Synergistic Effects of Chemical Treatment and Hybridization to Improve Thermo‐Mechanical Performance in Banana/Pineapple Reinforced Polymer Composites

The poor compatibility of natural fibers in polymer matrix composites affects their thermal and mechanical properties, which limits their applications. The present work investigates the improvement of thermal and mechanical behaviors of banana, pineapple, and their hybrid composites through alkaline pretreatment followed by acetylation (A‐A) treatment. Different configurations of composites, namely untreated banana (UBC), treated banana (TBC), untreated pineapple (UPC), treated pineapple (TPC), untreated hybrid (UHC), and treated hybrid (THC), were fabricated. Structural, mechanical, and thermal analyses were conducted on the composite specimens. The results reveal that cellulose chain packing and hydrophobicity of treated fibers were increased for improving interfacial adhesion with the unsaturated polyester matrix. At 40 wt%, TBC, TPC, and THC showed tensile modulus improvements of 29.4%, 26.3%, and 30.2% over UBC, UPC, and UHC, respectively. However, 40 wt% of THC improved flexural, impact strength, and hardness by 43.3%, 35.7%, and 11.1% compared to UHC. The stiffness of THC increased by 47.1% and its damping capacity was higher among all cases. Subsequently, the maximum degradation temperature and yield char of THC were improved to 387.9°C and 8.2%. Finally, theoretical and experimental models were developed to assess the ultimate strength of composites and were well correlated with microscopic analysis. This study concludes that the treated hybrid composites can be used for automotive door panels, bicycle frames, sporting goods, aircraft interior panels, and lightweight structural applications.