Grade X Paper Phenolic is a thermoplastic polymer reinforced with paper fibers. It is a light-weight material which can be used in a variety of applications as a more-durable glass substitute.  Paper-based phenolic is the most economical of the laminates, yet provides significant electrical properties and good mechanical properties.  The more X’s the better the electrical properties, while the fewer X’s represent superior mechanical properties.  Paper grades can be modified by adding plasticizers to make them more conducive to punching resulting in a “P” suffix added to the “X” designation (XP, XXP, XXXP).

  • Grade X certifies to MIL-I-24768/12 (PBM),
  • MIL-I-24768/19 (PBM-P)
  • MIL-I-24768/20 (PBM-PC)
  • MIL-I-24768/24 (PBM-PF)


Mechanical ASTM Test Method Value Units
Strength to Weight Ratio - - ksi
Specific Gravity @73 F D792 1.36 -
Tensile Strength @73 F, (ult)/(yld) D638 20,000 psi
Tensile Modulus of Elasticity @73 F D638 - psi
Tensile Elongation at Break @73 F D638 - %
Flexural Strength @73 F D790 25,000 psi
Flexural Modulus of Elasticity @73 F D790 1,800,000 psi
Shear Strength @73 F D732 12,000 psi
Comprehensive Strength, (% Deformation) @73 F D695 36,000 (10) psi
Comprehensive Modulus of Elasticity @73 F D695 - psi
Hardness, Rockwell, Scale as noted @73 F D785 M110 -
Hardness, Durometer, Shore D @73 F D2240 - -
Izod Impact, (Notched) @73 F D256 Type A 4.0 ft-lb/in of notch
Coefficient of Friction, (Dry vs Steel) Dynamic - - -
Limiting PV, (with 4 to 1 factor of safety applied) - - psi-ft/min
Thermal ASTM Test Method Value Units
Coefficient of Linear Thermal Expansion @73 F E-831 (TMA) - in/in/F
Heat Deflection Temperature @264 psi D648 - F
Tg-Glass transition termperature, (Amorphous) D3418 - F
Melting Point, (VS=Vicat Softening Temp.) D3418 - F
Continuous Service Temperature in Air, (Max.) - 285 F
Thermal Conductivity - - BTU-in/hr-ft2-F
Electric ASTM Test Method Value Units
Dielectric Strength, Short Term D149 500 Volts/mil
Volume Resistivity D257 - ohm-cm
Dielectric Constant @10E6 Hz D150 6 -
Dissipation Factor @10E6 Hz D150 0.06 -
Flammability @3.1 mm unless noted UL94 HB -
H2O ASTM Test Method Value Units
Water Absorption, Immersion, 24 hours D570(7) 1.10 % by weight
Water Absorption, Saturation D570(7) - % by weight