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Phenol Formaldehyde (PF, Phenolic)

Phenolic is a thermoset plastic. It has the highest dielectric strength and a moderately low density among thermoset plastics. The graph bars on the material properties cards below compare phenolic 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

3.8 GPa 0.55 x 106 psi

Elongation at Break

2.0 %

Tensile Strength: Ultimate (UTS)

48 MPa 7.0 x 103 psi

Thermal Properties

Glass Transition Temperature

170 °C 340 °F

Maximum Temperature: Autoignition

430 °C 810 °F

Maximum Temperature: Decomposition

260 °C 490 °F

Maximum Temperature: Mechanical

150 °C 300 °F

Specific Heat Capacity

1400 J/kg-K 0.33 BTU/lb-°F

Thermal Conductivity

0.25 W/m-K 0.14 BTU/h-ft-°F

Thermal Expansion

120 µm/m-K

Electrical Properties

Dielectric Constant (Relative Permittivity) At 1 MHz


Dielectric Strength (Breakdown Potential)

46 kV/mm 1.8 V/mil

Electrical Resistivity Order of Magnitude

11 10x Ω-m

Otherwise Unclassified Properties


1.3 g/cm3 81 lb/ft3

Limiting Oxygen Index (LOI)

27 %

Common Calculations

Stiffness to Weight: Axial

1.6 points

Stiffness to Weight: Bending

40 points

Strength to Weight: Axial

10 points

Strength to Weight: Bending

23 points

Thermal Diffusivity

0.14 mm2/s

Thermal Shock Resistance

7.5 points

Followup Questions

Further Reading

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

ASTM D883: Standard Terminology Relating to Plastics

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