PMMA · flame-retardant grade
PMMA-FR
Properties of the FR condition, compared with the other PMMA grades.
For lighting diffusers, transit glazing and electrical enclosures needing UL 94 V-0 or low smoke; expect some loss of clarity and toughness.
What is PMMA-FR?
PMMA-FR is PMMA in the FR grade — for lighting diffusers, transit glazing and electrical enclosures needing UL 94 V-0 or low smoke; expect some loss of clarity and toughness. PMMA-FR has a yield strength of 68 MPa (9.86 ksi) and a tensile strength of 58 MPa (8.41 ksi) — stronger than 75% of polymer grades. Elongation at break is 3% and the elastic modulus is 3.2 GPa (0.464 Msi). PMMA-FR has a density of 1.25 g/cm³ (0.0452 lb/in³), heavier than 64% of polymer grades. Its glass-transition temperature is 105°C (221 °F). Extruded is the default condition FabDigit quotes; FR is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 96/100, better than 99% of polymer grades
- Good UV / weathering resistance — 92/100, better than 93% of polymer grades
- Stiff — 3.2 GPa (0.464 Msi), better than 76% of polymer grades
- High strength — 68 MPa (9.86 ksi), better than 75% of polymer grades
Limitations
- Limited ductility — 3%, worse than 83% of polymer grades
- Limited service temperature — 70°C (158 °F), worse than 78% of polymer grades
PMMA-FR properties
Typical room-temperature values for PMMA-FR — 9 properties are specific to this condition; the rest are grade-level values shared by every PMMA grade. Each bar shows where the value sits among the polymer grades in FabDigit's library — further right is higher.
Physical6
PMMA-FR has a density of 1.25 g/cm³ (0.0452 lb/in³), heavier than 64% of polymer grades. Its glass-transition temperature is 105°C (221 °F).
Mechanical16
PMMA-FR has a yield strength of 68 MPa (9.86 ksi) and a tensile strength of 58 MPa (8.41 ksi) — stronger than 75% of polymer grades. Elongation at break is 3% and the elastic modulus is 3.2 GPa (0.464 Msi).
Thermal11
PMMA-FR is rated for continuous service to 70°C (158 °F). It conducts heat at 0.19 W/m·K (0.11 BTU/hr·ft·°F), worse than 69% of polymer grades. Thermal expansion is 70 µm/m·K (38.9 µin/in·°F).
Electrical7
PMMA-FR is an electrical insulator with a dielectric strength of 25 kV/mm (635 V/mil) and a resistivity of 1×10¹³ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (80/100), worse than 55% of polymer grades. UV resistance is excellent.
Sustainability4
Producing a kilogram of PMMA-FR takes about 101 MJ of energy and emits 6.4 kg of CO₂ — less than 56% of polymer grades. Typical recycled content is 2%.
Manufacturability8
PMMA-FR's machinability is very good (70/100, better than 73% of polymer grades); weldability good (55/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other PMMA grades and fills
PMMA is also supplied in 8 other conditions. The full side-by-side table is on the PMMA overview.
- ExtrudedDefaultLowest-cost transparent acrylic sheet with tight thickness tolerance; best for thermoforming, laser cutting and signage.70 MPa tensile
- CastChoose for machined and polished parts, thick sheet, chemical exposure and laser-engraved work — higher MW gives better crazing and thermal resistance.76 MPa tensile
- HHPick when clarity must survive lamp housings, headlight lenses or autoclave-adjacent temperatures above 100 °C.76 MPa tensile
- Optical GradePick for lenses, light guides, LED optics and display covers where transmission, low haze and low birefringence matter.72 MPa tensile
- INJFree-flowing pellet grade for thin-wall transparent moldings; dry 4 h at 80 °C before molding.72 MPa tensile
- FRFor lighting diffusers, transit glazing and electrical enclosures needing UL 94 V-0 or low smoke; expect some loss of clarity and toughness.58 MPa tensile
- Impact ModifiedUse where clarity is still needed but breakage or notch sensitivity is the failure mode — machine guards, signage, POP displays.47 MPa yield · 60 HRM
Working with PMMA-FR
Is PMMA easy to machine?
Machines cleanly with sharp, polished, high-rake carbide tools and high spindle speed / low feed; use 0° rake or step drills to avoid chipping, and anneal (80 °C, 1 h per 3 mm) before and after cutting to prevent crazing.
Can PMMA be welded?
Not conventionally weldable — join with methylene-chloride or MMA cement (solvent/polymerisable), UV-cure acrylic adhesive, or ultrasonic welding for molded parts; hot-gas/hot-plate welding is possible but leaves visible seams.
Can PMMA be formed, bent or molded?
Thermoform at 150–175 °C from dried sheet; injection mold at 220–265 °C melt / 50–90 °C mold after drying 3–4 h at 80 °C, and hold back pressure to avoid silver streaking.
What surface finishes work on PMMA?
Flame, diamond or buff polish gives optical edges; hard-coat lacquers improve scratch and chemical resistance; paints and inks must be acrylic/urethane-based — solvent-rich systems craze the surface.
PMMA 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 comonomadded in extrusion/injection grades for thermal-processing stability | 0 – 8 | 2 |
| acrylic impact modifier (core-shell rubbonly in impact-modified grades | 0 – 25 | 0 |
| UV absorber (benzotriazole/benzophenone)UV-resistant grades | 0 – 1 | 0 |
| processing aids / release agent / antiox | 0 – 1 | 0.3 |
| methyl methacrylate (MMA)polymerised MMA backbone; homopolymer for cast sheet | ≥ 92 (balance) | — |
PMMA-FR — frequently asked
What is PMMA-FR used for?
PMMA-FR is typically used for automotive taillight lenses, illuminated signage and lettering, machine guards and viewing windows, light pipes and optical lenses, display cases and retail fixtures and skylights and architectural glazing. In short: crystal clear; weatherproof.
What is the yield strength of PMMA-FR?
PMMA-FR has a typical yield strength of 68 MPa (9.86 ksi) and a tensile strength of 58 MPa (8.41 ksi) — stronger than 75% of polymer grades. Strength varies by condition: see the 9 listed tempers.
Is PMMA-FR easy to machine?
Yes — machinability is rated very good (70/100, better than 73% of polymer grades). Machines cleanly with sharp, polished, high-rake carbide tools and high spindle speed / low feed; use 0° rake or step drills to avoid chipping, and anneal (80 °C, 1 h per 3 mm) before and after cutting to prevent crazing.
Can PMMA-FR be welded?
Yes — weldability is rated good (55/100). Not conventionally weldable — join with methylene-chloride or MMA cement (solvent/polymerisable), UV-cure acrylic adhesive, or ultrasonic welding for molded parts; hot-gas/hot-plate welding is possible but leaves visible seams.
What surface finishes work on PMMA-FR?
Flame, diamond or buff polish gives optical edges; hard-coat lacquers improve scratch and chemical resistance; paints and inks must be acrylic/urethane-based — solvent-rich systems craze the surface.
Can PMMA-FR be formed, bent or molded?
Thermoform at 150–175 °C from dried sheet; injection mold at 220–265 °C melt / 50–90 °C mold after drying 3–4 h at 80 °C, and hold back pressure to avoid silver streaking.
What is the maximum service temperature of PMMA-FR?
PMMA-FR is rated for continuous use to about 70°C (158 °F), and briefly to 95°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in PMMA-FR?
Yes — PMMA-FR is available for CNC machining, sheet metal and injection molding with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ISO 7823-1/-2 (Poly(methyl methacrylate) sheets — cast and extruded) — ISO (2003)
- ASTM D788 Standard Classification for Poly(Methyl Methacrylate) Molding and Extrusion Compounds — ASTM (2018)
- PLEXIGLAS GS/XT and molding compound datasheets — Röhm GmbH (2023)
- ACRYLITE cast and extruded sheet technical data — Röhm America / Trinseo (2022)
- ACRYPET molding grade technical brochure — Mitsubishi Chemical (2021)
- CAMPUS plastics database — PMMA property profiles (ISO 10350) — CWFG (2024)
- Engineered Materials Handbook Vol. 2: Engineering Plastics — ASM International (1988)
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.