If you need components in the most extreme conditions, then Torlon (Polyamide-imide) is your best choice.
Torlon offers unmatched strength at elevated temperatures with a 500˚ Fahrenheit softening temperature and continuous service temperature. Torlon is stronger at 400˚ Fahrenheit than other engineering resins at room temperature.
Torlon is the highest-performance thermoplastic that is still melt-processible. It is tougher and more impact-resistant at cryogenic temperatures than other high-strength polymers. It also is highly resistant to chemicals, including strong acids and most organics.
Torlon comes in a couple of forms.
For extruded or injection-molded grades:
Torlon 4203 is typically used for electrical connectors and insulators because of its high dielectric strength and for other wear applications involving impact loading and abrasive wear.
Torlon 4301 has the same basic physical properties as Torlon 4203 but is designed more for wear and friction parts because of its low expansion rate and low coefficient of friction. This grade works well in applications such as reciprocating compressor parts, bearing cages, seals and non-lubricated bearings.
For extruded grades:
Torlon 4XG is a 30% glass-reinforced grade. The glass improves the load capacity and makes it ideal for applications in the aerospace, business equipment and electrical/electronics industries.
Torlon 4XCF is a 30% carbon-fiber-reinforced grade. Carbon fibers are added for non abrasive wear performance, which also gives it exceptional stiffness and has the lowest coefficient of thermal expansion of the four Torlon grades.