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Isoprene (Natural) Rubber (IR, NR)

IR rubber is a thermoset elastomer or rubber material. It has a fairly low density among rubber materials. In addition, it has the highest ductility and the lowest thermal conductivity. The graph bars on the material properties cards below compare IR rubber to other rubber materials (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

Elongation at Break

600 %

Tensile Strength: Ultimate (UTS)

19 MPa 2.8 x 103 psi

Thermal Properties

Glass Transition Temperature

-70 °C -94 °F

Maximum Temperature: Autoignition

300 °C 560 °F

Maximum Temperature: Decomposition

300 °C 570 °F

Specific Heat Capacity

1550 J/kg-K 0.37 BTU/lb-°F

Thermal Conductivity

0.14 W/m-K 0.081 BTU/h-ft-°F

Otherwise Unclassified Properties


1.0 g/cm3 59 lb/ft3

Limiting Oxygen Index (LOI)

19 %

Common Calculations

Strength to Weight: Axial

5.6 points

Strength to Weight: Bending

17 points

Thermal Diffusivity

0.1 mm2/s

Followup Questions

Further Reading

Rubber Formulary, The, Peter A. Ciullo and Norman Hewitt, 1999