Effect of hybrid layer dominance on mechanical performance, moisture diffusion, and biodegradation of kenaf/pineapple leaf fiber-reinforced PLA laminated biocomposites

Abstract Hybrid natural fiber-reinforced biocomposites can be sustainable materials for lightweight engineering, but the impact of layer dominance on the multifunctional performance of such biocomposites is still poorly known. This study focused on kenaf fiber (KF) and pineapple leaf fiber (PALF)-reinforced poly lactic acid (PLA) laminated biocomposites with KF/PALF/KF and PALF/KF/PALF stacking schemes. Laminates were prepared by compression molding at a total fiber mass fraction of 30 wt% and were characterized for mechanical, morphological, moisture, biodegradation, and thermal behaviour. At the level of ultimate properties, the kenaf-dominant KF/PALF/KF laminate demonstrated the highest tensile strength (78.9 MPa) and tensile modulus (5.20 GPa), with bending (136.8 MPa, 6.8 GPa, respectively) showing that the load and the interface were well maintained. Unlike PALF-rich biocomposites, the PALF-dominant layer was more vulnerable to impact, and the highest recorded impact strength of 7.2 kJ/m 2 was the one that also absorbed more moisture, reaching approximately 17%. A soil burial experiment showed that the PALF-rich biocomposites had a fast biodegradation rate, while only 34% weight was lost in the biodegradation of the kenaf-dominant composite configuration. The results of the KF/PALF/KF thermal analysis indicate that its higher stability compared to the other configuration is attributed to lower degradation onset and peak temperatures of Tonset (291.5 °C) and Tmax (349.3 °C). The correlation between features and functions is the biggest reason for the differences in properties, as evidenced by SEM. These results prove an efficient design method for changing hybrid layer dominance to achieve the mechanical and thermal properties as well as the biodegradation performance of PLA-based biocomposites made of sustainable materials.