Details
Material hierarchy: Polymer - Engineering Thermoplastic
Polyetherimide is abbreviated PEI. An amorphous, transparent amber polymer, polyetherimide combines high temperature resistance, rigidity, impact strength, and creep resistance. PEI has a glass transition temperature of 420°F and a DTUL of 390°F at 264 psi. Thorough drying is required before processing, and typical melt temperatures for injection molding run from 650 to 800°F. PEI resins qualify for UL94 V-O ratings at thicknesses as low as 0.010 inch and meet FAA standards for aircraft interiors.
Polyetherimide is soluble in partially halogenated solvents but resistant to alcohols, acids, and hydrocarbon solvents. It performs well under humid conditions and withstands UV and gamma radiation.
Glass-fiber-reinforced PEI grades are available for general-purpose molding and extrusion; carbon-fiber-reinforced and other specialy grades also are produced for high-strength applications; and PET itself can be made into a high-performance thermoplastic fiber.
PEI has found use in medical applications because of its heat radiation resistance, hydrolytic stability, and transparency; in the electronics field, it is used to make burn-in sockets, bobbins, and printed circuit substrates; automotive uses include lamp sockets and underhood temperature sensors; PEI sheeting is used in aircraft interiors; and extruded PET has been used as a metal replacement for furnace vent pipe.
PEI is an amorphous thermoplastic material, with a continuous use temperature range of up to 340°F (171°C). It has a medium difficulty to machine. It has excellent dimensional stability. It has good UV and hydrolysis resistance. It is transparent to visible infrared and microwave radiation. It has inherent flame retardancy.
The trade name for PEI is ULTEM.