Mechanical properties of flax fibre/polypropylene composites. Influence of fibre/matrix modification and glass fibre hybridization

The effect of fibre treatments and matrix modification on mechanical properties of flax fibre bundle/polypropylene composites was investigated. Treatments using chemicals such as maleic anhydride, vinyltrimethoxy silane, maleic anhydride-polypropylene copolymer and also fibre alkalization were carried out in order to modify the interfacial bonding between fibre bundles and polymeric matrix. Composites were produced by employing two compounding ways: internal mixing and extrusion. Mechanical behaviour of both flax fibre bundle and hybrid glass/flax fibre bundle composites was studied. Fracture surfaces were investigated by scanning electron microscopy. Results suggest that matrix modification led to better mechanical performance than fibre surface modification. A relevant fact is that silanes or MA grafted onto PP matrix lead to mechanical properties of composites even better than those for MAPP modification, and close to those for glass fibre/PP.