Unfilled Thermoplastic Polyimide (PI)
Unfilled thermoplastic PI is a grade of thermoplastic PI. It has the lowest strength and highest ductility compared to the other variants of thermoplastic PI. The graph bars on the material properties cards below compare unfilled thermoplastic PI 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
240 MPa 35 x 103 psi
Elastic (Young's, Tensile) Modulus
3.7 GPa 0.54 x 106 psi
Elongation at Break
7.5 %
Flexural Modulus
3.8 GPa 0.55 x 106 psi
Flexural Strength
170 MPa 24 x 103 psi
Impact Strength: Notched Izod
83 J/m 1.6 ft-lb/in
Shear Strength
110 MPa 16 x 103 psi
Tensile Strength: Ultimate (UTS)
110 MPa 16 x 103 psi
Thermal Properties
Glass Transition Temperature
260 °C 500 °F
Heat Deflection Temperature At 1.82 MPa (264 psi)
340 °C 640 °F
Maximum Temperature: Autoignition
600 °C 1110 °F
Maximum Temperature: Decomposition
530 °C 980 °F
Maximum Temperature: Mechanical
260 °C 500 °F
Specific Heat Capacity
1100 J/kg-K 0.26 BTU/lb-°F
Thermal Conductivity
0.11 W/m-K 0.064 BTU/h-ft-°F
Thermal Expansion
45 µm/m-K
Electrical Properties
Dielectric Constant (Relative Permittivity) At 1 MHz
3.2
Dielectric Strength (Breakdown Potential)
16 kV/mm 0.63 V/mil
Otherwise Unclassified Properties
Density
1.4 g/cm3 86 lb/ft3
Limiting Oxygen Index (LOI)
35 %
Water Absorption After 24 Hours
0.7 %
Water Absorption At Saturation
3.8 %
Common Calculations
Stiffness to Weight: Axial
1.5 points
Stiffness to Weight: Bending
37 points
Strength to Weight: Axial
22 points
Strength to Weight: Bending
36 points
Thermal Diffusivity
0.072 mm2/s
Thermal Shock Resistance
46 points
Followup Questions
Further Reading
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