Mert Yildirim
In this study, composites reinforced with jute fiber, false banana fiber, and hybrid jute/false banana fibers were fabricated using unsaturated polyester resin (UPR) as the matrix material via the vacuum infusion method. To examine the effects of fiber type and hybridization on density, water absorption, tensile behavior, and microstructural features, all composite samples were prepared with a fixed total fiber content of 30 wt.% and a UPR matrix content of 70 wt.%. Among the fabricated composites, the false banana fiber-reinforced polymer composite (FBFRPC) exhibited the lowest density, with a value of 1.16 g/cm3, whereas the jute fiber-reinforced polymer composite (JFRPC) showed the highest density of 1.22 g/cm3. Water absorption increased gradually with immersion time in all composite groups. After 72 h of immersion, the lowest water absorption was recorded for the JFRPC, at 5.30%, while the highest value was obtained for the FBFRPC at 6.20%. Scanning electron microscopy (SEM) analysis revealed that fiber type caused noticeable differences in fiber dispersion, resin impregnation, fiber pull-out behavior, and fiber-matrix interfacial bonding. The JFRPC demonstrated the highest tensile performance, reaching a maximum tensile stress of 51.20 MPa and a Young's modulus of 885.60 MPa. In contrast, the FBFRPC showed the lowest tensile strength but achieved the highest strain value of 7.40%, indicating greater deformation capability before fracture. Compared with the individual jute and false banana fiber composites, the hybrid jute/false banana fiber-reinforced polymer composite (JFBFRPC) provided a balanced combination of density, water absorption, microstructural characteristics, and tensile properties. Overall, the findings indicate that hybridization is an effective approach for developing lightweight unsaturated polyester composites reinforced with renewable lignocellulosic fibers for potential non-load-bearing and semi-structural applications.