Semi-Rigid PU Foam ISF
Grade
ISF = integral-skin (self-skinning) semi-rigid foam
Pick when a tough moulded skin and finished surface are required without a separate cover — steering wheels, grab handles, armrests.
Values for the ISF condition
Other Semi-Rigid PU Foam grades and fills
Semi-Rigid PU Foam is listed in 9 conditions; see the grade overview at Semi-Rigid PU Foam.
Compare all 9 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Energy-absorbing / crash-pad grade | Tuned low-resilience formulation with a long flat crush plateau for FMVSS 201 head-impact and helmet liners. | 0.1 | 0.45 | 60 | 28 Shore A |
Polyether-polyol semi-rigid foam | Substitute for the polyester default in humid, warm or wash-down service where hydrolytic ageing kills polyester foam. | 0.1 | 0.4 | 90 | 30 Shore A |
Flame-retardant semi-rigid foam | Use where interior burn-rate or transit fire codes apply; slight loss of tensile and elongation from FR loading. | 0.14 | 0.45 | 55 | 35 Shore A |
Light-stabilised / aliphatic-capped semi-rigid foam | For visible interior surfaces exposed to sunlight where yellowing of aromatic MDI foam is unacceptable. | 0.15 | 0.55 | 70 | 38 Shore A |
Low-density semi-rigid foam, ~60 kg/m³ | Lightest semi-rigid grade for soft-touch trim backing and light packaging cushions. | — | 0.3 | 85 | 20 Shore A |
SR-100Default Standard semi-rigid polyester foam, ~100 kg/m³ | The default all-round semi-rigid density for energy-absorbing pads and instrument-panel backing. | — | 0.55 | 70 | 35 Shore A |
Medium-high density semi-rigid foam, ~150 kg/m³ | Choose when higher crush plateau and dimensional stiffness are needed in thin sections. | — | 0.9 | 55 | 50 Shore A |
High-density semi-rigid foam, ~250 kg/m³ | Structural-leaning grade for armrests, load-bearing pads and machinable tooling blocks. | — | 2 | 40 | 20 Shore D |
ISFThis page Integral-skin (self-skinning) semi-rigid foam | Pick when a tough moulded skin and finished surface are required without a separate cover — steering wheels, grab handles, armrests. | — | 3 | 110 | 65 Shore A |
What is Semi-Rigid PU Foam ISF?
Semi-Rigid PU Foam ISF is Semi-Rigid PU Foam in the ISF grade — pick when a tough moulded skin and finished surface are required without a separate cover — steering wheels, grab handles, armrests. Semi-Rigid PU Foam ISF has a tensile strength of 3 MPa (0.435 ksi), weaker than 83% of polymer grades. Elongation at break is 110% and the elastic modulus is 0.04 GPa (0.0058 Msi). Semi-Rigid PU Foam ISF has a density of 0.4 g/cm³ (0.0145 lb/in³), lighter than 84% of polymer grades. Its glass-transition temperature is 60°C (140 °F). SR-100 is the default condition FabDigit quotes; ISF is available on request or by drawing note.
Advantages
- Lightweight — 0.4 g/cm³ (0.0145 lb/in³), better than 84% of polymer grades
Limitations
- Absorbs moisture — dry before molding — 8%, worse than 100% of polymer grades
- Poor heat conductor — 0.07 W/m·K (0.0376 BTU/hr·ft·°F), worse than 84% of polymer grades
- Needs corrosion protection — 70/100, worse than 78% of polymer grades
Semi-Rigid PU Foam ISF properties
Typical room-temperature values for Semi-Rigid PU Foam ISF; 11 are specific to this condition. Other listed values are Semi-Rigid PU Foam reference data and may not represent this condition. Bars are the position among polymer grades.
Physical4
Semi-Rigid PU Foam ISF has a density of 0.4 g/cm³ (0.0145 lb/in³), lighter than 84% of polymer grades. Its glass-transition temperature is 60°C (140 °F).
Mechanical12
Semi-Rigid PU Foam ISF has a tensile strength of 3 MPa (0.435 ksi), weaker than 83% of polymer grades. Elongation at break is 110% and the elastic modulus is 0.04 GPa (0.0058 Msi).
Thermal8
Semi-Rigid PU Foam ISF is rated for continuous service to 100°C (212 °F). It conducts heat at 0.07 W/m·K (0.0376 BTU/hr·ft·°F), worse than 84% of polymer grades. Thermal expansion is 70 µm/m·K (38.9 µin/in·°F).
Electrical3
Semi-Rigid PU Foam ISF has an electrical resistivity of 1×10⁹ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (70/100), worse than 78% of polymer grades. UV resistance is fair.
Sustainability4
Producing a kilogram of Semi-Rigid PU Foam ISF takes about 100 MJ of energy and emits 4.6 kg of CO₂ — less than 61% of polymer grades. Typical recycled content is 5%.
Manufacturability4
Semi-Rigid PU Foam ISF's machinability is good (55/100, worse than 64% of polymer grades); formability very good (75/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Semi-Rigid PU Foam ISF
Is Semi-Rigid PU Foam easy to machine?
Cut with band saw, oscillating knife, hot wire (skinned grades) or die; high-density blocks can be CNC routed with sharp single-flute cutters and strong vacuum extraction.
Can Semi-Rigid PU Foam be welded?
Not weldable; join by PU/hot-melt adhesive, flame lamination or in-mould bonding to substrates and skins.
Can Semi-Rigid PU Foam be formed, bent or molded?
Reaction-injected or poured into heated closed moulds at 35–60 °C with vent design and mould release; demould 3–8 min, full property build after 24 h post-cure.
What surface finishes work on Semi-Rigid PU Foam?
Integral-skin parts accept flexible PU paint after mould-release removal and IR flash-off; open-cell grades are covered with fabric, TPO or PVC skin rather than painted.
Semi-Rigid 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 |
|---|---|---|
| polyester polyol (or polyether polyol)B-component base resin | 40 – 60 | 50 |
| water (chemical blowing agent, CO2) | 1 – 4 | 2.5 |
| silicone surfactantcell regulator | 0.5 – 2 | 1.2 |
| amine / tin catalysts | 0.2 – 1.5 | 0.7 |
| chain extender / crosslinker (e.g. diethsets semi-rigid modulus | 0.5 – 4 | 2 |
| flame retardant (phosphate ester)FR variants only | 0 – 12 | 0 |
| polymeric MDI (isocyanate)A-component; index typ. 100–110 | ≥ 35 (balance) | — |
Semi-Rigid PU Foam ISF — frequently asked
What is Semi-Rigid PU Foam ISF used for?
Semi-Rigid PU Foam ISF is typically used for automotive sun visors and headliners, packaging energy-absorbing inserts, air filter media substrate and gasketing and sealing. In short: mid-stiffness energy absorber; dimensionally stable open-cell foam; bridges flexible and rigid PU.
What is the tensile strength of Semi-Rigid PU Foam ISF?
Semi-Rigid PU Foam ISF has a typical tensile strength of 3 MPa (0.435 ksi) — weaker than 83% of polymer grades. Strength varies by condition: see the 9 listed tempers.
Is Semi-Rigid PU Foam ISF easy to machine?
Reasonably — machinability is rated good (55/100, worse than 64% of polymer grades). Cut with band saw, oscillating knife, hot wire (skinned grades) or die; high-density blocks can be CNC routed with sharp single-flute cutters and strong vacuum extraction.
Can Semi-Rigid PU Foam ISF be welded?
Not weldable; join by PU/hot-melt adhesive, flame lamination or in-mould bonding to substrates and skins.
What surface finishes work on Semi-Rigid PU Foam ISF?
Integral-skin parts accept flexible PU paint after mould-release removal and IR flash-off; open-cell grades are covered with fabric, TPO or PVC skin rather than painted.
Can Semi-Rigid PU Foam ISF be formed, bent or molded?
Reaction-injected or poured into heated closed moulds at 35–60 °C with vent design and mould release; demould 3–8 min, full property build after 24 h post-cure.
What is the maximum service temperature of Semi-Rigid PU Foam ISF?
Semi-Rigid PU Foam ISF is rated for continuous use to about 100°C (212 °F), and briefly to 120°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Semi-Rigid PU Foam SR-100 and Semi-Rigid PU Foam UV-ST?
SR-100 is the default condition — the default all-round semi-rigid density for energy-absorbing pads and instrument-panel backing. UV-ST: for visible interior surfaces exposed to sunlight where yellowing of aromatic MDI foam is unacceptable.
Sources
- ASTM D3574 — Flexible Cellular Materials, Slab, Bonded and Molded Urethane Foams — ASTM International (2017)
- ASTM D1621 — Compressive Properties of Rigid Cellular Plastics — ASTM International (2016)
- Cellular Solids: Structure and Properties (Gibson & Ashby) — Cambridge University Press (1997)
- ASM Engineered Materials Handbook Vol. 2 — Engineering Plastics (cellular polymers) — ASM International (1988)
- Semi-rigid and integral-skin polyurethane system datasheets — Covestro / BASF / Huntsman (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.