【作者】 李太平；

【导师】 王成扬；

【作者基本信息】 天津大学 ， 化学工艺， 2004， 硕士

【摘要】 炭质中间相生长理论对制备高性能炭素制品具有重要的指导作用。目前,该理论仍有许多值得探讨的问题。本论文以一种中温煤沥青为主要原料,以改变原料组成的形式采用热缩聚法制备中间相炭微球(MCMB),考察了不同加入量的情况下MCMB的收率变化、形貌、织构和微结构特征。并进一步考察了它们成焦的难易和生焦的性状。在此基础上,考察了制备体系中的物理改性问题。整个实验过程中采用了粒度分析、SEM、OM等分析手段。在大量实验的基础上,丰富并完善了中间相的形成理论,对我实验室提出的“粒状单元构筑理论”(BGBU)给出了进一步的补充和证明。研究发现,1号煤沥青和蒽油均在不同程度上影响了MCMB的收率,炭微球断面结构也呈现出“瓢”形、“贝壳”形等多同非定义特征,其中间相沥青转化成生焦的难易和生焦的性状也发生了变化,这些结果运用改进后的BGBU理论都得到了比较合理的解释。在浸渍沥青中加入炭黑后,炭微球的消光纹复杂化并出现了新的镶嵌型炭微球。随炭黑加入比例的提高,中间相的收率和镶嵌型炭微球的比例也在增加。从断面结构上看,体系中出现了多种结构炭微球共生的情况;生球和熟球对中间相的作用机理是不同的:生球的加入显著提高了中间相的收率,但不改变其微观结构和形貌特征。因为生球作为“晶种”参与了中间相生长和发育的全过程。体系中“晶种”数量的增多和炭微球生长发育方式的多样化使得体系中生成的炭微球实现了由单分散性向多分散性的转变,使制备的炭微球中出现了两极分化现象;熟球对提高中间相收率的幅度不大,随着加入比例的提高,中间相的收率基本保持不变。因为体系在热缩聚反应达到一定阶段后,成核物质处于过饱和状态,熟球的加入只是起到了引发剂的作用而促进了液晶化过程,又由于液晶化过程消耗了较多的大片层芳香分子而使缩聚反应平衡向生成更多的稠环芳香分子方向进行。本论文的创新性在于运用独特的制样技术,利用SEM分析炭质中间相的形貌与织构。结合分子化学和超分子理论分析实验中出现的各种现象,丰富并完善了中间相的形成理论。更多还原

【Abstract】 The theory of development of carbonaceous mesophase is very important for thepreparation of high-performance carbonaceous products. Today, there are still manydisputable problems in this theory.In the thesis, MCMB were prepared from a coal tar pitch in a form of altering feedcomposition.adding with different sorts of light-composes. Yield variety, mophology,microtexture and microstructure characters of MCMB were assessed by varying theadding amount of additives(1# coal tar pitch and anthracene oil ). And the relevantcoking characters were assessed further to decide the easy or difficult to transform to theresultant coke and their physical nature. On the base of these, the problem of physicalqualitative changement is reviewed. Analyzing methods, such as Grain-Size Analysis,SEM, OM etc. were mainly used in the experiments. On the base of lots of experiments,the forming theory of carbonaceous mesophase was abundanted and perfected. A newtheory named by Building from Granular Basic Units (BGBU) providing by our lab wassupplemented and verified further.It was discovered that two kinds of additives(1# coal tar pitch and anthracene oil )changed the yields of MCMB in different levels, the cross section structure of MCMBbehaved different shapes, such as gourd shape, conch shape and so on. The natures ofgreen coke and difficuty changing from the relevant materal varied greatly. All theseresults were explained logically with the theory of BGBU after being supplemented. Inthe research process of physical qualitative changement, it was discovered that theextinction contour of MCMB complicated and a new kind of mosaic MCMB arisedafter being added with carbon black in dipping pitch. Yields of MCMB and theproportion of mosaic MCMB increased with the adding amount of additive carbonblack. It was concluded from cross section structure of MCMB that several kinds ofMCMB accreted in the producing system;The acting mechanism of green MCMB andgraphiting MCMB with same origin is different. The yields of secondary developmentof MCMB have improved greatly but its microstructure and mophology have not altered.The main reason lies in the green MCMB taken part in the process of development ofmesophase as crystal seeds. There is a polarized phenomenon arised among theMesocarbon microbeads due to the more crystal seeds and diversification of developingmodes of MCMB. In contrast, although the additive carbonizing MCMB also increasedthe yields of mesophase, the effect of it is leveled off to a value, which is not alteredwith the increase of carbonizing MCMB.The reason lies in the additive carbonizingMCMB only acted as an initiator to promote forming of liquid crystal when the LAMare supersaturated in the producing system. At the same time, the balance ofpolycondensation headed to produce more LAM as lots of LAM consumed in theprocess.In the process of analyzing the morphology and microstructure of MCMB underSEM, the unique technology of making SEM samples was explored, the theories in bothmolecular chemistry and supermolecule chemistry were combined to explain thephenomenions appeared in the experiments, so the forming theory of carbonaceousmesophase is abounded and perfected.更多还原