Abstract
The aim of this study was to relate the results of different surface characterisation methods, applied to treated and sized carbon fibres, to measurements of the interfacial shear strength. The latter were carried out by microdroplet debonding tests using a vinyl ester hybrid (VEH) system as the surrounding matrix. Further correlations were made to the interfacial failure modes detected by scanning electron microscopy. In a first stage, the surface free energies of single filaments were determined. This was followed by atomic force microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy, providing information about the quality and the quantity of the sizing. Besides the microdroplet tests, another testing method, using fibre bundles embedded in a VEH tensile bar, was used to measure fibre-matrix adhesion comparatively and to verify the interfacial failure mechanisms. This ‘microcomparative' model test seems to be suitable for obtaining interface dependent data in combination with ease of specimen preparation.
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