TPI Extem (Thermoplastic Polyimide): Tg 350°C — Highest Continuous Service Temperature of Any Melt-Processable Polymer
Published: 2026-05-31
Extem is Sabic's family of amorphous thermoplastic polyimides (TPI) with glass transition temperatures ranging from 247°C (Extem UH series) to 350°C (Extem XH series) — the highest continuous service temperature of any melt-processable...
Extem is Sabic's family of amorphous thermoplastic polyimides (TPI) with glass transition temperatures ranging from 247°C (Extem UH series) to 350°C (Extem XH series) — the highest continuous service temperature of any melt-processable (non-thermoset) polymer commercially available. Extem XH bridges the gap between injection-moldable thermoplastics (PEEK service limit ~260°C) and non-melt-processable polyimides (Vespel PI, which must be direct-formed by powder-metallurgy sintering or machined from stock shapes at enormous cost and waste). The ability to injection-mold a polymer with 300°C continuous service temperature — enabling complex geometries, threaded features, snap-fits, and thin walls that are impossible or cost-prohibitive in machined Vespel — is Extem's singular value proposition.
Extem requires extreme processing conditions: melt temperature 400-440°C, mold temperature 160-230°C (oil-heated — pushing the limits of conventional oil units rated for 200°C), and EXTREME drying requirements (150°C for 6-8 hours to <0.01% moisture — below the detection limit of most dew-point sensors). Standard injection molding machines are not capable of processing Extem — the barrel, screw, check ring, and hot runner system must be rated for sustained 440°C operation (specialty high-temperature machines with ceramic heater bands, liquid-cooled feed throat, and high-temperature-capable hydraulic or all-electric clamp).
Technical Properties
| Density | 1.46 g/cm³ |
|---|---|
| Tensile Strength | 120 MPa |
| Melting Point | N/A (Amorphous, Tg 350 °C) |
| Shrinkage Rate | 0.8% |
| Flexural Modulus | 5.5 GPa |
| Hdt | 330 °C at 1.82 MPa |
| Continuous Service Temp | 300 °C |
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 |
|---|---|
| Sabic Extem XH | |
| DuPont Vespel TP (discontinued) | |
| Mitsui Aurum |
Frequently Asked Questions
When is Extem worth the extreme processing difficulty vs machined Vespel?
The economic crossover depends on part complexity and production volume: for simple geometries (bushings, washers, seal rings) at low volumes (<1,000 parts/year), machined Vespel is more cost-effective. For complex geometries (connectors with snap-fits, sensor housings with internal threads, thin-walled insulators) at medium-to-high volumes (>5,000 parts/year), injection-molded Extem is dramatically cheaper — the mold amortization is offset by eliminating the machining cost (Vespel machining can be 5-20× the raw material cost due to extreme tool wear and slow cutting speeds required). Extem also enables design features impossible in machined stock shapes: living hinges (limited fatigue life at 300°C), internal undercuts, and gas-assist hollow sections for weight reduction. The qualification barrier is the primary obstacle — aerospace and semiconductor OEMs have 5-10 year material qualification timelines for new polymers in critical applications, and Vespel has a 50-year track record.
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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