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Rigid Thermoset Polyurethane (RPU)

RPU is a thermoset plastic. It has the lowest density among thermoset plastics. In addition, it has the highest ductility and the highest heat capacity. The graph bars on the material properties cards below compare RPU 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

2.2 GPa 0.32 x 106 psi

Elongation at Break

90 %

Flexural Modulus

2.0 GPa 0.29 x 106 psi

Flexural Strength

83 MPa 12 x 103 psi

Tensile Strength: Ultimate (UTS)

60 MPa 8.7 x 103 psi

Thermal Properties

Maximum Temperature: Autoignition

380 °C 720 °F

Maximum Temperature: Decomposition

270 °C 520 °F

Specific Heat Capacity

1750 J/kg-K 0.42 BTU/lb-°F

Thermal Conductivity

0.19 W/m-K 0.11 BTU/h-ft-°F

Thermal Expansion

63 µm/m-K

Vicat Softening Temperature

120 °C 240 °F

Other Material Properties


1.2 g/cm3 75 lb/ft3

Dielectric Strength (Breakdown Potential)

19 kV/mm 0.74 V/mil

Electrical Resistivity Order of Magnitude

13 10x Ω-m

Common Calculations

Stiffness to Weight: Axial

1.0 points

Stiffness to Weight: Bending

36 points

Strength to Weight: Axial

14 points

Strength to Weight: Bending

28 points

Thermal Diffusivity

0.090 mm2/s

Thermal Shock Resistance

31 points

Followup Questions

Further Reading

Polyurethanes: Science, Technology, Markets, and Trends, Mark F. Sonnenschein, 2015

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