Structural changes of polyacrylonitrile film by catalytic effects of nickel particles under carbonization process

Structural changes of polyacrylonitrile (PAN) film, prepared by gelation/crystallization from solutions, were studied by the effect of nickel particles on the carbonization at various temperatures under argon atmosphere. The carbonized PAN at 800°C showed thread-like structures extended from nickel particles. At 1000°C, the thread-like structures changed to rod-like structures whose one end side was closed by a nickel particle or the aggregation. The disruption of rod-like structures occurred at 1200°C, and the carbonization at 1400°C provided new growth of carbon layers on the surface of spherulitic nickel particles. At 1600°C, fibrous textures were observed as residual traces of disrupted carbon layers by the overflow of melted nickel due to the thermal expansion. The graphitization degrees for G- and T-components in the films carbonized at 1600°C were investigated on the basis of X-ray diffraction intensity distribution from the (002) plane. The analysis was done in terms of the comparison between the experimental and theoretical diffraction intensity curves. The theoretical calculation was carried out by using a concept concerning the para-crystalline theory proposed by Hoseman and Bagchi from the viewpoint of the lattice fluctuation of the c-axis.