High-Strength and Flame-Retardant Bamboo Fiber/Waterborne Epoxy Resin Green Composites: Comparison of Different In Situ Mineralization Pathways

Abstract To achieve functional applications of bamboo fiber (BF) composites, this study innovatively proposed a multi-pathway biomineralization strategy inspired by biomimetic mineralization techniques. It successfully achieved in situ mineralization of calcium carbonate (CaCO3), calcium oxalate (CaC2O4), and calcium phytate (PA-Ca) on delignified BF, and further prepared inorganic-organic hybrid composites by combining them with waterborne epoxy resin (WEP). The results demonstrate that compared to unmodified composites, the biomimetic mineralization strategy successfully achieves synergistic improvements in flame retardancy, mechanical properties, and dimensional stability. However, the three mineralization pathways exhibit distinct emphases in enhancing material performance: the CaC2O4 mineralized composites demonstrate the most outstanding flame retardancy and smoke suppression properties, achieving a limiting oxygen index (LOI) of 27.8% and significantly reducing heat release and smoke emission rates. The CaCO3 mineralized composites demonstrate superior mechanical reinforcement, with flexural strength increasing by 37%. The PA-Ca mineralized composites exhibit particularly remarkable water resistance improvement, reducing water absorption by 41%. This study confirms that targeted optimization of composites properties can be achieved by selecting specific mineralization pathways, offering an approach for preparing high-performance, eco-friendly flame-retardant biomass composites.