# 40% Graphite Thermoset PI (ASTM D6456 Type II Class 2)

ASTM D6456 type II class 2 is a grade of thermoset PI. It has the lowest ductility compared to the other variants of thermoset PI. The graph bars on the material properties cards below compare ASTM D6456 type II class 2 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 *MPa* 17 *x 10 ^{3} psi*

Elongation at Break

2.0 *%*

Flexural Modulus

4.8 *GPa* 0.7 *x 10 ^{6} psi*

Flexural Strength

68 *MPa* 9.9 *x 10 ^{3} psi*

Tensile Strength: Ultimate (UTS)

46 *MPa* 6.7 *x 10 ^{3} 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

1.7 *W/m-K* 1.0 *BTU/h-ft-°F*

Thermal Expansion

38 *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 *10 ^{x} Ω-m*

## Otherwise Unclassified Properties

Density

1.6 *g/cm ^{3}* 100

*lb/ft*

^{3}Limiting Oxygen Index (LOI)

40 *%*

Water Absorption After 24 Hours

0.14 *%*

Water Absorption At Saturation

3.6 *%*

## Common Calculations

Strength to Weight: Axial

8.0 *points*

Strength to Weight: Bending

18 *points*

Thermal Diffusivity

0.95 *mm ^{2}/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