Magnesium chloride-catalyzed modification of bamboo with 1,3-dimethylol-4,5-dihydroxyethyleneurea for enhanced dimensional stabilization

Abstract The effectiveness of 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) modification is influenced by factors such as catalyst and resin concentrations. This study systematically investigated the modification of moso bamboo with MgCl 2 -catalyzed DMDHEU resin to enhance its dimensional stability. The resin distribution, weight percentage gain (WPG), absolute dry density, moisture absorption, dimensional swelling behavior, the crystallinity, and chemical functional groups were analyzed. The results revealed that the best-performing formulation among the evaluated conditions was achieved at 3 wt% MgCl 2 and 30 wt% DMDHEU, yielding the volumetric anti-swelling efficiency of 52.7 %, the lowest moisture absorption of 7.3 %, and the most significant WPG of 3.8 %. Meanwhile, dense resin deposition was observed, completely filling and sealing the bamboo cell lumens and pits. Furthermore, ATR-FTIR and XRD analyses indicated that the modification involved chemical cross-linking between DMDHEU and bamboo cell wall polymers, reducing free hydroxyl groups, coupled with physical filling of micro-voids. These findings demonstrated that achieving synergistic chemical fixation and microstructural occlusion provided an effective strategy for producing dimensionally stable bamboo materials.