Rapid dissolution of cellulose in LiOH/Urea and NaOH/Urea aqueous solutions
Rapid dissolution of cellulose in LiOH/Urea and NaOH/Urea aqueous solutions
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DOI：
10.1002/mabi.200400222
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发表时间：
2005-06-24
影响因子：
4.6
通讯作者：
Zhang, L
中科院分区：
文献类型：
--
作者：
Cai, J;Zhang, L
系统地研究了纤维素在LiOH/尿素和NaOH/尿素水溶液中的快速溶解。用C-13核磁共振、光学显微镜、广角X射线衍射、红外光谱、差示扫描量热法和粘度计对纤维素的溶解行为和溶解度进行了表征。实验结果表明，粘均相对分子质量(M)分别为11.4×104和37.2×104的纤维素在预冷至-10℃的7%NaOH/12%尿素和4.2%LiOH/12%尿素水溶液中可在2分钟内溶解，而在KOH/尿素水溶液中均不能溶解。溶剂体系的溶解能力大小顺序为LiOH/尿素>；NaOH/尿素>；>；KOH/尿素水溶液。DSC和~(13)C核磁共振的结果表明，LiOH/尿素和NaOH/尿素水溶液作为非衍生化溶剂，破坏了纤维素分子内和分子间的氢键，阻止了纤维素分子间的相互靠近，使纤维素分散良好，形成实际溶液。
Rapid dissolution of cellulose in LiOH/urea and NaOH/urea aqueous solutions was studied systematically. The dissolution behavior and solubility of cellulose were evaluated by using C-13 NMR, optical microscopy, wide-angle X-ray diffraction (WAXD), FT-IR spectroscopy, DSC, and viscometry. The experiment results revealed that cellulose having viscosity-average molecular weight ((M) over bar (n)) of 11.4 x 104 and 37.2 x 104 could be dissolved, respectively, in 7% NaOH/12% urea and 4.2% LiOH/12% urea aqueous solutions pre-cooled to - 10 degrees C within 2 min, whereas all of them could not be dissolved in KOH/urea aqueous solution. The dissolution power of the solvent systems was in the order of LiOH/urea > NaOH/urea >> KOH/urea aqueous solution. The results from DSC and C-13 NMR indicated that LiOH/urea and NaOH/urea aqueous solutions as non-derivatizing solvents broke the intra- and inter-molecular hydrogen bonding of cellulose and prevented the approach toward each other of the cellulose molecules, leading to the good dispersion of cellulose to form an actual solution.