Improvement Of Mechanical Properties Due To Increased Fibre Matrix Adhesion In Flax Fibre Reinforced Polypropylene

The hydrophilic nature of natural fibres and the hydrophobic behaviour of standard polymers such as polypropylene and other polyolefins are the major cause for the lack of adhesion between fibre and matrix in natural fibre reinforced plastics (NFRP's). To overcome this incompatibility of fibre and matrix, different coupling agents can be incorporated into the compound. Our investigations revealed the bonding capability of three dendritic polyesters and one thermoplastic polyurethane in a flax fibre/PP compound. The treatment with different amounts of coupling agent led to an increase in mechanical properties such as bending strength, tensile strength and most of all CHARPY impact strength. In addition, it was possible to make a correlation between IR spectra and the chemical and physical interactions between fibre, matrix and adhesive. Therefore a relationship between intermolecular forces and mechanical properties could be concluded.