The influence of two-stage isothermal treatment on the change in the linear dimensions of the fiber, the average sizes of the coherent scattering regions, the texture and phase composition of the polyacrylonitrile fib...The influence of two-stage isothermal treatment on the change in the linear dimensions of the fiber, the average sizes of the coherent scattering regions, the texture and phase composition of the polyacrylonitrile fiber in the process of isothermal thermal stabilization is considered by the methods of dilatometry and X-ray diffraction analysis. It is shown that preliminary short-term heat treatment at a lower temperature affects the process of structural transformations of the polyacrylonitrile fiber material and the formation of a new highly dispersed phase of the thermally stabilized fiber.展开更多
Thermal stabilization is an important process in carbon fibers＇ production, during which the polyacryloni-trile fibers are heated from 180℃ to 280 ℃ in air. In this study, the samples were characterized by X-ray di...Thermal stabilization is an important process in carbon fibers＇ production, during which the polyacryloni-trile fibers are heated from 180℃ to 280 ℃ in air. In this study, the samples were characterized by X-ray diffraction,Fourier infrared spectroscopy, differential scanning calorimetry, small angle X-ray Scattering（SAXS） and mechanicaltensile tests. A new rule was suggested by the results of structural characterization for the cyclization, dehydrogena-tion and oxidation reactions that were observed to be drastic from 200 ℃ to 220 ℃, from 220 ℃ to 250 ℃, and inthe later period of the thermal stabilization reactions, respectively. The sizes, shapes and distributions of the sealedmicropores were obtained from the SAXS data. The breaking elongation was significantly affected by the drasticcyclization and dehydrogenation reactions. The breaking force was affected considerably by the bigger micropores,especially from 220 ℃ to 250 ℃, owing to the drastic dehydrogenation reactions.展开更多
文摘The influence of two-stage isothermal treatment on the change in the linear dimensions of the fiber, the average sizes of the coherent scattering regions, the texture and phase composition of the polyacrylonitrile fiber in the process of isothermal thermal stabilization is considered by the methods of dilatometry and X-ray diffraction analysis. It is shown that preliminary short-term heat treatment at a lower temperature affects the process of structural transformations of the polyacrylonitrile fiber material and the formation of a new highly dispersed phase of the thermally stabilized fiber.
文摘Thermal stabilization is an important process in carbon fibers＇ production, during which the polyacryloni-trile fibers are heated from 180℃ to 280 ℃ in air. In this study, the samples were characterized by X-ray diffraction,Fourier infrared spectroscopy, differential scanning calorimetry, small angle X-ray Scattering（SAXS） and mechanicaltensile tests. A new rule was suggested by the results of structural characterization for the cyclization, dehydrogena-tion and oxidation reactions that were observed to be drastic from 200 ℃ to 220 ℃, from 220 ℃ to 250 ℃, and inthe later period of the thermal stabilization reactions, respectively. The sizes, shapes and distributions of the sealedmicropores were obtained from the SAXS data. The breaking elongation was significantly affected by the drasticcyclization and dehydrogenation reactions. The breaking force was affected considerably by the bigger micropores,especially from 220 ℃ to 250 ℃, owing to the drastic dehydrogenation reactions.
