Preparation and Study of a Waste Corrugated Cardboard Fiber‐Based Foamed Material With Good Hydrophobicity and Flame‐Retardant Properties

ABSTRACT With environmental regulations becoming increasingly stringent, the application of traditional petroleum‐based foam cushioning materials is significantly constrained. Consequently, biodegradable biomass foams demonstrating exceptional cushioning performance have garnered significant scientific attention. This study innovatively employs waste corrugated cardboard as raw material to fabricate biomass foams through a microwave‐assisted foaming technique, systematically investigating the synergistic effects of fiber silane modification and kaolin doping on material performance. Characterization results revealed that the optimized foam achieved a maximum compressive stress of 0.53 MPa at 50% strain, with water absorption reduced by 20.1%. Combustion tests demonstrated superior thermal stability, exhibiting a 34.7% increase in limiting oxygen index compared with conventional counterparts. In summary, the silanization modification synergizes with kaolin to enhance char layer stability through chemical bonding and catalyzed carbonization, forming a multi‐level flame retardant system. This synergy also improves the compatibility between fibers and fillers while significantly boosting the material's hydrophobic properties, thereby substantially increasing its safety and practicality. This work presents a sustainable strategy for upcycling packaging waste into high‐performance functional materials, offering groundbreaking insights for developing next‐generation eco‐friendly cushioning solutions with dual moisture resistance and fire safety characteristics. The proposed methodology shows considerable potential for industrial translation in green packaging applications.