碱处理杨木浆提取半纤维素及其结构与性能

为了利用溶解浆在生产粘胶纤维时废液中的半纤维素,用杨木未漂浆和漂白浆为原料,通过碱处理提取半纤维素,并用梯度乙醇沉淀的方法制备出10组半纤维素。采用高压液相、X射线衍射、红外光谱和热重分析等技术对半纤维素的结构及性能进行分析。结果表明,两种浆料通过不同体积分数乙醇沉淀出的半纤维素,其结构均以木糖为主链,半纤维素中木糖质量分数高达100%。红外光谱及XRD结果显示,10组半纤维素的化学结构及结晶度均相似,随乙醇体积分数的提高,半纤维素中糖苷键逐渐减少。由热重分析可知,半纤维素在700℃时固体残留量随乙醇体积分数的升高而增加。其中,75%乙醇沉淀出的半纤维素,在温度至700℃时,最高固体残留率为36.2%。

Structure and Properties of Hemicellulose Extracted from Poplar Pulp by Alkali Treatment

In order to study the use of hemicelluloses in waste liquor of viscose fiber produced from dissolving pulp, ten groups extracted from poplar pulp by alkali treatment and precipitated by gradient ethanol were detected. The structure and properties of hemicelluloses were analyzed by GPC, XRD, FT-IR and TGA. The backbones of hemicelluloses were mainly xylose, and the content of xylose in hemicellulose was up to 100%. By FT-IR and XRD, the chemical structures and crystallinities of the ten hemicelluloses were all similar. The TGA result indicated that the residual masses of hemicelluloses were increased with the volume fraction of ethanol at 700 ℃. When the temperature was up to 700 ℃, the residual masses of hemicelluloses precipitated by 75% ethanol with solid residual rate of 36.2%.