【作者】 林起浪；

【导师】 李铁虎；

【作者基本信息】 西北工业大学 ， 材料学， 2002， 博士

【摘要】 本文进行了炭材料用基体前驱体煤沥青的改性研究。首先对煤沥青的分子结构进行设计，然后分别采用二乙烯基苯（DVB）、对甲基苯甲醛（PMB）对工业中温煤沥青进行了改性，并分析了煤沥青的改性机理；其次探讨了改性煤沥青的工艺、组成与性能之间的关系；最后研究了改性煤沥青的热解动力学、流变行为及中间相转化行为。 通过分子设计法对高残炭低粘度煤沥青的分子结构进行设计，提出了高残炭低粘度煤沥青分子结构的模型。煤沥青分子应以稠环芳烃为主，并具有较大的芳香度和适当的缩合度，含有较多的环烷结构和适量的短侧链取代基，具有良好的分子平面性和结构的整齐性。 采用FT-IR和¹H-NMR分别对DVB、PMB改性煤沥青的结构进行分析，表明DVB或PMB在对甲苯磺酸的作用下能够与煤沥青中的多环芳烃发生亲电取代反应，使煤沥青中的活性小分子交联形成大分子。此外，DVB在还会发生阳离子型自聚反应。 采用SEM对改性煤沥青的形貌进行观察，发现DVB改性煤沥青中出现很多微纤，随着反应程度的加深，微纤在搅拌的作用下相互缠结成核形成小球体；PMB改性煤沥青中也出现很多微纤，随着改性程度的加深，纤维直径越来越大，最后形成分布均匀且线性很好的纤维束。 通过对改性煤沥青的工艺、组成与性能的研究发现，工艺条件对改性煤沥青的组成和性能有不同程度的影响，尤其是反应温度的影响更为显著；DVB改性煤沥青的残炭率为53.4％～71.2％、软化点为89℃～151.0℃、密度为1.305g／cm³～1.358g／cm³，PMB改性煤沥青的残炭率为54.3％～67.6％、软化点为84.6℃～131.0℃、密度为1.306g／cm³～1.342g／cm³；改性煤沥青的甲苯不溶吡啶可溶物（TI-PS）的含量一般保持在16.0％～19.0％；改性煤沥青的甲苯可溶物（TS）、吡啶不溶物（PI）组份分别与残炭率、软化点、密度之间存在较好的线性关系。 采用TG／DTG和Kissinger法对改性煤沥青的热解行为进行研究。结果表明，DVB改性煤沥青的热解过程是一步完成的，其热解活化能E_a=218.31kJ／mol、指前因子lnA=37.68S^-1、反应级数n=1.04；PMB改性煤沥青的热解过程是较复杂的，其热解活化能E_a=180.91KJ／mol、指前因子lnA=31.75s^-1、反应级数n=1.11。 采用流变分析法对改性煤沥青的流变行为进行研究。结果表明，改性煤沥青 摘 要表现出非牛顿流体行为。随温度的升高或剪切速率的增加，改性媒沥青的粘度降低：随TS含量增加，改性煤沥青的流动活化能厂变小、指前因子A变大；煤沥青在改性过程中可通过工艺的调整来控制煤沥青的粘度，以满足不同的使用要求。 通过对改性煤沥青焦化产物光学结构的研究发现，随着热解温度的升高，改性煤沥青的甲基和亚甲基的仁H伸缩振动峰及弯曲振动峰的吸收强度逐渐减弱：随热解温度的升高，改性煤沥青的C／H原子比增加、芳香度提高；改性煤沥青焦化产物的偏光显微结构显著改善。随改性工艺和热聚合条件（温度、时间）的不同，改性煤沥青焦化产物的光学结构由超镶嵌uM)组织向广域m)组织转变。更多还原

【Abstract】 In this paper,the modification of coal tar pitch as carbon precursor is investigated. Firstly,we design the molecular structure for coal tar pitch,and modify industrial medium-temperature coal tar pitch with divinylbenzene (DVB) and p-methyl benzaldehyde (PMB) in the presence of p-toluene sulfonic acid (PTS),the modification mechanism of which is studied. Secondly,we study the relation among modification process,properties and fractions of modified coal tar pitch. Finally,we also study thermal decomposition,rheological behavior and mesophase transformation behavior of the modified coal tar pitch,respectively.We put forward a model for coal tar pitch with high carbon yield and low viscosity by molecular structure design. The molecule of coal tar pitch is supposed to be hydrocarbon with condensed rings which has higher aromaticity and condensation. Otherwise,it should have cycloalkane structure,some side chain substituting group and good order of the molecular structure.The molecular structure of modified coal tar pitch is studied using Fourier transform infra-red (FT-IR) and ’H nuclear magnetic resonance (’H-NMR) spectroscopy technologies. The results show that coal tar pitch can happen electrophilic substithtion reaction with DVB or PMB with help of PTS,which makes the molecular weight of coal tar pitch larger. Moreover,cationic polymerization of DVB also can happen in the condition.Scanning electron microscope (SEM) is used to observe the shape of modified coal tar pitch. There are many chain fibers in the coal tar pitch modified with DVB at initial stages. A great deal of small spheres,which form under the action of whipping,are found in the modified coal tar pitch with increase of modification degree. There are also many chain fibers in the coal tar pitch modified with PMB. The fibers grow with increase of modification degree,finally form bundles which present even distributing and good linearity.An overall study is made in the relation among modification process,properties and fractions of modified coal tar pitch. The results show that modification process,such as reaction temperature,greatly influences the properties and fractions. The properties of coal tar pitch modified with DVB are listed as follows:(l).Carbon yield is 53.4%-71.2%;(2).Softening point is 89 - 151.0;(3).Density tested at room temperature is 1.305g/cm3-1.358g/cm3. The properties (carbon yield,softening point,density) of coaltar pitch modified with PMB are 54.3%-67.6%,84.6C-131.0 and 1.306g/cm3-1.342g/cm3,respectively. The content of TI-PS,which dissolves in pyridine but toluene,keeps a value from 16.0% to 19.0%. However,Toluene soluble substances (TS) have good linearity relation with the properties of coal tar pitch,i.e.,carbon yield,softening point and density tested at room temperature. Pyridine insoluble substances (PI) have good linearity relation with these properties,too.The thermal decomposition behaviors of the modified coal tar pitches are studied using thermogravimetric analysis (TGA) and Kissinger expressions. The results show that the thermal decompsoition reaction of coal tar pitch modified with DVB proceeds in one-step,the energy of activation (Ea) of which is 218.31 kJ/mol. Pre-exponential factor InA is 37.68 s-1,and reaction order n is 1.04. However,the thermal decompsoition reaction of coal tar pitch modified with PMB is more complicated,the energy of activation (Ea) of which is 180.91 kJ/mol. Pre-exponential factor InA is 31.75 s-1,and reaction order n is 1.11.A viscometer is applied to study the rheological behaviors of modified coal tar pitches. The modified coal tar pitches behaves in non-Newton fluid. The viscous flow activation energy of modified coal tar pitches markedly increases with rise of TS content,and pre-exponential factor A decreases. The results also show that the viscousity can be controlled by adjusting modification process in order to meet different requirements.The optical texture of resultant semicokes of modified coal tar pitch is characterized by reflected polarized-light mi更多还原