【作者】 刘子铭；

【导师】 徐樑华；

【作者基本信息】 北京化工大学 ， 材料学， 2007， 硕士

【摘要】 热处理阶段尤其是预氧化阶段是整个聚丙烯腈(polyacrylonitrile)基碳纤维制备中的关键步骤,其过程极为复杂,影响因素颇多。这一过程的场效应,主要有温度场,时间场,张力场,气流场等,它们对PAN纤维结构及性能的变化起着重要的作用。对于场效应是如何起作用的以及如何通过场效应控制PAN纤维的微晶尺寸,目前仍是一个悬而未决的问题。本论文依据对PAN基碳纤维结构性能的深入分析,结合课题组的现有研究条件与基础,开展各种场效应在PAN纤维的预氧化碳化过程中对聚集态结构影响的研究,找到控制碳纤维中微晶尺寸大小的因素,并制得具有细晶化结构的PAN基碳纤维。用扫描电镜和透射电镜等表征手段对其进行定性表征、用XRD等测试手段对碳纤维中的微晶尺寸进行定量的表征。由此初步建立获得具有细晶化结构PAN基碳纤维的工艺、结构与性能间的相关性。实验结果表明：热处理温度在190℃以前,PAN氰基的热分解环化缓慢；200℃以后,氰基的热分解环化程度逐渐变大。当量时间从51min到60min为氰基热分解环化反应剧烈的区域,在这一区域适当延长热处理时间,有助于提高氰基的利用率,对纤维细晶化有利。同时在初期施加张力可以促进PAN原丝分子的热分解环化反应,尤其是分子内的环化反应,并且施加张力达到161.4CN/dtex以后可以使微晶尺寸变小,这对提高纤维强度是有利的。在预氧化第一阶段,气流场中的水分子起塑化作用,增强链段间的活动能力；预氧化第二阶段,水分子易与纤维中含氧官能团结合,起钝化作用。更多还原

【Abstract】 The heat treatment, especially the pre-oxidative stabilization of polyacrylonitrile is a crucial step in the production of PAN-based carbon fibers. I t is so complex and influenced. In the process, the field including temperature, time, tensility, airflow and so on, bring important action for the evolution law of molecular structure and properties of PAN fibers.In the paper, we will analyze structure and properties of PAN fibers, combine study condition and elements in item team, develope the study that influence of aggregation state structure by various field in pre-oxidative and carbonization, discover the factors of controlling crystal size in carbon fiber, and preparation PAN-based carbon fibers bearing microlite structure. By means of SEM, TEM, XRD etc, we investigate the structure and properties of PAN fibers. And this paper will also try to build technics-structure-properties pertinency of PAN-based carbon fibers bearing microlite structure.The results showed that before190℃, heat-decomposition and cyclization of cyanogens groups is slowness; After200℃, the reaction’s stage become deep. When the equivalent time increased from51min to60min, heat-decomposition and cyclization of cyanogens groups is drastic. In this scope, extending heat treatment time is advantageous to raising utilization of cyanogen groups and reducing crystalline size. In the forepart of heat-decomposition and cyclization cyanogens groups of PAN fiber, tensility can accelerate the heat-decomposition and cyclization of PAN molecule, especially molecular interior, when the tensility reach161.4CN/dtex, the crystalline size can minish, which is further some to increase fiber’s intensity. In the pre-oxidative first phases, H2O make fibers having plasticity and reinforce the molecular chain’s movement ability; In the pre-oxidative second phases, H2O combine oxygenous group and slower heat-decomposition and cyclization of cyanogens groups.更多还原