Preparation of a high-performance synthetic pitch from aromatic hydrocarbons containing N/Cl

含氮/氯芳烃制备高性能合成沥青

The preparation of a synthetic pitch from aromatic monomers could easily regulate structure orientation at the molecu-lar level,which would be useful in fabrication.An isotropic synthetic pitch was prepared by a chlorine-and/or nitrogen-induced sub-stitution polymerization reaction method using aromatic hydrocarbon precursors containing Cl and N,which for this study were chloromethyl naphthalene and quinoline.This method was verified by investigating the structural changes under different synthesis conditions,and the synthesis mechanism induced by aromatics containing Cl was also probed.The result shows that the pyridinic N in quinoline contains a lone pair of electrons,and is an effective active site to induce the polymerization reaction by coupling with aromatic hydrocarbons containing Cl.The reaction between such free radicals causes strong homopolymerization and oligomeriza-tion.A higher reaction temperature and longer reaction time significantly increased the degree of polymerization and thus increased the softening point of the pitch.A linear molecular structure was formed by the Cl substitution reaction,which produced a highly spinnable pitch with a softening point of 258.6℃,and carbon fibers with a tensile strength of 1163.82 MPa were obtained.This study provides a relatively simple and safe method for the preparation of high-quality spinnable pitch.

芳香族单体制备合成沥青在分子水平上易于调控取向结构,有利于高性能炭纤维的制备。本研究以含氮和含氯芳烃为前驱体,采用Cl和/或N诱导取代聚合反应制备了合成沥青。通过考察不同合成条件下沥青的结构变化,系统地验证了卤化强化合成工艺,并对制备高性能炭纤维的反应机理进行了深入探讨。结果表明,喹啉中的吡啶N具有较强的亲电功能,是与含氯芳烃偶联诱导聚合反应的有效活性位点。这些自由基之间的相互反应会引起强烈的均聚和寡聚。较高的合成温度和较长的保留时间有利于提高聚合度,从而提高合成沥青的软化点。通过指定的Cl自由基和甲基取代过程,形成了线性的分子结构,为制备高可纺沥青提供了条件。得到了软化点为258.6℃的高质量可纺沥青和抗拉强度为1 163.82 MPa的炭纤维。本研究有望为制备高质量可纺沥青提供一种相对简单、安全的方法。