160 MPa (23.2 ksi), stronger than 95% of polymer grades. Elongation at break is 3% and the elastic modulus is 5.9 GPa (0.856 Msi). PBI Unfilled has a density of 1.3 g/cm³ (0.047 lb/in³), heavier than 69% of polymer grades. Its glass-transition temperature is 427°C (801 °F).
Advantages
- High service temperature — 310°C (590 °F), better than 100% of polymer grades
- Conducts heat well — 0.41 W/m·K (0.237 BTU/hr·ft·°F), better than 95% of polymer grades
- Good corrosion resistance — 92/100, better than 91% of polymer grades
- Stiff — 5.9 GPa (0.856 Msi), better than 88% of polymer grades
- Good UV / weathering resistance — 70/100, better than 83% of polymer grades
Limitations
- Limited formability — 5/100, worse than 95% of polymer grades
- Difficult to weld — 5/100, worse than 90% of polymer grades
- Limited ductility — 3%, worse than 83% of polymer grades
PBI Unfilled properties
Typical room-temperature values for PBI Unfilled — 13 properties are specific to this condition; the rest are grade-level values shared by every PBI grade. Each bar shows where the value sits among the polymer grades in FabDigit's library — further right is higher.
Physical4
PBI Unfilled has a density of 1.3 g/cm³ (0.047 lb/in³), heavier than 69% of polymer grades. Its glass-transition temperature is 427°C (801 °F).
Mechanical11
PBI Unfilled has a tensile strength of 160 MPa (23.2 ksi), stronger than 95% of polymer grades. Elongation at break is 3% and the elastic modulus is 5.9 GPa (0.856 Msi).
Thermal9
PBI Unfilled is rated for continuous service to 310°C (590 °F). It conducts heat at 0.41 W/m·K (0.237 BTU/hr·ft·°F), better than 95% of polymer grades. Thermal expansion is 23 µm/m·K (12.8 µin/in·°F).
Electrical5
PBI Unfilled is an electrical insulator with a dielectric strength of 22 kV/mm (558.8 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (92/100), better than 91% of polymer grades. UV resistance is very good.
Sustainability1
Typical recycled content is 0%.
Manufacturability4
PBI Unfilled's machinability is fair (50/100, worse than 73% of polymer grades); weldability not recommended (5/100); formability not recommended (5/100).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other PBI grades and fills
PBI is also supplied in 3 other conditions. The full side-by-side table is on the PBI overview.
- UnfilledDefaultPick for maximum temperature capability, compressive strength and stiffness — semiconductor test sockets, insulator bushings, hot-gas seats.160 MPa tensile
- TU-60Pick when full PBI temperature is not needed and better toughness, easier machining and lower cost matter (structural insulators, seal rings to ~260 °C).130 MPa tensile
- TL-60Pick for dry-running bushings, wear rings and thrust washers at elevated temperature where a low, stable friction coefficient is required.95 MPa tensile
Working with PBI Unfilled
Is PBI easy to machine?
Machine like a hard, brittle ceramic-filled plastic: sharp polished carbide (or PCD for filled grades), high speed, light feeds, minimal heat, generous corner radii; parts are notch-sensitive and stock should be kept dry/annealed to control post-machining growth.
Can PBI be welded?
Not weldable or heat-staked — PBI does not melt; join by fasteners, press fit, adhesives (epoxy after abrasion/primer) or mechanical clamping.
Can PBI be formed, bent or molded?
Not melt-processable: shapes are produced by high-temperature/high-pressure sinter (compression) molding of resin powder, then finish-machined; no injection molding, extrusion or thermoforming.
What surface finishes work on PBI?
No plating or anodizing; typical finishing is fine machining/lapping, light bead-blast or vapor-honing, and thorough drying/annealing cycles before dimensional inspection — natural color is dark bronze-brown to black.
PBI 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.
| Element | Spec limit (wt %) |
|---|---|
| 3,3'-diaminobenzidine (monomer)amine monomer unit | — |
| diphenyl isophthalate (monomer)ester monomer unit | — |
| poly[2,2'-(m-phenylene)-5,5'-bibenzimidacondensation polymer of 3,3'-diaminobenzidine (tetraaminobiphenyl) with diphenyl isophthalate; unfilled grade | balance |
PBI Unfilled — frequently asked
What is PBI Unfilled used for?
PBI Unfilled is typically used for semiconductor test sockets, wafer-handling parts, hot-gas and valve seats, insulator bushings, seals and back-up rings and cryogenic-to-high-temperature structural insulators. In short: highest temperature plastic.
What is the tensile strength of PBI Unfilled?
PBI Unfilled has a typical tensile strength of 160 MPa (23.2 ksi) — stronger than 95% of polymer grades. Strength varies by condition: see the 4 listed tempers.
Is PBI Unfilled easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 73% of polymer grades). Machine like a hard, brittle ceramic-filled plastic: sharp polished carbide (or PCD for filled grades), high speed, light feeds, minimal heat, generous corner radii; parts are notch-sensitive and stock should be kept dry/annealed to control post-machining growth.
Can PBI Unfilled be welded?
Not readily — weldability is rated not recommended (5/100). Not weldable or heat-staked — PBI does not melt; join by fasteners, press fit, adhesives (epoxy after abrasion/primer) or mechanical clamping.
What surface finishes work on PBI Unfilled?
No plating or anodizing; typical finishing is fine machining/lapping, light bead-blast or vapor-honing, and thorough drying/annealing cycles before dimensional inspection — natural color is dark bronze-brown to black.
Can PBI Unfilled be formed, bent or molded?
Not melt-processable: shapes are produced by high-temperature/high-pressure sinter (compression) molding of resin powder, then finish-machined; no injection molding, extrusion or thermoforming.
What is the maximum service temperature of PBI Unfilled?
PBI Unfilled is rated for continuous use to about 310°C (590 °F), and briefly to 500°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in PBI Unfilled?
Yes — PBI Unfilled is available for CNC machining, sheet metal and injection molding with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- Celazole PBI U-60 / T-Series stock shapes technical data — Celanese / Boedeker & Drake Plastics distributor data (2023)
- TECAPBI blue product datasheet — Ensinger (2022)
- Engineered Materials Handbook, Vol. 2: Engineering Plastics — ASM International (1988)
- High-performance polymer property tables (PBI) — CAMPUS / UL Prospector (2023)
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.