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Unfilled Thermoset PI (ASTM D6456 Type I)

ASTM D6456 type I is a grade of thermoset PI. It has the highest strength and highest ductility compared to the other variants of thermoset PI. The graph bars on the material properties cards below compare ASTM D6456 type I 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

210 MPa 31 x 103 psi

Elongation at Break

5.9 %

Flexural Modulus

3.1 GPa 0.45 x 106 psi

Flexural Strength

100 MPa 14 x 103 psi

Impact Strength: Notched Izod

43 J/m 0.8 ft-lb/in

Poisson's Ratio


Tensile Strength: Ultimate (UTS)

81 MPa 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 W/m-K 0.17 BTU/h-ft-°F

Thermal Expansion

54 µm/m-K

Electrical Properties

Dielectric Constant (Relative Permittivity) At 1 MHz


Dielectric Strength (Breakdown Potential)

20 kV/mm 0.78 V/mil

Electrical Dissipation At 1 MHz


Electrical Resistivity Order of Magnitude

15 10x Ω-m

Otherwise Unclassified Properties


1.4 g/cm3 87 lb/ft3

Limiting Oxygen Index (LOI)

40 %

Water Absorption After 24 Hours

0.24 %

Water Absorption At Saturation

3.6 %

Common Calculations

Strength to Weight: Axial

16 points

Strength to Weight: Bending

30 points

Thermal Diffusivity

0.18 mm2/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

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