An organic-inorganic dual network built in fast-growing wood veneers to improve the flame retardant and mechanical properties of plywood

Fast-growing wood is widely used in plywood production due to its short growth cycle and low cost. However, its loose fiber structure, inferior material quality, and high flammability significantly limit the application range of plywood products and hinder high-value utilization. This paper reports a simple method for modifying fast-growing wood veneers. We modified phenolic resin with Mg(OH)₂@nano-silica composite particles and impregnated it into the veneers, constructing an organic-inorganic hybrid dual-network structure on both the surface and interior of the veneers. The plywood prepared from the modified veneers exhibited a bending strength of 115.6 MPa, a modulus of elasticity of 9.7 GPa, and a wet shear strength of 2.1 MPa, representing increases of 86.1 %, 47.0 %, and 90.9 %, respectively, compared to plywood made from unmodified veneers. Additionally, the peak heat release rate decreased by 15.3 %, and the ignition time was extended to 26 s. The uniformly distributed inorganic network effectively mitigated stress concentration and, together with the phenolic resin, formed an efficient thermal insulation layer, enhancing the flame retardancy of the material. This study offers a simple and effective treatment method for reinforcing fast-growing wood veneers, promoting the use of fast-growing wood in high-performance applications.