Modification of poplar (Populus adenopoda Maxim) wood by using maltodextrin (MA) combined with 1,3-dimethylol-4,5-dihydroxyethyleneurea (DM) resin was investigated in this study. The weight percent gain, dimensional stability, mechanical strength, and microscopic chemical change were determined before and after impregnation. Results indicated that the composite modifier was impregnated into the wood cell lumen, as verified by scanning electron microscopy and a change in weight percent gain. Anti-swelling efficiency was significantly improved compared with the untreated sample; however, the sample treated with MA obtained an anti-swelling efficiency that was slightly lower than that of the sample treated with sucrose. The flexural strength, flexural modulus, and compressive strength perpendicular to the grain increased with an increase in MA concentration, but the compressive modulus and impact strength were reduced. Fourier-transform infrared spectroscopy demonstrated that MA delayed the cross-linking of the DM resin cell wall, and X-ray diffraction analysis showed that the crystallinity of the cellulose crystalline region was reduced to a certain extent. In general, the poplar wood treated with combined MA and DM resin exhibited enhanced properties relative to those of the poplar wood treated with sucrose.

The impregnation of poplar wood (Populus adenopoda Maxim) with 1,3-dimethylol-4,5-dihydroxyethyleneurea and maltodextrin and the effects of ZnCl₂ and curing at 103 °C and 120 °C on the fixation rate and the leaching resistance of modified samples were investigated (103 °C curing, ZnCl₂ + 103 °C curing, 120 °C curing, and ZnCl₂ + 120 °C curing are denoted as 103, ZC-103, 120, and ZC-120, respectively), with the aim of improving the modification effect. The results showed that ZC-103 had the highest fixation rate, and its weight leaching ratio was higher than that of 120. Fourier-transform infrared spectroscopy showed that ZnCl₂ did not affect the functional groups of the modified chemicals. The flexural strength and modulus and the compressive strength perpendicular to the grain were highest for ZC-103. In summary, ZC-103 exhibited the highest fixation rate, indicating that the hardener ZnCl₂ bridged and increased the interfacial properties between the chemicals and cell walls and therefore increased the potential for macromolecule polycondensation between the chemicals and cell wall materials. This research paves the way for improving the fixation rate of impregnated wood and provides new insights into practical applications.

The drying characteristics of poplar wood (Populus adenopoda Maxim) under three treatments were investigated with the aim of improving the drying quality of the impregnated wood. Untreated materials, impregnated materials with 10% initial moisture content (MC), and impregnated materials with 20% initial MC—denoted as T1, T2, and T3, respectively—were examined during conventional drying. Relative to that of T1, the average drying rate of T2 was reduced by 46%, and that of T3 was reduced by 37%. The anti-swelling efficiency of T2 sharply increased, whereas that of T3 only slightly increased in width and thickness. The drying defects of T2 were markedly less than those of T1 and T3, attributed to the reduced residual stress and fixation of the modifier. Scanning electron microscopy indicated that large amounts of modifiers were deposited inside the cell cavity of T2, whereas small amounts of modifiers were deposited in the cell cavity of T3. The impregnation treatment generally reduced the average drying rate and MC uniformity and delayed the decrease in residual stress; however, it reduced the number of defects in the wood and considerably improved the dimensional stability of the wood. Meanwhile, impregnation treatment with increased initial MC could potentially lead to more drying defects and increase production cost.