The Manifold Interactions of ZnO and Stearic Acid in a Modern Silica-filled Tire Tread Compound

Abstract

Zink oxide and stearic acid are commonly used in typical sulfur-cured rubber compounds. Their role as activators is well recognized. But how manifold the interactions in a silica-filled rubber application are, will be discussed in this paper. A special emphasis is put on the “ideal” ratio between ZnO and stearic acid in a rubber compound. It is concluded that the formation of the active Zn-complex takes place only at the surface of the ZnO crystal, most of the ZnO remains unreacted in the rubber matrix.