Are microcomposites realistic models of the fibre/matrix interface? I. Micromechanical modelling

The ability of the microbond technique to characterise changes in the physi co-chemical structure of the interface between fibre and matrix has been ch ecked using eight epoxyde/glass fibre systems differing by their matrix che mistry, fibre surface treatments, and fibre diameter. It has been shown tha t the widely used average IFSS method can lead to biased results. The test is now considered as giving mode I or mixed-mode properties of the interfac e and not only a mode II interfacial toughness or interfacial shear strengt h (IFSS). Energy approaches are thus be preferred to stress criterion model s. The suitability of six theoretical models was checked. Difficulties were found in determining a parameter or method effectively representative of t he physico-chemical structure of the interface. The model providing the mos t reliable results was that of Scheer and Nairn. Significant plastic flow o f the polymeric droplet was observed, leading to a questioning of the hypot heses of ideal elastic components. (C) 2001 Elsevier Science Ltd. All right s reserved.