Natural fibre-based materials are gaining popularity in the composites industry, particularly for automotive structural and semi-structural applications, considering the growing interest and awareness towards sustainable product design. Surface treatment and nanofiller addition have become one of the most important aspects of improving natural fibre reinforced polymer composite performance. The novelty of this work is to examine the combined effect of fibre surface treatment with Alumina (Al₂O₃) and Magnesia (MgO) nanofillers on the mechanical (tensile, flexural, and impact) behaviour of biotex flax/PLA fibre reinforced epoxy hybrid nanocomposites. Al₂O₃ and MgO with a particle size of 50 nm were added in various weight proportions to the epoxy and flax/PLA fibre, and the composite laminates were formed using the vacuum bagging technique. The surface treatment of one set of fibres with a 5% NaOH solution was investigated for its effect on mechanical performance. The results indicate that the surface-treated reinforcement showed superior tensile, flexural, and impact properties compared to the untreated reinforcement. The addition of 3 wt. % nanofiller resulted in the best mechanical properties. SEM morphological images demonstrate various defects, including interfacial behaviour, fibre breakage, fibre pullout, voids, cracks, and agglomeration.

Natural fiber composites (NFCs) are gaining popularity in various technical sectors due to their environmental friendliness and low cost. In this study, alumina and magnesia were employed as nanofillers in various compositions of alkaline-treated and untreated jute fiber reinforced epoxy bio nanocomposites (BNCs). The synergetic effect of surface treatment and nanofillers was investigated in terms of mechanical properties (compression and interlaminar shear), water absorption behavior, and morphology of composites. Significant improvements in compressive and interlaminar shear strengths were reported, as well as a substantial decrease in the proportion of water absorbed. The optimal nanofiller concentration was observed at 3% in both alkaline-treated and untreated jute fiber-reinforced epoxy BNCs. The results demonstrate that nanofillers combined with surface treatment can significantly improve the strength and water absorption properties of jute fiber reinforced epoxy BNCs.