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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal DOI :
Korean Carbon Society
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Volume & Issues
Volume 15, Issue 4 - Oct 2014
Volume 15, Issue 3 - Jul 2014
Volume 15, Issue 2 - Apr 2014
Volume 15, Issue 1 - Jan 2014
Selecting the target year
Double-walled carbon nanotubes: synthesis, structural characterization, and application
Kim, Yoong Ahm ; Yang, Kap-Seung ; Muramatsu, Hiroyuki ; Hayashi, Takuya ; Endo, Morinobu ; Terrones, Mauricio ; Dresselhaus, Mildred S. ;
Carbon letters, volume 15, issue 2, 2014, Pages 77~88
DOI : 10.5714/CL.2014.15.2.077
Double walled carbon nanotubes (DWCNTs) are considered an ideal model for studying the coupling interactions between different concentric shells in multi-walled CNTs. Due to their intrinsic coaxial structures they are mechanically, thermally, and structurally more stable than single walled CNTs. Geometrically, owing to the buffer-like function of the outer tubes in DWCNTs, the inner tubes exhibit exciting transport and optical properties that lend them promise in the fabrication of field-effect transistors, stable field emitters, and lithium ion batteries. In addition, by utilizing the outer tube chemistry, DWCNTs can be useful for anchoring semiconducting quantum dots and also as effective multifunctional fillers in producing tough, conductive transparent polymer films. The inner tubes meanwhile preserve their excitonic transitions. This article reviews the synthesis of DWCNTs, their electronic structure, transport, and mechanical properties, and their potential uses.
Superhydrophobic carbon-based materials: a review of synthesis, structure, and applications
Meng, Long-Yue ; Park, Soo-Jin ;
Carbon letters, volume 15, issue 2, 2014, Pages 89~104
DOI : 10.5714/CL.2014.15.2.089
Materials with appropriate surface roughness and low surface energy can form superhydrophobic surfaces, displaying water contact angles greater than
. Superhydrophobic carbon-based materials are particularly interesting due to their exceptional physicochemical properties. This review discusses the various techniques used to produce superhydrophobic carbon-based materials such as carbon fibers, carbon nanotubes, graphene, amorphous carbons, etc. Recent advances in emerging fields such as energy, environmental remediation, and thermal management in relation to these materials are also discussed.
Removal of methylene blue using lemon grass ash as an adsorbent
Singh, Harminder ; Dawa, Tshering B. ;
Carbon letters, volume 15, issue 2, 2014, Pages 105~112
DOI : 10.5714/CL.2014.15.2.105
Wastewater from textile industries is a major cause of water pollution in most developing countries. In order to address the issues of water pollution and high cost for treatment processes, the use of an inexpensive and environmentally benign adsorbents has been studied. The objective was to find a better alternative to the conventional methods. Lemon grass waste (ash) collected from a lemon grass stream distillation subunit in Bhutan was tested for dye removal from aqueous solutions. The study investigated the removal of methylene blue using the following operational parameters: initial concentration (100-600 mg/L), contact time, adsorbent dose (0.1-0.55 gm/100 mL), and pH (3-10). It was found that the percentage removal of dye increased with a decrease of the initial concentration and increased contact time and dose of adsorbent. The basic pH solution of dye showed better adsorption capacity as compared to the acidic dye solution. Langmuir and Freundlich adsorption isotherms were fitted to the data well. Data fitted better to Lagergren pseudo 2nd order kinetics than a 1st order kinetic model. Surface morphology was also examined via scanning electron microscopy. An elemental analysis was also carried out and the chemical composition and functional groups were analyzed using energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy techniques, respectively. The obtained results indicate that lemon grass ash could be employed as a low cost alternative to commercial activated carbon in wastewater treatment for the removal of dyes.
Study on electrochemical performances of sulfur-containing graphene nanosheets electrodes for lithium-sulfur cells
Son, Ki-Soo ; Kim, Seok ;
Carbon letters, volume 15, issue 2, 2014, Pages 113~116
DOI : 10.5714/CL.2014.15.2.113
Due to their morphology, electrochemical stability, and function as a conducting carbon matrix, graphene nanosheets (GNS) have been studied for their potential roles in improving the performance of sulfur cathodes. In this study, a GNS/sulfur (GNS/S) composite was prepared using the infiltration method with organic solvent. The structure, morphology and crystallinity of the composites were examined using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The electrochemical properties were also characterized using cyclic voltammetry (CV). The CV data revealed that the GNS/S composites exhibited enhanced specific-current density and ~10% higher capacity, in comparison with the S-containing, activated-carbon samples. The composite electrode also showed better cycling performance for multiple charge/discharge cycles. The improvement in the capacity and cycling stability of the GNS/S composite electrode is probably related to the fact that the graphene in the composite improves conductivity and that the graphene is well dispersed in the composites.
Study on lowering the percolation threshold of carbon nanotube-filled conductive polypropylene composites
Park, Seung Bin ; Lee, Moo Sung ; Park, Min ;
Carbon letters, volume 15, issue 2, 2014, Pages 117~124
DOI : 10.5714/CL.2014.15.2.117
Conductive polymer composites (CPCs) consist of a polymeric matrix and a conductive filler, for example, carbon black, carbon fibers, graphite or carbon nanotubes (CNTs). The critical amount of the electrically conductive filler necessary to build up a continuous conductive network, and accordingly, to make the material conductive; is referred to as the percolation threshold. From technical and economical viewpoints, it is desirable to decrease the conductive-filler percolation-threshold as much as possible. In this study, we investigated the effect of polymer/conductive-filler interactions, as well as the processing and morphological development of low-percolation-threshold (
) conductive-polymer composites. The aim of the study was to produce conductive composites containing less multi-walled CNTs (MWCNTs) than required for pure polypropylene (PP) through two approaches: one using various mixing methods and the other using immiscible polymer blends. Variants of the conductive PP composite filled with MWCNT was prepared by dry mixing, melt mixing, mechanofusion, and compression molding. The percolation threshold (
) of the MWCNT-PP composites was most successfully lowered using the mechanofusion process than with any other mixing method (2-5 wt%). The mechanofusion process was found to enhance formation of a percolation network structure, and to ensure a more uniform state of dispersion in the CPCs. The immiscible-polymer blends were prepared by melt mixing (internal mixer) poly(vinylidene fluoride) (PVDF, PP/PVDF, volume ratio 1:1) filled with MWCNT.
Effect of stacking sequence on the flexural and fracture properties of carbon/basalt/epoxy hybrid composites
Lim, Jae Il ; Rhee, Kyong Yop ; Kim, Hyun Ju ; Jung, Dong Ho ;
Carbon letters, volume 15, issue 2, 2014, Pages 125~128
DOI : 10.5714/CL.2014.15.2.125
In this study, the effect of stacking sequence on the flexural and fracture properties of carbon/basalt/epoxy hybrid composites was investigated. Two types of carbon/basalt/epoxy hybrid composites with a sandwich form were fabricated: basalt skin-carbon core (BSCC) composites and carbon skin-basalt core (CSBC) composites. Fracture tests were conducted and the fracture surfaces of the carbon/basalt/epoxy hybrid composites were then examined using scanning electron microscopy (SEM). The results showed that the flexural strength and flexural modulus of the CSBC specimen respectively were ~32% and ~245% greater than those of the BSCC specimen. However, the interlaminar fracture toughness of the CSBC specimen was ~10% smaller than that of the BSCC specimen. SEM results on the fracture surface showed that matrix cracking is a dominant fracture mechanism for the CSBC specimen while interfacial debonding between fibers and epoxy resin is a dominant fracture process for the BSCC specimen.
Preparation of pitch from pyrolized fuel oil by electron beam radiation and its melt-electrospinning property
Jung, Jin-Young ; Lee, Young-Seak ;
Carbon letters, volume 15, issue 2, 2014, Pages 129~135
DOI : 10.5714/CL.2014.15.2.129
Spinnable pitch for melt-electrospinning was obtained from pyrolized fuel oil by electron beam (E-beam) radiation treatment. The modified pitch was characterized by measuring its elemental composition, softening point, viscosity, molecular weight, and spinnability. The softening point and viscosity properties of the modified pitch were influenced by 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
due to the formation of pitch by free radical polymerization. The range of the molecular weight distribution of the modified pitch becomes narrow with better spinning owing to the generated aromatic compounds with similar molecular weight. The diameter of melt-electrospun pitch fibers under applied power of 20 kV decreased 53% (
) compared to that of melt-spun pitch fibers (
). 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 fibers than those obtained with the conventional melt-spinning method.
Facile preparation of self-assembled wool-based graphene hydrogels by electron beam irradiation
Park, Mira ; Pant, Bishweshwar ; Choi, Jawun ; Park, Yong Wan ; Lee, Chohye ; Shin, Hye Kyoung ; Park, Soo-Jin ; Kim, Hak-Yong ;
Carbon letters, volume 15, issue 2, 2014, Pages 136~141
DOI : 10.5714/CL.2014.15.2.136
Three dimensional self-assembled graphene hydrogels were easily fabricated by electron beam irradiation (EBI) using an aqueous solution of wool/poly(vinyl alcohol) and graphene oxide (GO). After exposure to various levels of EBI radiation, the highly porous, self-assembled, wool-based graphene hydrogels were characterized using scanning electron microscopy and Fourier-transform infrared spectroscopy; to determine the gel fraction, degree of swelling, gel strength, kinetics-of-swelling analyses and removal of hexavalent chromium (Cr(VI)) from the aqueous solution. X-ray diffraction results confirmed that EBI played a significantly important role in reducing GO to graphene. The adsorption equilibrium of Cr(VI) was reached within 80 min and the adsorption capacity was dramatically increased as the acidity of the initial solution was decreased from pH 5 to 2. Changes in ionic strength did not exert much effect on the adsorption behavior.
Fabrication of isotropic bulk graphite using artificial graphite scrap
Lee, Sang-Min ; Kang, Dong-Su ; Kim, Woo-Seok ; Roh, Jea-Seung ;
Carbon letters, volume 15, issue 2, 2014, Pages 142~145
DOI : 10.5714/CL.2014.15.2.142
Isotropic synthetic graphite scrap and phenolic resin were mixed, and the mixed powder was formed at 300 MPa to produce a green body. New bulk graphite was produced by carbonizing the green body at
, and the bulk graphite thus produced was impregnated with resin and re-carbonized at
. The bulk density of the bulk graphite was
, and the porosity of the open pores was 29.8%. After one impregnation, the density increased to
while the porosity decreased to 25.2%. Differences in the pore distribution before and after impregnation were easily confirmed by observing the microstructure. In addition, by using an X-ray diffractometer, the degrees-of-alignment (Da) were obtained for one side perpendicular to the direction of compression molding of the bulk graphite (the "top-face"), and one side parallel to the direction of compression molding (the "side-face"). The anisotropy ratio calculated from the Da-values obtained was 1.13, which indicates comparatively good isotropy.
Effects of carbonization temperature on pore development in polyacrylonitrile-based activated carbon nanofibers
Lee, Hye-Min ; An, Kay-Hyeok ; Kim, Byung-Joo ;
Carbon letters, volume 15, issue 2, 2014, Pages 146~150
DOI : 10.5714/CL.2014.15.2.146
In this work, activated carbon nanofiber (ACNF) electrodes with high double-layer capacitance and good rate capability were prepared from polyacrylonitrile nanofibers by optimizing the carbonization temperature prior to
activation. The morphology of the ACNFs was observed by scanning electron microscopy. The elemental composition was determined by analysis of X-ray photoelectron spectroscopy.
-adsorption-isotherm characteristics at 77 K were confirmed by Brunauer-Emmett-Teller and Dubinin-Radushkevich equations. ACNFs processed at different carbonization temperatures were applied as electrodes for electrical double-layer capacitors. The experimental results showed that the surface morphology of the CNFs was not significantly changed after the carbonization process, although their diameters gradually decreased with increasing carbonization temperature. It was found that the carbon content in the CNFs could easily be tailored by controlling the carbonization temperature. The specific capacitance of the prepared ACNFs was enhanced by increasing the carbonization temperature.