Exposing the role of silica nanoparticles and fiber stacking in mechanical, water absorption, and bio-degradation behaviors of banana-papaya hybrid composites

Natural fiber composites are becoming more valuable in industries due to their eco-friendliness, high strength-to-weight ratio, and cost-effectiveness. This study aimed to develop and evaluate hybrid composites made from banana and papaya fibers, enhanced with silica nanoparticles, bonded with epoxy resin, to assess the effects of fiber layering sequence and silica content on their mechanical, water absorption, and biodegradation properties. Tri-layer composites with configurations such as BPB (Banana-Papaya-Banana) and PBP (Papaya-Banana-Papaya) were fabricated using the hand layup technique. Mechanical testing revealed that PBP composites exhibited superior tensile strength, which further improved when reinforced with silica nanoparticles (SiO2) in various concentrations. The PBP composite with 2 wt% SiO2 displayed optimal performance, showing tensile strength (83 MPa), flexural strength (104 MPa), impact strength (8.4 kJ m-2), and hardness (86 Shore-D) due to effective silica dispersion, enhancing load transfer and interfacial bonding. Thermal stability was also improved by the silica, making this composite suitable for high-temperature applications. Additionally, PBP/3 wt% SiO2 exhibited low water absorption (8% at 15 days) and minimal mass loss (14% at 60 days), highlighting its resistance to environmental degradation, which is essential for humid or marine environments. The PBP/2 wt% SiO2 composite is recommended for use in industries like automotive, manufacturing, and structural engineering, where its high mechanical properties, durability, and eco-friendliness make it a promising alternative to synthetic composites, thus supporting sustainable practices.