This work investigated the physicochemical properties of Chinese fir after ultrasound-assisted pretreatments with borax and sodium hydroxide additives in an aqueous solution. TGA, FTIR, and XRD were used to analyze the thermal degradation processes, changes in chemical structures, and crystallinity of the treated samples, respectively. Additionally, the release of volatiles from wood pyrolysis was measured on-line by the TG-FTIR apparatus. In thermal analysis, all samples showed main degradation stages at 220-500 °C, and alkaline compounds could efficiently shift the process to lower temperatures with lower maximum weight loss rate (MWLR) and more residues. From TG-FTIR, it was observed that CO₂ was the primary gas product from pyrolysis in the alkaline-treated samples, while there were more carbonyl compounds released in the control and deionized water groups. Due to the destruction and removal of hemicellulose and lignin after alkaline treatments, the related peaks changed greatly. Changes in the ester groups caused by saponification also accounted for one of the most significant differences between samples. Moreover, except for the deionized water group without sonication, the crystallinity of the samples increased from 6.34% to 11.29%. Overall, comparing the samples treated with or without ultrasound, the results showed that the ultrasound treatment did influence the samples’ physicochemical properties, and its’ effects varied by the basicity of the solution. This in-depth investigation offers a better understanding of ultrasound-assisted and alkaline pretreatments of wood materials.

这项工作调查了杉木在硼砂和氢氧化钠添加剂的水溶液中进行超声辅助预处理后的理化性质。TGA，FTIR和XRD分别用于分析处理样品的热降解过程，化学结构变化和结晶度。另外，通过TG-FTIR设备在线测量了木材热解过程中挥发物的释放。在热分析中，所有样品均显示出在220-500°C下的主要降解阶段，碱性化合物可以有效地将过程转移至较低的温度，从而降低最大失重率（MWLR）和残留量。从TG-FTIR观察到CO ₂是碱处理样品中热解的主要气体产物，而对照和去离子水组中释放出的羰基化合物更多。由于碱处理后半纤维素和木质素的破坏和清除，相关峰发生了很大变化。由皂化引起的酯基的变化也是造成样品之间最显着差异之一。而且，除了没有超声处理的去离子水组外，样品的结晶度从6.34％增加到11.29％。总体而言，比较使用或不使用超声处理的样品，结果表明，超声处理确实会影响样品的理化性质，其影响因溶液的碱性而异。