二甲基乙酰胺预活化处理时,微晶纤维素中吸附水被二甲基乙酰胺分子取代,使纤维素分子链间距离增加。预活化使纤维素分子链的氢键断裂导致微晶纤维素在氯化锂-二甲基乙酰胺体系中溶解度增加。在高温下微晶纤维素/氯化锂-二甲基乙酰胺溶液发生不可逆凝胶化,形成相互连接的丝状多孔结构。微晶纤维素的预活化路线和溶解温度影响微晶纤维素/氯化锂-二甲基乙酰胺溶液的溶胶-凝胶转变温度。微晶纤维素在溶胶-凝胶转变后再生时主要保留Ⅰ型聚集态结构,结晶度为71%。
During pre-activation using DMAc,the absorbed water inside cellulose was replaced by DMAc molecules,and the packaging of cellulose chains became more expanded.The disruption of hydrogen bonding of cellulose chains,especially inter molecule hydrogen bonding,during pre-activation was the most possible reason for the improvement of MCC's solubility in LiCl/DMAc system.The MCC/LiCl/DMAc solution became irreversibly gelled,and formed inter-connected silk-like porous structures.Also,the pre-activation routes and dissolution temperatures of MCC affected sol-gel transition temperatures of MCC/LiCl/DMAc solution.Moreover,the regenerated cellulose after sol-gel transition mainly reserved type I crystalline structure with a relatively high crystallinity of 71%.
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