Athletic shoes need to meet a wide variety of requirements. Complex chemical structures need to be transformed into tangible applications. Evonik accomplished this successfully by working closely with well-known sporting goods manufacturers during the development of athletic footwear using molding compounds based on polyamide 12 and polyamide 12 elastomers. Polyamides play a large role in the design of athletic footwear. The focus is essentially on semi-crystalline materials from the top of the polymer pyramid, so these high standards can be met. Compared with other polyamides, molding compounds based on polyamide 12 are characterized by high dimensional stability, constancy of properties in changing environmental conditions, and low water absorption.
Furthermore, athletic shoes need to be tough, which means the polymers need to meet very tough mechanical requirements, both static and dynamic ones. And the polyamides also need to be able to stand up to the effects of the weather.
Placing the feet in good hands
These properties can be achieved with VESTAMID® L polyamides 12 and VESTAMID® E polyamide 12 elastomers (PEBA, polyether block amides). PEBA as a block copolymer made of hard polyamide 12 segments and soft polyether segments, combines stability with flexibility. The polyamide 12 segments ensure dimensional stability, impact, and notched impact strength, even in cold weather, and high chemical resistance. The polyether segments ensure good elastic recovery, allowing shoe soles to absorb impact well and protect joints. This base material is customized in cooperation with plastics processors, sports equipment manufacturers, and athletes to the unique requirements of individual sports—which explains why soccer, basketball, baseball, and rugby players, golfers, sprinters, cyclists, and winter sports athletes alike all value this plastic under their feet. Moreover, manufacturers demand consistent processing characteristics and an array of design possibilities.
Because of its low density, the material is also extremely lightweight: In a 90-minute soccer match, it reduces the weight carried by the players by about 100 kilo grams compared to other sole materials—saving energy and increasing stamina. Because the mechanical properties of polyamide 12 elastomers are virtually immune to temperature, they are as well suited to marathon runs in Australian summers as they are to winter sports.