New Balance sneakers have more cushion for the pushin' thanks to DuPont's, Wilmington, Del., Hytrel thermoplastic polyester elastomer. The material forms an advanced heel-cushioning system that promises lasting resiliency. At the heart of the N-ergy S.C. System, from New Balance Athletic Shoe Inc., is a hollow component blow-molded from Hytrel. The part compresses on impact, absorbing shock and rebounding to its original shape after every heel strike. "The resiliency of Hytrel helps achieve a responsive, springy feel," says Sean Murphy, advanced products engineer at New Balance. "And the material keeps its resiliency with repetitive impact."
The elastomer material has low compression set and flex-fatigue resistance. The heel cartridge is a two-chamber design with a stabilizing outer rim providing motion control and support, and an elliptical center section that adds responsive cushioning.