Polyetherimide (PEI) is an amorphous thermoplastic that has high heat resistance, very good mechanical properties, and excellent chemical resistance. Its mechanical properties are very good even at elevated temperatures, and the material is naturally flame retardant.

PEI is naturally transparent with an orange tint, but is available in a number of opaque variants. The properties of PEI can be modified using additives such as fiberglass and mineral filler in order to further improve its mechanical properties.

PEI is available in in biocompatible variants, and ones approved for contact with foodstuffs and drinking water. Common application areas for PEI are in the automotive and aviation industries, and medical technology.

Primary properties:

● High rigidity
● Good creep resistance
● Good hydrolytic resistance (facilitating steam sterilization)
● Good chemical resistance
● High mechanical strength
● Unaffected by all types of sterilization
● High thermal resistance
● Naturally flame retardant
● High resistance to stress cracking
● Low smoke emission
● Glass-transition temperature of 215°C


ULTEM™ Resin