PMI Foam HF (Low-loss radome grade)
Grade
Radome and antenna cores where dielectric constant and loss tangent are the controlling properties.
Values for the HF condition
Other PMI Foam grades and fills
PMI Foam is listed in 15 conditions; see the grade overview at PMI Foam.
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 | — |
HFThis page 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 HF?
PMI Foam HF is PMI Foam in the HF grade — radome and antenna cores where dielectric constant and loss tangent are the controlling properties. PMI Foam HF has a tensile strength of 2 MPa (0.232 ksi), weaker than 85% of polymer grades. Elongation at break is 3% and the elastic modulus is 0.07 GPa (0.0102 Msi). PMI Foam HF has a density of 0.05 g/cm³ (0.0019 lb/in³), lighter than 88% of polymer grades. Its glass-transition temperature is 190°C (374 °F). 71IG is the default condition FabDigit quotes; HF is available on request or by drawing note.
Advantages
- Lightweight — 0.05 g/cm³ (0.0019 lb/in³), better than 88% of polymer grades
- Easy to machine — 85/100, better than 88% of polymer grades
- High service temperature — 180°C (356 °F), better than 85% of polymer grades
Limitations
- Hard to polish — 10/100, worse than 98% of polymer grades
- Poor heat conductor — 0.03 W/m·K (0.0173 BTU/hr·ft·°F), worse than 96% 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 HF properties
Typical room-temperature values for PMI Foam HF; 18 are specific to this condition. Other listed values are PMI Foam reference data and may not represent this condition. Bars are the position among polymer grades.
Physical2
PMI Foam HF has a density of 0.05 g/cm³ (0.0019 lb/in³), lighter than 88% of polymer grades. Its glass-transition temperature is 190°C (374 °F).
Mechanical9
PMI Foam HF has a tensile strength of 2 MPa (0.232 ksi), weaker than 85% of polymer grades. Elongation at break is 3% and the elastic modulus is 0.07 GPa (0.0102 Msi).
Thermal7
PMI Foam HF is rated for continuous service to 180°C (356 °F). It conducts heat at 0.03 W/m·K (0.0173 BTU/hr·ft·°F), worse than 96% 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 HF 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 HF's machinability is excellent (85/100, better than 88% of polymer grades); formability very good (70/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with PMI Foam HF
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.
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.
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 | — |
PMI Foam HF — frequently asked
What is PMI Foam HF used for?
PMI Foam HF 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 HF?
PMI Foam HF has a typical tensile strength of 2 MPa (0.232 ksi) — weaker than 85% of polymer grades. Strength varies by condition: see the 15 listed tempers.
Is PMI Foam HF 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 HF 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 HF?
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 HF 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 HF?
PMI Foam HF 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.