Adhesion and surface modification

This review emphasizes the role of interactions in particulate filled compo sites. In an introductory section a general view is given about the factors influencing composite properties. Two basic type of interactions must be c onsidered: particle/particle and matrix/filler interaction. The effect of t he former is detrimental to composite properties, it decreases strength and impact resistance. The occurrence and extent of aggregation is determined by the relative adhesion and shear forces during homogenization. Due to mat rix/filler interaction an interphase forms spontaneously in the composite w ith properties different from those of both components. The amount and char acteristics of the interphase strongly influence composite properties. The strength of adhesion between the components can be characterized by thermod ynamic quantities, mainly by the reversible work of adhesion. The most impo rtant techniques used for the estimation of the strength of interaction and the properties of the interphase are briefly reviewed. The modification of interactions is achieved through the surface treatment of the filler. Surf ace treatments are divided into four arbitrary groups and are discussed acc ordingly, i.e. non-reactive and reactive treatment, application of function alized polymers and introduction of a soft interlayer around the particles. The practical relevance of interactions and their modification is also men tioned in the last section.