Polyamide-Imide (PAI)
PAI 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 PAI include four common variations. This page shows summary ranges across all of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare PAI 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
260 to 300 MPa 37 to 44 x 103 psi
Elastic (Young's, Tensile) Modulus
4.0 to 8.3 GPa 0.58 to 1.2 x 106 psi
Elongation at Break
3.0 to 12 %
Flexural Modulus
4.0 to 6.8 GPa 0.58 to 1.0 x 106 psi
Flexural Strength
160 to 320 MPa 23 to 46 x 103 psi
Impact Strength: Notched Izod
45 to 140 J/m 0.84 to 2.5 ft-lb/in
Tensile Strength: Ultimate (UTS)
100 to 180 MPa 15 to 26 x 103 psi
Thermal Properties
Glass Transition Temperature
280 °C 530 °F
Heat Deflection Temperature At 1.82 MPa (264 psi)
280 °C 530 to 540 °F
Maximum Temperature: Autoignition
530 °C 980 °F
Maximum Temperature: Decomposition
490 °C 910 °F
Maximum Temperature: Mechanical
260 °C 500 °F
Specific Heat Capacity
910 to 1000 J/kg-K 0.22 to 0.24 BTU/lb-°F
Thermal Conductivity
0.26 to 0.53 W/m-K 0.15 to 0.31 BTU/h-ft-°F
Thermal Expansion
15 to 34 µm/m-K
Otherwise Unclassified Properties
Density
1.4 to 1.6 g/cm3 87 to 99 lb/ft3
Limiting Oxygen Index (LOI)
45 %
Water Absorption After 24 Hours
0.3 to 0.4 %
Water Absorption At Saturation
1.5 to 1.7 %
Common Calculations
Stiffness to Weight: Axial
1.6 to 3.2 points
Stiffness to Weight: Bending
38 to 47 points
Strength to Weight: Axial
19 to 34 points
Strength to Weight: Bending
33 to 49 points
Thermal Diffusivity
0.16 to 0.41 mm2/s
Thermal Shock Resistance
48 to 110 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