Study On The Modification Of Coal Tar Pitch Using As The Precursor Of Carbon Radix

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 material 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 have been drawn attention to many developed countries. It is crucial to develop a matrix precursor that 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 poly-nuclear aromatic (COPNA) resin is synthesized using medium-temperature coal tar pitch and p-methyl benzaldehyde as a cross-linking agent. The resin with higher ratio of property to cost (Rpc) may be used to be an excellent carbon precursor for C/C composite.The reaction mechanism of coal tar pitch modified has been studied with FT-IR spectrum, 'H-NMR spectrum and SEM. And medium-phased behaviors have been studied with FT-IR spectrum, element analysis and microstructure analysis DSC and TGA etc. have been used to analyze the structure and thermal properties of the resin. On the base of this, an overall analysis of the effect on material ratio and reaction condition against the properties such as carbon yield, softening point and density of pitch modified has been carried out.It is indicated that coal tar pitch can be used to synthesize COPNA resin with help of catalyst. It belongs to a positive ion-typed condensed polymerization reaction under catalysis of acid, in which there are two competitive reactions: some cross-linking agents produce pitch resin with the pitch, the other polymerizes themselves. The latter have great effect on producing the condensed poly-nuclear aromatic resin (COPNA). Besides, the modified pitch contains not only much fibre-shaped or slices-shaped structure, but also has low soft point as well as high carbon yield and good thermostability. Therefore, it is qualified to be an excellent carbon precursor.