Depending on the type of shoe, soles need to be extremely robust, elastic, slip resistant on dry or wet ground, or offer enhanced traction properties. ULTRASIL® and AEROSIL® silica made by Evonik are versatile reinforcement fillers for rubber compounds, enabling manufacturers to achieve the desired effect. Since polar silica is not compatible with non-polar rubber, it must be combined with silanes. DYNASYLAN® made by Evonik acts as an adhesion promoter, enabling silica and rubber to form chemical bonds. The Silica/Silane-system optimizes the strength, elasticity, and temperature behavior of shoe soles and reduces abrasion. Another advantage is that this filler system allows modern designs such as colored and translucent soles. Evonik also offers innovative VOC-free silanes that do not release ethanol during processing and are therefore considered harmless to health.