大麻纤维在氯化锂/N,N-二甲基乙酰胺溶解体系中的溶解特性

为提高大麻纤维溶解性能，对大麻纤维进行氢氧化钠预处理和氯化锂/N,N-二甲基乙酰胺（LiCl/DMAc）溶解处理。用质量分数为18%的氢氧化钠在60℃处理大麻纤维1～4h，然后将预处理后的大麻纤维在不同温度（70、80、95℃）下溶解于质量分数为10％的LiCl/DMAc溶解体系。用扫描电镜、红外光谱仪 和 X 射线衍射仪对溶解前后的大麻纤维进行表征，测试溶解后溶液黏度值。结果表明：氢氧化钠预处理后纤维素的晶型由纤维素Ⅰ转变为纤维素Ⅱ；溶解温度升高，大麻纤维溶解性增强，95℃条件下，预处理2h和3h的大麻纤维在10%LiCl/DMAc溶解体系中能够完全溶解，溶解质量分别为1.0～1.2g和1.2～1.5g；预处理3h的大麻纤维/LiCl/DMAc溶液黏度值更大，溶液稳定。

Dissolution properties of hemp fiber in lithium chloride/N,N-dimethylacetamide

In order to improve the solubility of hemp fibers, samples were subjected to alkali pretreatment and lithium chloride /N, N- Dimethylacetamide (LiCl/DMAc) solution treatment. Native hemp fibers were immersed in 18% alkali liquor and 60℃ bath temperature for 1 -4 h. After pretreatment, hemp fibers were dissolved in 10% LiCl/DMAc solvent system at different temperatures (70 C, 80 C and 95 C).The changes of the surface morphology, crystallization structure and solubility of hemp fibers were indicated by scanning electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction and solubility test. The results show that with the alkali treatment crystal form of cellulose I turned into cellulose II . Solubility of hemp fibers increased when LiCl/DMAc treatment temperature wereraised from 70℃ to 95℃. After alkaline activation, hemp fibers could be dissolved1.0-1.2g for 2h and 1.2-1.5g for 3h in 10% LiCl/DMAc soluble system. The viscosity valueof the hemp/LiCl/DMAc with hemp fiber pretreated byNaOH for 3 h is greater for 3 h NaOH preteratmenthemp fibers in. The solution ofhemp/LiCl/DMAc isstable.