No thermoplastic carries more load at higher temperature. PBI keeps 380 MPa of compressive strength at 400 °C, expands less than PEEK, and will not burn in air. It is also the most difficult grade we machine — brittle, moisture-hungry and available only in a narrow range of stock sizes.
Values for a Celazole U-60 class moulded stock shape. Glass-filled and graphite-modified versions exist for wear duty, with proportionally lower strength.
| Property | Value | What it means in design |
|---|---|---|
| Heat deflection temperature | 435 °C at 0.45 MPa | The highest of any machinable thermoplastic — the reason PBI exists |
| Continuous service temperature | ~400 °C inert, ~300 °C in air | Oxidation limits air service; purge or inert-gas environments unlock the full range |
| Compressive strength | ~380 MPa | Roughly double PEEK — carries valve-seat and seal loads metal-free |
| Tensile strength | ~160 MPa | High, but elongation is only 3 % — very little plastic deformation before failure |
| Flexural modulus | ~5.9 GPa | The stiffest grade in our range; deflection is rarely the design limit |
| Coefficient of thermal expansion | ~23 µm/m·K | Close to stainless steel, which simplifies metal-to-polymer fits |
| Water absorption | ~0.4 % / 24 h, higher at saturation | Parts grow measurably in humid air — condition before finishing and before final inspection |
| Limiting oxygen index | 58 % | Will not sustain combustion in air; negligible smoke |
| Chemical resistance | Good, with clear exceptions | Resists fuels, oils, glycols and alcohols; attacked by strong alkalis and hot concentrated acids |
| Machinability | Difficult | Abrasive and notch-sensitive; expect slower cycles and higher inspection cost |
| Availability | Rod, plate, limited sizes | Large or thick sections may not exist as stock — check before you design around them |
| Cost index | 30–50 × PMMA | The most expensive grade we quote; specify it only where the duty demands it |
Standard U-60 class material, machined from moulded stock. The default for insulators, seal rings and high-temperature fixtures.
Improved dimensional stability and wear resistance with reduced strength. Abrasive to tooling; we plan extra tool changes into the cycle.
Lower friction and thermal expansion for bearing and seal duty, at the price of electrical insulation — graphite grades are conductive.
Rod up to roughly 75 mm and plate to about 25 mm thickness are standard. Beyond that, lead time and cost rise steeply — tell us early if the design needs more.
For large parts we quote a moulded near-net blank plus finish machining, which is usually cheaper than machining everything out of plate.
Lot certificate, dimensional report and material traceability as standard. First-article inspection to AS9102 available on request.
Seal rings, valve seats, backup rings and wear components for downhole tools at 250 °C+ in brine and hydrocarbon service.
High-temperature wafer handling, chamber fixtures and insulators that must not outgas or shed particles at process temperature.
Bushings, seals and thermal isolators close to engines, where the fire-performance requirement rules out other polymers.
Contact pads, guides and fixtures for hot glass handling — PBI does not scratch the ware and survives the radiant heat.
Insulating spacers, supports and sample holders for furnaces and autoclaves where ceramic would crack on thermal shock.
Electrical isolation under mechanical load at temperature — the combination that eliminates both metal and ceramic.
PBI is the last resort before ceramic. Confirm you actually need 400 °C before accepting the cost and lead time.
Send the duty cycle, media and load. We will tell you honestly whether PBI is needed, or whether PI or PEEK will do the job at a fraction of the cost.
