纤维素在ZnCl2水溶液中的溶解性能及其再生结构

本文比较了不同质量分数的ZnCl2水溶液溶解不同聚合度纤维素的能力，结果表明，质量分数为65％以下的ZnCl2水溶液由于其Zn2＋被完全水化作用而不能溶解纤维素，当达到或超过该浓度时，Zn2＋可与纤维素分子链作用，使纤维素溶解，且65％ZnCl2水溶液的溶解效果最佳；但随着纤维素聚合度的增大，其溶解度下降；本文研究还表明通过添加尿素可改善纤维素的溶液的流动性。经ZnCl2水溶液溶解后的再生纤维素的聚合度（DP）下降；x-射线衍射分析表明再生纤维素为纤维素Ⅱ结晶变体；红外分析结果显示ZnCl2水溶液是纤维素的非衍生化溶剂，且再生纤维素分子内氢键减弱。

Dissolution of Cellulose in Zncl2 Aqueous Solution and Structure of Regenerated Cellulose

In this article, dissolving ability for cellulose of various concentrated ZnCl2 aqueous solutions was studied. It can’t dissolve cellulose unless the salt concentration is bigger than 65% (wt%). It seems that Zn2＋ ion is saturated by water molecular at low salt concentration. When salt concentration is equal to or larger than 65% Zn2＋ ion could connect with hydrogen groups of cellulose and dissolve it. 65% ZnCl2 aqueous solution has the best dissolving effect, whose dissolving ability is decreasing using higher DP of cellulose with degradation of cellulose. Adding urea could enhance the fluidity of cellulose/ 65% ZnCl2 solution. The result of WAXD showed that the crystal system of cellulose is changed from cellulose I to cellulose Ⅱ by dissolving in ZnCl2 aqueous solution. By FT-IR, ZnCl2 aqueous solution is a direct solvent for cellulose and intramolecular hydrogen bond of regenerated cellulose prepared from ZnCl2 aqueous solution is decreased