Effect of maleic-anhydride grafting on the properties of flax reinforced polypropylene textile composites

The use of maleic anhydride (MA) coupling agent in polypropylene (PP) matrix system is promising technique to enhance the fibre-matrix interface in composite applications. However, most of the previous studies are focused on either treatment of the natural fibres or the PP matrix with this coupling agent, which are not commercially viable. In this work, a cost-effective technique “hybrid yarns” was used to manufacture commingled reinforcing flax fibres and MA-grafted PP matrix fibres. Two types of twist-less flax/PP and flax/MAPP hybrid yarns were produced containing 40% flax and 60% matrix fibres by volume. Both PP and MAPP fibres were thermally and rheologically characterised using DSC, MFI, TGA, DTA and capillary rheometer. It is found that the composites manufactured from flax/MAPP blends exhibited 15% higher strength and 25% higher modulus compared to those made of flax/PP. This was due to the improved flax/matrix interface, the higher melt flow rate and lower share viscosity behaviour of the MAPP matrix fibres compared to the standard PP fibres used.