PMMA Impact Modified
Grade
also Acrylite, Perspex
Use where clarity is still needed but breakage or notch sensitivity is the failure mode — machine guards, signage, POP displays.
Values for the Impact Modified condition
Other PMMA grades and fills
PMMA is listed in 8 conditions; see the grade overview at PMMA.
- Impact Modified
- FR
- UV Resistant
- Extruded
- INJ
- Optical Grade
- Cast
- HH
Compare all 8 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Impact ModifiedThis page rubber-toughened acrylic (HI-PMMA / acrylic-impact blends) | Use where clarity is still needed but breakage or notch sensitivity is the failure mode — machine guards, signage, POP displays. | 47 | 50 | 35 | 60 HRM |
FR V-0 | For lighting diffusers, transit glazing and electrical enclosures needing UL 94 V-0 or low smoke; expect some loss of clarity and toughness. | 56 | 58 | 3 | 87 Shore D |
UV-absorber stabilised outdoor grade | For long-life outdoor glazing, signage faces and automotive lenses, or to shield UV-sensitive contents behind the sheet. | 68 | 70 | 4.5 | 89 Shore D |
ExtrudedDefault standard extruded sheet / general purpose grade | Lowest-cost transparent acrylic sheet with tight thickness tolerance; best for thermoforming, laser cutting and signage. | 70 | 4.5 | 92 HRM | |
General-purpose injection-molding pellet grade | Free-flowing pellet grade for thin-wall transparent moldings; dry 4 h at 80 °C before molding. | 70 | 72 | 4 | 90 Shore D |
low-birefringence, high-purity molding/sheet grade | Pick for lenses, light guides, LED optics and display covers where transmission, low haze and low birefringence matter. | 72 | 4 | ||
As cast | Choose for machined and polished parts, thick sheet, chemical exposure and laser-engraved work — higher MW gives better crazing and thermal resistance. | 76 | 4 | 100 HRM | |
Heat-resistant / high-Tg acrylic copolymer | Pick when clarity must survive lamp housings, headlight lenses or autoclave-adjacent temperatures above 100 °C. | 76 | 3.5 |
What is PMMA Impact Modified?
PMMA Impact Modified is PMMA in the Impact Modified grade — use where clarity is still needed but breakage or notch sensitivity is the failure mode — machine guards, signage, POP displays. PMMA Impact Modified has a yield strength of 47 MPa (6.82 ksi) and a tensile strength of 50 MPa (7.25 ksi) — weaker than 55% of polymer grades. Elongation at break is 35% and the elastic modulus is 2.2 GPa (0.319 Msi). PMMA Impact Modified has a density of 1.16 g/cm³ (0.0419 lb/in³), lighter than 55% of polymer grades. Its glass-transition temperature is 105°C (221 °F). Extruded is the default condition FabDigit quotes; Impact Modified 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
- Easy to machine — 72/100, better than 76% of polymer grades
Limitations
- Low fracture toughness — 1.2 MPa·√m (1.09 ksi·√in), worse than 77% of polymer grades
- Limited service temperature — 70°C (158 °F), worse than 77% of polymer grades
PMMA Impact Modified properties
Typical room-temperature values for PMMA Impact Modified; 17 are specific to this condition. Other listed values are PMMA reference data and may not represent this condition. Bars are the position among polymer grades.
Physical6
PMMA Impact Modified has a density of 1.16 g/cm³ (0.0419 lb/in³), lighter than 55% of polymer grades. Its glass-transition temperature is 105°C (221 °F).
Mechanical16
PMMA Impact Modified has a yield strength of 47 MPa (6.82 ksi) and a tensile strength of 50 MPa (7.25 ksi) — weaker than 55% of polymer grades. Elongation at break is 35% and the elastic modulus is 2.2 GPa (0.319 Msi).
Thermal11
PMMA Impact Modified 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 68% of polymer grades. Thermal expansion is 70 µm/m·K (38.9 µin/in·°F).
Electrical7
PMMA Impact Modified 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 52% of polymer grades. UV resistance is excellent.
Sustainability4
Producing a kilogram of PMMA Impact Modified 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 Impact Modified's machinability is very good (72/100, better than 76% of polymer grades); weldability good (55/100); formability good (55/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with PMMA Impact Modified
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 Impact Modified — frequently asked
What is PMMA Impact Modified used for?
PMMA Impact Modified 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 Impact Modified?
PMMA Impact Modified has a typical yield strength of 47 MPa (6.82 ksi) and a tensile strength of 50 MPa (7.25 ksi) — weaker than 55% of polymer grades. Strength varies by condition: see the 8 listed tempers.
Is PMMA Impact Modified easy to machine?
Yes — machinability is rated very good (72/100, better than 76% 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 Impact Modified 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 Impact Modified?
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 Impact Modified 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 Impact Modified?
PMMA Impact Modified 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.
What is the difference between PMMA Extruded and PMMA INJ?
Extruded is the default condition — lowest-cost transparent acrylic sheet with tight thickness tolerance; best for thermoforming, laser cutting and signage. INJ: free-flowing pellet grade for thin-wall transparent moldings; dry 4 h at 80 °C before molding. Yield strength is 47 MPa in Extruded versus 70 MPa in INJ.
Can FabDigit make parts in PMMA Impact Modified?
Yes — PMMA Impact Modified 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.