Mechanical properties of short-flax-fibre reinforced compounds

The mechanical properties of flax/polypropylene compounds, manufactured both with a batch kneading and an extrusion process were determined and compared with the properties of Natural fibre Mat Thermoplastic (NMT) composites. The fibre length and width distributions of the fibres from the compounds were determined and used to model the expected properties of the materials, which led to reasonable predictions of the interfacial shear stress. It was found that, given their mechanical properties, flax fibres are quite effective in improving strength and stiffness of a compound and effective compatibilisation of the fibre/matrix interphase can be easily reached. The most important factor limiting the properties of the compounds lies in the intricate structure of the fibres themselves, after the interfacial strength is optimised, the internal fibre structure becomes the weakest point.