Processing structure property relationship of flax/hemp/glass hybrid laminates: multifactor effects of TiO₂, SiC, and fiber sequencing on mechanical and thermal performance

This study investigates the mechanical, moisture resistance, and thermal behavior of hybrid flax/hemp/glass fiber reinforced epoxy composites incorporated with TiO₂ and SiC nanoparticles.
The composites were fabricated using compression molding with different stacking sequences and varying nanofiller contents to evaluate their influence on tensile strength, flexural strength, microhardness, fracture toughness, water absorption, and thermal stability. The results indicate that both fiber stacking configuration and hybrid nanoparticle reinforcement significantly influence the performance of the composites. Among the tested configurations, the Sequence-3 laminate containing 2 wt. % SiC and 3 wt. % TiO₂ exhibited the best overall performance. Compared with the baseline composite, this optimized structure demonstrated a 33% increase in tensile strength, 18% improvement in flexural strength, 22% enhancement in microhardness, and 9% increase in fracture toughness, indicating improved load transfer and crack resistance. In addition, the incorporation of hybrid nanoparticles reduced water absorption by approximately 18%, enhancing moisture resistance of the composite system. Thermogravimetric analysis further confirmed improved thermal stability, with delayed degradation temperatures attributed to the barrier effect and strong interfacial bonding provided by SiC and TiO₂ nanoparticles. Overall, the synergistic interaction between hybrid fibers and nanofillers significantly improves the structural, thermal, and environmental performance of the composites, demonstrating their potential as sustainable lightweight materials for advanced engineering and structural applications.