PMI Foam
A rigid, closed-cell structural foam with a very high strength/stiffness-to-weight ratio and good thermoformability, widely used as a high-performance sandwich core in aerospace and high-end sporting goods.
Reference datasheet — PMI Foam is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the 71IG condition
PMI Foam grades and fills
PMI Foam is supplied in 15 conditions, soft to hard. 71IG is the default FabDigit quotes; the values on this page are for it.
Compare all 15 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
32 kg/m³ prepreg-grade PMI foam | Lowest-density grade: pick for minimum-weight, low-load radome and interior sandwich panels. | 1 | 3.5 | ||
in-mould foamed / particle-foam PMI | Use for complex near-net-shape cores moulded directly from PMI granules, avoiding block machining waste. | 1 | 3 | ||
52 kg/m³ prepreg-grade PMI foam | Most common lightweight core for sporting goods, antenna and light aircraft panels. | 2 | 3.5 | ||
52 kg/m³ high-temperature PMI foam | Light WF-family core for 180 °C/0.7 MPa autoclave cure cycles where IG would creep. | 2 | 3 | ||
Low-loss radome grade | Radome and antenna cores where dielectric constant and loss tangent are the controlling properties. | 2 | 3 | ||
High-elongation / damage-tolerant PMI foam | Use where impact damage tolerance and elongation matter more than peak modulus (leading edges, sports gear). | 2 | 8 | ||
71IGDefault 75 kg/m³ prepreg-grade PMI foam (standard) | The all-round default: best strength/weight compromise for autoclave-cured aerospace sandwich parts. | 2 | 3 | ||
75 kg/m³ high-temperature PMI foam | Standard high-temperature core: higher shear stiffness than 71 IG and cure-stable to ~200 °C. | 2 | 3 | ||
Fine-cell, sealed-skin prepreg grade | Pick when low resin uptake and a smooth skin-to-core bond line matter (thin prepreg face sheets). | 2 | 4.5 | ||
Resin-infusion / RTM optimised PMI foam | Select for liquid-composite moulding: low resin uptake surface and dimensional stability under injection pressure. | 4 | 4 | ||
High-temperature-stable general grade | Cost-effective grade for high-temperature tooling cores and long dwell cure cycles. | 4 | 3.5 | ||
110 kg/m³ prepreg-grade PMI foam | Choose where core shear/crush loads or fastener bearing are high, e.g. helicopter rotor blades and control surfaces. | 4 | 3 | ||
110 kg/m³ high-temperature PMI foam | High-load, high-temperature core for rotor blades, engine nacelle and RTM/prepreg tooling cores. | 4 | 3 | ||
205 kg/m³ high-temperature PMI foam | Dense grade for locally reinforced inserts, fastener/hard-point areas and press-cure tooling. | 7 | 3.5 | ||
~300 kg/m³ high-density PMI foam | Highest-density standard grade: bearing pads, edge close-outs and machined tooling blocks. | 11 | 3.5 |
What is PMI Foam?
A rigid, closed-cell structural foam with a very high strength/stiffness-to-weight ratio and good thermoformability, widely used as a high-performance sandwich core in aerospace and high-end sporting goods. PMI Foam has a density of 0.08 g/cm³ (0.0027 lb/in³), lighter than 87% of polymer grades. Its glass-transition temperature is 190°C (374 °F). PMI Foam has a tensile strength of 2 MPa (0.319 ksi), weaker than 84% of polymer grades. Elongation at break is 3% and the elastic modulus is 0.09 GPa (0.0133 Msi).
What is PMI Foam used for?
- Aircraft sandwich panel cores
- Radome and wind blade cores
- Automotive/motorsport composite cores
- Prosthetics and sporting goods cores
Advantages
- Easy to machine — 85/100, better than 88% of polymer grades
- Lightweight — 0.08 g/cm³ (0.0027 lb/in³), better than 87% of polymer grades
- High service temperature — 180°C (356 °F), better than 85% of polymer grades
Limitations
- Poor heat conductor — 0.03 W/m·K (0.0168 BTU/hr·ft·°F), worse than 98% of polymer grades
- Hard to polish — 10/100, worse than 98% of polymer grades
- Limited ductility — 3%, worse than 83% of polymer grades
- High embodied carbon — 8 kg CO₂/kg, worse than 83% of polymer grades
PMI Foam properties
Typical room-temperature values for PMI Foam-71IG; bars are the position among polymer grades.
Physical2
PMI Foam has a density of 0.08 g/cm³ (0.0027 lb/in³), lighter than 87% of polymer grades. Its glass-transition temperature is 190°C (374 °F).
Mechanical9
PMI Foam has a tensile strength of 2 MPa (0.319 ksi), weaker than 84% of polymer grades. Elongation at break is 3% and the elastic modulus is 0.09 GPa (0.0133 Msi).
Thermal7
PMI Foam is rated for continuous service to 180°C (356 °F). It conducts heat at 0.03 W/m·K (0.0168 BTU/hr·ft·°F), worse than 98% of polymer grades. Thermal expansion is 36 µm/m·K (20 µin/in·°F).
Electrical2
Chemical & Environmental2
UV resistance is fair.
Sustainability3
Producing a kilogram of PMI Foam takes about 140 MJ of energy and emits 8 kg of CO₂ — more than 81% of polymer grades. Typical recycled content is 0%.
Manufacturability3
PMI Foam's machinability is excellent (85/100, better than 88% of polymer grades); formability very good (75/100).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the polymer family
Yield strength against density for every polymer grade FabDigit runs. PMI Foam is highlighted; hover a dot for its name, or open the interactive family chart.
Working with PMI Foam
Is PMI Foam easy to machine?
CNC-mills, saws, sands and hot-wire cuts easily with sharp tools and vacuum extraction; the dust is abrasive and irritant, so seal machined faces before bonding.
Can PMI Foam be welded?
Not weldable in the metals sense; sections are joined with epoxy paste adhesive or splice films, or thermally fused during hot forming.
Can PMI Foam be formed, bent or molded?
Hot-form flat blanks at about 180–200 °C over a tool (short soak, cool under restraint); IG grades tolerate 0.3 MPa autoclave pressure and WF grades up to ~0.7 MPa — dry the core 2–4 h at 100–130 °C before cure to prevent blistering.
PMI 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 |
|---|---|---|
| methacrylic acid (monomer unit)imidized with methacrylonitrile to form the polymethacrylimide ring | 45 – 60 | 52 |
| methacrylonitrile (monomer unit) | 40 – 55 | 46 |
| cross-linker / blowing agent residues (fexpansion agents and additives; exact package proprietary | 0.5 – 3 | 2 |
| polymethacrylimide matrixclosed-cell solid phase; ~95 vol % gas at 75 kg/m³ | balance |
What surface finishes work on PMI Foam?
No plating or polishing; finish by resin/adhesive skinning, filling with lightweight epoxy paste, or bonding prepreg face sheets, then paint the laminate rather than the foam.
How much does PMI Foam cost?
PMI Foam is a high-cost polymer ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
PMI Foam — frequently asked
What is PMI Foam used for?
PMI Foam is typically used for aircraft sandwich panel cores, radome and wind blade cores, automotive/motorsport composite cores and prosthetics and sporting goods cores. In short: autoclave-capable foam core; highest stiffness-to-weight core; hot-formable closed-cell foam.
What is the tensile strength of PMI Foam?
PMI Foam has a typical tensile strength of 2 MPa (0.319 ksi) — weaker than 84% of polymer grades. Strength varies by condition: see the 15 listed tempers.
Is PMI Foam easy to machine?
Yes — machinability is rated excellent (85/100, better than 88% of polymer grades). CNC-mills, saws, sands and hot-wire cuts easily with sharp tools and vacuum extraction; the dust is abrasive and irritant, so seal machined faces before bonding.
Can PMI Foam be welded?
Not weldable in the metals sense; sections are joined with epoxy paste adhesive or splice films, or thermally fused during hot forming.
What surface finishes work on PMI Foam?
No plating or polishing; finish by resin/adhesive skinning, filling with lightweight epoxy paste, or bonding prepreg face sheets, then paint the laminate rather than the foam.
Can PMI Foam be formed, bent or molded?
Hot-form flat blanks at about 180–200 °C over a tool (short soak, cool under restraint); IG grades tolerate 0.3 MPa autoclave pressure and WF grades up to ~0.7 MPa — dry the core 2–4 h at 100–130 °C before cure to prevent blistering.
What is the maximum service temperature of PMI Foam?
PMI Foam is rated for continuous use to about 180°C (356 °F), and briefly to 200°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does PMI Foam cost?
PMI Foam is a high-cost polymer ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ROHACELL IG / IG-F Product Information — Evonik Industries (2023)
- ROHACELL WF Product Information — Evonik Industries (2023)
- ROHACELL HERO / RIST / Triple F technical brochures — Evonik Industries (2022)
- ASM Handbook Vol. 21: Composites — Sandwich Core Materials — ASM International (2001)
- ASTM C365 / C273 / C297 (core compression, shear and flatwise tension test methods) — ASTM (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.