GPPS FOAM
Grade
ASTM D4549 · GB GB/T 4454 · ISO 1622
FOAM = foam-extrusion (PSP/XPS sheet) grade
High-MW, blowing-agent-compatible GPPS for foamed food trays and insulation sheet; properties are density-driven.
Values for the FOAM 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 |
|---|---|---|---|---|---|
FOAMThis page 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 |
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 FOAM?
GPPS FOAM is GPPS in the FOAM grade — high-MW, blowing-agent-compatible GPPS for foamed food trays and insulation sheet; properties are density-driven. GPPS FOAM has a tensile strength of 1 MPa (0.174 ksi), weaker than 85% of polymer grades. Elongation at break is 3% and the elastic modulus is 0.02 GPa (0.0029 Msi). GPPS FOAM has a density of 0.09 g/cm³ (0.0033 lb/in³), lighter than 86% 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
- Easy to machine — 85/100, better than 88% of polymer grades
- Lightweight — 0.09 g/cm³ (0.0033 lb/in³), better than 86% of polymer grades
- Readily welded — 80/100, better than 86% of polymer grades
- Low moisture uptake — 0.04%, better than 86% of polymer grades
Limitations
- Poor heat conductor — 0.04 W/m·K (0.0202 BTU/hr·ft·°F), worse than 93% of polymer grades
- 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
GPPS FOAM properties
Typical room-temperature values for GPPS FOAM; 18 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 FOAM has a density of 0.09 g/cm³ (0.0033 lb/in³), lighter than 86% of polymer grades. Its glass-transition temperature is 100°C (212 °F).
Mechanical16
GPPS FOAM has a tensile strength of 1 MPa (0.174 ksi), weaker than 85% of polymer grades. Elongation at break is 3% and the elastic modulus is 0.02 GPa (0.0029 Msi).
Thermal11
GPPS FOAM is rated for continuous service to 70°C (158 °F). It conducts heat at 0.04 W/m·K (0.0202 BTU/hr·ft·°F), worse than 93% of polymer grades. Thermal expansion is 75 µm/m·K (41.7 µin/in·°F).
Electrical7
GPPS FOAM 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 FOAM 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 FOAM's machinability is excellent (85/100, better than 88% of polymer grades); weldability very good (80/100); formability good (55/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with GPPS FOAM
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 FOAM — frequently asked
What is GPPS FOAM used for?
GPPS FOAM 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 FOAM?
GPPS FOAM has a typical tensile strength of 1 MPa (0.174 ksi) — weaker than 85% of polymer grades. Strength varies by condition: see the 5 listed tempers.
Is GPPS FOAM easy to machine?
Yes — machinability is rated excellent (85/100, better than 88% 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 FOAM 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 FOAM?
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 FOAM 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 FOAM?
GPPS FOAM is rated for continuous use to about 70°C (158 °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.