Development and Characterization of Biocomposites Reinforced with Silane-Treated Regenerated Bamboo–Viscose and Biomass-Derived Silica Nanoparticles

The increasing demand for sustainable engineering materials has accelerated the development of high-performance biocomposites reinforced with renewable resources. In the present investigation, hybrid epoxy biocomposites were developed using silane-treated regenerated bamboo-viscose (RBV) fibers and biomass-derived biosilica nanoparticles extracted from Manihot esculenta (cassava) tuber skins. Both the regenerated fibers and biosilica nanoparticles were surface modified using 3-aminopropyltrimethoxysilane (3-APTMS) to enhance interfacial compatibility with the epoxy matrix. Hybrid composites containing 40 vol.% RBV fiber and varying biosilica contents (05 vol.%) were fabricated through the hand lay-up technique followed by post-curing. The developed composites were characterized using tensile, flexural, compression, impact, hardness, thermal conductivity, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The results demonstrated that the incorporation of silane-treated reinforcements significantly enhanced the mechanical performance compared with neat epoxy. The composite containing 3 vol.% biosilica (MPB2) exhibited the optimum mechanical performance with tensile, flexural, compression, and impact strengths of 156 MPa, 182 MPa, 163 MPa, and 6.96 J, respectively. Thermal conductivity decreased from 0.45 to 0.27 W m K, indicating improved thermal insulation characteristics. Thermogravimetric analysis revealed enhanced thermal stability with increased degradation temperature and higher residual char formation due to the barrier effect of biosilica nanoparticles. Microstructural characterization confirmed improved fiber-matrix adhesion and homogeneous nanoparticle dispersion following silane treatment. Overall, the developed hybrid biocomposites demonstrate the synergistic benefits of regenerated bamboo-viscose fibers and biomass-derived biosilica nanoparticles, providing a sustainable alternative for lightweight structural and thermal insulation applications.