PU-PP-like FR (Flame-retardant)
Flame-retardant grade
Specify for electrical enclosures and appliance prototypes needing V-0 behaviour at 3 mm.
Values for the FR condition
Other PU-PP-like grades and fills
PU-PP-like is listed in 6 conditions; see the grade overview at PU-PP-like.
Compare all 6 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Ultra-tough / living-hinge grade | Pick when parts must flex repeatedly (hinges, clips, battery doors) and impact survival matters more than stiffness. | 18 | 24 | 150 | 65 Shore D |
Pigmented / black-through cast | Use pre-pigmented resin when parts must be coloured through so scratches do not show a light substrate. | 23 | 27 | 65 | 72 Shore D |
FRThis page Flame-retardant | Specify for electrical enclosures and appliance prototypes needing V-0 behaviour at 3 mm. | 24 | 26 | 30 | 78 Shore D |
Mineral / talc filled | Use for stiffer, more dimensionally stable housings where hinge flexibility is not required. | — | 32 | 15 | 80 Shore D |
Heat-resistant PP-like | Use where cast parts see paint-bake, under-hood or hot-water exposure above 80 °C. | 32 | 35 | 25 | 80 Shore D |
Glass-fiber / glass-bead reinforced | Choose for maximum stiffness and creep resistance in cast prototypes simulating filled PP. | — | 40 | 6 | 84 Shore D |
What is PU-PP-like FR?
PU-PP-like FR is PU-PP-like in the FR grade — specify for electrical enclosures and appliance prototypes needing V-0 behaviour at 3 mm. PU-PP-like FR has a yield strength of 24 MPa (3.48 ksi) and a tensile strength of 26 MPa (3.77 ksi) — weaker than 100% of polyurethane grades. Elongation at break is 30% and the elastic modulus is 1.6 GPa (0.232 Msi). PU-PP-like FR has a density of 1.25 g/cm³ (0.0452 lb/in³), heavier than 90% of polyurethane grades. Its glass-transition temperature is 55°C (131 °F).
Advantages
- Conducts heat well — 0.25 W/m·K (0.144 BTU/hr·ft·°F), better than 90% of polyurethane grades
- Low moisture uptake — 0.3%, better than 81% of polyurethane grades
Limitations
- Low strength — 24 MPa (3.48 ksi), worse than 100% of polyurethane grades
PU-PP-like FR properties
Typical room-temperature values for PU-PP-like FR; 25 are specific to this condition. Other listed values are PU-PP-like reference data and may not represent this condition. Bars are the position among polyurethane grades.
Physical4
PU-PP-like FR has a density of 1.25 g/cm³ (0.0452 lb/in³), heavier than 90% of polyurethane grades. Its glass-transition temperature is 55°C (131 °F).
Mechanical11
PU-PP-like FR has a yield strength of 24 MPa (3.48 ksi) and a tensile strength of 26 MPa (3.77 ksi) — weaker than 100% of polyurethane grades. Elongation at break is 30% and the elastic modulus is 1.6 GPa (0.232 Msi).
Thermal10
PU-PP-like FR is rated for continuous service to 75°C (167 °F). It conducts heat at 0.25 W/m·K (0.144 BTU/hr·ft·°F), better than 90% of polyurethane grades. Thermal expansion is 130 µm/m·K (72.2 µin/in·°F).
Electrical5
PU-PP-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 (75/100), better than 58% of polyurethane grades. UV resistance is poor.
Sustainability4
Producing a kilogram of PU-PP-like FR takes about 100 MJ of energy and emits 4.6 kg of CO₂ — less than 83% of polyurethane grades. Typical recycled content is 0%.
Manufacturability6
PU-PP-like FR's machinability is good (55/100, worse than 64% of polyurethane grades); weldability not recommended (10/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with PU-PP-like FR
Is PU-PP-like easy to machine?
Machines and drills easily but is gummy — use sharp single-flute or high-rake tools, high speed with low feed, and air blast to avoid melted swarf and burrs.
Can PU-PP-like be welded?
Thermoset, so no thermal welding: join with PU or cyanoacrylate adhesives, or cast-in inserts and self-tapping screws.
Can PU-PP-like be formed, bent or molded?
Degas both components, mix by weight ratio, cast under vacuum into silicone tooling at ~60–70 °C mold temperature, demold in 20–60 min and oven post-cure 2–8 h at 70–80 °C to reach full properties and dimensional stability.
What surface finishes work on PU-PP-like?
Sands and primes readily; solvent-based PU or acrylic paints, soft-touch coatings, pad printing and vacuum metallizing all adhere well — degrease and remove silicone mold release first, and use UV-stable topcoats since aromatic grades yellow.
PU-PP-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 |
|---|---|---|
| aromatic isocyanate prepolymer (MDI-basesome non-yellowing grades use aliphatic HDI/IPDI chemistry | 40 – 55 | 48 |
| catalyst / chain extender / defoamer | 0.5 – 3 | 1.5 |
| mineral or glass filler (filled variantstalc, CaCO3, glass beads or milled fibre in MIN/GF grades | 0 – 30 | 0 |
| pigment / UV stabilizer / flame retardan | 0 – 15 | 1 |
| polyol blend (polyether or polyester, Pachain extender + polyol; sets flexibility and hinge performance | ≥ 40 (balance) | — |
PU-PP-like FR — frequently asked
What is PU-PP-like FR used for?
PU-PP-like FR is typically used for living hinges, flexible clips, container/lid prototypes and automotive interior trims. In short: cast living-hinge resin; highest elongation PU prototype; gummy to machine.
What is the yield strength of PU-PP-like FR?
PU-PP-like FR has a typical yield strength of 24 MPa (3.48 ksi) and a tensile strength of 26 MPa (3.77 ksi) — weaker than 100% of polyurethane grades. Strength varies by condition: see the 6 listed tempers.
Is PU-PP-like FR easy to machine?
Reasonably — machinability is rated good (55/100, worse than 64% of polyurethane grades). Machines and drills easily but is gummy — use sharp single-flute or high-rake tools, high speed with low feed, and air blast to avoid melted swarf and burrs.
Can PU-PP-like FR be welded?
Not readily — weldability is rated not recommended (10/100). Thermoset, so no thermal welding: join with PU or cyanoacrylate adhesives, or cast-in inserts and self-tapping screws.
What surface finishes work on PU-PP-like FR?
Sands and primes readily; solvent-based PU or acrylic paints, soft-touch coatings, pad printing and vacuum metallizing all adhere well — degrease and remove silicone mold release first, and use UV-stable topcoats since aromatic grades yellow.
Can PU-PP-like FR be formed, bent or molded?
Degas both components, mix by weight ratio, cast under vacuum into silicone tooling at ~60–70 °C mold temperature, demold in 20–60 min and oven post-cure 2–8 h at 70–80 °C to reach full properties and dimensional stability.
What is the maximum service temperature of PU-PP-like FR?
PU-PP-like FR is rated for continuous use to about 75°C (167 °F), and briefly to 90°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- PX 200 / PX 220 series polyurethane vacuum casting resin technical data — Axson Technologies (Sika) (2021)
- Uralite polyurethane casting systems data sheets — H.B. Fuller / Uralite (2020)
- Hei-Cast polyurethane casting resin series — H&K Japan (2020)
- Polyurethane thermoset property ranges — CAMPUS / CES material data (2022)
- ISO 527 / ISO 178 / ISO 75 plastics test methods — ISO (2019)
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.