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        검색결과 4

        1.
        2014.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Pyrolized fuel oil (PFO) was reformed by novel electron beam (E-beam) radiation, and the elemental composition, chemical bonds, average molecular weight, solubility, softening point, yields, and density of the modified patches were characterized. These properties of modified pitch were dependent on the reforming method (heat or E-beam radiation treatment) and absorbed dose. Aromaticity (Fa), average molecular weight, solubility, softening point, and density increased in proportion to the absorbed dose of E-beam radiation, with the exception of the highest absorbed dose, due to modification by free radical polymerization and the powerful energy intensity of E-beam treatment. The H/C ratio and yield exhibited the opposite trend for the same reason. These results indicate that novel E-beam radiation reforming is suitable for the preparation of aromatic pitch with a high β-resin content.
        4,000원
        2.
        2014.07 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A hierarchical pore structured novolac-type phenol based-activated carbon with micropores and mesopores was fabricated. Physical activation using a sacrificialsilicon dioxide (SiO2) template and chemical activation using potassium hydroxide (KOH) were employed to pre-pare these materials. The morphology of the well-developed pore structure was character-ized using field-emissionscanning electron microscopy. The novolac-type phenol-based activated carbon retained hierarchical pores (micropores and mesopores); it exhibited high Brunauer-Emmett-Teller specificsurface areas and hierarchical pore size distributions. The hierarchical pore novolac-type phenol-based activated carbon was used as an electrode in electric double-layer capacitors, and the specificcapacitance and the retained capacitance ratio were measured. The specificcapacitances and the retained capacitance ratio were en-hanced, depending on the SiO2 concentration in the material. This result is attributed to the hierarchical pore structure of the novolac-type phenol-based activated carbon.
        4,000원
        3.
        2014.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Spinnable pitch for melt-electrospinning was obtained from pyrolized fuel oil by electron beam (E-beam) radiation treatment. The modifiedpitch was characterized by measuring its elemental composition, softening point, viscosity, molecular weight, and spinnability. The softening point and viscosity properties of the modifiedpitch were influencedby reforming types (heat or E-beam radiation treatment) and the use of a catalyst. The softening point and molecular weight were increased in proportion to absorbed doses of E-beam radiation and added AlCl3 due to the formation of pitch by free radical polymerization. The range of the molecular weight distribution of the modifiedpitch becomes narrow with better spinning owing to the generated aromatic compounds with similar molecular weight. The diameter of melt-electrospun pitch fibersunder applied power of 20 kV decreased 53% (4.7 ± 0.9 μm) compared to that of melt-spun pitch fibers(10.2 ± 2.8 μm). It is found that E-beam treatment for reforming could be a promising method in terms of time-savings and cost-effectiveness, and the melt-electrospinning method is suitable for the preparation of thinner fibersthan those obtained with the conventional melt-spinning method.
        4,000원
        4.
        2014.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Multi-walled carbon nanotube (MWCNT)/epoxy composites are prepared by a vacuum assisted resin transfer molding (VARTM) method. The mechanical properties, fracture surface morphologies, and thermal stabilities of these nanocomposites are evaluated for epoxy resins with various amounts of MWCNTs. Composites consisting of different amounts of MWCNTs displayed an increase of the work of adhesion between the MWCNTs and the matrix, which improved both the tensile and impact strengths of the composites. The tensile and impact strengths of the MWCNT/epoxy composite improved by 59 and 562% with 0.3 phr of MWCNTs, respectively, compared to the epoxy composite without MWCNTs. Thermal stability of the 0.3 phr MWCNT/epoxy composite increased compared to other epoxy composites with MWCNTs. The enhancement of the mechanical and thermal properties of the MWCNT/epoxy nanocomposites is attributed to improved dispersibility and strong interfacial interaction between the MWCNTs and the epoxy in the composites prepared by VARTM.
        4,000원