BASF Polyurethane, Wyandotte, Mich.,will debut what appears to be the first expandable TPU (E-TPU). Branded Infinergy, it is based on Elastollan TPU which is expanded by using an innovative procedure. Being a closed-cell particle foam, Infinergy has a low bulk weight, with a density of 110 killograms per cubic meter. After processing on standard molding machines, it has a molded part weight of 200 to 320 kg/cu m, which positions it between the generally lighter EPS or EPP and the heavier elastomeric PUR foams.
Infinergy absorbs little water—less than 2% by volume in 24hrs; has very high breaking elongation of between 100-150% depending on density; and a combination of good abrasion- and chemical- resistance. One of its key features is its excellent recovery behavior, which reportedly makes it the most elastic particle foam currently on the market. Tests of resilience elasticity show that the rebound height of E-TPU can be as much as 55%, which is significantly higher than EPS (less than 20%) or EPP (30%). The first commercial application of Infinergy foam is the midsole of the new Adidas “Energy Boost” running shoe.