Fe₃O₄ nano particles filled densified bamboo with improved strength, fracture toughness, fire and water resistance

Natural bamboo has potential as a sustainable alternative to petroleum-based lightweight materials. However, its sensitivity to environmental conditions limits its usage. Here, we improved the traditional alkali treatment densification process by innovatively transporting Fe₃O₄ nanoparticles (NPs) into the interior of natural bamboo without any carriers. Fe₃O₄ NPs decorated densified bamboo exhibited a tensile strength of 401.8 MPa and an extraordinary flexural strength of 429.1 MPa, over 300% higher than natural bamboo. Fracture toughness reached a record 14.91 MJ m⁻³, more than five times that of natural bamboo. Real-time acoustic emission (AE) analysis revealed that Fe₃O₄ NPs played a pivotal role in the formation and reinforcement of interlocking structures. Furthermore, the strategy alleviates the deleterious impacts of water on bamboo, simultaneously bolstering its underwater mechanical stability and substantially enhancing its flame-retardant characteristics. This research provides valuable insights into reinforcing porous materials, facilitating the use of sustainable bamboo in high-performance applications.