The dimensional stabilisation of wood using thermosetting resins relies on the resin uptake into the cell walls. This study tested if a conditioning step after the impregnation and before the final heat-curing enhances the cell wall uptake to improve dimensional stabilisation without increasing the chemical consumption. Small blocks of Scots pine sapwood were vacuum-impregnated with an aqueous melamine formaldehyde solution and conditioned at 33, 70, or 95 % RH for up to 1 week before drying and curing the blocks at 103 °C. However, the conditioning step decreased the cell wall bulking and the moisture exclusion effect compared to the immediate heat curing of the impregnated samples. Analyses of the resin-treated samples by scanning electron microscopy, IR spectroscopy and confocal Raman microspectroscopy provided evidence of wood hydrolysis and polycondensation of the resin within the cell lumen during the conditioning step. Hydrolysis and removal of wood constituents may have counterbalanced the cell wall bulking of the resin. Polycondensation of the resin in the lumen increased its molecule size, which could have hindered the cell wall diffusion of the resin.

中文翻译：

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用三聚氰胺甲醛树脂处理木材过程中的调节步骤对尺寸稳定性的影响

使用热固性树脂的木材的尺寸稳定性依赖于树脂对细胞壁的吸收。这项研究测试了浸渍之后和最终热固化之前的调节步骤是否可以增强细胞壁的吸收，从而在不增加化学品消耗的情况下提高尺寸稳定性。将小块欧洲赤松边材用三聚氰胺甲醛水溶液真空浸渍，并在 33%、70% 或 95% 相对湿度下调节长达 1 周，然后在 103°C 下干燥和固化。然而，与浸渍样品的立即热固化相比，调节步骤降低了细胞壁膨胀和防潮效果。通过扫描电子显微镜、红外光谱和共焦拉曼显微光谱对树脂处理的样品进行分析，提供了在调节步骤期间木材水解和细胞腔内树脂缩聚的证据。木材成分的水解和去除可能抵消了树脂细胞壁的膨胀。树脂在管腔中的缩聚增加了其分子尺寸，这可能阻碍树脂的细胞壁扩散。