Polyetherimide

Polyetherimide (PEI) is a high‑performance, amorphous thermoplastic in the polyimide family. It combines rigid imide rings with ether linkages in the backbone, producing a material that remains stiff and dimensionally stable at elevated temperatures. PEI resins are typically transparent to amber and are available in pellets, sheets, and films for molding, extrusion, and thermoforming.

PEI is distinguished by a high glass transition temperature, typically around 210–217°C, which supports high continuous-use temperatures relative to many engineering plastics. It offers high strength and stiffness, excellent electrical insulation, and inherent flame retardancy. Chemical resistance is good to many hydrocarbons and oils, though performance can vary with strong bases, certain solvents, or aggressive oxidizers. The polymer is amorphous, with low shrinkage and good dimensional stability, and many grades retain properties after sterilization methods used in medical applications.

Processing and applications: PEI can be processed by injection molding, extrusion, sheet thermoforming, and additive manufacturing tools compatible with high-temperature thermoplastics. Commercially, grades are marketed under trade names such as Ultem, produced by major manufacturers. PEI is widely used in electrical and electronic components (connectors, housings), medical devices (parts requiring sterilization), aerospace and automotive components, and other applications demanding heat resistance and flame retardancy. Certain grades meet regulatory standards for medical devices and food-contact applications.

Availability and handling: PEI is a recyclable thermoplastic that is typically supplied in glassy to translucent forms. It can be fabricated with standard plastics processing equipment and is compatible with many finishing and joining technologies, making it a versatile choice for high-temperature, flame-retardant parts.