SOME PHYSICOCHEMICAL ASPECTS OF THE FIBER-MATRIX INTERPHASE IN COMPOSITE-MATERIALS

This paper deals with the influence of interphase formation on the str ess transfer capacity of the fibre-matrix interface in single fibre co mposites and constitutes a brief review of our recent work. This influ ence is studied through the deviation of the experimental results from a recent theoretical analysis relating the interfacial shear strength to the reversible work of adhesion established between the fibre and the matrix. Two examples of interphases are considered: a transcrystal line layer in carbon fibre-PEEK composites and a pseudo-glassy interph ase in carbon fibre-elastomer systems. In the former case, the low tra nsverse mechanical properties of the transcrystalline layer lead to a decrease of the interfacial shear strength, whereas, in the latter cas e, the glassy behaviour of the interphase explains the improved interf acial stress transfer capacity.