Polyetherimide (PEI)
PEI is a thermoplastic, further classified an an imide plastic. It can have a moderately high tensile strength among the thermoplastics in the database.
The properties of PEI include two common variations. This page shows summary ranges across both of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare PEI to: imide plastics (top), all thermoplastics (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.
Mechanical Properties
Compressive (Crushing) Strength
140 to 180 MPa 20 to 25 x 103 psi
Elastic (Young's, Tensile) Modulus
3.4 to 5.6 GPa 0.49 to 0.81 x 106 psi
Elongation at Break
3.0 to 34 %
Flexural Modulus
3.4 to 5.9 GPa 0.49 to 0.86 x 106 psi
Flexural Strength
140 to 210 MPa 21 to 30 x 103 psi
Impact Strength: Notched Izod
55 to 110 J/m 1.0 to 2.1 ft-lb/in
Rockwell M Hardness
110 to 130
Tensile Strength: Ultimate (UTS)
110 to 160 MPa 16 to 24 x 103 psi
Thermal Properties
Glass Transition Temperature
210 °C 420 °F
Heat Deflection Temperature At 1.82 MPa (264 psi)
200 to 210 °C 390 to 410 °F
Maximum Temperature: Autoignition
530 °C 990 °F
Maximum Temperature: Decomposition
530 °C 980 °F
Maximum Temperature: Mechanical
170 °C 340 °F
Specific Heat Capacity
1050 to 1220 J/kg-K 0.25 to 0.29 BTU/lb-°F
Thermal Conductivity
0.18 to 0.23 W/m-K 0.1 to 0.13 BTU/h-ft-°F
Thermal Expansion
20 to 53 µm/m-K
Electrical Properties
Dielectric Constant (Relative Permittivity) At 1 MHz
3.2 to 3.7
Dielectric Strength (Breakdown Potential)
30 to 33 kV/mm 1.2 to 1.3 V/mil
Electrical Resistivity Order of Magnitude
14 to 15 10x Ω-m
Otherwise Unclassified Properties
Density
1.3 to 1.5 g/cm3 80 to 94 lb/ft3
Limiting Oxygen Index (LOI)
47 to 50 %
Water Absorption After 24 Hours
0.17 to 0.25 %
Water Absorption At Saturation
0.9 to 1.3 %
Common Calculations
Stiffness to Weight: Axial
1.5 to 2.1 points
Stiffness to Weight: Bending
39 points
Strength to Weight: Axial
24 to 30 points
Strength to Weight: Bending
40 to 44 points
Thermal Diffusivity
0.11 to 0.14 mm2/s
Thermal Shock Resistance
44 to 100 points
Followup Questions
Further Reading
Reinforced Plastics Durability, Geoffrey Pritchard (editor), 1999
SPI Plastics Engineering Handbook of the Society of the Plastics Industry, Inc., 5th ed., Michael L. Berins (editor), 2000
Modern Plastics Handbook, Charles A. Harper (editor), 1999
Plastics Materials, 7th ed., J. A. Brydson, 1999