Effects of deep eutectic solvents pretreatment on performance of surface mineralized wood

Objective In order to solve the problems of difficult penetration and less mineralization sites in wood mineralization modification, deep eutectic solvent (DES) pretreatment was used to open the penetration channel and construct active sites of fast-growing poplar, and the effects of DES pretreatment on the properties of surface mineralized wood were studied.

Method Poplar wood was pretreated with DES to construct mineralization sites, and SiO₂ was induced to realize in-situ mineralization on the wood surface. Then surface mineralized wood was prepared by hot pressing. The effects of DES pretreatment on physical and mechanical properties of surface mineralized wood were analyzed. Surface-mineralized wood was prepared under optimal conditions, and its microstructure morphology and thermal properties were analyzed.

Result (1) The density, mass gain rate and surface hardness of surface mineralized wood increased at first and then decreased with the increase of DES pretreatment time, and increased by 35.25%, 16.35% and 51.53%, respectively when pretreated for 2 h compared with untreated wood. The hydrophobicity of surface mineralized wood was greatly improved, and the initial contact angle increased by 74.08% after 0.5 h pretreatment. (2) DES pretreatment can significantly improve the mechanical properties of surface mineralized wood. When DES pretreatment time was 2 h, the modulus of rupture and elasticity of surface mineralized wood increased by 20.53% and 214.55%, respectively. (3) The surface mineralization treatment introduced SiO₂ into the wood to form an organic-inorganic hybrid structure, which improved the fire resistance of wood. When the surface mineralized wood was pretreated for 2 h, the mass residual ratio of the surface mineralized wood increased by 70.81% compared with the untreated wood, and the heat release rate reduced by 69.9 kW/m², and the total heat release reduced by 27.3 MJ/m².

Conclusion After DES pretreatment and surface mineralization, the physical and mechanical properties of fast-growing poplar are improved, and the thermal stability and fire resistant properties are good.