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        검색결과 3

        1.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The oxygen-rich activated carbon (AC) was facilely developed using petroleum coke as a raw material by KOH activation under the rapid heating rate. The porosity and surface chemistry of ACs prepared under different heating rates were characterized and their adsorption properties for methylene blue (MB) were investigated. The results showed that the AC5 prepared under the heating rate of 5 °C min−1 had the highest surface area compared with the AC10, AC15 or AC20, while the AC20 prepared under the heating rate of 20 °C min−1 consisted of the highest oxygen content and most –OH functional group compares with the other ACs. These indicated that rapid heating rate was against the formation of more developed porosity, however, it was beneficial to producing more oxygen functional groups. As to MB adsorption, AC15 exhibited the maximum adsorption capacity for MB of 884 mg g−1 due to high surface area of 2803 m2 g−1 and high oxygen content of 23.27%. Moreover, despite the fact that AC20 had much lower surface area than the AC5, the AC20 showed higher MB adsorption capacity than the AC5. This was because the AC20 has the highest content of –OH, which was a positive impetus for MB adsorption. Therefore, rapid heating rate was an effective and simple approach to preparing the oxygen-rich ACs for improving the adsorption capacity of MB.
        4,000원
        2.
        2019.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Commercial ultra-high-strength PAN-based carbon fibers (T1000G) were heat-treated at the temperature range of 2300– 2600 °C under a constant stretching of 600 cN. After continuous high-temperature graphitization treatment, microstructures, mechanical properties and thermal stability of the carbon fibers were investigated. The results show that the T1000G carbon fibers present the similar round shape with a smooth surface before and after graphitization, indicating the carbon fibers are fabricated by dry–wet spinning. In comparison, the commercial high-strength and high-modulus PAN-based carbon fibers (M40JB and M55JB) present elliptical shapes with ridges and grooves on the surface, indicating the carbon fibers are fabricated by wet spinning. After graphitization treatment from 2300 to 2600 °C under a constant stretching of 600 cN, the Young’s modulus of the T1000G carbon fibers increases from about 436 to 484 GPa, and their tensile strength decreases from about 5.26 to 4.45 GPa. The increase in Young’s modulus of the graphitized T1000G carbon fibers is attributed to the increase in the crystallite sizes and the preferred orientation of graphite crystallites along the fiber longitudinal direction under a constant stretching condition. In comparison with the M40JB and the M55JB carbon fibers, the graphitized T1000G carbon fibers are easier to be oxidized, which can be contributed to the formation of more micropores and defects during the graphitization process, thus leading to the decrease in the tensile strength.
        4,000원
        3.
        2018.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we tried to prepare an isotropic spinnable pitch which can be useful to prepare the general purpose carbon fiber through the co-carbonization of biomass tar with ethylene bottom oil under two different preparation methods (atmospheric distillation, pressurized distillation). The results showed that the ethylene bottom oil added co-carbonization was very effective to decrease of the oxygen contents for obtaining a stable spinnable pitch. The pressurized distillation was more effective to reduce the oxygen functional groups of pitches than atmospheric distillation. The obtained spinnable pitch by the pressurized distillation showed higher pitch yield of 42% and lower oxygen content of 9.12% than the spinnable pitch by the atmospheric distillation. The carbon fiber derived from the pressurized distillation spinnable pitch by carbonization at 800ºC for 5 min showed that the higher tensile strength of carbon fiber was increased up to 800 MPa.
        4,000원