【作者】 张松洁；

【导师】 邵惠丽；

【作者基本信息】 东华大学 ， 材料学， 2004， 硕士

【摘要】 Lyocell纤维生产工艺是把纤维素直接溶解在N-甲基吗啉-N-氧化物（NMMO）的水溶液中，然后进行特殊的干湿法纺丝的工艺。该种工艺制得的纤维素纤维具有干强和湿强高、穿着舒适、生物可降解、整个生产路线不污染环境且工艺流程简单先进、作为溶剂的NMMO可经回收后循环再利用等特点，因此，有望成为代替生产工艺严重污染环境的粘胶纤维的新一代再生纤维素纤维。 目前，市场供应的Lyocell纤维一般是用聚合度为500～600左右的纤维素原料纺制得到的，并主要应用于服装面料等民用领域。然而，Lyocell纤维具有截面呈圆形、结构均匀、强度较高、可纺细旦丝等一些作为优质碳纤维原丝所需的基本特点，因此，该纤维除用于服装领域外，还可望作为优质碳纤维原丝，以扩展其在工业领域的用途。为尽快地开拓Lyocell纤维在碳纤维原丝等领域的应用前景，首先必须采用合适的纺丝原液（如聚合度或相对分子质量较高的纤维素／NMMO·H₂O溶液、经适当改性的纤维素／NMMO·H₂O溶液等）在合适的纺丝条件下，制得性能符合要求的Lyocell纤维。目前国外只有德国图林根纺织和塑料研究所对此领域在进行初步研究，但由于涉及军工，几乎无任何报道。国内除本课题组的研究人员曾用民用Lyocell纤维作过一些初步尝试外，也未见有其他相关报道。 为此，本论文针对国内外在研制Lyocell基碳纤维原丝研究领域中的某些空白，首先对不同相对分子质量，尤其是高相对分子质量的纤维素／NMMO·H₂O溶液以及经NH₄Cl改性的溶液流变性能及其可纺性进行了探讨，研究表明：本论文实验范围内的各种纤维素／NMMO·H₂O溶液体系均属于切力变稀型流体，它们的零切粘度值与各自对应纤维素原料的相对分子质量成正比，且随纤维素相对分子质量的增大，相应纤维素／NMMO·H₂O溶液的弹性增加，所形成的纤维素／NMMO·H₂O溶液的粘度东华大学硕士学位论文摘要对温度的变化更为敏感，溶液的结构化程度也更大，其可纺性相应有所下降;纤维素加MMO·玩O溶液的流动曲线随NH4CI添加量的增加而上移，溶液的零切粘度和表观粘度相应增加。此外，为了更好地了解原料的差异性，以便为原料的有效选择及纺丝工艺的确定提供指导，本论文还利用简便的动态流变的方法预测了不同纤维素浆粕的相对分子质量及其分布，并用‘GPc和铜氨法的结果验证了动态流变方法预测纤维素的相对分子质量及其分布在本论文实验条件下是可行的。 本论文的研究工作表明，采用高相对分子质量的纤维素原料是制得高强度Lyocell基碳纤维原丝的有效途径之一。本论文采用了刀尸二1 360的脱脂棉为原料，通过正交实验对气隙长度、拉伸比、凝固浴组成和喷丝板孔数等工艺参数进行了分析，在此基础上，确定了最佳工艺条件，并成功地制得了拉伸强度为8.95cN/dtex、弹性模量为x63.4ocN人ltex的Lyoeell纤维。 本论文的研究工作还表明，除了采用高相对分子质量的纤维素原料外，利用NH4CI改性中等相对分子质量纤维素的纺丝原液，也可以制得力学性能较好的Lyocell纤维，但NH4CI对Lyocell纤维的改性效果与纤维素原料的性质、纺丝原液中纤维素的质量百分数以及NH4CI的添加量等因素有关。 本论文采用广角X射线一衍射仪和带有U一CTB补偿器的BX一51型偏光显微镜等对各种条件下制得的Lyocell纤维的聚集态结构和形态结构进行了分析。在本论文实验范围内，随着拉伸比的适当提高，纤维的分子总取向增加，且非晶区的取向提高较为明显，与此同时，结晶度也相应增加;另外通过NH4CI改性的方式可以提高纤维的结晶度和取向度，从而提高纤维的力学性能。研究结果还表明:Lyocell纤维有着比其他粘胶碳纤维原丝更圆的截面形态结构，表面光滑，因而Lyocell纤维具有更接近于优质碳纤维原丝的形态结构特征。更多还原

【Abstract】 Cellulose dissolves in N-methyl-rnorpholine-N-oxide (NMMO)/water directly without forming cellulosic derivatives. Then the solution is spun into fibers via special dry-jet wet spinning. This process is called Lyocell process. Lyocell fibers, made via Lyocell process, are of excellent properties, such as high dry strength, high wet strength, degradable, and the process is environmentally friendly and the solvent can be recycled. Owing to these advantages, Lyocell fiber is a promising substitute for the viscose fiber (Rayon), whose process pollutes the environment heavily.Nowadays, most of Lyocell fibers are spun from the cellulose pulp of the polymerization degree between 500 and 600, and their usage is limited in raiment industry. However, several properties of Lyocell fibers accord with the standards for the precursor of excellent carbon fiber, such as round cross section, homogenous structure, and high strength. So Lyocell fiber is the potential precursor of carbon fiber. Currently, only Thuringian Institute for Textil-und Kunststoff-Forschung(TITK) has done some research on this process and due to the military secret, little report is revealed. In China, only researchers from our group have done some research on this area.In the dissertation, research was proceeded concerning Lyocell fiber for the precursor of carbon fiber. The studies on the rheological properties of different cellulose/NMMO H2O solutions and with the presence of NH4Cl showed that these solutions were shear thinning solutions under our experimental conditions. The zero shear viscosity is proportional to the polymerization degree of the pulp. And with the increase of the polymerization degree, the elasticity of the solution and the structural viscosity increased accordingly, the viscosity was more sensitive to the change of the temperature, and the spinnability declined. With the increase of NHUCI, the zero shear viscosity and apparent viscosity of cellulose/NMMO H2O solutions increased. The dynamic rheology method is used to predict the molecular weight and molecular weight distribution of different cellulose pulps, and the results were validated by GPC and curammonium method.The research showed that using cellulose pulps of high molecular weight was an effective way to improve the strength of Lyocell fiber for the precursor of carbon fiber. Sothe degreased-cotton with DP=13 60 was selected and an orthogonal experiment was designed to optimize the processing conditions. Lyocell fibers of high mechanical properties were produced, the strength 8.95cN/dtex and the modulus 163.40 cN/dtex.In addition to cellulose pulps of high molecular weight, cellulose pulps of medium molecular weight modified by NEfyCl could also be spun into Lyocell fibers with good mechanical properties. However, the modification effect was influenced by the properties of cellulose pulps, cellulose concentration in solutions and the amount of NHUCl.Wide-angle X-ray diffraction and Polarizing Microscope were used to investigate the structure of different Lyocell fibers. The results illustrated that under our experimental conditions, with the increase of drawing-down ratio, the overall degree of orientation and crystalliniry increased. Besides, the addition of NH4Cl caused the crystallinity and orientation of modified Lyocell fibers to rise, and thus the fibers’ mechanical performance improved as well. The surface of Lyocell fiber was smoother than that of Rayon, and the cross section was round, so the morphology and the structure of Lyocell fibers were closer to the standards for the precursor of carbon fiber.Zhang Songjie Major: Material Science Supervised by Prof. Shao Huili更多还原