Polyetherimide (PEI) is an amorphous high-performance thermoplastic known for its excellent thermal, mechanical, and electrical properties. It has a high glass transition temperature of approximately 215–220 °C, enabling continuous use at elevated temperatures with good dimensional stability.

PEI exhibits high stiffness and strength, maintains mechanical performance under heat, and offers low creep behavior. It is inherently flame resistant and typically achieves UL 94 V-0 ratings without flame-retardant additives, while also generating low smoke during combustion.

The material provides very good electrical insulation properties over a wide temperature range and good chemical resistance to many oils, hydrocarbons, and cleaning agents. Depending on grade, PEI can withstand repeated sterilization processes.

PEI can be processed by injection molding and extrusion, requiring high processing temperatures and thorough pre-drying. Its balanced performance profile makes it suitable for demanding applications in electrical and electronics, automotive, aerospace, industrial, and medical sectors.