Effect of pH on Chemical Components and Mechanical Properties of Thermally Modified Wood
Effect of pH on Chemical Components and Mechanical Properties of Thermally Modified Wood
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DOI：
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发表时间：
2012-01
影响因子：
1.4
通讯作者：
Wang Wang-Wang;Jinzhen Cao;F. Cui;Xing Wang
中科院分区：
文献类型：
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作者：
Wang Wang-Wang;Jinzhen Cao;F. Cui;Xing Wang
为探讨木材热处理过程中酸度与降解性的关系，以青杨为试材，研究了酸度与木材热降解的关系。用不同pH值的八水合硼酸二钠(DOT，pH=8.3)、一乙醇胺(MEA，pH=12)和四种由硼酸和氢氧化钠组成的缓冲溶液(BA/NaOH，pH=6，7，8，9)浸渍木材样品。然后将样品分别在180℃、200℃和2208℃下加热4h。随后测定了热改性样品的弯曲静曲强度和弹性模量、质量损失、pH值以及木质素和半纤维素的百分比，并与未经前处理和/或热处理的对照样品进行了比较。实验结果表明，DOT和缓冲溶液减少了热处理木材的质量损失，增加了弯曲抗弯强度和抗弯弹性模量，而MEA处理增加了质量损失，弯曲抗弯强度和抗弯强度与未处理的对照相当，甚至低于未处理的对照。化学分析表明，在180~200℃温度范围内，DOT和BA/NaOH预处理抑制了半纤维素的降解，这可能是半纤维素力学性能改善的原因。
To investigate the correlation between acidity and degradation during thermal treatment of wood, Cathay poplar ( Populus cathayana Rehd.) wood samples were impregnated with solutions of different pH values, which included disodium octoborate tetrahydrate (DOT, pH = 8.3), monoethanolamine (MEA, pH = 12), and four buffering solutions composed of boric acid and sodium hydroxide (BA/NaOH, pH = 6, 7, 8, 9). Samples were then heated for 4 h at 180, 200, and 2208deg;C, respectively. Bending MOR and MOE, mass losses, pH values, and percentages of lignin and hemicelluloses were subsequently determined in thermally modified samples and compared with control samples without pretreatment and/or thermal treatment. Results of the experiments indicated that DOT and buffering solutions decreased mass loss of thermally treated wood and increased bending MOR and MOE, whereas MEA pretreatment increased mass loss and showed comparable or even lower bending MOR and MOE than the untreated control with or without thermal treatments. Chemical analyses suggested that degradation of hemicelluloses was inhibited by DOT and BA/NaOH pretreatments within the temperature range 180-200°C, which may explain the mechanical property improvement.