In Chapter 1, we investigated stepwise stabilization process of 48k filaments polyacrylonitrile (PAN) precursor to observe thermal behavior of PAN fibers. We also controlled parameters such as oven temperature, air flow direction, velocity, thermal residence time, and tow size to optimize stabilizat...
In Chapter 1, we investigated stepwise stabilization process of 48k filaments polyacrylonitrile (PAN) precursor to observe thermal behavior of PAN fibers. We also controlled parameters such as oven temperature, air flow direction, velocity, thermal residence time, and tow size to optimize stabilization process for large tow carbon fibers. FT-IR, elemental analyzer, density column, X-ray diffractometer were used to evaluate stabilization degree and chemical structural evolution during thermal stabilization. The oxidation process of PAN fibers makes cross-linking reaction more easily between intermolecular chains and enduces cyclization reaction of acrylonitrile. In addition, the degree of air diffusion into fibers affects the mechanical properties of the final carbon fiber. The carbon fiber with ca. 10 % of oxygen content and 1.40 g/cm3 of density showed the best mechanical properties with 2.5 GPa in tensile strength and 214 GPa in tensile modulus.
In Chapter 2, the method to produce PAN-based carbon fiber having greater elastic modulus by blending CNT(carbon nanotube) was investigated. In general, PAN-based carbon fiber has excellent tensile strength (3-7 GPa) but shows a lower elastic modulus (200-300 GPa) than pitch based carbon fiber (400–500 GPa). CNT reinforced carbon fibers were studied in this research, which had both high tensile strength and high elastic modulus. Carbon nanotube (CNT), which is a nanomaterial, shows exceptional mechanical properties, high specific conductivity, and low density. However, CNTs are not completely dispersed in the polymer matrix due to aggregation, it is not easy to realize the merits of the CNT as a filler. In this study, functional group was induced to CNT to improve a dispersity of CNT in AN(acrylonitrile) monomer. AN monomer was polymerized to PAN and the PAN was solution spun to produce CNT reinforced PAN filament. It was converted to carbon fiber by using normal carbonization process and mechanical properties was measured. When the density of stabilized PAN was 1.31 g/cm3 and the content of CNT was 0.2wt%, Carbon fiber showed the maximum tensile strength of 4.5 GPa and elastic modulus of 440 GPa.
In Chapter 1, we investigated stepwise stabilization process of 48k filaments polyacrylonitrile (PAN) precursor to observe thermal behavior of PAN fibers. We also controlled parameters such as oven temperature, air flow direction, velocity, thermal residence time, and tow size to optimize stabilization process for large tow carbon fibers. FT-IR, elemental analyzer, density column, X-ray diffractometer were used to evaluate stabilization degree and chemical structural evolution during thermal stabilization. The oxidation process of PAN fibers makes cross-linking reaction more easily between intermolecular chains and enduces cyclization reaction of acrylonitrile. In addition, the degree of air diffusion into fibers affects the mechanical properties of the final carbon fiber. The carbon fiber with ca. 10 % of oxygen content and 1.40 g/cm3 of density showed the best mechanical properties with 2.5 GPa in tensile strength and 214 GPa in tensile modulus.
In Chapter 2, the method to produce PAN-based carbon fiber having greater elastic modulus by blending CNT(carbon nanotube) was investigated. In general, PAN-based carbon fiber has excellent tensile strength (3-7 GPa) but shows a lower elastic modulus (200-300 GPa) than pitch based carbon fiber (400–500 GPa). CNT reinforced carbon fibers were studied in this research, which had both high tensile strength and high elastic modulus. Carbon nanotube (CNT), which is a nanomaterial, shows exceptional mechanical properties, high specific conductivity, and low density. However, CNTs are not completely dispersed in the polymer matrix due to aggregation, it is not easy to realize the merits of the CNT as a filler. In this study, functional group was induced to CNT to improve a dispersity of CNT in AN(acrylonitrile) monomer. AN monomer was polymerized to PAN and the PAN was solution spun to produce CNT reinforced PAN filament. It was converted to carbon fiber by using normal carbonization process and mechanical properties was measured. When the density of stabilized PAN was 1.31 g/cm3 and the content of CNT was 0.2wt%, Carbon fiber showed the maximum tensile strength of 4.5 GPa and elastic modulus of 440 GPa.
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