PMMA INJ
Grade
also Acrylite, Perspex
INJ = general-purpose injection-molding pellet grade
Free-flowing pellet grade for thin-wall transparent moldings; dry 4 h at 80 °C before molding.
Values for the INJ condition
Other PMMA grades and fills
PMMA is listed in 8 conditions; see the grade overview at PMMA.
Compare all 8 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
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 | |
INJThis page 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 INJ?
PMMA INJ is PMMA in the INJ grade — free-flowing pellet grade for thin-wall transparent moldings; dry 4 h at 80 °C before molding. PMMA INJ has a yield strength of 70 MPa (10.2 ksi) and a tensile strength of 72 MPa (10.4 ksi) — stronger than 79% of polymer grades. Elongation at break is 4% and the elastic modulus is 3.3 GPa (0.479 Msi). PMMA INJ has a density of 1.19 g/cm³ (0.043 lb/in³), heavier than 53% of polymer grades. Its glass-transition temperature is 105°C (221 °F). Extruded is the default condition FabDigit quotes; INJ 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 — 3.3 GPa (0.479 Msi), better than 80% of polymer grades
- High strength — 70 MPa (10.2 ksi), better than 79% of polymer grades
Limitations
- Low fracture toughness — 1.1 MPa·√m (1 ksi·√in), worse than 82% of polymer grades
- Limited ductility — 4%, worse than 78% of polymer grades
- Limited service temperature — 72°C (162 °F), worse than 75% of polymer grades
PMMA INJ properties
Typical room-temperature values for PMMA INJ; 28 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 INJ has a density of 1.19 g/cm³ (0.043 lb/in³), heavier than 53% of polymer grades. Its glass-transition temperature is 105°C (221 °F).
Mechanical16
PMMA INJ has a yield strength of 70 MPa (10.2 ksi) and a tensile strength of 72 MPa (10.4 ksi) — stronger than 79% of polymer grades. Elongation at break is 4% and the elastic modulus is 3.3 GPa (0.479 Msi).
Thermal11
PMMA INJ is rated for continuous service to 72°C (162 °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 INJ 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 INJ 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 INJ's machinability is good (68/100, better than 71% of polymer grades); weldability poor (30/100); formability fair (35/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with PMMA INJ
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 INJ — frequently asked
What is PMMA INJ used for?
PMMA INJ 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 INJ?
PMMA INJ has a typical yield strength of 70 MPa (10.2 ksi) and a tensile strength of 72 MPa (10.4 ksi) — stronger than 79% of polymer grades. Strength varies by condition: see the 8 listed tempers.
Is PMMA INJ 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 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 INJ be welded?
Not readily — weldability is rated poor (30/100). 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 INJ?
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 INJ 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 INJ?
PMMA INJ is rated for continuous use to about 72°C (162 °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 FR?
Extruded is the default condition — lowest-cost transparent acrylic sheet with tight thickness tolerance; best for thermoforming, laser cutting and signage. FR: for lighting diffusers, transit glazing and electrical enclosures needing UL 94 V-0 or low smoke; expect some loss of clarity and toughness. Yield strength is 70 MPa in Extruded versus 56 MPa in FR.
Can FabDigit make parts in PMMA INJ?
Yes — PMMA INJ 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.