Performance Evaluation of Hybrid Kenaf–Pineapple Leaf–Flax Fiber Reinforced Vinyl Ester Composites: Mechanical and Thermal Characteristics for Diverse Engineering Prototype Applications

In this work, hybrid natural fiber reinforced vinyl ester composites made of pineapple leaf fiber (PALF), Flax fiber (FF), and kenaf fiber (KF) are examined for their mechanical, thermal, and moisture-absorption properties. With various fiber ratios but a constant total fiber loading of 50 wt. %, six hybrid configurations were fabricated. Balanced fiber distribution that improved interfacial bonding and stress transfer allowed HC6(20KF/20PALF/10FF) to attain the maximum tensile (73.67 MPa) and flexural strength (187.31 MPa), according to mechanical characterization. Instead, HC4 had the best impact strength (15 kJ/m²) and hardness (93 Shore-D) which signifies higher energy absorption with a higher PALF and FF content. HC6 composite demonstrated the greatest modulus efficiency factor (η 6 = 0.37), which is a reflection of high reinforcement efficiency and interfacial quality, which is congruent with the SEM and FTIR results. Further Thermogravimetric analysis showed a high level of thermal stability, where degradation started above 290°C and a residual mass at 750 ^o C was 6.7%. On the whole, the results indicate that surface modification and synergistic hybridization of PALF, KF, and FF fibers significantly enhance the strength, durability, and heat resistance and can be used in structural and automotive applications.