醇溶剂对Lyocell常温纺丝液性质及其纤维结构与性能的影响OA

Lyocell fibers are dubbed the"green fibers in the 21st century"due to their excellent performance,renewable raw materials,closed-loop production process,and complete biodegradability.They show broad application prospects in textiles,medical materials,and filtration materials.However,during current industrial production,people generally adopt a high-temperature spinning process,in which the cellulose/N-methylmorpholine-N-oxide(NMMO)solution is extruded and molded at 90-110℃.This high-temperature spinning characteristic not only increases production energy consumption but also intensifies the degradation of cellulose and NMMO,leading to reduced fiber quality and lower solvent recovery rates.To a certain extent,these issues constrain cost reduction,efficiency improvement,and sustainable development in the industry.Therefore,efforts to lower the spinning temperature of Lyocell solutions and develop new spinning processes that operate stably at room temperature or near-room temperature are of great significance for promoting energy conservation,consumption reduction,quality improvement,efficiency enhancement,and green manufacturing in the Lyocell fiber industry. To improve the spinnability of Lyocell solutions at room temperature and develop a room-temperature spinning technology for Lyocell fibers,the special role of water molecules in the cellulose/NMMO aqueous solution as well as the structural similarity between alcohol molecules and water molecules was taken into consideration,and methanol,ethanol,and propanol were selected as additives to prepare spinning solutions by mixing them with the Lyocell solution.The fluidity,microscopic morphology,and rheological properties of the resulting spinning solutions were tested at different temperatures.The thermal stability and room-temperature spinnability of the composite spinning solutions were investigated.The conventional high-temperature Lyocell solutions and the alcohol-assisted room-temperature spinning solutions were used for dry-jet wet spinning.Infrared spectroscopy,thermal analysis,and X-ray diffraction were further employed to analyze the effects of high-temperature spinning and room-temperature spinning on the structure of the regenerated fibers.The microscopic morphology and mechanical properties of the regenerated fibers were characterized to verify the feasibility of the room-temperature spinning technology for Lyocell fibers. The results of solution property studies showed that the addition of alcohol solutions effectively reduced the low-temperature solidification phenomenon of the Lyocell solution.The conventional solution solidified and losed fluidity when cooled to 50℃,while the solution with added alcohol solvent maintained fluidity when cooled to 30℃.Rheological tests showed that the spinning solution with ethanol solvent exhibited the lower viscosity,structural viscosity index and viscous flow activation energy.Characterization results of the regenerated fibers indicated that room-temperature spinning did not alter the microscopic morphology,chemical structure,or thermal stability of Lyocell fiber,but it increased the crystallinity of the fiber and thereby enhanced its mechanical strength.Among the tested conditions,the regenerated fiber obtained by ethanol-assisted room-temperature spinning achieved a strength of 271 MPa,which was 56%higher than that obtained by the conventional high-temperature spinning method.This study demonstrates that alcohol solvents can improve the spinnability of cellulose/NMMO solutions at room temperature,and further facilitate the development of room-temperature spinning technology for Lyocell fibers.