ROLE OF THE INTERMOLECULAR DISTANCE AT TH E FIBER-MATRIX INTERFACE INMODEL COMPOSITES

In a previous study concerning fibre-matrix junctions in single-fibre composites, a linear relationship had been established between the int erfacial shear strength tau and the reversible adhesion energy W at th e interface. In the present study, the validity of such a relationship is examined from a theoretical point of view. It appears that its mat hematical form is entirely justified in terms of static friction and, thus, tau can be considered as the resistance, due to the existence of molecular interactions, to the interfacial slipping between both mate rials. The most important parameter in this approach appears to be the equilibrium intermolecular distance lambda at the interface. It is sh own, in good agreement with results available in the literature, that lambda decreases when the work of adhesion increases, in particular wh en strong acid-base interactions are involved at the interface.