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15% Graphite Thermoset PI (ASTM D6456 Type II Class 1)

ASTM D6456 type II class 1 is a grade of thermoset PI. It has the second highest strength and second highest ductility compared to the other variants of thermoset PI. The graph bars on the material properties cards below compare ASTM D6456 type II class 1 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

180 MPa 27 x 103 psi

Elongation at Break

4.0 %

Flexural Modulus

3.1 GPa 0.45 x 106 psi

Flexural Strength

91 MPa 13 x 103 psi

Impact Strength: Notched Izod

43 J/m 0.8 ft-lb/in

Poisson's Ratio


Tensile Strength: Ultimate (UTS)

61 MPa 8.8 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

0.86 W/m-K 0.5 BTU/h-ft-°F

Thermal Expansion

49 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


1.5 g/cm3 92 lb/ft3

Limiting Oxygen Index (LOI)

40 %

Water Absorption After 24 Hours

0.19 %

Water Absorption At Saturation

3.6 %

Common Calculations

Strength to Weight: Axial

11 points

Strength to Weight: Bending

23 points

Thermal Diffusivity

0.52 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

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