Enhanced properties of the inner part of date palm wood through double-stage treatment: synergistic effects of low-viscosity melamine–formaldehyde resin impregnation and densification

Abstract This study investigates the enhancement of the physical and mechanical properties of date palm wood ( Phoenix dactylifera ) through a two-stage treatment process. This process involves impregnation with low-viscosity melamine–formaldehyde (MF) resin, followed by densification. The goal is to address the inherent weaknesses of palm wood and explore its potential for high-value applications. Wood samples were treated with different resin concentrations 5, 10, and 25% (wt. %) and subjected to a 50% compression ratio. Physical properties such as density, water absorption, and thickness swelling were evaluated, while mechanical tests included bending strength (MOR), stiffness (MOE), impact resistance, and screw-holding capacity (SHC). Additionally, formaldehyde emissions were measured to assess environmental impact. Key findings revealed significant improvements in both physical and mechanical properties. Density increased nearly fourfold in the most intensively treated samples, while water absorption and thickness swelling were significantly reduced, indicating improved dimensional stability. Mechanical properties showed substantial enhancements, with MOR improving by 241%, MOE by 136.36%, and SHC by 114%. Notably, formaldehyde emissions were low, thus meeting the emission limits specified in the Chinese National Standard GB/T 17657. The combination of impregnation and densification demonstrated synergistic effects, often outperforming single treatments. These findings suggest that the proposed treatment method offers a promising approach to valorizing date palm waste, potentially addressing environmental concerns while creating high-performance, environmentally friendly wood products suitable for various applications. This study contributes valuable insights to the field of wood modification, opening new possibilities for utilizing date palm wood in industries requiring materials with enhanced strength and dimensional stability. Graphical Abstract