Interphase investigation in glass fibre composites by micro-thermal analysis

The micro-thermal analysis combines the advantages of both microscopy (visualisation) and thermal analysis (characterisation), with high spatial resolution. The experiment was performed on glass fibre composites based on cyanate resin matrix in order to highlight the interphase in these composites. Two types of glass fibres, which differed only by the sizing, were inserted in the resin. The subsurface distribution of the glass monofilaments can be observed into the conductivity images. Localised thermal analysis were carried out by positioning the probe over selected regions: glass monofilaments, bulk resin and interphase. The glass transition decreases from the bulk resin value to a value about 40 °C lower, for composites with sizing glass monofilaments. A less dense cross-linkage can be observed in the interfacial area.