Polyetherimide (PEI)

Alternative and trade names


Polyetherimide (PEI) has the following features:

  • Long-Term Heat Resistance: Excellent stability of physical and mechanical properties at elevated temperatures thanks to high glass transition temperature of 217°C. available with relative thermal indices (RTI) up to 180°C
  • Strength and Stiffness: Outstanding strength and amorphous thermoplastic among the available alternatives, with predictable stiffness and strength up to 200°C. unfilled, transparent grades are equal in strength to other thermoplastics with opacifying fillers.
  • Dimensional Stability: Among the most dimensionally stable thermoplastics available, offering predictability over a wide temperature range. filled grades offer exceptionally high-tolerance dimensional capabilities.
  • Environmental Stress & Cracking Resistance: Unlike most other amorphous thermoplastics, ultem resins retain strength and resist stress cracking when exposed to automotive and aircraft fluids, aliphatic hydrocarbons, alcohols, acids, and weak aqueous solutions.
  • Flammability, Smoke Generation and Toxicity: Inherent flame resistance without additives in most grades - exceptionally difficult to ignite, with a limiting oxygen index (LOI) of 47%, meeting ul94 v0 specifications in sections as thin as 0.41 mm. generates extremely low smoke per the nbs smoke evolution test, with products of combustion no more toxic than those of wood.
  • Properties


    Density ρ

    1.27 - 1.3 g/cm³ at 20 °C


    Elastic modulus E

    2.9 - 3.3 GPa at 20 °C

    Elongation A

    60 - 100 % at 20 °C

    Impact strength, Charpy notched Ivnot

    3 - 4 kJ/m² at 20 °C

    Impact strength, Charpy unnotched Iunnot

    110 kJ/m² at 20 °C

    no break

    Max allowed stress σmax

    85 - 110 MPa at 20 °C

    at 6-10% strain


    Coefficient of thermal expansion α

    5.5E-5 - 6E-5 1/K at 20 °C


    UL 94 V0

    Max service temperature, long Tmaxlong

    170 °C

    Max service temperature, short Tmaxshort

    190 °C

    Specific heat capacity cp

    1200 J/(kg·K) at 20 °C

    Thermal conductivity λ

    0.22 W/(m·K) at 20 °C


    Dielectric constant εr

    3.2 - 3.5 [-] at 20 °C

    Electrical resistivity ρel

    1.00E+13 - 1.00E+15 Ω·m at 20 °C




    Technological properties

    Application areas

    High voltage breaker housings, multi-way connectors, parts for microwaves, parts for break cylinders, carburetor housings, sterilization containers

    Processing methods

    Injection molding

    This material data has been provided by M-Base.

    All metrics apply to room temperature unless otherwise stated. SI units used unless otherwise stated.
    Equivalent standards are similar to one or more standards provided by the supplier. Some equivalent standards may be stricter whereas others may be outside the bounds of the original standard.