Vespel Polyimide: Properties, Uses & Cost Guide
Tensile data verified against MatWeb.com database & manufacturer datasheets · Last updated July 2026
Published: 2026-05-26
Polyimide (PI), commercially known as DuPont Vespel, is the highest-temperature-rated polymer commercially available, with continuous service capability at 300°C in air and intermittent use to 480°C. It does not melt—it decomposes before melting...
Polyimide (PI), commercially known as DuPont Vespel, is the highest-temperature-rated polymer commercially available, with continuous service capability at 300°C in air and intermittent use to 480°C. It does not melt—it decomposes before melting (Td ~550°C in nitrogen). This non-melting property is both its greatest advantage (maintains mechanical properties to 300°C) and its greatest processing challenge (cannot be injection molded; parts are produced by direct-forming—sintering polyimide powder under high pressure and temperature, similar to powder metallurgy). Vespel parts are machined from sintered stock shapes (rod, plate, tube) using carbide tooling.
Vespel is the material of last resort: specified when PEEK (260°C max) is insufficient, when the environment includes plasma exposure (semiconductor etch chambers), or when the application requires the lowest outgassing in ultra-high vacuum (Vespel's total mass loss in vacuum is <0.1% per ASTM E595, qualifying it for spacecraft and satellite mechanisms). It is the standard material for semiconductor wafer handling (wafer clamp rings, CMP retaining rings, chamber liners), aerospace bearings and bushings (jet engine variable stator vane bushings), and nuclear reactor components requiring radiation resistance (PI retains 50% of its mechanical properties after 10ⁱ⁰ rad gamma irradiation).
Recommended Applications
Vespel Polyimide is commonly specified for:
⚠ Not Recommended For
Vespel Polyimide is not recommended for:
- Moisture absorption applications without sealing (Vespel PI absorbs 1-3% moisture — dimensional stability affected)
- Cost-sensitive applications where PAI or PEEK suffices (PI is 5-10× the cost of PEEK)
- Continuous service in strong bases above 200°C (use PBI for extreme alkaline resistance)
Selection & Application Guide
Vespel (polyimide) is the highest-temperature polymer available commercially, with continuous service up to 310°C and short-term exposure to 480°C. Choose Vespel when no other polymer can survive the thermal environment — aerospace hot-section bearings, semiconductor furnace components, and high-vacuum insulators. Vespel cannot be injection molded; it is manufactured by compression molding and sintering, limiting geometry and increasing cost.
Real-World Applications
Vespel SP-21 (15% graphite filled) provides self-lubricating, high-temperature bushings for jet engine variable stator vanes and other hot-section components where metal bearings would seize.
Vespel's low outgassing, thermal stability, and resistance to plasma etching gases make it standard for wafer processing chamber components and lift pins.
Vespel's low outgassing (TML <1%, CVCM <0.1%) and excellent dielectric properties suit it for insulating components in high-vacuum, high-voltage equipment.
Vespel SP-211 (15% graphite + 10% PTFE) provides low-wear thrust washers for automatic transmissions, replacing bronze at lower weight and eliminating the need for lubrication.
Processing & Cost Considerations
Manufacturing Tips
- Vespel is not injection moldable — it is manufactured by direct-forming (compression molding and sintering) into standard shapes (rods, plates, tubes, rings) which are then CNC machined to final geometry. This limits design freedom but allows very precise tolerances.
- Machined Vespel parts achieve tolerances of ±0.025mm or better with standard CNC equipment. Use carbide or diamond tooling. Vespel machines cleanly without burrs, producing excellent surface finishes.
- Different Vespel grades serve different purposes: SP-1 (unfilled) for maximum temperature and electrical insulation, SP-21 (15% graphite) for bearing/wear applications, SP-211 (graphite + PTFE) for maximum PV capability, SP-3 (15% MoS2) for extreme wear conditions.
Vespel is among the most expensive polymers at $400-1200/kg for standard shapes, with custom compounds even higher. The high cost is driven by the compression molding/sintering manufacturing process and low production volumes. CNC machining from standard shapes adds further cost. Despite the expense, Vespel is justified when metal components fail due to temperature, weight, or corrosion, and no other polymer can survive the operating environment.
Technical Properties
| Density | 1.43 g/cm³ |
|---|---|
| Tensile Strength | 85 MPa |
| Melting Point | N/A (Does not melt; Tg ~360°C) |
| Shrinkage Rate | N/A (Direct-formed, not molded) |
| Flexural Modulus | 3.1 GPa |
| Hdt | 360 °C |
| Continuous Service Temp | 300 °C (air); 350°C (inert) |
Engineering Tool: Shrinkage & Cost Estimator
Calculate part weight, mold cavity dimensions accounting for shrinkage, and material cost — all locally in your browser.
Equivalents & Cross-References
| Equivalent / Alternate | Action |
|---|---|
| DuPont Vespel SP-1 | |
| Vespel SP-21 (15% graphite) | |
| Meldin 7001 |
Frequently Asked Questions
Why can't polyimide Vespel be injection molded?
Polyimide does not exhibit a melt phase—its glass transition temperature (Tg) is approximately 360°C, and thermal decomposition begins at approximately 550°C. The processing window between 'soft enough to flow' and 'decomposing' is effectively zero. Most injection-moldable thermoplastics have a processing window of 100-200°C between melting and decomposition. Vespel parts are produced by direct-forming: polyimide powder is compressed in a mold at 140-350 MPa and sintered at 380-400°C, creating a solid part without ever passing through a liquid phase. This is fundamentally the same process as powder metallurgy for metals.
Can Vespel be injection molded?
No. Vespel polyimide cannot be processed by injection molding — it does not melt into a flowable state. It is manufactured by direct-forming (isostatic compression molding and sintering at >300°C under pressure). Parts are produced as standard shapes (rods, plates, rings) and machined to final geometry. If injection molding is required, consider Torlon (PAI) as the closest moldable alternative.
How does Vespel compare to PEEK for high-temperature applications?
Vespel offers 50°C higher continuous service temperature (310°C vs 260°C for PEEK) and better creep resistance at extreme temperatures. PEEK is injection moldable, has higher impact strength, and costs 3-5× less. Choose Vespel only when PEEK's temperature limit is insufficient. For most applications below 250°C, PEEK is the more practical and economical choice.
What is the maximum PV limit for Vespel SP-21?
Vespel SP-21 (15% graphite filled) has a PV limit of approximately 500,000 psi-fpm in continuous dry running, and up to 1,000,000 psi-fpm with marginal lubrication. This is among the highest PV ratings of any polymer, making Vespel the standard for unlubricated high-temperature bearings in aerospace and industrial equipment.
Is Vespel resistant to cryogenic temperatures?
Yes. Vespel retains useful mechanical properties down to -270°C (cryogenic temperatures). It does not become brittle like many other polymers and maintains its dimensional stability. This makes Vespel suitable for liquid nitrogen and liquid helium environments in scientific and medical equipment.
How does Vespel perform in plasma environments?
Vespel has excellent resistance to oxygen plasma, CF4 plasma, and other etching gases used in semiconductor manufacturing. It erodes at a much lower rate than other polymers (PEEK, PPS) in plasma environments, and its low particle generation is critical for cleanroom applications.
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References & Industry Standards
- ASTM International. Standard Specifications for Engineering Plastics & Thermoplastics. astm.org
- UL Prospector. Plastics & Elastomers Material Database. ulprospector.com
- MatWeb. Material Property Data for Engineering Thermoplastics. matweb.com
- ISO 1043. Plastics — Symbols and Abbreviated Terms. iso.org