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Glass polyester is a cost-effective choice for fabricated parts

Glass Polyester (GPO-1, GPO-2,GPO-3)

  • Economical general purpose laminate
  • Good electrical properties
    (GPO-1, 2 & 3)
  • Excellent structural properties
    (GPO-1, 2 & 3)
  • Flame-resistant
    (GPO-2 & 3)
  • UL recognized laminate
    GPO-2 & 3)
  • Arc- and track-resistant


Glass Polyester is a Glass-Mat Reinforced Polyester. GPO-1 is a cost-effective, general purpose laminate.  It is a solid choice for applications in which good electrical properties, good physical strength and moderate heat resistance are required.

  GPO-2 is the laminate of choice when arc or flame resistance is required. It has good electrical and physical properties and heat resistance.

  GPO-3 is the laminate to choose when arc, flame and carbon track-resistance are needed. GPO-3 offers good physical strength and moderate heat resistance. It is used extensively in the making of electrical components.


  • High amperage mounting panels (GPO-2)
  • Switch bases (GPO-2)
  • Terminal strips (GPO-2)
  • Arc shoot components (GPO-2)
  • Phase and end barriers (GPO-3)
  • Insulating and bus bar supports (GPO-3)
  • Mounting panels in switchgear and other types of electrical apparatus (GPO-3)


Our application engineers can help. With decades of experience in plastic material selection, we'll help you choose the optimal plastic for your application and budget.


To compare
the cost of this material to other thermosets, click here.

General Material Properties

Property   Metric units   English units
Density   1.7e3 - 2.5e3 kg/m^3 USD/kg   0.0614 - 0.0903 lb/in^3 USD/lb
Yield Strength   3.66e7 - 4.04e7 Pa   5.3 - 5.86 ksi
Tensile Strength   2.5e7 - 5.5e7 Pa   3.63 - 7.98 ksi
Hardness (Vickers)   1.35e8 - 1.49e8 Pa   13.8 - 15.2 HV
Impact Strength (notched)   4e3 - 3e4 J/m^2   1.9 - 14.3 ft.lbf/in^2
Fracture Toughness   1.41e6 - 2.69e6 Pa/m^0.5   1.28 - 2.45 ksi/in^0.5
Young's Modulus   9e9 - 1.44e10 Pa   1.31 - 2.09 10^6 psi
Max Service Temperature   151 - 168 °C   304 - 334 °F
Insulator or Conductor   Insulator   Insulator
Specific Heat Capability   1.09e3 - 1.42e3 J/kg °C   0.26 - 0.34 BTU/lb. °F
Thermal Expansion Coefficent   2.00E-05 strain/°C   11.1 µstrain/°F
CO2 Footprint   7.59 - 8.38 kg/kg   7.59 - 8.38 lb/lb
Recycleable   No   No

The information on this page is intended as general guidance only and is only accurate at the time of posting (see date below). Specific material properties vary by manufacturer. Please contact a Dielectric application engineer for help in choosing the optimal material for your application and budget.

Posting Date: September 10, 2012