Enhancing the thermal stability, water repellency, and flame retardancy of wood treated with succinic anhydride and melamine-urea-formaldehyde resins

The flame retardancy and dimensional stability of wood were improved by pretreating wood with succinic anhydride (SA), and then impregnating the SA-treated wood with melamine-urea-formaldehyde (MUF) resin. The SA-treated wood obtained graft anchors on the cell wall, which reduced the water-absorbing groups of wood and enhanced the retention of the MUF resin, leading to an efficiently fire-proof protection layer and water repellency. Field-emission scanning electron microscopy and Fourier-transform infrared spectroscopy demonstrated that the grafting experiment was successful. The water repellency experiments revealed that the pretreated wood impregnated with MUF resin had enhanced hydrophobicity and great improvement in dimensional stability. In addition, the limiting oxygen index value of the modified wood increased by 74%, the flame-retardant performance was improved, and precious rescue time was provided for when a fire occurs. The facile two-step wood modification process substantially enhanced the thermal stability, water repellency, and fire-retardant performance of wood, and therefore represents a novel direction toward hydrophobic and fire-retardant structural materials.