The Research On Functionalization And Polystyrene Composite Of Multi-walled Carbon Nanotubes

Carbon nanotubes have attracted enormous attention due to their unique structure, remarkable mechanical properties and potential applications. However, carbon nanotubes are insoluble in common solvent and polymer matrix result in limiting the scope of application. In this dissertation, the research work firstly compared the effect of different chemical oxidation on the carboxyl of multi-walled carbon nanotubes (MWCNTs). Then MWCNTs modified by styryl groups and polystyrene were prepared on the basis of carboxyl MWCNTs. Thirdly, three kinds of MWCNTs/polystyrene composites were prepared using functionalized MWCNTs mentioned before. Their mechanical and thermal properties were compared and discussed.(1) The effect on the carboxyl on the surface of MWCNTs treated by different chemic treatments. The results indicate that the tubular structures of carbon nanotubes are not distinctly destroyed by three kinds of treatments. Multi-walled carbon nanotubes treated by hydrogen peroxide/mix-acid solution has the most impressive performance under the same condition, which has the most carboxyl characteristic peaks. Besides, Zeta potential and valid diameter of that sample is the lowest of all.(2) Styryl-modified muli-walled carbon nanotubes were prepared by esterification based on carboxylate and halides approaches. The results show that styryl group covently bond to the surface of MWCNTs; the structure of MWCNTs has not been distinctly broken. The grafting rate of styryl group on the surface of MWCNTs indicates in TGA result is as high as 36%. Besides, the results of dispersibility show that MWCNTs can well dissolve in organic solution, such as toluene and THF.(3) Polystyrene grafted muli-walled carbon nanotubes have been successfully prepared in presence of Styry-modified MWCNTs. The results indicated that polystyrene successfully grafted onto muli-walled carbon nanotubes .According to the results of TGA mensuration, the Grafting Rate of polystyrene is 70%. The TEM characterization results indicate that the coating thickness of polystyrene is about 8~13nm.(4) MWCNTs-COOH/PS composites,Styryl-modified MWCNTs/PS composites and MWCNTs/PS composites are prepared via solution blend. Diverse functionalized carbon nanotubes, as well as different carbon nanotube content effect on the mechanical and thermal property are discussed. The results indicate that mechanical and thermal properties are almost increased in accord with the increasing of the content of carbon nanotube, except MWCNTs-COOH/PS composites, that of which first rising after decline. In the same circumstances in the content of carbon nanotubes, the mechanical and thermal property of composites prepared by in situ polymerization improve access to the largest compared to the solution blend methods. Besides, the mechanical and thermal property of composites prepared by solution blend of styryl-modified MWCNTs and polystyrene in THF is superior to that of MWCNTs-COOH/PS composites.