PU-PMMA-like FR
Flame-retardant grade
FR = flame-retardant casting grade
Specify for electrical enclosure or lighting prototypes needing a flame rating; clarity is usually lost.
Values for the FR condition
Other PU-PMMA-like grades and fills
PU-PMMA-like is listed in 5 conditions; see the grade overview at PU-PMMA-like.
Compare all 5 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Impact-modified / tough clear | Choose for snap-fits, thin walls or drop-tested transparent housings where full optical clarity is not required. | 42 | 50 | 35 | 76 Shore D |
Mineral-filled rigid grade | Use for large flat opaque panels where dimensional stability matters more than transparency. | — | 45 | 2.5 | — |
FRThis page Flame-retardant casting grade | Specify for electrical enclosure or lighting prototypes needing a flame rating; clarity is usually lost. | 50 | 55 | 6 | 85 Shore D |
Tinted / pigmented | Use for smoked lenses, coloured light guides or self-coloured show parts, avoiding paint on transparent geometry. | 55 | 62 | 9 | 83 Shore D |
Heat-resistant clear | Use for lamp lenses or parts near heat sources needing HDT above ~90 °C; slightly more brittle. | 66 | 70 | 5 | 86 Shore D |
What is PU-PMMA-like FR?
PU-PMMA-like FR is PU-PMMA-like in the FR grade — specify for electrical enclosure or lighting prototypes needing a flame rating; clarity is usually lost. PU-PMMA-like FR has a yield strength of 50 MPa (7.25 ksi) and a tensile strength of 55 MPa (7.98 ksi) — stronger than 67% of polyurethane grades. Elongation at break is 6% and the elastic modulus is 2.9 GPa (0.421 Msi). PU-PMMA-like FR has a density of 1.28 g/cm³ (0.0462 lb/in³), heavier than 90% of polyurethane grades. Its glass-transition temperature is 75°C (167 °F).
Advantages
- Polishes to a fine finish — 85/100, better than 98% of polyurethane grades
- Stiff — 2.9 GPa (0.421 Msi), better than 95% of polyurethane grades
- Conducts heat well — 0.26 W/m·K (0.15 BTU/hr·ft·°F), better than 95% of polyurethane grades
- Good UV / weathering resistance — 55/100, better than 95% of polyurethane grades
- Low, predictable mold shrinkage — 0.2%, better than 75% of polyurethane grades
Limitations
- Low fracture toughness — 1.1 MPa·√m (1 ksi·√in), worse than 100% of polyurethane grades
- Heavy — 1.28 g/cm³ (0.0462 lb/in³), worse than 90% of polyurethane grades
- Limited ductility — 6%, worse than 83% of polyurethane grades
PU-PMMA-like FR properties
Typical room-temperature values for PU-PMMA-like FR; 28 are specific to this condition. Other listed values are PU-PMMA-like reference data and may not represent this condition. Bars are the position among polyurethane grades.
Physical6
PU-PMMA-like FR has a density of 1.28 g/cm³ (0.0462 lb/in³), heavier than 90% of polyurethane grades. Its glass-transition temperature is 75°C (167 °F).
Mechanical15
PU-PMMA-like FR has a yield strength of 50 MPa (7.25 ksi) and a tensile strength of 55 MPa (7.98 ksi) — stronger than 67% of polyurethane grades. Elongation at break is 6% and the elastic modulus is 2.9 GPa (0.421 Msi).
Thermal11
PU-PMMA-like FR is rated for continuous service to 75°C (167 °F). It conducts heat at 0.26 W/m·K (0.15 BTU/hr·ft·°F), better than 95% of polyurethane grades. Thermal expansion is 90 µm/m·K (50 µin/in·°F).
Electrical6
PU-PMMA-like FR is an electrical insulator with a dielectric strength of 18 kV/mm (457.2 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (70/100), worse than 74% of polyurethane grades. UV resistance is good.
Sustainability4
Producing a kilogram of PU-PMMA-like FR takes about 105 MJ of energy and emits 5.2 kg of CO₂ — more than 64% of polyurethane grades. Typical recycled content is 0%.
Manufacturability7
PU-PMMA-like FR's machinability is fair (48/100, worse than 71% of polyurethane grades); weldability not recommended (5/100); formability not recommended (6/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with PU-PMMA-like FR
Is PU-PMMA-like easy to machine?
Machines and drills easily with sharp carbide and low feed pressure; avoid heat build-up and stress-crazing near clear surfaces, and support thin walls to prevent chipping.
Can PU-PMMA-like be welded?
Thermoset — cannot be heat-welded; join with cyanoacrylate, two-part PU or acrylic-based structural adhesive.
Can PU-PMMA-like be formed, bent or molded?
Degas both components, vacuum-cast into a silicone mould at 25–40 °C resin temperature, demould after 20–60 min and oven post-cure 60–75 °C for 2–4 h to reach full Tg and clarity.
What surface finishes work on PU-PMMA-like?
Sand progressively to 2000–3000 grit then buff, or apply a clear PU/acrylic topcoat for optical gloss; can be dyed in the mix, vapour-polished only with caution, and takes primer/paint well.
PU-PMMA-like 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 |
|---|---|---|
| aliphatic polyisocyanate (HDI/IPDI-basedaliphatic chemistry chosen for non-yellowing clarity | 40 – 55 | 48 |
| catalyst (organometallic/amine) | 0.01 – 0.5 | 0.1 |
| UV absorber + HALSpresent in UV-stabilized variant | 0 – 1.5 | 0.5 |
| degassing / flow additive | 0 – 1 | 0.3 |
| pigment paste or mineral fillervariant-dependent; zero in clear default | 0 – 40 | 0 |
| polyol blend (polyester/polyether polyoltypical mix ratio 100:90–100:110 by weight | ≥ 45 (balance) | — |
PU-PMMA-like FR — frequently asked
What is PU-PMMA-like FR used for?
PU-PMMA-like FR is typically used for lens prototypes, display cases, signage models and optical demonstration parts. In short: highest-gloss clear PU; acrylic look, no tooling; rigid transparent prototype resin.
What is the yield strength of PU-PMMA-like FR?
PU-PMMA-like FR has a typical yield strength of 50 MPa (7.25 ksi) and a tensile strength of 55 MPa (7.98 ksi) — stronger than 67% of polyurethane grades. Strength varies by condition: see the 5 listed tempers.
Is PU-PMMA-like FR easy to machine?
Reasonably — machinability is rated fair (48/100, worse than 71% of polyurethane grades). Machines and drills easily with sharp carbide and low feed pressure; avoid heat build-up and stress-crazing near clear surfaces, and support thin walls to prevent chipping.
Can PU-PMMA-like FR be welded?
Not readily — weldability is rated not recommended (5/100). Thermoset — cannot be heat-welded; join with cyanoacrylate, two-part PU or acrylic-based structural adhesive.
What surface finishes work on PU-PMMA-like FR?
Sand progressively to 2000–3000 grit then buff, or apply a clear PU/acrylic topcoat for optical gloss; can be dyed in the mix, vapour-polished only with caution, and takes primer/paint well.
Can PU-PMMA-like FR be formed, bent or molded?
Degas both components, vacuum-cast into a silicone mould at 25–40 °C resin temperature, demould after 20–60 min and oven post-cure 60–75 °C for 2–4 h to reach full Tg and clarity.
What is the maximum service temperature of PU-PMMA-like FR?
PU-PMMA-like FR is rated for continuous use to about 75°C (167 °F), and briefly to 100°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- PX223 / PX223HT clear polyurethane casting resin technical data — Axson Technologies (Sika) (2020)
- UPX 8400 / clear vacuum-casting PU resin data sheets — Huntsman Advanced Materials (2019)
- Hei-Cast series polyurethane casting resins — H&K / Hei-Cast (2021)
- ISO 527 / ISO 178 / ISO 75 plastics test methods — ISO (2019)
- 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.