Laminating Delignified Wood Veneers toward High-Strength, Flame-Retardant Composites for Structural Applications

Developing a high-strength, flame-resistant structural material derived from wood is desirable for advanced applications in the transportation, construction, automotive, and aerospace sectors. Here, a low-cost and high-efficiency top-down method was designed for processing natural wood veneers into lightweight yet strong bulk structural wood-based composites. The composites were produced using delignified wood veneers as a continuous reinforcing material and epoxy resin as the adhesive, followed by hot pressing. Densification of the veneers and good adhesion among the veneers played a pivotal role in the mechanical performance of the composites. A record-high flexural strength of 436.1 MPa and a toughness of 12.3 MJ·m^–3 were achieved. Furthermore, the low density of the wood composite led to a specific flexural strength of 323.0 MPa·cm³·g^–1, which is significantly greater than those reported for other wood-based composites and some metal materials (e.g., steels and alloys). We also explored the feasibility of using the composite in unmanned drones. In addition, the delignified wood veneers were infiltrated with 1.5% ammonium polyphosphate (APP), which improved the fire-retardant and self-extinguishing properties of the composites. This work demonstrates that high-strength wood products exhibit significant potential in many applications.