Surface layer reinforcement modification for wood with high strength and flame retardancy performances

• Published in: Construction & building materials 2024-11, Vol.450, p.138672, Article 138672
• Main Authors: Tan, Ke, Wang, Yong, Li, Xiazhen, Mou, Qunying, Deng, Layun, Peng, Jian, Li, Xianjun
• Format: Article
• Language: English
• Subjects: High value-added; Modification; Poplar wood; Sandwich structure; Structural application; Surface layer reinforcement
• ISSN: 0950-0618
• DOI: 10.1016/j.conbuildmat.2024.138672

The high-value utilization of low-value wood can effectively address the shortage of wood resource, while also contributing to the global green sustainable development and the implementation of “dual carbon” strategy. The present study employed an innovative technology to achieve controllable surface reinforcement modification of fast-growing poplar wood, resulting in improved strength and exceptional flame retardancy for structural applications. The achievement was realized through a three-step method, involving delignification, impregnation, and surface densification, while minimizing the loss of wood volume. The results demonstrated that surface functional densification can significantly improve the mechanical properties of fast-growing poplar wood, with the modulus of rupture (MOR) and modulus of elasticity (MOE) reaching 140.6 MPa and 11.8 GPa, respectively, representing a 3.4-fold and 2.5-fold increase compared to the control group (CK). The samples were found to possess thin surface-densified layers, while the core layer remained unaltered, thereby exhibiting a sandwich structure with significant disparity in density between the layers, reaching up to a factor of 2. The pores structure of the surface layers underwent significant densification, with a gradual deformation distributed throughout its thickness direction. A process optimized for surface densification involving a 2-hour delignification duration and a pressure of 3 MPa. The sample subjected to surface functional modification exhibited a 90-second delay in the peak of heat release compared with the CK. The heat release rate (HRR) experienced a significant deceleration, accompanied by notable reductions in total heat release (THR) and smoke production rate (SPR). The mechanisms underlying the enhancement of surface functionality were elucidated from the perspectives of physical mechanics, microstructure, and flame retardancy, providing a theoretical foundation for the efficient utilization of fast-growing wood. •The successful realization of structural utilization for fast-growing poplar wood was achieved.•A surface layer modification was achieved through a straightforward three-step treatment.•An optimized process was proposed for surface densification treatment.•The mechanisms of surface layer reinforcement was proposed.