Fatigue and impact strengths of kenaf fibre reinforced polypropylene composites: effects of fibre treatments

The effects of two fibre treatments (alkali-alone treatment and combined alkali-silane treatment) on the fatigue and impact strengths of kenaf fibre reinforced polypropylene composites are investigated. Test results showed that fibre treatments improve the fatigue and impact strengths of the composites, with alkali-silane treatment being the most effective one. Alkali concentration of 5% to 6% is found to be the optimal concentration for both alkali-alone and combined alkali-silane treatments. Microscopy examination revealed that the damage mechanisms of the composites are significantly influenced by the fibre treatment. The failure modes of alkali-alone treated kenaf/PP composites are predominantly characterized by fibre pull-outs, suggesting poor fibre-matrix adhesion; whereas the failure modes of alkali-silane treated kenaf/PP composites are characterised by fibre breakage and matrix cracks indicating improved fibre-matrix adhesion due to the additional silane treatment.