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2009, Vol.10, No.3

  • 1.

    Fundamental Understanding of Nanoporous Carbons for Energy Application Potentials

    Katsumi Kaneko | Miki Arai | Masahiro Yamamoto and 22other persons | 2009, 10(3) | pp.177~180 | number of Cited : 2
    Abstract
    The importance of nanopore structures of carbons is shown in terms of interaction potential for various molecules including supercritical gases such as H2 and CH4. The key factors for adsorption of supercritical H2 and CH4 are shown for single wall carbon nanohorn, single wall carbon nanotube, and double wall carbon nanotube. The cluster formation of molecules is a key process for water adsorption on hydrophobic carbon nanopores. The X-ray absorption spectroscopic examination elucidates an explicit dehydration structure of ions confined in carbon nanopores.
  • 2.

    Influence of Heating Rate and Temperature on Carbon Structure and Porosity of Activated Carbon Spheres from Resole-type Phenolic Beads

    Arjun Singh | Darshan Lal | 2009, 10(3) | pp.181~189 | number of Cited : 0
    Abstract
    Activated carbon spheres (ACS) were prepared at different heating rates by carbonization of the resole-type phenolic beads (PB) at 950oC in N2 atmosphere followed by activation of the resultant char at different temperatures for 5 h in CO2 atmosphere. Influence of heating rate on porosity and temperature on carbon structure and porosity of ACS were investigated. Effect of heating rate and temperature on porosity of ACS was also studied from adsorption isotherms of nitrogen at 77 K using BET method. The results revealed that ACS have exhibited a BET surface area and pore volume greater than 2260 m2/g and 1.63 cm3/g respectively. The structural characteristics variation of ACS with different temperature was studied using Raman spectroscopy. The results exhibited that amount of disorganized carbon affects both the pore structure and adsorption properties of ACS. ACS were also evaluated for structural information using Fourier Transform Infrared (FTIR) Spectroscopy. ACS were evaluated for chemical composition using CHNS analysis. The ACS prepared different temperatures became more carbonaceous material compared to carbonized material. ACS have possessed well-developed pores structure which were verified by Scanning Electron Microscopy (SEM). SEM micrographs also exhibited that ACS have possessed well-developed micro- and meso-pores structure and the pore size of ACS increased with increasing activation temperature.
  • 3.

    Amino Silane, Vinyl Silane, TESPD, ZS (TESPD/Zinc Complex) Effects on Carbon Black/Clay Filled Chlorobutyl Rubber (CIIR) Compounds Part III: Comparative Studies on Hard Clay and Soft Clay Filled Compounds

    Kim Kwang-Jea | 2009, 10(3) | pp.190~197 | number of Cited : 1
    Abstract
    Various silanes, amino silane, vinyl silane, sulfur silane (TESPD), and ZS (TESPD/zinc soap complex), are added into chlorinated isobutylene-isoprene copolymer (CIIR)/soft clay/carbon black (CB) and CIIR/hard clay/CB compounds and they are investigated with respect to the vulcanization characteristics, the processability, and the mechanical properties. Comparing hard clay and soft clay filled compounds, hard clay (Suprex) filled system shows a higher die C tear than the soft clay (GK) filled one. The other properties (Mooney, extrusion torque/pressure, torque rise (MH-ML), modulus at 300%) are close to each other. Among various silanes, the ZS treated hard clay (Suprex) compound shows the highest mechanical property following hard clay(S)/vinyl silane(V) and soft clay(GK)/vinyl silane(V) compounds. The TESPD and the ZS effectively helps a formation of a strong 3-dimensional network structure between silica and CIIR via coupling reaction due to bifunctional nature of TESPD. In addition to that, the ZS added compounds show both a better processability and mechanical properties compared to the S2 ones at low concentration due to improved compatibility between zinc soap and CIIR matrix. Only the ZS added compound shows both improved processabilities (Mooney, Extrusion torque-& pressure) and improved mechanical properties (degree of crosslinking, elongation modulus, tear, and fatigue to failure counts) on both CIIR/hard clay/CB and CIIR/soft clay/CB compounds.
  • 4.

    Thermostable Adsorption Filter Immobilized with Super Activated Carbons by Quinoline Soluble Isotropic Pitch Binder

    Yeong Tae Park | Chul Gyou Im | Yeong Tae Kim and 1other persons | 2009, 10(3) | pp.198~201 | number of Cited : 0
    Abstract
    Among other filters such as light filter, wave filter, air filter, ultra filter and filter paper, a novel adsorption filter from thermostable polyester nonwoven fabrics immobilized with functional super activated carbon by means of quinoline soluble, activateable isotropic pitch binder were developed in this study. The activated carbon precursor is available in the market branded as coconut shell based activated carbon(CCS-AC) produced by Dongyang Carbon Co. Ltd. BET-surface area of this precursor was 1,355 m2/g, after KOH-activation it increased over 2,970 m2/g and was named as super activated carbon. In the preliminary research, this precursor was impregnated with PdCl2(0.188 wt%) KMnO4(3 wt%) and redox-agent(CuCl2, 0.577 wt%) in order to promote TOF up to 100/h and Selectivity up 99% and patented as a functional AC for the ethylene adsorption. The enhancement of the isotropic pitch binder to the AC-immobilized adsorption filter was BET-surface area upgraded by 266 m2/g and promoted the Iodine- and MB-adsorption by 1.4 times, respectively and also micro pore wide ranges <5Å~30 Å>.
  • 5.

    Relationship Between Exothermic Heat and Carbon Contents of Pitch-based Carbon Fiber

    Jae Young Lee | Jong Hyun Oh | Xiao Ping Yang and 1other persons | 2009, 10(3) | pp.202~207 | number of Cited : 5
    Abstract
    Pitch-based carbon fiber tows were prepared from naphtha cracking bottom oil by reforming and carbonization. The relationship between exothermic heat and carbon contents of the fiber was investigated by changing the carbonization conditions. The carbon contents and the crystallinities of isotropic pitch-based carbon fibers were 86.8~93.8 wt% and 33.7~40.1%, respectively, which were linearly proportional to the increase of carbonization temperature from 700 to 1000oC. The exothermic heat (temperature increase) of fiber tows was measured in a short time, which was also linearly proportional to the increase of carbon contents due to the increase of crystallinity, even though the crystallinity was low. Therefore, the carbon contents or carbonization degree of fibers can rapidly and indirectly be estimated by measuring the surface temperature increase of fibers.
  • 6.

    Effect of pH-dependent Solubility on Release Behavior of Alginate-Chitosan Blend Containing Activated Carbon

    오애리 | Dong-Hwee Jin | 윤주미 and 2other persons | 2009, 10(3) | pp.208~212 | number of Cited : 2
    Abstract
    Alginate-chitosan blend containing coconut-based activated carbon was prepared as a drug delivery carrier in order to improve the loading and releasing capacity of the drug. The activated carbon was incorporated as effective adsorbent for drug due to the extremely high surface area and pore volume, high adsorption capacity, micro porous structure and specific surface activity. Alginate-chitosan blend containing coconut-based activated carbon showed the sustained release for a longer period. Alginate-chitosan blend showed higher release of drug as the pH increased and higher release of drug as the content of chitosan decreased due to the pH-dependent solubility of blend components.
  • 7.

    Preparation and Electroactivities of Carbon Nanotubes-supported Metal Catalyst Electrodes Prepared by a Potential Cycling

    Seok Kim | Yongju Jung | PARK SOOJIN | 2009, 10(3) | pp.213~216 | number of Cited : 2
    Abstract
    The electrochemical deposition of Pt nanoparticles on carbon nanotubes (CNTs) supports and their catalytic activities for methanol electro-oxidation were investigated. Pt catalysts of 4~12 nm average crystalline size were grown on supports by potential cycling methods. Electro-plating of 12 min time by potential cycling method was sufficient to obtain small crystalline size 4.5 nm particles, showing a good electrochemical activity. The catalysts’ loading contents were enhanced by increasing the deposition time. The crystalline sizes and morphology of the Pt/support catalysts were evaluated using X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). The electrochemical behaviors of the Pt/support catalysts were investigated according to their characteristic current-potential curves in a methanol solution. In the result, the electrochemical activity increased with increased plating time, reaching the maximum at 12 min, and then decreased. The enhanced electroactivity for catalysts was correlated to the crystalline size and dispersion state of the catalysts.
  • 8.

    Hydrogen Adsorption of PAN-based Porous Carbon Nanofibers using MgO as the Substrate

    정민정 | Im Ji Sun | Euigyung Jeong and 2other persons | 2009, 10(3) | pp.217~220 | number of Cited : 2
    Abstract
    In this study, porous electrospun carbon fibers were prepared by electrospinning with PAN and MgCl2, as a MgO precursor. MgO was selected as a substrate because of its chemical and thermal stability, no reaction with carbon, and ease of removal aftercarbonization by dissolving out in acidic solutions. MgCl2 was mixed with polyacrylonitrile (PAN) solution as a precursor ofMgO with various weight ratios of MgCl2/PAN. The average diameter of porous electrospun carbon fibers increased from 1.3 to3 μm, as the MgCl2 to PAN weight ratio increased. During the stabilization step, MgCl2 was hydrolyzed to MgOHCl by heattreatment. At elevated temperature of 823 K for carbonization step, MgOHCl was decomposed to MgO. Specific surface area andpore structure of prepared electrospun carbon fibers were decided by weight ratio of MgCl2/PAN. The amount of hydrogenstorage increased with increase of specific surface area and micropore volume of prepared electrospun carbon fibers.
  • 9.

    CO2 Adsorption of Amine Functionalized Activated Carbons

    Longyue Meng | Ki-Sook Cho | 박수진 | 2009, 10(3) | pp.221~224 | number of Cited : 5
    Abstract
    In this work, the CO2 adsorption behaviors of amine functionalized activated carbons (ACs) were investigated. The surface of ACs was modified with urea, melamine, diethylenetriamine (DETA), pentaethylenehexamine (PEHA), polyethylenimine (PEI), and 3-aminopropyl-triethoxysilane (ATPS). The various surface properties of amine functionalized ACs were characterized by Boehm’s method, nitrogen full isotherms, XPS, and TGA analyses. The active ingredients impregnated on the ACs show significant influence on the adsorption for CO2 and its volumes adsorbed on amine functionalized ACs are larger than that on the pristine ACs, which is due to the grafted amine groups of the AC surfaces.
  • 10.

    Thermal Emissivity of Nuclear Graphite as a Function of Its Oxidation Degree (1) -Effects of Density, Porosity, and Microstructure-

    서승국 | Eung-Seon Kim | Se-Hwan Chi and 3other persons | 2009, 10(3) | pp.225~229 | number of Cited : 1
    Abstract
    Thermal emissivity of commercial nuclear graphites (IG-110, PCEA, IG-430 and NBG-18) following changes in oxidation degrees were examined. Specimens were oxidized to 0%, 5%, and 10% in air flow of 5l/min at 600oC using a furnace, and the thermal emissivities were measured using an infrared spectrum analyzer. The measuring temperatures for the thermal emissivity were 100oC, 200oC, 300oC, 400oC and 500oC. Also density and porosity of the specimens were observed to compare with thermal emissivity. Results showed that emissivity increased with oxidation, and the 10% oxidized NBG-18 showed the highest emissivity (0.890) which value is larger for 24% than the value of as-received specimen. Investigation of factors affecting the emissivity revealed that increases in the surface roughness and porosity due to oxidation were responsible for the increase in emissivity after oxidation.
  • 11.

    Low Temperature Growth of High-Quality Carbon Nanotubes by Local Surface Joule Heating without Heating Damage to Substrate

    Hursungtaek | Dong-Gu Lee | 2009, 10(3) | pp.230~233 | number of Cited : 0
    Abstract
    In this study, a low temperature growth of high-quality carbon nanotubes on glass substrate using a local surface heating without heating damage to substrate was tried and characterized. The local joule heating was induced to only Ni/Ti metal film on glass substrate by applying voltage to the film. It was estimated that local surface joule heating method could heat the metal surface locally up to around 1200oC by voltage control. We could successfully obtain high-quality carbon nanotubes grown at 300oC by applying 125 V for joule heating as same as carbon nanotubes grown at 900oC.
  • 12.

    Improvement of the Field Emission Stability of Carbon Nanotube Paste Emitter by Post-treatments

    Young Chul Choi | Mun Seok Jeong | 2009, 10(3) | pp.234~238 | number of Cited : 1
    Abstract
    The field emitters were fabricated by screen-printing of carbon nanotube paste, and their emission stabilities were evaluated. It was found that the emission stability measured in a sealed device is much higher than that measured in a vacuum chamber in spite of similar pressure. This was because oxygen gas was scarcely remained in the sealed device, while the gas is continuously supplied into the vacuum chamber during the stability measurement. It was found that the plasma treatment etched the protruded CNTs, resulting in the uniform height of CNT tips. As a result, the stability was increased remarkably. It was also found that the stability of CNT paste emitter was improved by electrical aging and that the optimum condition for the aging was varied with the size of emitter.
  • 13.