아빠는 공부쟁이

Angel Chang The wildly complex anatomy of a sneaker 02:04 The outer soles of most shoes are made of rubber that’s gone through a process called vulcanization. This technique adds sulfur to superheated raw rubber to create a material that’s both elastic and sturdy. Until recently, sneakers used natural rubber for this process. But today, most outer soles are made with a synthetic blend of natural..