Viscoelastic PU Foam FR (Flame-retardant viscoelastic)
Flame-retardant grade
ASTM D3574 Type V
Choose the flame-retardant formulation required for export mattresses, public furniture and transport seating under 16 CFR 1633, BS 5852 or GB 17927; feel is firmer and cost higher.
Values for the FR condition
Other Viscoelastic PU Foam grades and fills
Viscoelastic PU Foam is listed in 9 conditions; see the grade overview at Viscoelastic PU Foam.
Compare all 9 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Low-density viscoelastic, ~35–45 kg/m³ | Choose for cost-driven thin laminated parts — insoles, earplugs, packaging liners and thin mattress comfort toppers — accepting tensile strength of only 0.07 MPa. | — | 0.07 | 120 | — |
Open-cell / high-airflow faster-recovery viscoelastic | Choose the open-cell, high-airflow version for summer mattress layers, automotive seats and sports protection where breathability and faster recovery matter most. | — | 0.09 | 140 | — |
FRThis page Flame-retardant viscoelastic | Choose the flame-retardant formulation required for export mattresses, public furniture and transport seating under 16 CFR 1633, BS 5852 or GB 17927; feel is firmer and cost higher. | — | 0.09 | 120 | — |
Partially bio-based polyol viscoelastic | Pick the partially bio-based soy or castor polyol version for projects with carbon-footprint or eco-label needs such as CertiPUR-US; mechanicals stay close to the standard type. | — | 0.09 | 140 | — |
VE50Default Standard viscoelastic slabstock, ~50 kg/m³ | Default density for mattresses, pillows and seat cushions, balancing pressure distribution against cost at 50 kg/m³. | — | 0.1 | 150 | — |
Graphite / copper / phase-change filled conductive-cooling viscoelastic | Use graphite, copper or phase-change filled foam to conduct body heat away in high-end mattresses; conductivity reaches 0.055 W/m·K but the fillers slightly lower tear strength. | — | 0.1 | 130 | — |
Gel-infused / gel-bead viscoelastic | Pick the gel-infused version for mattress comfort layers and pillows that must reduce heat build-up; density rises to 70 kg/m³ and conductivity to 0.05 W/m·K at higher cost. | — | 0.11 | 140 | — |
Medium-high density viscoelastic, ~55–65 kg/m³ | Pick for mid- to high-end mattresses, pillows and office seating where ~55–65 kg/m³ adds support and durability over the standard density at higher cost. | — | 0.13 | 170 | — |
High-density viscoelastic, ≥75 kg/m³ | Use at ≥75 kg/m³ for heavy users, sustained loading and medical anti-decubitus pads: highest durability and indentation resistance, but slowest recovery and noticeable heat build-up. | — | 0.18 | 190 | — |
What is Viscoelastic PU Foam FR?
Viscoelastic PU Foam FR is Viscoelastic PU Foam in the FR grade — choose the flame-retardant formulation required for export mattresses, public furniture and transport seating under 16 CFR 1633, BS 5852 or GB 17927; feel is firmer and cost higher. Viscoelastic PU Foam FR has a tensile strength of 0.09 MPa (0.0131 ksi), weaker than 99% of polymer grades. Elongation at break is 120% and the elastic modulus is 2.8×10⁻⁴ GPa (4.06×10⁻⁵ Msi). Viscoelastic PU Foam FR has a density of 0.06 g/cm³ (0.002 lb/in³), lighter than 88% of polymer grades. Its glass-transition temperature is 15°C (59 °F). VE50 is the default condition FabDigit quotes; FR is available on request or by drawing note.
Advantages
- Lightweight — 0.06 g/cm³ (0.002 lb/in³), better than 88% of polymer grades
- Forms and bends easily — 85/100, better than 81% of polymer grades
Limitations
- Low stiffness — 2.8×10⁻⁴ GPa (4.06×10⁻⁵ Msi), worse than 99% of polymer grades
- Needs corrosion protection — 58/100, worse than 92% of polymer grades
- Degrades in UV without stabilisers — 20/100, worse than 88% of polymer grades
- Poor heat conductor — 0.04 W/m·K (0.0248 BTU/hr·ft·°F), worse than 85% of polymer grades
Viscoelastic PU Foam FR properties
Typical room-temperature values for Viscoelastic PU Foam FR; 17 are specific to this condition. Other listed values are Viscoelastic PU Foam reference data and may not represent this condition. Bars are the position among polymer grades.
Physical2
Viscoelastic PU Foam FR has a density of 0.06 g/cm³ (0.002 lb/in³), lighter than 88% of polymer grades. Its glass-transition temperature is 15°C (59 °F).
Mechanical9
Viscoelastic PU Foam FR has a tensile strength of 0.09 MPa (0.0131 ksi), weaker than 99% of polymer grades. Elongation at break is 120% and the elastic modulus is 2.8×10⁻⁴ GPa (4.06×10⁻⁵ Msi).
Thermal7
Viscoelastic PU Foam FR is rated for continuous service to 90°C (194 °F). It conducts heat at 0.04 W/m·K (0.0248 BTU/hr·ft·°F), worse than 85% of polymer grades.
Electrical2
Viscoelastic PU Foam FR has an electrical resistivity of 1×10⁹ Ω·m.
Chemical & Environmental3
Corrosion resistance is good (58/100), worse than 92% of polymer grades. UV resistance is poor.
Sustainability4
Producing a kilogram of Viscoelastic PU Foam FR takes about 103 MJ of energy and emits 4.5 kg of CO₂ — less than 54% of polymer grades. Typical recycled content is 2%.
Manufacturability5
Viscoelastic PU Foam FR's machinability is good (58/100, worse than 55% of polymer grades); weldability poor (20/100); formability excellent (85/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Viscoelastic PU Foam FR
Is Viscoelastic PU Foam easy to machine?
Cut with band saw, horizontal splitting/peeling machines, CNC oscillating knife, hot wire or waterjet. The slow-recovery hysteresis keeps cut faces dimensionally stable, but blades must be kept sharp to avoid tearing and cell crush.
Can Viscoelastic PU Foam be welded?
Thermoset foam cannot be melt-welded; bond with water-based or hot-melt adhesive, flame lamination, or high-frequency welding of the fabric facing.
Can Viscoelastic PU Foam be formed, bent or molded?
Continuous slabstock is cured 24–72 h before cutting; alternatively cold-cure moulded at roughly 35–65 °C tool temperature, with de-skinning or crush rolling after demould to open the cells. Finished parts can be compressed and vacuum roll-packed for shipping.
What surface finishes work on Viscoelastic PU Foam?
Normally covered with fabric, TPU waterproof film or an antimicrobial treatment; plating and anodizing do not apply, spray coatings must be flexible water-based systems, and a light stabilizer is required to limit yellowing under prolonged sunlight.
Viscoelastic PU Foam 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 |
|---|---|---|
| polyether polyol ( / Tg)polyol blend sets Tg near room temperature for slow recovery | 50 – 62 | 57 |
| TDI / MDI polyisocyanateTDI-80/20 or TDI-MDI blend | 30 – 42 | 36 |
| water (blowing agent)reacts to generate CO₂ for blowing | 1 – 2.5 | 1.6 |
| silicone surfactantcell stabilization and open-cell control | 0.5 – 1.5 | 1 |
| amine + tin catalystgel/blow balance | 0.2 – 1 | 0.5 |
| crosslinker / chain extender | 0 – 2 | 0.8 |
| flame retardant / gel / graphite additivFR, GEL and GR variants only | 0 – 15 | 0 |
Viscoelastic PU Foam FR — frequently asked
What is Viscoelastic PU Foam FR used for?
Viscoelastic PU Foam FR is typically used for mattresses and pillows, orthopedic and medical cushions, helmet and protective padding and acoustic insulation panels. In short: slow-recovery pressure relief; lowest-rebound flexible foam; body-conforming cushioning layer.
What is the tensile strength of Viscoelastic PU Foam FR?
Viscoelastic PU Foam FR has a typical tensile strength of 0.09 MPa (0.0131 ksi) — weaker than 99% of polymer grades. Strength varies by condition: see the 9 listed tempers.
Is Viscoelastic PU Foam FR easy to machine?
Reasonably — machinability is rated good (58/100, worse than 55% of polymer grades). Cut with band saw, horizontal splitting/peeling machines, CNC oscillating knife, hot wire or waterjet. The slow-recovery hysteresis keeps cut faces dimensionally stable, but blades must be kept sharp to avoid tearing and cell crush.
Can Viscoelastic PU Foam FR be welded?
Not readily — weldability is rated poor (20/100). Thermoset foam cannot be melt-welded; bond with water-based or hot-melt adhesive, flame lamination, or high-frequency welding of the fabric facing.
What surface finishes work on Viscoelastic PU Foam FR?
Normally covered with fabric, TPU waterproof film or an antimicrobial treatment; plating and anodizing do not apply, spray coatings must be flexible water-based systems, and a light stabilizer is required to limit yellowing under prolonged sunlight.
Can Viscoelastic PU Foam FR be formed, bent or molded?
Continuous slabstock is cured 24–72 h before cutting; alternatively cold-cure moulded at roughly 35–65 °C tool temperature, with de-skinning or crush rolling after demould to open the cells. Finished parts can be compressed and vacuum roll-packed for shipping.
What is the maximum service temperature of Viscoelastic PU Foam FR?
Viscoelastic PU Foam FR is rated for continuous use to about 90°C (194 °F), and briefly to 120°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASTM D3574 — Standard Test Methods for Flexible Cellular Materials—Slab, Bonded, and Molded Urethane Foams — ASTM International (2017)
- 16 CFR 1633 Standard for the Flammability of Mattress Sets — US CPSC (2007)
- Handbook of Polymeric Foams and Foam Technology (2nd ed.) — Hanser (2004)
- Cellular Solids: Structure and Properties (2nd ed.) — Cambridge University Press (1997)
- Viscoelastic slabstock foam technical data (Carpenter Co., FoamPartner/Recticel, Sinomax ) (2023)
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.