HR Foam HR35
Grade
HR35 = low-density HR slabstock, ~32–38 kg/m³
Choose for cost-sensitive furniture backs, upholstery and packaging cushioning at ~32–38 kg/m³; resilience stays good but load bearing and durability are lower.
Values for the HR35 condition
Other HR Foam grades and fills
HR Foam is listed in 9 conditions; see the grade overview at HR Foam.
Compare all 9 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Super-soft / hyper-soft HR | Pick for mattress and pillow top layers and soft back cushions: indentation hardness is low at ~38 kg/m³ while resilience stays high and hysteresis low. | — | 0.08 | 180 | — |
HR35This page Low-density HR slabstock, ~32–38 kg/m³ | Choose for cost-sensitive furniture backs, upholstery and packaging cushioning at ~32–38 kg/m³; resilience stays good but load bearing and durability are lower. | — | 0.1 | 150 | — |
Conductive / antistatic HR | Choose the carbon-loaded conductive version for electronic component packaging and ESD workstation pads with controlled surface resistance; tensile strength drops to 0.1 MPa. | — | 0.1 | 110 | — |
Combustion-modified / flame-retardant HR | Choose for public, medical and vehicle cushioning that must meet BS 5852 Crib 5, CAL TB117 or GB 17927 fire requirements; combustion modifiers trim tensile strength to 0.11 MPa. | — | 0.11 | 110 | — |
Medical / antimicrobial-treated HR | Pick for medical mattresses, wheelchair cushions and rehabilitation supports needing low VOC and antimicrobial treatment, and suitable for use with waterproof film. | — | 0.12 | 130 | — |
HR45Default Standard HR slabstock, ~42–48 kg/m³ | Default slabstock for sofa seat cushions, mattress comfort layers and office chair pads at ~42–48 kg/m³, giving the best balance of resilience and durability. | — | 0.13 | 130 | — |
Cold-cure molded HR | Use the cold-cure molded version for automotive seats and headrests with bonded covers: one-shot molding avoids cutting scrap but needs mold temperature and release agent control. | — | 0.14 | 110 | — |
High-density HR slabstock, ~52–58 kg/m³ | Pick for high-end sofas, mattresses and long sitting or lying use, where ~52–58 kg/m³ gives the best sag resistance and fatigue life at higher weight and cost. | — | 0.16 | 120 | — |
High load-bearing / firm HR | Use for heavy-duty seating, truck and bus cushions and mattress support layers, where 60 kg/m³ gives a high support (SAG) factor and strong sag resistance at a firmer feel. | — | 0.17 | 100 | — |
What is HR Foam HR35?
HR Foam HR35 is HR Foam in the HR35 grade — choose for cost-sensitive furniture backs, upholstery and packaging cushioning at ~32–38 kg/m³; resilience stays good but load bearing and durability are lower. HR Foam HR35 has a tensile strength of 0.1 MPa (0.0145 ksi), weaker than 99% of polymer grades. Elongation at break is 150% and the elastic modulus is 1.5×10⁻⁵ GPa (2.18×10⁻⁶ Msi). HR Foam HR35 has a density of 0.04 g/cm³ (0.0013 lb/in³), lighter than 92% of polymer grades. Its glass-transition temperature is -55°C (-67 °F). HR45 is the default condition FabDigit quotes; HR35 is available on request or by drawing note.
Advantages
- Forms and bends easily — 93/100, better than 98% of polymer grades
- Lightweight — 0.04 g/cm³ (0.0013 lb/in³), better than 92% of polymer grades
- Easy to machine — 86/100, better than 91% of polymer grades
Limitations
- Low stiffness — 1.5×10⁻⁵ GPa (2.18×10⁻⁶ Msi), worse than 100% of polymer grades
- Poor heat conductor — 0.04 W/m·K (0.022 BTU/hr·ft·°F), worse than 90% of polymer grades
- Degrades in UV without stabilisers — 25/100, worse than 76% of polymer grades
HR Foam HR35 properties
Typical room-temperature values for HR Foam HR35; 15 are specific to this condition. Other listed values are HR Foam reference data and may not represent this condition. Bars are the position among polymer grades.
Physical2
HR Foam HR35 has a density of 0.04 g/cm³ (0.0013 lb/in³), lighter than 92% of polymer grades. Its glass-transition temperature is -55°C (-67 °F).
Mechanical8
HR Foam HR35 has a tensile strength of 0.1 MPa (0.0145 ksi), weaker than 99% of polymer grades. Elongation at break is 150% and the elastic modulus is 1.5×10⁻⁵ GPa (2.18×10⁻⁶ Msi).
Thermal7
HR Foam HR35 is rated for continuous service to 95°C (203 °F). It conducts heat at 0.04 W/m·K (0.022 BTU/hr·ft·°F), worse than 90% of polymer grades.
Electrical2
HR Foam HR35 has an electrical resistivity of 1×10¹⁰ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (78/100), worse than 61% of polymer grades. UV resistance is poor.
Sustainability4
Producing a kilogram of HR Foam HR35 takes about 103 MJ of energy and emits 5 kg of CO₂ — less than 54% of polymer grades. Typical recycled content is 0%.
Manufacturability3
HR Foam HR35's machinability is excellent (86/100, better than 91% of polymer grades); weldability fair (40/100); formability excellent (93/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with HR Foam HR35
Is HR Foam easy to machine?
Cut with band saw, horizontal splitting machine, oscillating knife or CNC contour and profile cutting. Hot-wire cutting is not suitable because PU chars and smokes; keep blades sharp and use extraction to avoid torn edges and dust.
Can HR Foam be welded?
Not weldable; bond with water-based or hot-melt adhesive, flame lamination, or high-frequency welding and sewing when combined with fabric.
Can HR Foam be formed, bent or molded?
Two routes: TDI-based continuous box or vertical slabstock foaming with 24 h cure before cutting (Type R), or MDI cold-cure moulding (Type Q) at 45–70 °C mould temperature with 4–6 min demould. Formulation index and cell-opening control set resilience and compression set.
What surface finishes work on HR Foam?
Can be flame- or adhesive-laminated to fabric and nonwoven, fitted with a waterproof TPU film, and die-cut to shape. Plating and hard paint films are not possible, and the open cells absorb solvent-based adhesives.
HR 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 (high-reactivity, EO-timain polyol, functionality 3, OH value 28–35 mgKOH/g | 40 – 60 | 50 |
| polymer (graft SAN/PHD) polyolprovides load bearing and support factor | 5 – 25 | 12 |
| TDI 80/20 or MDI / TDI-MDI blend isocyanTDI for slabstock, MDI for cold-cure molding; index 95–105 | 28 – 40 | 34 |
| water (blowing agent)reacts with NCO to generate CO₂ for blowing | 2 – 4.5 | 3.2 |
| amine + tin catalysts | 0.2 – 1 | 0.5 |
| silicone surfactant (cell opener type) | 0.3 – 1.5 | 0.8 |
| flame retardant / additives (optional)CMHR grades use intumescent or phosphorus FR and melamine | 0 – 15 | 0 |
HR Foam HR35 — frequently asked
What is HR Foam HR35 used for?
HR Foam HR35 is typically used for furniture and mattress cushioning, automotive seat cushions, molded seating pads and sports padding. In short: high-resilience flexible PU; better fatigue than slabstock; higher support factor.
What is the tensile strength of HR Foam HR35?
HR Foam HR35 has a typical tensile strength of 0.1 MPa (0.0145 ksi) — weaker than 99% of polymer grades. Strength varies by condition: see the 9 listed tempers.
Is HR Foam HR35 easy to machine?
Yes — machinability is rated excellent (86/100, better than 91% of polymer grades). Cut with band saw, horizontal splitting machine, oscillating knife or CNC contour and profile cutting. Hot-wire cutting is not suitable because PU chars and smokes; keep blades sharp and use extraction to avoid torn edges and dust.
Can HR Foam HR35 be welded?
With care — weldability is rated fair (40/100). Not weldable; bond with water-based or hot-melt adhesive, flame lamination, or high-frequency welding and sewing when combined with fabric.
What surface finishes work on HR Foam HR35?
Can be flame- or adhesive-laminated to fabric and nonwoven, fitted with a waterproof TPU film, and die-cut to shape. Plating and hard paint films are not possible, and the open cells absorb solvent-based adhesives.
Can HR Foam HR35 be formed, bent or molded?
Two routes: TDI-based continuous box or vertical slabstock foaming with 24 h cure before cutting (Type R), or MDI cold-cure moulding (Type Q) at 45–70 °C mould temperature with 4–6 min demould. Formulation index and cell-opening control set resilience and compression set.
What is the maximum service temperature of HR Foam HR35?
HR Foam HR35 is rated for continuous use to about 95°C (203 °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 (2017)
- JIS K 6401 Flexible cellular polymeric materials — Polyurethane foam — JSA (2011)
- ISO 2439 Flexible cellular polymeric materials — Determination of hardness (indentation technique) — ISO (2008)
- Cellular Solids: Structure and Properties (Gibson & Ashby) — Cambridge University Press (1997)
- Engineered Materials Handbook Vol. 2: Engineering Plastics — ASM International (1988)
- HR slabstock and cold-cure molded foam technical data — FXI / Carpenter / Recticel (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.