PMMA-GP FR (Flame-retardant grade)
Flame-retardant grade
ASTM D788 · JIS K6717 · GB GB/T 8834 · ISO 8257-1 PMMA
Only where a flame rating is mandatory — expect reduced clarity, lower impact and higher cost versus HB base resin.
Values for the FR condition
Other PMMA-GP grades and fills
PMMA-GP is listed in 6 conditions; see the grade overview at PMMA-GP.
Compare all 6 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Impact-modified (rubber-toughened) PMMA | Use when brittle fracture or snap-fit/assembly stress is the failure mode and 2–4× notched impact is worth some clarity and stiffness loss. | — | 52 | 25 | 70 HRM |
FRThis page Flame-retardant grade | Only where a flame rating is mandatory — expect reduced clarity, lower impact and higher cost versus HB base resin. | 60 | 62 | 3 | 88 Shore D |
Light-diffusing grade | Pick for LED luminaire covers needing uniform luminance and LED hot-spot hiding rather than clarity. | 64 | 66 | 4 | 89 Shore D |
High-flow / thin-wall optical molding grade | Pick for light guides, thin lenses and long flow paths where fill pressure and birefringence must stay low. | 66 | 68 | 3.5 | 89 Shore D |
Heat-resistant (high-Tg copolymer) PMMA | Choose for lamp lenses, automotive interiors and parts seeing 90–110 °C where standard GP would distort. | 73 | 75 | 3.5 | 90 Shore D |
Cell-cast sheet | Use cast sheet for machined/laser-engraved parts, aquaria and premium glazing where the highest MW, stiffness and solvent-crack resistance matter. | 74 | 76 | 5 | 92 Shore D |
What is PMMA-GP FR?
PMMA-GP FR is PMMA-GP in the FR grade — only where a flame rating is mandatory — expect reduced clarity, lower impact and higher cost versus HB base resin. PMMA-GP FR has a yield strength of 60 MPa (8.7 ksi) and a tensile strength of 62 MPa (8.99 ksi) — stronger than 69% of polymer grades. Elongation at break is 3% and the elastic modulus is 3 GPa (0.435 Msi). PMMA-GP FR has a density of 1.24 g/cm³ (0.0448 lb/in³), heavier than 63% of polymer grades. Its glass-transition temperature is 105°C (221 °F).
Advantages
- Polishes to a fine finish — 98/100, better than 100% of polymer grades
- Good UV / weathering resistance — 95/100, better than 95% of polymer grades
Limitations
- Needs corrosion protection — 58/100, worse than 92% of polymer grades
- Limited ductility — 3%, worse than 83% of polymer grades
- Low fracture toughness — 1.1 MPa·√m (1 ksi·√in), worse than 82% of polymer grades
- Limited service temperature — 70°C (158 °F), worse than 77% of polymer grades
PMMA-GP FR properties
Typical room-temperature values for PMMA-GP FR; 29 are specific to this condition. Other listed values are PMMA-GP reference data and may not represent this condition. Bars are the position among polymer grades.
Physical6
PMMA-GP FR has a density of 1.24 g/cm³ (0.0448 lb/in³), heavier than 63% of polymer grades. Its glass-transition temperature is 105°C (221 °F).
Mechanical17
PMMA-GP FR has a yield strength of 60 MPa (8.7 ksi) and a tensile strength of 62 MPa (8.99 ksi) — stronger than 69% of polymer grades. Elongation at break is 3% and the elastic modulus is 3 GPa (0.435 Msi).
Thermal11
PMMA-GP FR is rated for continuous service to 70°C (158 °F). It conducts heat at 0.2 W/m·K (0.116 BTU/hr·ft·°F), worse than 56% of polymer grades. Thermal expansion is 70 µm/m·K (38.9 µin/in·°F).
Electrical7
PMMA-GP FR is an electrical insulator with a dielectric strength of 25 kV/mm (635 V/mil) and a resistivity of 5×10¹² Ω·m.
Chemical & Environmental3
Corrosion resistance is good (58/100), worse than 92% of polymer grades. UV resistance is excellent.
Sustainability4
Producing a kilogram of PMMA-GP FR takes about 100 MJ of energy and emits 6 kg of CO₂ — less than 61% of polymer grades. Typical recycled content is 0%.
Manufacturability8
PMMA-GP FR's machinability is good (68/100, better than 71% of polymer grades); weldability fair (40/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with PMMA-GP FR
Is PMMA-GP easy to machine?
Machines cleanly with sharp, polished, high-rake carbide tools at high speed and light feed; use coolant/air blast to avoid gumming, anneal (80 °C) before and after heavy cuts to prevent crazing and cracking at drilled holes.
Can PMMA-GP be welded?
Not hot-gas/ultrasonic-friendly for optics — join by solvent cementing (dichloromethane, MMA-based cements) or UV-cure acrylic adhesive; hot-plate and vibration welding are possible for opaque parts.
Can PMMA-GP be formed, bent or molded?
Dry 4–6 h at 80–90 °C to <0.05 % moisture; inject at 220–260 °C melt with 50–90 °C mold, slow fill and high hold pressure for low internal stress; sheet thermoforms at 150–180 °C.
What surface finishes work on PMMA-GP?
Excellent flame, diamond and buff polishing to optical clarity; accepts hard-coat, anti-reflective and metallizing (vacuum Al) — avoid alcohol/ammonia cleaners and ester-based paints that cause stress crazing.
PMMA-GP 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 |
|---|---|---|
| methyl acrylate / ethyl acrylate comonomthermal-stability comonomer in most molding grades | 0 – 8 | 3 |
| processing lubricant / mold releasestearate or fatty alcohol | 0 – 0.5 | 0.2 |
| chain transfer agent residue / antioxida | 0 – 0.3 | 0.1 |
| methyl methacrylate (MMA)polymer backbone | ≥ 90 (balance) | — |
PMMA-GP FR — frequently asked
What is PMMA-GP FR used for?
PMMA-GP FR is typically used for injection molded lenses, signage letters, consumer housings and automotive light covers. In short: baseline optical moulding grade; polishes to optical clarity; brittle versus polycarbonate.
What is the yield strength of PMMA-GP FR?
PMMA-GP FR has a typical yield strength of 60 MPa (8.7 ksi) and a tensile strength of 62 MPa (8.99 ksi) — stronger than 69% of polymer grades. Strength varies by condition: see the 6 listed tempers.
Is PMMA-GP FR easy to machine?
Reasonably — machinability is rated good (68/100, better than 71% of polymer grades). Machines cleanly with sharp, polished, high-rake carbide tools at high speed and light feed; use coolant/air blast to avoid gumming, anneal (80 °C) before and after heavy cuts to prevent crazing and cracking at drilled holes.
Can PMMA-GP FR be welded?
With care — weldability is rated fair (40/100). Not hot-gas/ultrasonic-friendly for optics — join by solvent cementing (dichloromethane, MMA-based cements) or UV-cure acrylic adhesive; hot-plate and vibration welding are possible for opaque parts.
What surface finishes work on PMMA-GP FR?
Excellent flame, diamond and buff polishing to optical clarity; accepts hard-coat, anti-reflective and metallizing (vacuum Al) — avoid alcohol/ammonia cleaners and ester-based paints that cause stress crazing.
Can PMMA-GP FR be formed, bent or molded?
Dry 4–6 h at 80–90 °C to <0.05 % moisture; inject at 220–260 °C melt with 50–90 °C mold, slow fill and high hold pressure for low internal stress; sheet thermoforms at 150–180 °C.
What is the maximum service temperature of PMMA-GP FR?
PMMA-GP FR is rated for continuous use to about 70°C (158 °F), and briefly to 90°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ISO 8257-1/-2 Plastics — Poly(methyl methacrylate) moulding and extrusion materials — ISO (2021)
- ASTM D788 Standard Classification System for Poly(Methyl Methacrylate) Molding and Extrusion Compounds — ASTM (2018)
- Engineered Materials Handbook Vol. 2: Engineering Plastics — ASM International (1988)
- PLEXIGLAS / ACRYLITE moulding compound data sheets — Röhm GmbH (2023)
- ACRYPET PMMA resin grade data — Mitsubishi Chemical (2023)
- CAMPUS plastics database — PMMA moulding grades (ISO 10350 datasets) — CWFG / CAMPUS consortium (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.