【作者】 施君；

【导师】 卢建军；

【作者基本信息】 太原理工大学 ， 化学工艺， 2010， 硕士

【摘要】 聚酰亚胺微球同时具有聚酰亚胺的优异性能(热稳定性、耐溶剂、耐磨性等)和高分子微球在尺寸和结构上的优势,将在催化载体、分离纯化、离子交换等领域有着广阔的应用前景。目前,聚酰亚胺微球的实验研究主要包括:聚酰亚胺实体微球、聚酰亚胺/无机粒子纳米复合微球、聚酰亚胺多孔微球、聚酰亚胺中空微球;制备的方法主要是悬浮聚合法、分散聚合法、再沉淀法等。但是这些制备方法存在过程繁琐、粒子粘结、粒径难控、使用大量的稳定剂等问题。采用沉淀聚合法制备聚酰亚胺微球,具有过程简单、且不需添加如何稳定剂等特性。在沉淀聚合法制备聚酰亚胺微球过程中,实验考查了几个方面:①沉淀聚合法制备聚酰胺酸微球的影响因素;②聚酰胺酸亚胺化制备聚酰亚胺微球的工艺条件优化;③聚酰亚胺微球的热性能研究。研究表明:(1)沉淀聚合法制备聚酰胺酸微球分别以四种不良溶剂(甲醇、乙醇、四氢呋喃、丁酮)作为反应体系,制备出四种聚酰胺酸微球。结果显示,以丁酮为溶剂时得到的PAA粒子具有最好的球形形貌;且粒径分布较窄,平均粒径为8.8μm。丁酮(MEK)与N-甲基吡咯烷酮(NMP)混合溶剂为反应体系(MEK与NMP的体积比20:1、18:1、15:1、13:1、10:1、8:1)时,制备出的聚酰胺酸微球。结果显示当MEK与NMP的体积比为8:1时,粒子具有最好的球型形貌;且为粒径最大,平均粒径为16.5μm。(2)聚酰胺酸亚胺化制备聚酰亚胺微球的工艺条件优化采用两种不同的加热形式将聚酰胺酸微球亚胺化,即等温度梯度加热(由室温梯度加热到350℃,从100℃开始停30min,后每升温50℃停留30min)和等时间间隔加热(由室温直接加热到350℃,每隔15min取一次样,总共去5次样),最后得到PI微球。结果显示由等温度梯度加热得到的PI微球形貌、粒径分布、反应程度均优于等时间间隔加热得到的PI微球;等温度梯度加热得到的PI微球的平均粒径为8.8μm,粒径分布较窄。(3)聚酰亚胺微球的热性能本文尝试对聚酰亚胺微球的热性能为做了初步的研究,利用凝胶渗透色谱(GPC)分析了三个分子量不同的PI微球,再以DSC对其进行分析。结果表明数均分子量大的聚酰亚胺(a<b<c)微球,其玻璃化温度(Tg)也较高(a<b<c)。更多还原

【Abstract】 Polyimide (PI) microspheres have excellent performance of PI , such as high thermal stability, solvent resistance, wear resistance; and characteristics of microspheres in size and structural. In future, it is used in the catalyst carrier, purification, ion exchange. Currently, polyimide microspheres are mainly the following aspects: entity microspheres of polyimide; composite microspheres of polyimide/inorganic nanoparticle; porous microspheres of polyimide; hollow microspheres of polyimide. The ways of polyimide microspheres prepared are mainly suspension polymerization, dispersion polymerization, re-precipitation method. However, these problems are existed in process of polyimide microspheres prepared, such as complicated process, particles adhesion, particle size difficult to control, using a large number of stabilizing agents.Polymerization of precipitation has these features with the process simple, not adding stabilizing agents. Experiment examines the following aspects:①Preparation of polyamic acid (PAA) microspheres by polymerization;②Polyimide microspheres prepared with imidization of polyamic acid by the process conditions;③The thermal transition behavior of polyimide microspheres. (1) Preparation of polyamic acid (PAA) microspheres by precipitation methodThe polyamic acid (PAA) microspheres were prepared using the precipitation method in solvents such as methanol, ethanol, tetrahydrofuran (THF), Methyl ethyl ketone(MEK) N-metyl-2-pyrrolidone (NMP). Scanning electron microscopy (SEM) photographs show better PAA microsphere morphology while methyl ethyl ketone as solvent, and the average particle size is about 8.8μm. Subsequently, in order to get the larger size microspheres, methyl ethyl ketone (MEK) and N-methyl pyrrolidone (NMP) was used as mixed solvent for the reaction system. When the volume ratio of MEK and NMP was 8:1, the particles have better microspheres morphology, and average particle size is 16.5μm. The particle size increased with increasing the volume ratio of NMP.(2) Polyimide microspheres prepared with imidization of polyamic acid by the process conditionsBased on the front work, selecting the PAA microspheres at the volume ratio of MEK and NMP 8:1, two different forms of heating their sub-amination, such as temperature gradient heating and other time intervals, eventually PI microspheres were obtained. SEM images show microspheres morphology of PI by the temperature gradient heating are better than by the other time intervals; infrared spectroscopy displays the temperature gradient heating better the thermal of PI microspheres performance by temperature gradient heating was better than by the other time intervals .(3) The thermal transition behavior of polyimide microspheresThis article attempts to study the thermal preliminary behavior of polyimide microspheres. Gel permeation chromatography (GPC) analysis three different molecular weight of PI microspheres. The show that glass transition temperature (Tg) of polyimide microspheres increases with the number average molecular weight increasing.更多还原