GPO-2 H (Hardened)
Heat-treated state
ASTM D709 Grade GPO-2
Use for motor/transformer insulation and continuous duty above 155 °C where standard GPO-2 would embrittle.
Values for the H condition
Other GPO-2 grades and fills
GPO-2 is listed in 3 conditions; see the grade overview at GPO-2.
Compare all 3 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
HThis page Hardened | Use for motor/transformer insulation and continuous duty above 155 °C where standard GPO-2 would embrittle. | — | 80 | 1.2 | 107 HRM |
UL 94 V-0 / 5VA recognized flame-retardant build | Specify when a UL Yellow Card flame rating and RTI listing must be shown on the drawing. | — | 80 | 1 | 108 HRM |
High physical strength / heavy-mat build | Pick when the part is structurally loaded (bus supports, cleats, arc barriers) and flexural/impact strength governs. | — | 105 | 1.4 | 110 HRM |
What is GPO-2 H?
GPO-2 H is GPO-2 heat treated to H — use for motor/transformer insulation and continuous duty above 155 °C where standard GPO-2 would embrittle. GPO-2 H has a tensile strength of 80 MPa (11.6 ksi), weaker than 77% of composite grades. The elastic modulus is 11 GPa (1.6 Msi). GPO-2 H has a density of 1.85 g/cm³ (0.0668 lb/in³), heavier than 67% of composite grades. Its glass-transition temperature is 120°C (248 °F).
Advantages
- Low embodied carbon — 4.5 kg CO₂/kg, better than 79% of composite grades
Limitations
- Hard to polish — 20/100, worse than 90% of composite grades
GPO-2 H properties
Typical room-temperature values for GPO-2 H; 18 are specific to this condition. Other listed values are GPO-2 reference data and may not represent this condition. Bars are the position among composite grades.
Physical4
GPO-2 H has a density of 1.85 g/cm³ (0.0668 lb/in³), heavier than 67% of composite grades. Its glass-transition temperature is 120°C (248 °F).
Mechanical10
GPO-2 H has a tensile strength of 80 MPa (11.6 ksi), weaker than 77% of composite grades. The elastic modulus is 11 GPa (1.6 Msi).
Thermal9
GPO-2 H is rated for continuous service to 180°C (356 °F). It conducts heat at 0.3 W/m·K (0.173 BTU/hr·ft·°F), worse than 63% of composite grades. Thermal expansion is 20 µm/m·K (11.1 µin/in·°F).
Electrical7
GPO-2 H is an electrical insulator with a dielectric strength of 14 kV/mm (355.6 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (74/100), worse than 56% of composite grades. UV resistance is fair.
Sustainability4
Producing a kilogram of GPO-2 H takes about 78 MJ of energy and emits 4.5 kg of CO₂ — less than 87% of composite grades. Typical recycled content is 0%.
Manufacturability2
GPO-2 H's machinability is fair (36/100, better than 53% of composite grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with GPO-2 H
Is GPO-2 easy to machine?
Machine dry with carbide or PCD tooling, high speed / moderate feed, and dust extraction — glass content is highly abrasive and the dust is a respiratory irritant.
Can GPO-2 be welded?
Not weldable or heat-formable (cross-linked thermoset); join by bolting, riveting or epoxy/acrylic structural adhesive with abraded surfaces.
Can GPO-2 be formed, bent or molded?
Supplied as flat press-cured sheet, rod or tube; parts are produced by punching (thin gauges, warm), sawing, routing and CNC milling rather than forming.
What surface finishes work on GPO-2?
Edges should be deburred and sealed with epoxy or polyurethane varnish to limit moisture ingress; can be painted or silk-screened after solvent wipe, plating is not applicable.
GPO-2 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| unsaturated polyester resinstyrene-crosslinked, often DCPD or isophthalic type | 25 – 35 | 30 |
| glass fiber (chopped strand mat / continE-glass reinforcement | 20 – 35 | 28 |
| flame retardant + additiveshalogenated or phosphorus FR, catalyst, pigment, mold release | 1 – 5 | 3 |
| mineral filler (CaCO3 / alumina trihydraATH also acts as flame retardant / smoke suppressant | ≥ 30 (balance) | — |
GPO-2 H — frequently asked
What is GPO-2 H used for?
GPO-2 H is typically used for appliance insulation parts, structural electrical boards and junction box components. In short: strongest GPO grade; impact-resistant polyester laminate; moderate cost, higher flexural strength.
What is the tensile strength of GPO-2 H?
GPO-2 H has a typical tensile strength of 80 MPa (11.6 ksi) — weaker than 77% of composite grades. Strength varies by condition: see the 3 listed tempers.
Is GPO-2 H easy to machine?
Not especially — machinability is rated fair (36/100, better than 53% of composite grades). Machine dry with carbide or PCD tooling, high speed / moderate feed, and dust extraction — glass content is highly abrasive and the dust is a respiratory irritant.
Can GPO-2 H be welded?
Not weldable or heat-formable (cross-linked thermoset); join by bolting, riveting or epoxy/acrylic structural adhesive with abraded surfaces.
What surface finishes work on GPO-2 H?
Edges should be deburred and sealed with epoxy or polyurethane varnish to limit moisture ingress; can be painted or silk-screened after solvent wipe, plating is not applicable.
Can GPO-2 H be formed, bent or molded?
Supplied as flat press-cured sheet, rod or tube; parts are produced by punching (thin gauges, warm), sawing, routing and CNC milling rather than forming.
What is the maximum service temperature of GPO-2 H?
GPO-2 H is rated for continuous use to about 180°C (356 °F), and briefly to 220°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASTM D709 – Standard Specification for Laminated Thermosetting Materials — ASTM International (2023)
- NEMA LI 1 – Industrial Laminated Thermosetting Products — NEMA (2020)
- Glass-mat polyester laminate (GPO-1/GPO-2/GPO-3) datasheets — Electrical laminate producers (2023)
- Engineered Materials Handbook: Composites — ASM International (1987)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.