PMMA-HR DIFF
Heat-treated state
JIS K6717 · ISO 8257-3 PMMA-HR
DIFF = light-diffusing (opal) heat-resistant grade
Contains diffusing particles to hide LED hot spots in luminaire covers while keeping the higher HDT.
Values for the DIFF condition
Other PMMA-HR grades and fills
PMMA-HR is listed in 4 conditions; see the grade overview at PMMA-HR.
Compare all 4 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Impact-modified heat-resistant acrylic | Choose where snap-fits, thin walls or handling drops would crack standard PMMA; trades stiffness, clarity and HDT for toughness. | — | 50 | 30 | 60 HRM |
Flame-retardant compound | Phosphorus/halogen-free FR compound for luminaire and rail-interior parts needing a V-rating; clarity and HDT drop. | 56 | 58 | 3 | 88 Shore D |
DIFFThis page Light-diffusing (opal) heat-resistant grade | Contains diffusing particles to hide LED hot spots in luminaire covers while keeping the higher HDT. | 66 | 68 | 3 | 89 Shore D |
Extra-high-heat maleimide copolymer | Pick when the transparent part sees LED/halogen heat above 110 °C and PC yellowing is unacceptable. | — | 73 | 2.5 | — |
What is PMMA-HR DIFF?
PMMA-HR DIFF is PMMA-HR heat treated to DIFF — contains diffusing particles to hide LED hot spots in luminaire covers while keeping the higher HDT. PMMA-HR DIFF has a yield strength of 66 MPa (9.57 ksi) and a tensile strength of 68 MPa (9.86 ksi) — stronger than 76% of polymer grades. Elongation at break is 3% and the elastic modulus is 3.2 GPa (0.464 Msi). PMMA-HR DIFF has a density of 1.19 g/cm³ (0.043 lb/in³), heavier than 53% of polymer grades. Its glass-transition temperature is 125°C (257 °F).
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 77% of polymer grades
- High strength — 66 MPa (9.57 ksi), better than 76% of polymer grades
Limitations
- 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
- Difficult to weld — 15/100, worse than 78% of polymer grades
PMMA-HR DIFF properties
Typical room-temperature values for PMMA-HR DIFF; 27 are specific to this condition. Other listed values are PMMA-HR reference data and may not represent this condition. Bars are the position among polymer grades.
Physical6
PMMA-HR DIFF has a density of 1.19 g/cm³ (0.043 lb/in³), heavier than 53% of polymer grades. Its glass-transition temperature is 125°C (257 °F).
Mechanical16
PMMA-HR DIFF has a yield strength of 66 MPa (9.57 ksi) and a tensile strength of 68 MPa (9.86 ksi) — stronger than 76% of polymer grades. Elongation at break is 3% and the elastic modulus is 3.2 GPa (0.464 Msi).
Thermal11
PMMA-HR DIFF is rated for continuous service to 95°C (203 °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 68 µm/m·K (37.8 µin/in·°F).
Electrical7
PMMA-HR DIFF 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 (78/100), worse than 61% of polymer grades. UV resistance is excellent.
Sustainability4
Producing a kilogram of PMMA-HR DIFF takes about 103 MJ of energy and emits 6.3 kg of CO₂ — less than 54% of polymer grades. Typical recycled content is 0%.
Manufacturability8
PMMA-HR DIFF's machinability is good (65/100, better than 66% of polymer grades); weldability poor (15/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with PMMA-HR DIFF
Is PMMA-HR easy to machine?
Machines cleanly with sharp positive-rake, polished-flute tools and high speed / low feed; use air or mist cooling and anneal (80 °C, 2–4 h) before and after cutting to avoid crazing at drilled holes.
Can PMMA-HR be welded?
Not fusion-welded in practice — join by solvent cementing (methylene-chloride-free acrylic cements are preferred for HR grades), acrylic adhesives, ultrasonic or hot-plate welding of thick sections.
Can PMMA-HR be formed, bent or molded?
Dry 4 h at 80–90 °C to <0.05 % moisture; injection mould at 240–275 °C melt with 70–110 °C tool, moderate injection speed and high hold pressure for optical parts; sheet thermoforms at 165–195 °C.
What surface finishes work on PMMA-HR?
Flame-, diamond- or buff-polishes to optical clarity; accepts hard/anti-scratch and AR coatings, vacuum metallization and pad printing — avoid alcohol- or ester-based cleaners which cause stress cracking.
PMMA-HR 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 |
|---|---|---|
| N-substituted maleimide (e.g. N-cyclohexraises Tg / Vicat; alternative route uses maleic anhydride or glutarimide ring formation | 5 – 25 | 14 |
| styrene / α-methylstyreneoptional comonomer to balance copolymerization and flow | 0 – 10 | 3 |
| methyl acrylatethermal-stability comonomer in some grades | 0 – 2 | 0.5 |
| additives (UV absorber, lubricant, antiograde-dependent | 0 – 1.5 | 0.5 |
| methyl methacrylate (MMA)backbone monomer | ≥ 70 (balance) | — |
PMMA-HR DIFF — frequently asked
What is PMMA-HR DIFF used for?
PMMA-HR DIFF is typically used for automotive interior trim, LED lighting components, headlamp lenses and hot-environment glazing. In short: highest heat acrylic; optical clarity retained hot; low elongation, notch-sensitive.
What is the yield strength of PMMA-HR DIFF?
PMMA-HR DIFF has a typical yield strength of 66 MPa (9.57 ksi) and a tensile strength of 68 MPa (9.86 ksi) — stronger than 76% of polymer grades. Strength varies by condition: see the 4 listed tempers.
Is PMMA-HR DIFF easy to machine?
Reasonably — machinability is rated good (65/100, better than 66% of polymer grades). Machines cleanly with sharp positive-rake, polished-flute tools and high speed / low feed; use air or mist cooling and anneal (80 °C, 2–4 h) before and after cutting to avoid crazing at drilled holes.
Can PMMA-HR DIFF be welded?
Not readily — weldability is rated poor (15/100). Not fusion-welded in practice — join by solvent cementing (methylene-chloride-free acrylic cements are preferred for HR grades), acrylic adhesives, ultrasonic or hot-plate welding of thick sections.
What surface finishes work on PMMA-HR DIFF?
Flame-, diamond- or buff-polishes to optical clarity; accepts hard/anti-scratch and AR coatings, vacuum metallization and pad printing — avoid alcohol- or ester-based cleaners which cause stress cracking.
Can PMMA-HR DIFF be formed, bent or molded?
Dry 4 h at 80–90 °C to <0.05 % moisture; injection mould at 240–275 °C melt with 70–110 °C tool, moderate injection speed and high hold pressure for optical parts; sheet thermoforms at 165–195 °C.
What is the maximum service temperature of PMMA-HR DIFF?
PMMA-HR DIFF is rated for continuous use to about 95°C (203 °F), and briefly to 115°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)
- JIS K 6717 Poly(methyl methacrylate) moulding and extrusion materials — JSA (2018)
- ISO 7823-1/-2 Poly(methyl methacrylate) sheets — ISO (2003)
- Heat-resistant acrylic moulding compound datasheets (Röhm Plexiglas hw/8N series, Kuraray Parapet HR, Mitsubishi Chemical Acrypet VH) — various producers (2023)
- CAMPUS plastics database — PMMA heat-resistant grades (ISO 10350-1 datasets) — CAMPUS consortium (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.