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MESOPHASE FORMATION IN SYNTHETIC PITCHES: AN INVESTIGATION OF THE EFFECTS OF CHEMICAL STRUCTURES ON MESOPHASE FORMATION.

机译:合成沥青中的中间相形成:化学结构对中间相形成的影响的研究。

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摘要

Simple 2 to 4-ring polynuclear aromatic compounds were reacted to produce synthetic pitches for study of the effects of chemical structure on mesophase formation. With a known starting material, the reactivities of different sites of model compounds, the molecular weight, the C/H ratio, and spectra studies, the structure of these pitches can be better defined than with pitches produced from petroleum.;Solvent fractionation techniques were used to obtain cuts from the synthesized pitches. The mesophase formation of these fractions was studied by heat-treatment and metallographic examination. The chemical structures of these fractions were hypothesized.;Four mechanisms were proposed for mesophase formation, namely: (1) building-up of molecular weight, (2) cracking-off of the disruptive alkyl side arms, (3) volatilization of the low molecular weight species, and (4) ring fusion. Ladder-type molecule pitches form mesophase much easier than disc-like molecules. Polyphenyl pitches were essentially isotropic. The polyphenyls tend to form less condensed, non-polar structures which are a deterrent to mesophase formation. The disc-like molecules have a relatively high C/H ratio. Due to this high C/H ratio, disruptive low molecular weight species are difficult to remove by solvent fractionation techniques. Mesophase formation does not occur easily.;The critical structures for mesophase in pitch were determined from samples that were heat-treated to form tiny mesophase spheres. The critical molecular weight and C/H ratio of simple 2 to 4-ring compounds are found to range from 700 to 900 and 1.70 to 2.15, respectively.;Both catalytic and pyrolytic syntheses were performed. The pyrolytic syntheses, which were run in an autoclave, were calculated to occur in the liquid phase except for naphthalene. All catalytic syntheses involved liquid phase reactions, since the reaction temperatures are lower than the atmospheric boiling point of the compounds. Two component syntheses were also carried out.;Molecular weight distribution is also important for mesophase formation. The low molecular weight species inhibit mesophase formation, while the high molecular weight species are essential for mesophase formation.
机译:简单的2至4环多核芳香族化合物反应生成合成沥青,用于研究化学结构对中间相形成的影响。使用已知的原料,模型化合物不同部位的反应性,分子量,C / H比和光谱研究,与使用石油生产的沥青相比,可以更好地定义这些沥青的结构。用于从合成音高中获取音调。通过热处理和金相检验研究了这些馏分的中间相形成。假设了这些馏分的化学结构。提出了四种中间相形成机理,即:(1)分子量增加,(2)破坏性烷基侧链的裂解,(3)低级烃的挥发。分子量种类,以及(4)环融合。梯形分子间距比盘状分子更容易形成中间相。聚苯沥青基本上是各向同性的。聚苯基倾向于形成较少凝结的非极性结构,这对中间相的形成具有阻碍作用。盘状分子具有相对较高的C / H比。由于高的C / H比,破坏性的低分子量物质很难通过溶剂分馏技术去除。中间相的形成不容易发生。;沥青中中间相的关键结构是从经过热处理形成微小中间相球体的样品中确定的。简单的2至4环化合物的临界分子量和C / H比分别在700至900和1.70至2.15范围内;进行催化和热解合成。计算出在高压釜中进行的热解合成发生在除了萘以外的液相中。所有的催化合成都涉及液相反应,因为反应温度低于化合物的大气沸点。还进行了两个组分的合成。分子量分布对于中间相的形成也很重要。低分子量物质抑制中间相的形成,而高分子量物质对于中间相的形成至关重要。

著录项

  • 作者

    CHEN, SHIH-HUEI.;

  • 作者单位

    Rensselaer Polytechnic Institute.;

  • 授予单位 Rensselaer Polytechnic Institute.;
  • 学科 Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 1982
  • 页码 325 p.
  • 总页数 325
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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