木粉多元醇液化残余物的结构表征
Structural characterization of the powder with polyhydric alcohols
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摘要: 为了探究木粉多元醇液化过程中缩聚反应阶段液化残余物的化学基团、结晶度以及微观形态的变化，进而探明缩聚反应机理，以聚乙二醇和丙三醇为液化剂、H2SO4为催化剂，对桦木木粉液化，并用FTIR、XRD和SEM对液化残余物进行分析。结果表明：1)在0～180 min液化时间内，缩聚反应约发生在70 min以后。2)与木粉相比，分解反应和缩聚反应阶段的液化残余物在1 500、1 607和1 248 cm-1处基于木素的芳香环和甲氧基的吸收特征峰消失，在1 739 cm-1处基于糖类化合物基团的吸收特征峰明显变小。3)在分解反应阶段，液化残余物的结晶度有所增大；而在缩聚反应阶段，结晶度保持一段恒定值，后呈增大趋势。4)在缩聚反应阶段，液化残余物的微观形态出现块状堆积物。Abstract: In this study, Betula dahurica wood powder was liquefied with polyethylene glycol and glycerin as the liquefying reagents and sulfuric acid as a catalyst to investigate chemical groups, crystallinity and microcosmic morphological characteristics of liquefied wood residues by FTIR, XRD and SEM, and the mechanism of condensation reaction was verified. The results showed: 1) the condensation reaction occurred after about 70 min within liquefying time of 180 min. 2) Comparing to wood powder, the absorption characteristic peaks of aromatic rings and methoxy groups from lignin at 1 500, 1 607 and 1 248 cm-1 disappeared, and the absorbing peak at 1 739 cm-1 from carbohydrates became obviously smaller for the liquefied wood residues during decomposed and condensed reactions. 3) The crystallinity of the residues increased in decomposed reaction; however in condensation reaction, it had an increasing trend after it kept constant for a period of time. 4) The blocky accumulation was found from microcosmic morphology of liquefied residue in condensation reaction.
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Keywords:
- chemical groups /
- crystallinity /
- microcosmic morphology /
- liquefied wood residues
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