Synthesis And Performance Study On The Mesophase Pitch

The optical anisotropy from organisms like the pitch carbonized is called mesophase, which owns the properties like the liquid crystal. The mesophase pitch is a mixture made up of multi flat tray shape condensed nuclear hydrocarbon whose molecular weight varies from 370 to 2000.Because it has many satisfactory properties, it is established to be an excellent matrix for high level carbon materials, such as high module fiber, super heat-conducting materials, super active carbon, high level composite, fluorine-carbon materials and battery electrode. These high level materials will play important roles in national defence industries, aeronautic, high-tech industries and daily life and so forth. Therefore, it is crucial to manufacture mesophase pitch with low price, excellent performance and well process.In this paper, under the action of an acid catalyst, the oligomers are synthesized using medium-temperature coal tar pitch and benzaldehyde as a cross-linking agent, and then mesophase pitch is prepared with the pyrogenation reaction. The mesophase with higher ratio of property to cost (Rpc) may be used to be an excellent matrix for carbon materials.The reaction mechanism of coal tar pitch modified has been studied with FT-IR spectrum, ^-NMR spectrum and SEM; pyrogenation process and medium-phased behaviors have been studied with FT-IR spectrum, element analysis and microstructure analysis; TGA has been used to analyze the structure and thermal properties of the oligomers and mesophase pitch. On the base of these, an overall analysis of the effects of material ratio and reaction conditions against the properties such as yield, softening point, carbon yield and density of pitch modified has been carried out; the effects of material ratio and reaction conditions and the pyrogenation conditions against the structure and properties are also analyzed.The results indicate that coal tar pitch can be used to synthesize oligomers with the help of catalyst. It is likely to belong to a positive ion-typed condensed polymerization reaction under the catalysis of acid. When the mass ratio of BA/Pitch is 20%, reaction is at 170℃ for 8 hours and the dosage of catalyst is 5%, the yield, the carbon yield and the density of oligomers are very high, the softening point is moderate; when pyrogenation is at 400 ℃ for 4 hours, it is prone to get outstanding mesophase pitch with developed optical anisotropy, lower softening point and good thermo-stability.