Synthesis, Characterization And Physical Properties Of Carbon And Carbon Nanocomposite Materials

Carbonaceous materials are widely used and play an important role in many fields. The research and development of novel types of carbonaceous materials is a topic which scientists are much concerned. On the basis of comprehensive and thorough investigation of literatures concerning the developments of carbon and carbon related composites, the point of this dissertation is to synthesize the new structure of micro-scale carbon and carbon related composites, and study their formation mechanism. Some controllable and novel methods were proposed to prepare the above mentioned functional materials, such as reduction pyrolysis route, catalytic decomposition method and catalytic decomposition self-assemble method, et al. various carbon materials were successfully synthesized, including carbon nanoparticles, carbon nanotubes, microspheres assembled by carbon nanotubes, different morphologies Fe₃O₄@carbon composites, and hollow carbon structures. Combining the experimental analysis results and the study of the related reports, the formation mechanisms were studied, respectively. We also investigated the the stabilities of polystyrene/CNTs nanocomposites and the catalytic performance of the catalysts of carbon nanotubes and microspheres assembled by carbon nanotubes as surports, and studied the magnetic properties of Fe₃O₄@carbon composites. The experiment work is now summarized as follow:1. Based on solvothermal routes, a reduction pyrolysis approach is established to synthesize carbon nanoparticles. Carbon nanoparticles were produced with a yield of about 90% by pyrolysis perfluocarbon (boiling poit: 50℃) under the reductant of Na. Through the investigation of reaction temperature, the result indicated that the reaction temperature played the key role on the size of carbon nanoparticles. In addition, we also found that perfluocarbon (boiling poit: 50℃) was not decomposed with the absent of Na until 500℃. It is believed that this novel method should be developed and applied in some special fields. More importantly, it might bring the unpredictable results.2. Using the self-synthesized LaNiO₃,LaCoO₃ and LaFeO₃ as catalysts, carbon nanotubes were successfully synthesized by catalytic pyrolysis of ethanol, and the yield of carbon nanotubes reached above 75%, in which ethanol was used carbon source. The toxic or corrosive reagents have been completely avoided and no extreme condition such as non-oxygen environment is required. We used as above prepared carbon nanotubes as filler to prepare polystyrene/CNTs nanocomposites, tested the thermal stability and studied thermal degradation mechanism.3. Developed catalytic pyrolysis approach, we successfully synthesized larger diameter of carbon nanotubes and microspheres assembled by carbon nanotubes by catalytic pyrolysis of polymer in autoclave, using Ni or ferrocene as catalysts, and ferrocene acted both as carbon source and catalyst. We used as above prepared carbon nanotubes and microspheres as support to prepare catalysts and tested the catalytic performance.4. In order to protect Fe₃O₄ from oxidation and possessed well acid resistance, an original self-assembly route by employing the redox reactions among ferrocene, polytheylene, malated-polypropyle and water has been used to synthesize one-dimensional chain Fe₃O₄ nanoparticles encapsulated in worm-shaped carbon shell, and the magnetic properties of the samples before HCl treatment and after HCl treatment were measured. The results indicated that the composite possess well acid resistance.5. Based on successfully prepared one-dimensional chain Fe₃O₄ nanoparticles encapsulated in worm-shaped carbon shell, we prepared hexapod-like Fe₃O₄@carbon composites, flake Fe₃O₄@carbon composites and chain Fe₃O₄@carbon composites. Without any templet, we completed the controllable synthesis from three dimensions to one dimension. Their magnetic properties have been examined. The corresponding hollow carbon structures were also obtained by HCl treatment.