GPPS HH
Grade
ASTM D4549 · GB GB/T 4454 · ISO 1622
HH = high-heat / high-molecular-weight (extrusion & sheet) grade
Low-MFR, low-lubricant grade for extruded sheet, thermoforming and slightly higher service temperature.
Values for the HH condition
Other GPPS grades and fills
GPPS is listed in 5 conditions; see the grade overview at GPPS.
Compare all 5 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Foam-extrusion (PSP/XPS sheet) grade | High-MW, blowing-agent-compatible GPPS for foamed food trays and insulation sheet; properties are density-driven. | — | 1 | 3 | — |
Flame-retardant grade | Use where a UL 94 V-0/V-2 rating is mandatory (housings, electrical parts); loses clarity and some stiffness. | — | 38 | 1.8 | — |
High-flow / easy-flow injection grade | Pick for thin-wall, long-flow or multi-cavity moldings where fill pressure matters more than strength. | — | 42 | 2 | 84 Shore D |
HHThis page High-heat / high-molecular-weight (extrusion & sheet) grade | Low-MFR, low-lubricant grade for extruded sheet, thermoforming and slightly higher service temperature. | — | 50 | 3 | — |
20 % glass-fiber reinforced PS | Niche stiff/dimensionally-stable PS for low-cost structural brackets; opaque and abrasive to tooling. | — | 80 | 1.5 | — |
What is GPPS HH?
GPPS HH is GPPS in the HH grade — low-MFR, low-lubricant grade for extruded sheet, thermoforming and slightly higher service temperature. GPPS HH has a tensile strength of 50 MPa (7.25 ksi), stronger than 54% of polymer grades. Elongation at break is 3% and the elastic modulus is 3.2 GPa (0.464 Msi). GPPS HH has a density of 1.05 g/cm³ (0.0379 lb/in³), lighter than 69% of polymer grades. Its glass-transition temperature is 100°C (212 °F).
Advantages
- Polishes to a fine finish — 85/100, better than 92% of polymer grades
- Readily welded — 80/100, better than 86% of polymer grades
- Low moisture uptake — 0.04%, better than 86% of polymer grades
- Stiff — 3.2 GPa (0.464 Msi), better than 77% of polymer grades
- Low embodied carbon — 3.4 kg CO₂/kg, better than 76% of polymer grades
Limitations
- Needs corrosion protection — 60/100, worse than 89% of polymer grades
- Degrades in UV without stabilisers — 20/100, worse than 88% of polymer grades
- Low fracture toughness — 1 MPa·√m (0.91 ksi·√in), worse than 87% of polymer grades
- Limited ductility — 3%, worse than 83% of polymer grades
- Poor heat conductor — 0.15 W/m·K (0.0867 BTU/hr·ft·°F), worse than 80% of polymer grades
GPPS HH properties
Typical room-temperature values for GPPS HH; 10 are specific to this condition. Other listed values are GPPS reference data and may not represent this condition. Bars are the position among polymer grades.
Physical6
GPPS HH has a density of 1.05 g/cm³ (0.0379 lb/in³), lighter than 69% of polymer grades. Its glass-transition temperature is 100°C (212 °F).
Mechanical16
GPPS HH has a tensile strength of 50 MPa (7.25 ksi), stronger than 54% of polymer grades. Elongation at break is 3% and the elastic modulus is 3.2 GPa (0.464 Msi).
Thermal11
GPPS HH is rated for continuous service to 72°C (162 °F). It conducts heat at 0.15 W/m·K (0.0867 BTU/hr·ft·°F), worse than 80% of polymer grades. Thermal expansion is 75 µm/m·K (41.7 µin/in·°F).
Electrical7
GPPS HH is an electrical insulator with a dielectric strength of 22 kV/mm (558.8 V/mil) and a resistivity of 1×10¹⁴ Ω·m.
Chemical & Environmental3
Corrosion resistance is good (60/100), worse than 89% of polymer grades. UV resistance is poor.
Sustainability4
Producing a kilogram of GPPS HH takes about 92 MJ of energy and emits 3.4 kg of CO₂ — less than 74% of polymer grades. Typical recycled content is 0%.
Manufacturability8
GPPS HH's machinability is good (55/100, worse than 64% of polymer grades); weldability very good (80/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with GPPS HH
Is GPPS easy to machine?
Machines easily at high speed with sharp, positive-rake, polished tools and air cooling — but is notch-sensitive and crazes; avoid cutting fluids containing solvents and always drill with slow feed to prevent cracking.
Can GPPS be welded?
Excellent for ultrasonic, hot-plate/spin welding and solvent bonding (toluene/MEK-based or cyanoacrylate); solvent joints must be stress-relieved to avoid crazing.
Can GPPS be formed, bent or molded?
Very easy injection molding at 190–250 °C melt / 20–70 °C mold with 0.3–0.7 % shrinkage; extruded sheet thermoforms cleanly, but drying is unnecessary and over-shear causes yellowing and monomer odor.
What surface finishes work on GPPS?
Reproduces high-gloss mold surfaces directly; accepts vacuum metallizing, hot stamping and UV/hard-coating, but solvent-based paints and adhesive tapes readily stress-crack the part.
GPPS 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 |
|---|---|---|
| residual styrene monomer≤ 0.02 % typical for food/medical grades | 0 – 0.06 | 0.03 |
| mineral oil / internal lubricantflow & mold-release aid; higher in high-flow grades | 0 – 3 | 1.5 |
| stearate + antioxidant additives | 0 – 0.5 | 0.2 |
| styrene (polystyrene homopolymer)amorphous atactic homopolymer | ≥ 99 (balance) | — |
GPPS HH — frequently asked
What is GPPS HH used for?
GPPS HH is typically used for disposable cutlery/cups, CD/DVD cases, packaging trays, toys and lab ware. In short: cheapest clear thermoplastic; easiest styrenic to mold; brittle and solvent-sensitive.
What is the tensile strength of GPPS HH?
GPPS HH has a typical tensile strength of 50 MPa (7.25 ksi) — stronger than 54% of polymer grades. Strength varies by condition: see the 5 listed tempers.
Is GPPS HH easy to machine?
Reasonably — machinability is rated good (55/100, worse than 64% of polymer grades). Machines easily at high speed with sharp, positive-rake, polished tools and air cooling — but is notch-sensitive and crazes; avoid cutting fluids containing solvents and always drill with slow feed to prevent cracking.
Can GPPS HH be welded?
Yes — weldability is rated very good (80/100). Excellent for ultrasonic, hot-plate/spin welding and solvent bonding (toluene/MEK-based or cyanoacrylate); solvent joints must be stress-relieved to avoid crazing.
What surface finishes work on GPPS HH?
Reproduces high-gloss mold surfaces directly; accepts vacuum metallizing, hot stamping and UV/hard-coating, but solvent-based paints and adhesive tapes readily stress-crack the part.
Can GPPS HH be formed, bent or molded?
Very easy injection molding at 190–250 °C melt / 20–70 °C mold with 0.3–0.7 % shrinkage; extruded sheet thermoforms cleanly, but drying is unnecessary and over-shear causes yellowing and monomer odor.
What is the maximum service temperature of GPPS HH?
GPPS HH is rated for continuous use to about 72°C (162 °F), and briefly to 80°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ISO 1622-1/-2 Plastics — Polystyrene (PS) moulding and extrusion materials — ISO (2012)
- ASTM D4549 Standard Classification System for Polystyrene Molding and Extrusion Materials — ASTM (2020)
- ASM Engineered Materials Handbook Vol. 2: Engineering Plastics — ASM International (1988)
- CAMPUS plastics database — GPPS injection/extrusion grades — CWFG / material producers (2024)
- General purpose polystyrene grade datasheets and processing guides — INEOS Styrolution / Trinseo / Total Energies / (Formosa Chemicals) (2024)
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.