Vespel Polyimide: Extreme-Temperature Polymer for Aerospace & Semiconductor
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).
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.
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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