【作者】 刘峰钰；

【导师】 王成国；

【作者基本信息】 山东大学 ， 材料学， 2011， 硕士

【摘要】 高性能原丝是制备优质碳纤维的基础,性能良好的碳纤维前驱体聚丙烯腈(PAN)和高质量的PAN纺丝原液是获得高性能原丝的必要条件。在聚合阶段,本文采用水相沉淀聚合法,制备较高分子量的丙烯腈(AN)与衣康酸(IA)的聚合物PAN。在溶解阶段,选用具有较高溶解能力的有机溶剂二甲基亚砜(DMSO)和二甲基乙酰胺(DMAc)配制PAN纺丝溶液,经过滤、脱泡后获得实验所需的PAN纺丝原液。通过对PAN纺丝原液进行正交实验和流变性研究,探讨固含量、温度、分子量、剪切速率以及溶剂等因素对纺丝原液表观黏度的影响,并拟合出相应的流变方程。在对纺丝原液进行上述研究过程中发现：采用不同的溶剂,纺丝原液的实验数据和分析结果相差较大。因此,对纺丝原液经压膜、水洗、烘干、研磨后得到的PAN聚合物粉末进行DSC、TG和XRD测试,对其热性能和结构进行分析。PAN纺丝原液制备工艺包括烘干、溶解、脱泡、剪切和预过滤等。通过优化制备工艺,可以获得高质量PAN纺丝原液。同时,纺丝原液制备工艺还与选用的溶剂有关。与DMSO相比,采用DMAc为溶剂时,搅拌和脱泡时间更短、溶解温度更低,但由于其易挥发,PAN/DMAc纺丝原液溶解过程应在N2加压的氛围下进行通过PAN纺丝原液正交试验发现,四因素对其表观黏度的影响与溶剂有关。对于PAN/DMSO.PAN/MAc纺丝原液,四因素对其表观黏度影响程度分别为：固含量>分子量>温度>剪切速率；温度>固含量>分子量>剪切速率,且温度对PAN/DMAc纺丝原液表观黏度的影响程度远大于其它三因素。对PAN纺丝原液的流变性研究表明,PAN纺丝原液表现出明显的剪切变稀现象,属于非牛顿流体中的假塑性流体,其表观黏度随分子量的增加、固含量的升高而增大。同时,PAN纺丝原液存在临界分子量和临界剪切速率,PAN/DMSO纺丝原液的临界分子量和临界剪切速率分别约为：35×104,4～8S-1;PAN/DMAc纺丝原液的临界分子量和临界剪切速率分别约为：27×104,1.5～2S-1,且临界点不随温度的变化而改变。在相同条件下,PAN/DMAc纺丝原液表观黏度要远远小于PAN/DMSO纺丝原液的表观黏度。因此,在配制PAN纺丝原液时,要充分协调PAN聚合物分子量、温度和固含量之间的关系,并采用合适的溶剂,从而获得黏度合适的纺丝原液。通过PAN纺丝原液的流变曲线发现：在临界分子量之前,lgη与lgM、1gγ、1g(wt)、1/T存在线性关系。据此,拟合出PAN/DMSO、PAN/DMAc纺丝原液的方程分别为：1gη=-31.45+5.331gM+377/T+3.531g(wt)-0.2631gγ: 1gη=-10.70+2.601gM+1767/T+7.931g(wt)-0.0891gγ.根据拟合方程可以预测一定条件下PAN纺丝原液表观黏度,为纺丝工艺提供指导PAN纺丝原液流变特性指数的研究发现；黏流活化能随固含量的升高而增大,随分子量、剪切速率的增加逐渐减小；非牛顿指数随温度升高而增大,随分子量、固含量的增加而减小；结构指数随固含量、分子量增加而增大,随温度升高而减小,且因分子量变化引起的结构指数的变化幅度,要远大于因固含量、温度变化引起的变化幅度。同时,与PAN/DMAc纺丝原液相比,PAN/DMSO纺丝原液的黏流活化能和结构黏度指数较大,非牛顿指数较小。通过DSC.TG.和XRD分析发现：溶解过程中,PAN聚合物基团未发生改变；溶剂破坏了PAN的结晶区域,使PAN的结晶度降低,且与选用DMSO相比,选用DMAc为溶剂配制的纺丝原液对PAN结晶区域的破坏程度较大；与PAN聚合物相比,PAN纺丝原液聚合物更稳定,最大失重速率和其对应的温度均有所降低,放热峰更宽、放热速率更低；与PAN/DMAc纺丝原液中聚合物相比,PAN/DMSO纺丝原液中聚合物的热稳定性更好,最大失重速率和其对应的温度更低、放热峰更宽,放热速率更低。更多还原

【Abstract】 High performance precursor is the basis of high quality carbon fiber, while high performance polyacrylonitrile (PAN) and high quality of PAN spinning solution are necessary conditions of obtaining high performance precursor. In polymerization stage, aqueous deposited polymerization is utilized to synthesize high molecular weight PAN polymers using by acrylonitrile (AN) and itaconic acid (IA) as monomers. In dissolving stage, the high dissolved ability organic solvents dimethylsulphoxide (DMSO) and dimethylacetamide (DMAc) were choosed to prepare PAN spinning solution. After defoaming and filtering, the experimental PAN spinning solution was obtained. The influence of various factors such as solid content,temperature, molecular weight, shear rate and solvents on the apparent viscosity of spinning solution was explored by orthogonal experiment and spinning solution rheological research of PAN spinning solution. And fitting correspond rheological equations. In the process of above research for spinning solution findings:using different solvents, experimental data and analysis results of spinning solution vary greatly. Therefore, after getting PAN polymer powder by membrance, washing, drying and grinding of spinning solution, the thermal properties and structure were analysised by using DSC, TG and XRD.The preparation techniques of PAN spinning solution including:dry, solubility, defoam, shear and pre-filtering. Through optimize the preparation technology, high quality PAN spinning solution can be obtained. Meanwhile, the spinning solution preparation technology is connectted with solvent. Compared with DMSO, using DMAc as solvent, the stir and defoam time was shorter, the solubility temperature was lower, but due to its volatile, the dissolving process of PAN/DMAc spinning solution should be under pressure in the atmosphere of N2.As the orthogonal test of PAN spinning solution shown, the influence of four factors on apparent viscosity is connect with solvent. To PAN/DMSO and PAN/DMAc spinning solution, the influence degree of four factors on apparent viscosity respectively is:content of solid> molecular weight> temperature> shear rate; temperature> content of solid> molecular weight > shear rate, and the influence of temperature on PAN/DMAc spinning solution apparent viscosity is more degree than the other three factors.The rheological properties research of PAN spinning solution shows that, the PAN spinning solution displays thinning shear phenomenon obviously, belongs to the plastic fluid of non-newtonian fluid, its apparent viscosity increases with the increasing of the molecular weight and the content of solid. Meanwhile, the PAN spinning solution exists critical molecular weight and critical shear rate, the critical molecular weight and critical shear rate of PAN/DMSO spinning solution and they are approximately to:35×104,4S-1～8S-1; the critical molecular weight and critical shear rate of PAN/DMAc spinning solution are approximately to:27×104,1.5S-1～2S-1, and the critical point is not changed with temperature. Under the same conditions, the apparent viscosity of PAN/DMAc spinning solution is far less than that of PAN/DMSO spinning solution. Therefore, when the PAN spinning solution is in the configuration, the relationship of polymer molecular weight, temperature and the solid content, and adopt the appropriate solvent should be fully coordinate to get the suitable viscosity of spinning solution.The rheological curves of PAN spinning solution finds that:before the critical molecular weight, linear relationship exists between 1gηwith 1gM, 1gγ, 1g(wt),1/T. The equation of PAN/DMSO and PAN/DMAc spinning solution respectively are:1gη=-31.45+5.331gM+377/T+3.531g(wt)-0.2631gγ, 1gη=-10.70+2.601gM+1767/T+7.931g(wt)-0.0891gγ. According the regression equation, the apparent viscosity of PAN spinning solution with certain conditions can be predicted and guidance for spinning process can be provided.The study on rheological property indexs of the PAN spinning solution discovers that:sticky flow activation energy increases with the increasing of solid content, decreases with the increasing of molecular weight and shear rate; non-newtonian index increases with the increasing of temperature, decreases with the increasing of molecular weight and solid content; structure index increases with the increasing of solid content and molecular weight, decreases with the increasing of temperature; and the change extent caused by molecular weight is far outweigh than that caused by temperature and solid content. Meanwhile, compared to PAN/DMSO spinning solution, the sticky flow activation energy and structure index of PAN/DMAc spinning solution is greater, the non-newtonian index is smaller.The analysis of DSC, TG, XRD explores that:the PAN polymer group unchanged during the dissolving process; solvent destroys the crystallization area of PAN, making the crystallinity decrease. Compared to DMSO, the content of the damaged crystallization caused by DMAc is deeper; compared to PAN polymer, the PAN polymer of spinning solution is more stable, maximum weightlessness rate and the corresponding temperature are greatly reduced, exothermic peak is wider and the corresponding rate is lower; compared to the polymer of PAN/DMAc spinning solution, the polymer of PAN/DMSO spinning solution thermal stability is better, maximum weightlessness rate and the corresponding temperature are lower, exothermic peak is wider and the corresponding rate is lower.更多还原