ABSTRACT
Abstract-Silanes are often used as coupling agents in different kinds of composite materials. The performance of a silane is influenced by the other sizing components, storage conditions of the sized material and processing conditions of the final products. Electrokinetic investigations reflect changes in the chemical and physical properties at the outermost solid surfaces very sensitively and help to distinguish between dissociation and adsorption processes at the solid surface. In this way, functional groups at the outermost layer are characterized and the effectiveness of the coupling agent used is determined. Streaming potential measurements are especially suited for studying such changes in the surface chemistry of solids with different shapes. In this paper we discuss the influences of the basic material, storage conditions, other sizing components and the matrix material on the effectiveness of the silanes. It was shown that the adsorption processes of different sizing components were determined by competitive reactions. A cylindrical cell was used for investigation of the fibre and powder substrate materials.
