采用X射线衍射与显微镜分析技术研究了天然棉纤维素在乙醇、异丙醇、乙醇-异丙醇等不同有机介质中碱化时,纤维素的润胀程度、吸附碱量及结构参数的变化.同时借助1H-NMR、化学滴定法表征了不同介质中纤维素羧甲基化产物大分子的一级结构.结果表明:介质对聚阴离子纤维素合成过程中碱纤维素及其醚化物的结构与性能具有很大影响.随着溶剂体系中异丙醇含量的增加,纤维素碱吸附量提高,润胀率增大,醇解程度降低,产品取代度增加,水溶性变好,取代基团-CH_2COONa在葡萄糖单元环内C_2,C_3及C_6位的分布也更均匀.
The influence of ethanol, isopropanol and mixture thereof used during the polyanionic cellulose (PAC) manufacturing on the structure of alkali cellulose and PAC was studied by means of X-ray diffraction, microscope, 1H-NMR and chemical titrimetry method. The result shows that the structure and property of alkali cellulose and PAC is hardly dependent on the organic solvent in the manufacturing process. With increasing of isopropanol, swelling ratio and adsorption quantity of cellulose base increase and crystalline grade of cellulose decrease, degree of substitution of the PAC and its solubility improve, and the distribution of the substituent in C_2, C_3, C_6 of the anhydroglucose unit (AGU) becomes more even.
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