纤维素氨基甲酸酯的结构及其溶解机制

 采用红外、13C固体碳谱、元素分析、X射线衍射、扫描电子显微镜、热重、差热等手段对纤维素氨基甲酸酯的结构进行了表征。结果表明：氮质量分数为3.45%的纤维素氨基甲酸酯分子每一个链段的化学式为( C7H1106 )2N1，即平均每2个纤维素链段中的1个伯羟基被酰氨基取代。CC的基本组成单元仍为纤维素，只是反应后其结晶结构发生了变化，随着反应的进行，产物的晶面增加，取向度、结晶度及热稳定性降低。采用显微镜观察CC的溶解过程，得出CC的溶解过程是分子无限溶胀的结果。首先发生在非晶区内，而后由氨基甲酸酯产生的溶液来溶剂化微晶的表面并渗入微晶的内部，从而使CC的晶胞溶胀、扩散，最后全部溶解。

Structure and dissolution mechanism of cellulose carbamate

The structure of the cellulose carbamate were characterized by means of FTIR ,13 CP MAS、 element analysis, XRD, SEM, TG, DSC etc. The results showed that the chemical formula of cellulose carbamate with nitrogen mass fraction of 3.45% is ( C7H1106 )2N1 , namely, on average, one primary hydroxyl group of cellulose was substituted by one acyl amine.The basic structure of cellulose carbamate is cellulose, however its crystral structure was changed after reaction, and as the reaction went on, the crystalline surface of the product increased, the orientation degree, crystralline grade and thermal-stability decreased . It was observed by microscope that the dissolving process of CC was ascribed to the infinite swelling of CC molecules, which first occurred in amorphous region, then in miscro-crystalline surface by the resulting solotion which then penetrated into the inside of the microcrystals. Making crystal cells swell, diffuse, and finally CC was completely dissolved.