FEP vs. Thermoset PI
FEP belongs to the thermoplastics classification, while thermoset PI belongs to the thermoset plastics. There are 20 material properties with values for both materials. Properties with values for just one material (14, in this case) are not shown.
For each property being compared, the top bar is FEP and the bottom bar is thermoset PI.
Metric UnitsUS Customary Units
Mechanical Properties
| Elongation at Break, % | 300 | |
| 2.0 to 5.9 |
| Flexural Modulus, GPa | 0.6 | |
| 3.1 to 4.8 |
| Flexural Strength, MPa | 24 | |
| 60 to 100 |
| Tensile Strength: Ultimate (UTS), MPa | 20 | |
| 37 to 81 |
Thermal Properties
| Glass Transition Temperature, °C | 60 | |
| 360 |
| Heat Deflection Temperature At 1.82 MPa (264 psi), °C | 50 | |
| 370 |
| Maximum Temperature: Autoignition, °C | 630 | |
| 380 |
| Maximum Temperature: Mechanical, °C | 200 | |
| 260 |
| Specific Heat Capacity, J/kg-K | 1170 | |
| 1130 |
| Thermal Conductivity, W/m-K | 0.22 | |
| 0.29 to 1.7 |
| Thermal Expansion, µm/m-K | 95 | |
| 38 to 54 |
Electrical Properties
| Dielectric Constant (Relative Permittivity) At 1 MHz | 2.0 | |
| 3.1 |
| Dielectric Strength (Breakdown Potential), kV/mm | 22 | |
| 20 |
| Electrical Resistivity Order of Magnitude, 10x Ω-m | 16 | |
| 15 |
Otherwise Unclassified Properties
| Density, g/cm3 | 2.1 | |
| 1.4 to 1.6 |
| Limiting Oxygen Index (LOI), % | 80 | |
| 40 |
| Water Absorption After 24 Hours, % | 0.010 | |
| 0.14 to 0.24 |
Common Calculations
| Strength to Weight: Axial, points | 2.6 | |
| 6.5 to 16 |
| Strength to Weight: Bending, points | 7.6 | |
| 16 to 30 |
| Thermal Diffusivity, mm2/s | 0.088 | |
| 0.18 to 0.95 |