Polyamide 12 for the Next Generation of Sports Shoes
Have Athletes and Materials Reached their Limits?
Can a human run 100 m in 9.29 s? Or is 9.48 s the theoretical limit? While the scientists are still arguing, the fastest men in the world are trying to beat the current world record of 9.58 s set by Usain Bolt. But, personal performance apart, the most important sports appliance is the shoe, e. g., the Sonicsprint Elite spiked shoe, offered by Asics Corporation, Kobe, Japan, which contains the polyamide 12 elastomer Daiamid from Daicel-Evonik Ltd., Tokyo, Japan.
Movement and speed are a challenge for material researchers and shoe developers. They have been cooperating closely for years on implementing the latest scientific findings in the ideal fit. In the past, well-known sports manufacturers have relied for their sports shoe sole developments on the very lightweight Vestamid polyamide 12 molding compounds from Evonik Industries AG, Essen, Germany, and Daiamid by the Daicel-Evonik joint venture, due to their low density of only 1 g/cm3.
The Vestamid and Daiamid grades of the polyamide 12 family are stiff, but at the same time so resilient that they emit most of the energy they absorb on deformation again as an impulse. Because of the good mechanical stability of the materials, structural measures can be used to save weight, for example by using soles that do not cover the entire surface or – as with the sole of the Asic sprint shoe – through a superior reinforcing technology. The combination of stiffness and flexibility that this provides gives the shoe the explosiveness that a sprinter needs at the starting block.
Daicel-Evonik has also succeeded in another development: The R Compo sole is a composite of polyamide 12 and rubber nubs, balancing excellent grip with low abrasion.
Translated from Kunststoffe 1/2015, p. 11.
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