E-TPU boosts running energy

For every midsole, adidas needs about 2,500 of these small beads. To convert them into the desired form, they are treated with hot steam, a process in which the outmost layer of the beads melts slightly, causing them to bond into a stable shape. The internal air cell structure remains unaffected by this process.

A midsole made from Infinergy can be compressed to an extreme degree: by about half of its volume at a pressure of two bar. This property is particularly effective in absorbing the shock impact on the foot. As soon as the compressive impulse subsides, the foam returns to its original shape at lightning speed. The sole therefore absorbs the runner's energy, but then returns a large amount to the runner. This rebound elasticity of the individual Infinergy beads literally transforms the running shoes into energy stores: "When the foot is pushed off the ground, the force expended is largely returned to the athlete. This results in completely new and improved running behavior. Many runners have told us that the shoe feels like it is almost alive," explains Gerd Manz, Senior Innovation Director Global Brands at adidas. Another advantage of BASF's specialty foam: It’s not only lightweight, but it also remains elastic over a wide temperature range. The particles make sure that the Energy Boost shoe also retains its positive properties at minus 20 degrees Celsius. "The running characteristics are therefore the same at frosty temperatures as at summerlike 30 degrees Celsius," says Manz.

Very lightweight and elastic - these special properties make Infinergy a material with a wide range of applications. Some of these are currently in the trial phase (see info box on the last page). Others may still be a long way off, but are certainly feasible: in the future, BASF's foam could, for example, make the "flat-less" bicycle tire that many cyclists are dreaming of become a reality. Infinergy is also potentially suitable as flooring for running tracks. For the automotive industry manufacturers, who are always searching for lightweight and robust materials, BASF's specialty foam could also open up completely new opportunities.