Experimental and Numerical Investigation of the Mechanical Properties of Compression‐Molded Alkali‐Treated Sisal/False Banana Fiber‐Reinforced Polymer Composites

ABSTRACT Natural fiber‐reinforced polymer composites are increasingly recognized as sustainable alternatives to synthetic composites due to their low density, renewability, and reduced environmental impact. In this study, alkali‐treated hybrid sisal/false banana fibers were used to reinforce a polyester resin matrix. The fibers were chemically modified via 5 wt.% NaOH alkali treatment to enhance fiber–matrix interfacial bonding. Composite laminates were fabricated using compression molding, and their tensile, flexural, and impact behaviors were experimentally evaluated for the designed hybrid configurations according to ASTM standards. Water absorption tests were conducted to evaluate the environmental durability, and finite element analysis was performed to simulate the tensile and flexural responses and validate the experimental results. The alkali‐treated hybrid composites exhibited significantly improved interfacial adhesion, resulting in tensile strengths of 13.67 ± 5.69 MPa (HYB‐AT‐1), 47.00 ± 12.17 MPa (HYB‐AT‐2), and 35.33 ± 3.21 MPa (HYB‐AT‐3); flexural strengths of 127.67 ± 5.25, 112.00 ± 4.00, and 117.67 ± 8.33 MPa; and impact strengths of 2.78 ± 0.05, 2.54 ± 0.53, and 5.31 ± 1.68 J for HYB‐AT‐1, HYB‐AT‐2, and HYB‐AT‐3, respectively. Among the hybrid configurations, HYB‐AT‐1 exhibited a flexural‐dominant performance profile, combining the highest flexural strength with moderate tensile and impact resistance and relatively low water absorption, indicating enhanced bending performance and environmental durability. HYB‐AT‐2 confirmed superior tensile strength, whereas HYB‐AT‐3 presented the highest impact resistance, reflecting the strong influence of fiber composition on property‐specific performance optimization. Good agreement between experimental and numerical results confirmed the reliability of the developed finite element model. These findings show that alkali‐treated hybrid sisal/false banana fiber composites can be tailored to achieve application‐specific performance, making them promising candidates for lightweight structural and semi‐structural applications.