Eco-friendly composite engineering: optimising tensile properties of Flax/Kenaf composites with mineral additives for lightweight structural use

This study optimises and characterises hybrid polymer composites reinforced with flax and kenaf fibres and mineral additives for lightweight structural applications. Using response surface methodology, the effects of fibre content and additive type (Al(OH)3, Mg(OH)2, talc) on tensile strength, yield strength, and elongation were systematically analyzed. The resulting quadratic models showed high predictive accuracy, confirmed by strong coefficients of determination (R² values above 0.9) and highly significant ANOVA results (model p-values < 0.005 and F-values > 15), along with a non-significant lack-of-fit. Kenaf fibre was a dominant factor in improving strength at the expense of ductility, while Flax fibre contributed more evenly to strength and flexibility. Talc was found to reduce mechanical strength and was excluded from the final optimised formulation. Fractography and FTIR analysis confirmed strong fibre – matrix adhesion and successful additive integration. This study provides a practical framework for designing sustainable, high-performance composites for automotive and construction sectors.