碳材料用基体沥青的改性研究

【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， 2001， 硕士

【摘要】 碳材料是一种性能优良的无机非金属材料，其中碳纤维增强碳（以下简称C/C）是一种高级复合材料，具有很好的物理、化学和力学性能，但是，C/C复合材料价格昂贵、工艺复杂等问题严重影响了其应用和发展，目前主要局限于航空航天等高技术领域使用。因此，研究低成本、高性能的C/C复合材料已受到世界各国的普遍关注。而研制价格低廉、性能优异、工艺性良好的基体材料则是C/C复合材料的关键。 本文研究了碳材料用基体前驱体——沥青的改性。以来源丰富、价格低廉的工业用中温煤沥青为原料，以二乙烯基苯（DVB）为交联剂，在酸性催化剂作用下合成了R_pc（性能价格比）值较高的碳材料用基体前驱体——缩合多环芳烃树脂（COPNA）。 采用FT-IR光谱和¹H-NMR分析沥青改性的机理。采用SEM对改性沥青的显微结构进行分析。在常温下发现中间相小球，此外，该沥青在550℃炭化后，其气孔率明显地减少。采用差示扫描量热法（DSC）、热重分析（TGA）、差热分析（DTA）等热分析手段分析了改性沥青的热行为。全面分析了改性对沥青的残碳率、软化点、密度和溶解性的影响。采用正交设计方法对合成工艺进行优化，并提出数学模型，对各种影响因素进行了多元线性回归分析。 研究表明，煤沥青在催化剂作用下能与DVB反应合成COPNA树脂。该反应为酸催化下的阳离子型缩聚反应，其中包含有生成树脂和交联剂自身聚合两个反应，后者在很大程度上影响缩合多环芳烃树脂的生成。此外，经过改性的煤沥青不仅含有大量的中间相小球体，而且具有较低的软化点、优良的热稳定性和较高的残碳率。因此，改性后的煤沥青极有希望作为性能优良的碳材料用基体前驱体。更多还原

【Abstract】 Carbon-fibric-reinforced carbon composite (C/C for short) is an advanced composite with excellent physical, chemical and mechanical behavior in carbon materials, which is a kind of inorganic materials with excellent properties. However, the application and development of C/C composite have been greatly obstructed due to its high price and complicated process, which make it only applied to the aeronautic and some high-tech industries at present. Accordingly, study on C/C composite with low price and satisfactory properties has been drawn attention to many developed countries. It is crucial to develop a matrix precursor which can markedly reduce the production cost and improve the properties of the composite. In this paper, the modification of coal tar pitch as a carbon precursor is investigated. Under the action of an acid catalyst. the condensed polynuclear aromatic (CQPNA) resin is synthesized using medium梩emperture coal tar pitch and divinylbenzene (DVB) as a cross-linking agent. The resin with higher ratio of property to cost (R~~) may be used to be an excellent carbon precursor for C/C composite. The reaction mechanism has been studied with FT桰R spectrum and 1H-NMR. The microstructure of modified coal tar pitch has been studied with SEM. A great deal of mesocarbon microbead (MCMB) is found at normal temperature. In addition, the residue, which is acquired with the modified coal tar pitch treated with 5500C for two hours, has much smaller bore compared to that of the unmodified coal tar pitch. DSC, TGA and DTA have been used to analyze the structure and properties of the resin. An overall study of the effect of modification on the properties has been carried out, which follows that the modification can greatly improve the properties of coal tar pitch such as carbonization yield, soft point, density and dissolved properties. Moreover, the method of design in quadrature has been applied to optimize the experimental process, and the mathematic model is put forward to analyze various factors during test by linear multianalvsis. It is indicated that coal tar pitch can be used to synthesize COPNA resin with help of catalyst. The reaction is a positive ion梩yped condensation polymerization catalyzed by acid, in which there are two competitive reactions: some cross-linking agents produce pitch resin with the pitch, the other polymerize themselves. The latter have great effect on producing the condensed polynuclear aromatic resin (COPNA). Besides, the modified pitch has not only much mesocarbon microbead ? II ? S ABSTACT (MCMB), but also low soft point as well as high carbon yield and good thermostability. Therefore, it is qualified to be an excellent carbon precursor.更多还原