Study On The Preparation And Characterization For The CNT Laminated Film Based On PAN Precursors

In this paper, polyacrylonitrile (PAN)-based carbon nanotubes (CNTs) composite were produced by insitu polymerization and solution blending. Effects of CNTs content on the structure and the performance of composite were studied. The structure and proformance of CNTs before and after treated with structures and properties of composite were found, the result and analysis could be shown by Raman spectra (LRS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TG), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and transmission electron microscopy(TEM). The surface resistivity of composite film was tested by using Fluke 1508 type insulation resistance tester.It has been found that we can remove the impurities of CNTs by using nitric acid (65%) in room temperature very well, and can graft -COOH,-OH group onto the CNTs whitout disrupting the excellent length-diameter ratio stucture of CNTs.Composites which produced by insitu polymerization were studied and found some phenomenon as follows:with the increase of the content of CNTs, the reactions conversion increased gradually, but when the content reached to 0.3%, the conversion began to decline; at the same time, the preoxidation temperature of polymer was in advance because of CNTs, which reduced the exothermic reaction, and improvd the peoperty of PAN; in some extent, it hindered polymer crystallization, but the structure and crystal of polymer could change.The analysis of DS,XRD showed that the carbon nanotubes could improve the thermal properties of composite materials, and alleviated the exothermic reaction. During the preoxidation process the position of crystallization of composite was varied from 2θ≈16°to 2θ≈25°, which suggested the structure of aromatization appear; in addition, they produced a shoulder peak at about 2θ≈10°-40°in carbonization stage, the cyclization was completed, it had different distribution of the order and the disorder region.The analysis of FTIR showed that the stretching vibrations of C=N and the CH2 decreased during the preoxidation process and nearly disappeared such as C=C and C=N at the temperature of 255℃, it made us believe that the ladder structure appeared gradually. It has been found that the C=N group in films decreased quickly than that the pure PAN, and the cycilzation rate of film increased from 20.24% to 70.41%, when the content of CNTs was 2%, however, the effect of CNTs was not basically discovered in carbonization stage (400℃). On one hand, the part of carbon nanotubes in the composites was in a single dispersion state, on the other hand, the aggregate structure of the carbon nanotubes was found.When the content of CNTs reached to 5%, the surface resistivity of composite film reduced to 5.74 MΩfrom>104 MΩquickly, and it has a little change with the content of CNTs increase.