A QUANTITATIVE EVALUATION OF THE INTERFACE OF FLAX FIBRE COMPOSITES THROUGH MICRODROPLET TESTS

摘要

Several fibre modifications based on silane treatments are carried out to optimise the interface quality of flax-epoxy composites. Their effect on the interface strength is evaluated by the microdroplet pull-out technique and transverse three-point bending. An apparent interface strength of (23±7) MPa for untreated flax-epoxy composites is recorded during microdroplet tests, which is according to literature. Although the scatter on the results can be quite large with this type of micromechanical experiments, certain silane treatments cause a significant loss up to 0.25 of the untreated values. Transverse three point bending results seem to support these findings. Remarkably, mildly treated fibres provide an increase of almost 50 % on the transverse composite performance, while the microdroplet strength of the composites reinforced with these fibres is considerably lower. Furthermore, scanning microscope studies on the fracture surfaces of the composite specimens support the measurements of the transverse bending tests.