What PEBA and TPE foams are
PEBA, polyether block amide, is a block copolymer with rigid polyamide segments and flexible polyether segments. The best-known commercial grade is Arkema's Pebax. The polyamide gives strength; the polyether gives low density and very high elasticity.
Other TPE foams follow the same principle with different chemistry, for example TPEE (thermoplastic polyester elastomer) and olefin-based elastomers. Many brands also blend these polymers, or combine them with EVA, to balance rebound, weight, stability and cost.
How PEBA foams are made
Performance TPE foams are usually made by physical foaming with supercritical fluids rather than chemical blowing agents:
- Saturation — Polymer pellets or preforms are saturated with nitrogen or carbon dioxide in a supercritical state under high pressure.
- Foaming — A rapid pressure drop or heating step makes the dissolved gas nucleate into a very large number of fine cells at once.
- Shaping — The foam is formed into its final shape, either by expanding in a mold, by bead-fusing, or by compression molding a foamed preform.
The result is a uniform, very low-density foam that stays a thermoplastic. The process needs high-pressure equipment and tight control, which adds to cost.
Cushioning: 8 / 8, Max
Very low density lets brands build tall, soft midsoles that still weigh little. PEBA foams compress deeply under load, spreading impact over a longer stroke, then recover almost immediately. The feel is soft and lively at the same time, which older foams could not combine.
Rebound: 8 / 8, Max
PEBA-based foams return the highest share of input energy among common midsole materials, measurably above ETPU and far above EVA in ball rebound testing such as ISO
8307. Paired with a stiff plate, this is the core of modern road racing shoes. Rules have followed: World Athletics limits sole thickness for road racing shoes to 40 mm.
Durability: 6 / 8, High
PEBA foams resist compression set better than EVA, but the softest, lightest grades lose some of their peak responsiveness sooner than ETPU or PU. Very soft foam is also easier to scuff, tear and deform at the edges. Durability depends heavily on density and on how the foam is protected with rubber and carrier foams.
Where PEBA and TPE foams are used
- Road racing shoes — paired with carbon or composite plates for marathon and track racing.
- Tempo and super-trainers — the same foams in more stable, more durable builds for training.
- Trail racing — light, protective cushioning for long distances, usually with a firmer carrier.
- Court and training shoes — increasingly used as a forefoot or heel insert for responsiveness.
Designing with PEBA and TPE foams
Choose PEBA when weight and energy return lead the brief and the price point allows it.
- For long service life at lower cost, ETPU or blended foams are often the better choice.
- Add stability with geometry — wider bases, sidewalls, plates or a firmer carrier foam.
- Protect the foam with rubber in high-wear zones; exposed PEBA wears quickly.
- Consider blends with EVA or other TPEs to trade a little rebound for cost and durability.
- Check stack height against World Athletics rules for any shoe meant for competition.