PEI vs. PEEK
Both PEI and PEEK are thermoplastics. There are 26 material properties with values for both materials. Properties with values for just one material (6, in this case) are not shown.
For each property being compared, the top bar is PEI and the bottom bar is PEEK.
Metric UnitsUS Customary Units
Mechanical Properties
| Compressive (Crushing) Strength, MPa | 140 to 180 | |
| 120 to 300 |
| Elastic (Young's, Tensile) Modulus, GPa | 3.4 to 5.6 | |
| 4.0 to 24 |
| Elongation at Break, % | 3.0 to 34 | |
| 1.6 to 43 |
| Flexural Modulus, GPa | 3.4 to 5.9 | |
| 3.8 to 19 |
| Flexural Strength, MPa | 140 to 210 | |
| 150 to 330 |
| Impact Strength: Notched Izod, J/m | 55 to 110 | |
| 78 to 120 |
| Tensile Strength: Ultimate (UTS), MPa | 110 to 160 | |
| 97 to 200 |
Thermal Properties
| Glass Transition Temperature, °C | 210 | |
| 240 |
| Heat Deflection Temperature At 1.82 MPa (264 psi), °C | 200 to 210 | |
| 160 to 300 |
| Maximum Temperature: Autoignition, °C | 530 | |
| 600 |
| Maximum Temperature: Decomposition, °C | 530 | |
| 570 |
| Maximum Temperature: Mechanical, °C | 170 | |
| 330 |
| Specific Heat Capacity, J/kg-K | 1050 to 1220 | |
| 1390 to 1700 |
| Thermal Conductivity, W/m-K | 0.18 to 0.23 | |
| 0.25 to 0.93 |
| Thermal Expansion, µm/m-K | 20 to 53 | |
| 15 to 52 |
Electrical Properties
| Electrical Resistivity Order of Magnitude, 10x Ω-m | 14 to 15 | |
| 3.0 to 14 |
Otherwise Unclassified Properties
| Density, g/cm3 | 1.3 to 1.5 | |
| 1.3 to 1.5 |
| Limiting Oxygen Index (LOI), % | 47 to 50 | |
| 38 |
| Water Absorption After 24 Hours, % | 0.17 to 0.25 | |
| 0.060 to 0.3 |
| Water Absorption At Saturation, % | 0.9 to 1.3 | |
| 0.22 to 0.5 |
Common Calculations
| Stiffness to Weight: Axial, points | 1.5 to 2.1 | |
| 1.5 to 10 |
| Stiffness to Weight: Bending, points | 39 | |
| 36 to 73 |
| Strength to Weight: Axial, points | 24 to 30 | |
| 20 to 41 |
| Strength to Weight: Bending, points | 40 to 44 | |
| 36 to 55 |
| Thermal Diffusivity, mm2/s | 0.11 to 0.14 | |
| 0.1 to 0.51 |
| Thermal Shock Resistance, points | 44 to 100 | |
| 34 to 57 |