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本文以α-纤维素为原料,ClSO_3H-DMF为酯化剂,采用多相硫酸酯化法制备纤维素硫酸酯(Cellulose Sulfate,CS)。通过元素分析确定了CS的硫酸酯基取代度为2.0左右,13C-NMR测试表明,CS的硫酸酯基取代模式是C-6完全硫酸酯基取代和C-2部分或完全取代。CS在去离子水中具有良好的溶解性。根据相近取代度的CS系列产物的分子量与特性粘度的关系,通过Mark-Houwink拟合,确定了CS的糖链在稀溶液中呈现一种较为紧密的构象。在浓溶液中,CS的动力粘度随浓度增加而增大;外加盐能够促进CS聚电解质的电荷排斥作用,导致其动力粘度增加;添加二价盐Ca~(2+)可产生CS糖链的络合,显著提高CS的动力粘度;溶液pH环境为影响CS动力粘度的主要因素之一,在中性条件下动力粘度最大,酸性或碱性环境都会使其动力粘度下降。
In this paper, cellulose sulfate (Cellulose Sulfate, CS) was prepared by a multi-phase sulfuric acid esterification method using α-cellulose as the raw material and ClSO_3H-DMF as the esterification agent. The degree of substitution of CS by CS was determined to be about 2.0 by elemental analysis. The 13C-NMR test showed that the CS-based substitution pattern of the sulfates was C-6 complete sulfate substitution and C-2 partial or complete substitution. CS has good solubility in deionized water. According to the relationship between the molecular weight and the intrinsic viscosity of CS series products with similar degree of substitution, the sugar chain of CS was found to have a more compact conformation in dilute solution by Mark-Houwink fitting. In the concentrated solution, the kinetic viscosity of CS increased with the increase of concentration. The addition of salt promoted the charge repulsion of CS polyelectrolytes, resulting in an increase of kinetic viscosity. The addition of divalent salt Ca ~ (2+) Complexation, and significantly improve the dynamic viscosity of CS. The pH environment of the solution is one of the main factors that affect the kinetic viscosity of CS. Under the neutral conditions, the kinetic viscosity is the largest, and its kinetic viscosity will be decreased in acidic or alkaline environment.