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Epoxy is a thermoset plastic. It has a moderately low density among the thermoset plastics in the database. The graph bars on the material properties cards below compare epoxy 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

Elastic (Young's, Tensile) Modulus

2.4 GPa 0.35 x 106 psi

Elongation at Break

4.5 %

Poisson's Ratio


Shear Modulus

0.85 GPa 0.12 x 106 psi

Tensile Strength: Ultimate (UTS)

67 MPa 9.7 x 103 psi

Thermal Properties

Glass Transition Temperature

120 °C 250 °F

Maximum Temperature: Autoignition

430 °C 800 °F

Maximum Temperature: Decomposition

430 °C 800 °F

Maximum Temperature: Mechanical

130 °C 270 °F

Specific Heat Capacity

1500 J/kg-K 0.36 BTU/lb-°F

Thermal Conductivity

0.2 W/m-K 0.12 BTU/h-ft-°F

Thermal Expansion

100 µm/m-K

Electrical Properties

Dielectric Strength (Breakdown Potential)

16 kV/mm 0.63 V/mil

Electrical Resistivity Order of Magnitude

13 10x Ω-m

Otherwise Unclassified Properties


1.3 g/cm3 81 lb/ft3

Limiting Oxygen Index (LOI)

20 %

Refractive Index


Common Calculations

Stiffness to Weight: Axial

1.0 points

Stiffness to Weight: Bending

34 points

Strength to Weight: Axial

14 points

Strength to Weight: Bending

28 points

Thermal Diffusivity

0.1 mm2/s

Thermal Shock Resistance

20 points

Followup Questions

Further Reading

Epoxy Polymers: New Materials and Innovations, Jean-Pierre Pascault and Roberto J. J. Williams (editors), 2010

ASTM C904: Standard Terminology Relating to Chemical-Resistant Nonmetallic Materials

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