The effect of alkali treatment on the adhesion characteristics of sisal fibres

The effect of alkali treatment on the wetting ability and coherence of sisal-epoxy composites has been examined. Treatment of sisal fibre in a 0.5N solution of sodium hydroxide, resulted into more rigid composites with lower porosity and hence higher density. The treatment has been shown to improve the adhesion characteristics, due to improved work of adhesion because it increases the surface tension and surface roughness. The resulting composites showed improvements in the compressive strength and water resistance. It has been suggested that the removal of intracrystalline and intercrystalline lignin and other surface waxy substances by the alkali substantially increases the possibility for mechanical interlocking and chemical bonding. The alkali treatment is simple and is recommended to precede other sophisticated surface modification treatments on plant fibres similar to sisal fibre.