Adidas has made Futurecraft.Loop, a performance running shoe out of thermoplastic polyurethane. It is 100 per cent recyclable. The technology allows the entire shoe to be ground up, melted back into raw material, and used for new products. Like most running sneakers, the shoe is a jumble of textures. It has a knit upper that looks and feels like woven polyester, except in spots where it turns into a more rigid material to provide support. The midsole is fused pellets, resembling styrofoam. A stabilizing torsion bar in the midsole is a hard, molded plastic, while the outsole is tough but flexible. The laces replicate the look of cloth, and the insole has a knit pattern on the top but a material like pressed plastic pellets on the underside.
Today, the average performance running sneaker uses 12 to 15 different materials. That material mix is part of the reason a running shoe can’t be easily recycled. The materials would all have to be separated, or one might contaminate the recycling process of another. It’s not even possible to separate certain fiber blends, and some items, such as cotton, can’t yet be recycled without a substantial loss in quality.
The challenge of making a running shoe from a single polymer is that it needs to replicate the functions and performance of all those other materials replaced. That’s what Adidas has done on the Futurecraft.Loop.