Natural bamboo is rapidly replacing wood, but it is highly hygroscopic and has poor dimensional stability. Herein, Moso bamboo was subjected to hygrothermal treatment at different temperatures. The hydrophobicity and dimensional stability of bamboo increased, as indicated by the 16.5% decrease in volumetric swelling and three-fold increase in the contact angle at 220 °C. The fibers and parenchyma cells delaminated, and pores appeared after treatment at 200 °C. These changes were attributed to the significant degradation of hemicelluloses. The acetyl groups of hemicelluloses decomposed into acetic acid. The apparent crystallinity of cellulose increased mainly due to the reduced hemicellulose content. Furthermore, a breakage of xylan and β-O-4 bonds was observed, and S units were condensed after treatment at 220 °C. In addition, the syringyl/guaiacyl ratio showed more than a five-fold increase, while associated ferulic acid decreased after hygrothermal treatment, indicating that the dense structure of the cell walls was broken. These data were used to propose a mechanism for changes in the bamboo cell walls during hygrothermal treatment. This simple and environmentally-friendly approach holds great potential for use in high-humidity environments.

中文翻译：

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湿热处理对毛竹(Phyllostachys edulis)物理性质和化学成分的影响

天然竹正在迅速取代木材，但吸湿性强，尺寸稳定性差。在此，毛竹在不同温度下进行湿热处理。竹子的疏水性和尺寸稳定性增加，如在 220°C 时体积膨胀减少 16.5% 和接触角增加三倍所示。200℃处理后，纤维和薄壁细胞分层，出现气孔。这些变化归因于半纤维素的显着降解。半纤维素的乙酰基分解为乙酸。纤维素的表观结晶度增加主要是由于半纤维素含量降低。此外，观察到木聚糖和 β-O-4 键断裂，S 单元在 220 °C 处理后缩合。此外，紫丁香基/愈创木酰基比增加了五倍以上，而相关的阿魏酸在湿热处理后减少，表明细胞壁的致密结构被破坏。这些数据用于提出湿热处理过程中竹细胞壁变化的机制。这种简单且环保的方法在高湿度环境中具有巨大的应用潜力。