GPPS GF20
Reinforced grade
ASTM D4549 · GB GB/T 4454 · ISO 1622
GF20 = 20 % glass-fiber reinforced PS
Niche stiff/dimensionally-stable PS for low-cost structural brackets; opaque and abrasive to tooling.
Values for the GF20 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 |
High-heat / high-molecular-weight (extrusion & sheet) grade | Low-MFR, low-lubricant grade for extruded sheet, thermoforming and slightly higher service temperature. | — | 50 | 3 | — |
GF20This page 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 GF20?
GPPS GF20 is GPPS in the GF20 grade — niche stiff/dimensionally-stable PS for low-cost structural brackets; opaque and abrasive to tooling. GPPS GF20 has a tensile strength of 80 MPa (11.6 ksi), stronger than 83% of polymer grades. Elongation at break is 1.5% and the elastic modulus is 7 GPa (1.02 Msi). GPPS GF20 has a density of 1.2 g/cm³ (0.0434 lb/in³), heavier than 57% of polymer grades. Its glass-transition temperature is 100°C (212 °F).
Advantages
- Low, predictable mold shrinkage — 0.15%, better than 97% of polymer grades
- Polishes to a fine finish — 85/100, better than 92% of polymer grades
- Stiff — 7 GPa (1.02 Msi), better than 90% 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
- Limited ductility — 1.5%, worse than 98% 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 service temperature — 65°C (149 °F), worse than 83% of polymer grades
GPPS GF20 properties
Typical room-temperature values for GPPS GF20; 12 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 GF20 has a density of 1.2 g/cm³ (0.0434 lb/in³), heavier than 57% of polymer grades. Its glass-transition temperature is 100°C (212 °F).
Mechanical16
GPPS GF20 has a tensile strength of 80 MPa (11.6 ksi), stronger than 83% of polymer grades. Elongation at break is 1.5% and the elastic modulus is 7 GPa (1.02 Msi).
Thermal11
GPPS GF20 is rated for continuous service to 65°C (149 °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 30 µm/m·K (16.7 µin/in·°F).
Electrical7
GPPS GF20 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 GF20 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 GF20's machinability is fair (40/100, worse than 82% 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 GF20
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 GF20 — frequently asked
What is GPPS GF20 used for?
GPPS GF20 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 GF20?
GPPS GF20 has a typical tensile strength of 80 MPa (11.6 ksi) — stronger than 83% of polymer grades. Strength varies by condition: see the 5 listed tempers.
Is GPPS GF20 easy to machine?
Not especially — machinability is rated fair (40/100, worse than 82% 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 GF20 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 GF20?
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 GF20 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 GF20?
GPPS GF20 is rated for continuous use to about 65°C (149 °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.