Adidas Shoe Technologies
When it comes to sneaker technology, shoes are divided into three major areas: the upper, the midsole, and the outsole. Depending on the materials and combinations used, one model of sneaker can vary greatly from another.
Uppers, the top part of the shoe with the laces, fancy designs and bright colors that holds the shoe together, usually come in one of three materials, leather, synthetic leather, and mesh.
Special editions, retro and vintage models, Converse and casual shoes like the Nike Vandal, the Air Force 1, and the Nike After Party for women may have a canvas upper.
Midsoles are used to cushion and provide support and protection for the foot. There are four types of materials used in commercially produced sneakers. Midsoles are often constructed of a combination of materials. Midsole materials are Phylon, polyurethane, Phylite, and EVA.
Phylon is very lightweight, low-profile and responsive. Phylon is made of EVA foam pellets that are compressed, heat expanded and then cooled in a mold. Compression-molded Phylon Midsoles can be sculpted into a variety of designs that are identified by their fine wrinkles.
PU or Polyurethane
PU is the most dense, durable and stable midsole material. PU is poured into a mold to create a firm midsole that provides maximum protection from impact. PU is identified by its smooth rubbery feel and tendency to turn yellow with age. PU is the heaviest midsole material, but it is also the most durable.
Phylite is an injection-molded unit made of a combination of 60% Phylon and 40% rubber. Phylite is lighter than rubber, but heavier than Phylon and functions as both midsole and outsole. By eliminating a separate midsole and outsole the weight of the shoe is greatly reduced and flexibility is increased.
EVA is soft, light and flexible. It is the least expensive midsole material and is often used in entry-level shoes. Midsoles are cut and shaped from flat sheets of EVA foam. EVA will compress and become flat over time as the air trapped within the foam is squeezed out. Once EVA is compacted, it does not return to its original shape and no longer provides cushioning. EVA compresses faster than other midsole materials.