Choose ETPU when the part is worn or flexed millions of times: midsoles, insoles, sports pads. Choose EPP for parts that are cushioned, carried or shipped. ETPU returns 57% of the energy it absorbs against 30% for EPP, and keeps doing that after a million cycles. It does not carry more load: ETPU molds at 180–300 kg/m³ against 20–66 kg/m³ for EPP, three to fifteen times the polymer, and gives 40–80 kPa at 10% strain against 50–325 kPa.
DBM molds both materials on steam-chest machines in the same hall. Figures are typical property ranges for molded parts, not guaranteed limits; what your part reaches depends on geometry, wall thickness and as-molded density. We confirm final numbers in writing before you commit to tooling.
Both are closed-cell bead foams fused with steam in a chest mold, but they are different families. EPP is a rigid-family polyolefin foam: light, stiff for its weight, absorbs a hit and recovers. ETPU is a foamed elastomer: soft, elastic, heavy. Transit protection is EPP work; a part compressed by a body for the life of a product is ETPU work.
The EPP and ETPU columns of the thirteen-material dataset behind our comparison tool, printed in full. A wide range is usually a density range, not uncertainty.
| Property | EPP | ETPU | What the gap means for your part |
|---|---|---|---|
| Molded density (kg/m³) | 20–66 | 180–300 | The decisive row. Same volume, three to fifteen times the polymer mass, and on a foam part polymer mass is most of the cost. |
| Compression stress at 10% strain (kPa) | 50–325 | 40–80 | Read together with the row above. EPP does not merely cover the ETPU load range, it sits above it: the lightest EPP grade at 20–25 kg/m³ already matches it, and at 54–66 kg/m³ EPP reaches 255–325 kPa, three to four times the ETPU ceiling, at a fifth to a third of the density. |
| Energy return / rebound (%) | 30 | 57 | The row where ETPU is clearly ahead: it returns close to twice the energy. And unlike load capacity, this is the property it keeps: recovery behaviour over millions of cycles is what the density is really buying. |
| Long-term service temperature (°C) | 100 | 80 | A 20 °C margin to EPP. Engine bays, appliances, hot-fill lines and dark sea containers all sit in the band where only EPP is comfortable. |
| Minimum service temperature (°C) | −40 | −30 | EPP has 10 °C more service margin. The practical difference is that ETPU is specified to stay soft and elastic near its limit, while EPP simply stays intact. |
| Thermal conductivity, W/(m·K) | 0.036–0.042 | 0.045–0.055 | EPP insulates better, and neither is the material you would pick for insulation when EPS or Beaded EPE is on the table. |
| Feel and rigidity | Semi-rigid: cushions under load, not under a finger | Very soft, running-midsole feel | The clearest single difference. Press both with a thumb: ETPU gives, EPP does not. |
| Flame behaviour | GB 8410 ≤70–90 mm/min | No flame rating held; can be modified to reach one | EPP is published with a horizontal burn rate against the automotive interior method and offers flame-retardant grades across the density range. ETPU carries no rating as we mold it. |
| Chemical resistance | Polyolefin base: good with acid, alkali, alcohols; not aromatics or chlorinated solvents | Good with oil; not strong acid/alkali or hot water (urethane hydrolysis) | They fail in different directions. ETPU is the better answer around oils and greases; EPP is the better answer around cleaning chemistry and hot water. |
| Weather resistance | PP tertiary hydrogen triggers photo-oxidation; chalks outdoors within months without additives | Depends on type: aromatic (MDI) yellows badly, aliphatic (HDI/IPDI) weathers well but costs more. Scored low by default | For an outdoor ETPU part the chemistry type has to be specified up front: it is a cost decision as much as a durability one. |
| End of life | Thermoplastic, re-pelletisable, no cross-linking | Thermoplastic and recyclable | Both are thermoplastic and both can be reprocessed. EPP has by far the wider established collection route. |
Same dataset, all thirteen materials
ETPU molds at 180–300 kg/m³, EPP at 20–66 kg/m³. Same part volume, three to fifteen times the polymer. Foam price follows polymer mass plus machine time, so that row alone explains most of the gap between the two quotes. Specify ETPU only for elastomeric behaviour EPP cannot give.
ETPU gives 40–80 kPa at 10% strain at 180–300 kg/m³. The 20–25 kg/m³ EPP grade already gives 50–70 kPa; the 54–66 kg/m³ grade gives 255–325 kPa. EPP sits above the ETPU load range, not inside it. Where the drawing gives a load and a deflection, EPP is the cheaper and the better answer.
ETPU is specified with compression recovery above 90% and very low permanent set. That is about repetition, not a single event. A midsole is compressed something like a million times in the life of a shoe. Under that cycling an elastomer returns to its original height; a rigid-family foam takes on permanent deformation.
EPP is semi-rigid: it cushions under load but does not move under a fingertip. ETPU is soft, with the running-midsole feel it is known for. Where a person touches the foam, feel is a specification: an insole that feels like EPP is rejected at the first fitting. Expansion ratio tunes ETPU feel; on EPP, hardness comes with density.
EPP runs continuously to 100 °C; ETPU is an 80 °C material. Engine bays, appliance air paths and dark sea containers sit in the band where only EPP has margin. Cold limits are close: EPP −40 °C, ETPU −30 °C. On chemistry they fail in opposite directions: strong acid, strong alkali and hot water hydrolyse urethane; oils and greases are the reverse.
We publish EPP burn rates against GB 8410, the horizontal method for automotive interiors: ≤70 mm/min at 54–66 kg/m³, ≤80 at 40–50 kg/m³, ≤90 at 27–33 kg/m³, with flame-retardant grades across the range. ETPU as we mold it holds no rating. Outdoors it has to be typed first: aromatic MDI yellows under UV, aliphatic HDI or IPDI weathers well and costs more.
Both materials are molded in a vented aluminium steam chest on the same machines. ETPU molds at 0.6–2.2 bar and 110–130 °C, inside the EPP equipment envelope. The tool is priced off the part, not off the bead. What changes is the running cost: heavier parts, more polymer per shot, a longer stabilisation.
Ten application families, the material we start from, and the reason. Where a third material is the better answer we say so.
| Application | Start from | Typical density | Why |
|---|---|---|---|
| Footwear midsoles and insoles | ETPU | 180–300 kg/m³ | A million compressions per product life. Over 90% compression recovery and elastomeric softness are the entire specification. |
| Returnable dunnage and KLT inserts | EPP | 27–50 kg/m³ | Stiffness, dimensional stability and low weight. Nothing in the duty cycle asks for an elastomer. |
| Sports and training pads with direct body contact | ETPU | 180–300 kg/m³ | Repeated impact against a person. Feel and fatigue life outrank weight and cost. |
| Automotive energy absorption | EPP | 40–66 kg/m³ | Cabin temperatures, a burn-rate specification, and a core that has to work at low mass. |
| High-cycle vibration and impact pads | ETPU | 180–300 kg/m³ | Permanent set is the failure mode. An elastomer keeps returning to height where a rigid foam slowly stops. |
| Protective packaging and transit cushioning | EPP | 20–50 kg/m³ | The part is shipped, so mass is money twice over, in the bead and in the freight. |
| Appliance and HVAC internals | EPP | 27–50 kg/m³ | Warm air paths above ETPU's ceiling, automated assembly, and no requirement for elastomeric feel. |
| Ergonomic grips and contact surfaces | ETPU | 180–300 kg/m³ | A human hand is the test instrument. Semi-rigid foam fails that test before any data is collected. |
| Battery module trays and ESS packaging | EPP | 40–66 kg/m³ | Load-bearing, returnable, and normally required to hold a flame specification, which EPP can and ETPU cannot. |
| Soft seals, gaskets and conforming pads | Neither (EVA) | 30–50 kg/m³ | A third material fits better. Cross-linked EVA seals better than either and costs far less than ETPU. |
EPP is ordered by density grade, and the grade decides the part more than the polymer does. ETPU is one bead family: expansion ratio is the tuning variable. EPP compression figures are at 10% strain to ISO 844.
| Density grade | Material | Density (kg/m³) | Key values | Where it belongs |
|---|---|---|---|---|
| 20–25 kg/m³ | EPP | 20–25 | 50–70 kPa @10% · tensile 420–560 kPa | Ultra-light cushioning, insulation and dunnage where weight is the constraint. |
| 27–33 kg/m³ | EPP | 27–33 | 70–100 kPa @10% · tensile 550–750 kPa | Protective packaging and lightweight parts with strong energy absorption. |
| 40–50 kg/m³ | EPP | 40–50 | 130–175 kPa @10% · tensile 800–1000 kPa | Structural cushioning: automotive, handling trays, heavier returnable packaging. |
| 54–66 kg/m³ | EPP | 54–66 | 255–325 kPa @10% · tensile 1050–1350 kPa | Structural and load-bearing parts, and the grade that carries three to four times what ETPU reaches, at a fraction of the density. |
| ETPU, about 10× expansion | ETPU | 180–300 | 40–80 kPa @10% · compression recovery >90% | The elastomeric option: midsoles, insoles, high-cycle pads. Expansion ratio is the design variable, so the density is set by the part rather than by a fixed grade. |
A molded foam part is priced from the polymer in it, the machine time needed to fuse and stabilise it, and the tooling spread across the run. Geometry fixes the volume, so the material fixes the mass. A part with a one-litre foam volume holds roughly 27–33 grams of polymer in EPP at 27–33 kg/m³, and 180–300 grams in ETPU.
Specify the load and the deflection you can accept rather than a grade or a density. Over-specified density is the usual way a foam part costs more than it should, and on ETPU it costs several times more.
Every comparison here comes from the same eleven-property dataset. If the pair above is not yours, one of these is.
| Comparison | The decision it settles |
|---|---|
| EPP vs EPS foam | Recovery against cost. Whether the part is struck once or many times, and whether insulation or reuse leads the specification. |
| EVA vs EPP foam | Soft conforming contact against structural load. Whether the foam touches a surface or carries it. |
| EPP vs Beaded EPE foam | Rigidity and repeated impact against soft wrap, surface safety and service down to −70 °C. |
| EPP vs EPO foam | Where a PS/polyolefin composite bead at 16 kg/m³ is better value than either EPS or EPP. |
| All thirteen, ranked | Every material sorted on each of the seven properties that settle a spec. |
| EPE vs Beaded EPE foam | The same polyethylene shaped two ways: what the forming route costs and buys. |
| Cut vs molded foam | Which forming process the part needs: shape freedom and seams against tooling commitment. |
Family and density. EPP is a rigid-family polyolefin bead foam molded at 20–66 kg/m³: light, stiff for its weight, and built to absorb an impact and recover. ETPU is a foamed elastomer molded at 180–300 kg/m³: soft, elastic, and built to be compressed and released millions of times. Both are steam-chest bead foams, but EPP protects and carries while ETPU flexes for a living.
Yes. Our comparison dataset lists ETPU at 57% against 30% for EPP, so it returns close to twice the energy. On top of that comes behaviour over repetition: ETPU is specified with compression recovery above 90% and very low permanent set, so it keeps returning to its original height after a million cycles. That fatigue behaviour, as much as the single-impact rebound number, is what you are buying with ETPU.
Mostly because of density. ETPU molds at 180–300 kg/m³ against 20–66 kg/m³ for EPP, so the same geometry contains three to fifteen times as much polymer. Foam cost is dominated by polymer mass plus machine time, so that ratio drives the price before bead prices are even compared. Tooling cost is close to identical, because both are molded in the same steam-chest tool.
EPP, and not only once weight is taken into account. ETPU gives 40–80 kPa at 10% strain at 180–300 kg/m³; our EPP grade at 54–66 kg/m³ gives 255–325 kPa, three to four times as much, and even the 20–25 kg/m³ grade gives 50–70 kPa. EPP therefore sits above the ETPU load range rather than inside it, at a fraction of the density. If the drawing specifies a load and a deflection rather than a feel, EPP is both the cheaper and the better engineering answer.
EPP runs continuously to 100 °C with short excursions higher, and is rated down to −40 °C. ETPU is an 80 °C material at the top end and is rated to −30 °C and keeps its elasticity and softness at around −25 °C rather than merely staying intact. So warm environments (engine bays, appliance air paths, sealed containers) are EPP cases, and cold flexible ones favour ETPU.
Yes. ETPU molds in a vented aluminium steam chest at 0.6–2.2 bar and 110–130 °C, inside the same equipment envelope as EPP, and one grade will mold without steam at 100–150 °C. That means tooling is priced off the part rather than off the bead, and switching material between the two does not automatically require a new tool. Shrinkage differs, though, so a tool cut for one is rarely dimensionally perfect in the other.
You do not have to name a material. Tell us how often the part is compressed, by what, and at what temperature. We come back with a material, a density, a sample plan and a price within 48 hours.