PU Foam · grade
PU Foam Closed Cell
Properties of the Closed Cell condition, compared with the other PU Foam grades.
Pick for thermal insulation panels, cold-chain, buoyancy and pour-in-place structural filling where low λ and water resistance are required.
What is PU Foam Closed Cell?
PU Foam Closed Cell is PU Foam in the Closed Cell grade — pick for thermal insulation panels, cold-chain, buoyancy and pour-in-place structural filling where low λ and water resistance are required. PU Foam Closed Cell has a tensile strength of 0.3 MPa (0.0435 ksi), weaker than 94% of polymer grades. Elongation at break is 6% and the elastic modulus is 0.01 GPa (0.0012 Msi). PU Foam Closed Cell has a density of 0.04 g/cm³ (0.0014 lb/in³), lighter than 91% of polymer grades. Its glass-transition temperature is 120°C (248 °F). Open Cell is the default condition FabDigit quotes; Closed Cell is available on request or by drawing note.
Advantages
- Lightweight — 0.04 g/cm³ (0.0014 lb/in³), better than 91% of polymer grades
- Easy to machine — 85/100, better than 88% of polymer grades
Limitations
- Poor heat conductor — 0.02 W/m·K (0.0133 BTU/hr·ft·°F), worse than 100% of polymer grades
- Hard to polish — 5/100, worse than 99% of polymer grades
- Low stiffness — 0.01 GPa (0.0012 Msi), worse than 83% of polymer grades
- Limited formability — 15/100, worse than 80% of polymer grades
- Degrades in UV without stabilisers — 25/100, worse than 76% of polymer grades
PU Foam Closed Cell properties
Typical room-temperature values for PU Foam Closed Cell — 18 properties are specific to this condition; the rest are grade-level values shared by every PU Foam grade. Each bar shows where the value sits among the polymer grades in FabDigit's library — further right is higher.
Physical3
PU Foam Closed Cell has a density of 0.04 g/cm³ (0.0014 lb/in³), lighter than 91% of polymer grades. Its glass-transition temperature is 120°C (248 °F).
Mechanical7
PU Foam Closed Cell has a tensile strength of 0.3 MPa (0.0435 ksi), weaker than 94% of polymer grades. Elongation at break is 6% and the elastic modulus is 0.01 GPa (0.0012 Msi).
Thermal8
PU Foam Closed Cell is rated for continuous service to 105°C (221 °F). It conducts heat at 0.02 W/m·K (0.0133 BTU/hr·ft·°F), worse than 100% of polymer grades. Thermal expansion is 60 µm/m·K (33.3 µin/in·°F).
Electrical3
PU Foam Closed Cell has an electrical resistivity of 1×10¹⁰ Ω·m.
Chemical & Environmental2
UV resistance is poor.
Sustainability4
Producing a kilogram of PU Foam Closed Cell takes about 102 MJ of energy and emits 4.6 kg of CO₂ — less than 55% of polymer grades. Typical recycled content is 10%.
Manufacturability6
PU Foam Closed Cell's machinability is excellent (85/100, better than 88% of polymer grades); weldability poor (30/100); formability poor (15/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other PU Foam grades and fills
PU Foam is also supplied in 6 other conditions. The full side-by-side table is on the PU Foam overview.
- Open CellDefaultPick for cushioning, seating, gaskets, filtration, acoustic absorption and packaging where compliance and breathability matter.0.13 MPa tensile
- Tooling BoardPick for CNC-machined styling models, vacuum-form and layup tools where dimensional stability and clean machined surfaces matter.12 MPa tensile
- Integral SkinPick for steering wheels, armrests, grips and housings needing a tough elastomeric skin over a foam core straight from the mold.4 MPa tensile
- Closed CellPick for thermal insulation panels, cold-chain, buoyancy and pour-in-place structural filling where low λ and water resistance are required.0.3 MPa tensile
Working with PU Foam Closed Cell
Is PU Foam easy to machine?
Cuts easily with hot wire, band knife, oscillating blade or waterjet; CNC-mill rigid and tooling grades with sharp single-flute cutters, high rpm and strong dust extraction (respirator required).
Can PU Foam be welded?
Thermoset — cannot be melt-welded; join flexible foam by flame lamination or hot-melt/PU adhesives and rigid foam by epoxy/PU adhesives.
Can PU Foam be formed, bent or molded?
Two-component reactive processing: free-rise slabstock, hot/cold-cure molding, or pour-in-place and spray application; control mold temp 35–65 °C and demold after full cream/gel/rise cycle.
What surface finishes work on PU Foam?
Open-cell surfaces cannot be polished — laminate with fabric/film or flock; rigid and tooling boards sand well and accept sealer plus PU/epoxy topcoat, and integral-skin parts are in-mold painted.
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 |
|---|---|---|
| TDI / MDI isocyanateTDI typical for flexible slabstock, polymeric MDI for rigid foam | 28 – 55 | 38 |
| water / blowing agentwater (CO2 generation) or HFO/HFC/pentane physical blowing agent in rigid foam | 1 – 5 | 3 |
| silicone surfactantcell regulator | 0.3 – 2 | 1 |
| amine / tin catalyst | 0.1 – 1 | 0.4 |
| flame retardantphosphate/halogen-free FR only in FR grades | 0 – 15 | 0 |
| polyether polyolpolyester polyol used for hydrolysis-sensitive/high-strength foams | ≥ 40 (balance) | — |
PU Foam Closed Cell — frequently asked
What is PU Foam Closed Cell used for?
PU Foam Closed Cell is typically used for furniture and seating cushions, mattress cores, packaging and case inserts, gasket and sealing strips, rigid insulation panels and CNC tooling board patterns and moulds. In short: cushioning open-cell foam.
What is the tensile strength of PU Foam Closed Cell?
PU Foam Closed Cell has a typical tensile strength of 0.3 MPa (0.0435 ksi) — weaker than 94% of polymer grades. Strength varies by condition: see the 7 listed tempers.
Is PU Foam Closed Cell easy to machine?
Yes — machinability is rated excellent (85/100, better than 88% of polymer grades). Cuts easily with hot wire, band knife, oscillating blade or waterjet; CNC-mill rigid and tooling grades with sharp single-flute cutters, high rpm and strong dust extraction (respirator required).
Can PU Foam Closed Cell be welded?
Not readily — weldability is rated poor (30/100). Thermoset — cannot be melt-welded; join flexible foam by flame lamination or hot-melt/PU adhesives and rigid foam by epoxy/PU adhesives.
What surface finishes work on PU Foam Closed Cell?
Open-cell surfaces cannot be polished — laminate with fabric/film or flock; rigid and tooling boards sand well and accept sealer plus PU/epoxy topcoat, and integral-skin parts are in-mold painted.
Can PU Foam Closed Cell be formed, bent or molded?
Two-component reactive processing: free-rise slabstock, hot/cold-cure molding, or pour-in-place and spray application; control mold temp 35–65 °C and demold after full cream/gel/rise cycle.
What is the maximum service temperature of PU Foam Closed Cell?
PU Foam Closed Cell is rated for continuous use to about 105°C (221 °F), and briefly to 120°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in PU Foam Closed Cell?
Yes — PU Foam Closed Cell is available for CNC machining, sheet metal and injection molding with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM D3574 — Flexible Cellular Materials, Slab/Bonded/Molded Urethane Foams — ASTM (2022)
- ASTM D1622 / ASTM D1621 — Density and Compressive Properties of Rigid Cellular Plastics — ASTM (2020)
- ASTM C591 — Unfaced Preformed Rigid Cellular Polyisocyanurate Thermal Insulation — ASTM (2023)
- ASM Engineered Materials Handbook Vol.2 — Engineering Plastics — ASM International (1988)
- Cellular Solids: Structure and Properties (Gibson & Ashby) — Cambridge University Press (1997)
- Elastoflex / Elastopor rigid & flexible PU systems — BASF (2023)
- Baydur / Bayfit polyurethane system data — Covestro (2023)
- RenShape / SikaBlock PU modelling board datasheets — Sika (2023)
- CES EduPack polymer foam eco & mechanical data — Ansys Granta (2022)
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.