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Thermoset Polyimide (PI)

Thermoset PI is a thermoset plastic. The properties of thermoset PI include five 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 thermoset PI to other thermoset plastics (top) 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

120 to 210 MPa 17 to 31 x 103 psi

Elongation at Break

2.0 to 5.9 %

Flexural Modulus

3.1 to 4.8 GPa 0.45 to 0.7 x 106 psi

Flexural Strength

60 to 100 MPa 8.7 to 14 x 103 psi

Impact Strength: Notched Izod

21 to 43 J/m 0.4 to 0.8 ft-lb/in

Tensile Strength: Ultimate (UTS)

37 to 81 MPa 5.4 to 12 x 103 psi

Thermal Properties

Glass Transition Temperature

360 °C 680 °F

Heat Deflection Temperature At 1.82 MPa (264 psi)

370 °C 700 °F

Maximum Temperature: Autoignition

380 °C 720 °F

Maximum Temperature: Decomposition

330 °C 630 °F

Maximum Temperature: Mechanical

260 °C 500 °F

Specific Heat Capacity

1130 J/kg-K 0.27 BTU/lb-°F

Thermal Conductivity

0.29 to 1.7 W/m-K 0.17 to 1.0 BTU/h-ft-°F

Thermal Expansion

38 to 54 µm/m-K

Electrical Properties

Dielectric Constant (Relative Permittivity) At 1 MHz

3.1

Dielectric Strength (Breakdown Potential)

20 kV/mm 0.78 V/mil

Electrical Resistivity Order of Magnitude

15 10x Ω-m

Otherwise Unclassified Properties

Density

1.4 to 1.6 g/cm3 87 to 100 lb/ft3

Limiting Oxygen Index (LOI)

40 %

Water Absorption After 24 Hours

0.14 to 0.24 %

Water Absorption At Saturation

3.6 %

Common Calculations

Strength to Weight: Axial

6.5 to 16 points

Strength to Weight: Bending

16 to 30 points

Thermal Diffusivity

0.18 to 0.95 m2/s

Followup Questions

Further Reading

ASTM D6456: Standard Specification for Finished Parts Made from Polyimide Resin

Thermosets: Structure, Properties and Applications, Qipeng Guo (editor), 2012

Reinforced Plastics Durability, Geoffrey Pritchard (editor), 1999

Modern Plastics Handbook, Charles A. Harper (editor), 1999

Plastics Materials, 7th ed., J. A. Brydson, 1999

CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015