Epoxy vs. PEI
Epoxy belongs to the thermoset plastics classification, while PEI belongs to the thermoplastics. There are 20 material properties with values for both materials. Properties with values for just one material (12, in this case) are not shown.
For each property being compared, the top bar is epoxy and the bottom bar is PEI.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 2.4 | |
| 3.4 to 5.6 |
| Elongation at Break, % | 4.5 | |
| 3.0 to 34 |
| Tensile Strength: Ultimate (UTS), MPa | 67 | |
| 110 to 160 |
Thermal Properties
| Glass Transition Temperature, °C | 120 | |
| 210 |
| Maximum Temperature: Autoignition, °C | 430 | |
| 530 |
| Maximum Temperature: Decomposition, °C | 430 | |
| 530 |
| Maximum Temperature: Mechanical, °C | 130 | |
| 170 |
| Specific Heat Capacity, J/kg-K | 1500 | |
| 1050 to 1220 |
| Thermal Conductivity, W/m-K | 0.2 | |
| 0.18 to 0.23 |
| Thermal Expansion, µm/m-K | 100 | |
| 20 to 53 |
Electrical Properties
| Dielectric Strength (Breakdown Potential), kV/mm | 16 | |
| 30 to 33 |
| Electrical Resistivity Order of Magnitude, 10x Ω-m | 13 | |
| 14 to 15 |
Otherwise Unclassified Properties
| Density, g/cm3 | 1.3 | |
| 1.3 to 1.5 |
| Limiting Oxygen Index (LOI), % | 20 | |
| 47 to 50 |
Common Calculations
| Stiffness to Weight: Axial, points | 1.0 | |
| 1.5 to 2.1 |
| Stiffness to Weight: Bending, points | 34 | |
| 39 |
| Strength to Weight: Axial, points | 14 | |
| 24 to 30 |
| Strength to Weight: Bending, points | 28 | |
| 40 to 44 |
| Thermal Diffusivity, mm2/s | 0.1 | |
| 0.11 to 0.14 |
| Thermal Shock Resistance, points | 20 | |
| 44 to 100 |