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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 1, Issue 2 - Dec 2000
Volume 1, Issue 1 - Jun 2000
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Influence of Surface Free Energy of Carbon Black/Thermoplastic Resin Composites on PTC Characteristics
Park, Soo-Jin ; Kim, Hyun-Chel ; Lee, Jae-Rock ;
Carbon letters, volume 1, issue 1, 2000, Pages 1~5
The effect of surface free energy on the positive temperature coefficient (PTC) of carbon black/thermoplastic resin composites was investigated. The thermoplastic resins such as EVA, LDPE, LLDPE and HDPE were used with the addition of 30 wt.% of the carbon black. The surface free energy of the composites was studied in the context of two-liquid contact angle measurements, i.e., deionized water and diiodomethane. It was observed that the resistivity on PTC composites Was greatly increased near the crystalline melting temperature, due to the thermal expansion of polymeric matrix. From the experimental results, it was proposed that the decrease of surface free energy induced by interactions between carbon black surfaces and polymer chains is an important factor to the fabrication of a PTC composite made of carbon black and polymeric matrix.
Activated Carbon Fibers from Chemically Modified Coal Tar Pitches
Ryu, S.K. ; Shim, J.W. ; Yang, K.S. ; Mochida, I. ;
Carbon letters, volume 1, issue 1, 2000, Pages 6~11
Coal tar pitch was chemically modified with 10 wt% benzoquinone (BQ) to raise the softening point of isotropic pitch precursor and the precursor was melt-spun into pitch fibers, stabilized, carbonized and activated with steam at
. The weight loss of carbon fiber-benzoquinone (CF-BQ) increased with the increase of activation time like other fibers, but was lower than those of Kureha fiber at the same activation time in spite of larger geometric surface area. Those adsorption isotherms fitted into 'Type I' according to Brunauer, Deming, Deming and Teller classification. However, there was very thin low-pressure hysteresis that lower closure points of the hysteresis are about 0.42-0.45. From the pore size distribution curves, there might be some micropores having narrow-necked bottle; a series of interconnected pore is more likely than discrete bottles. FT-IR studies showed that the functional groups such as carboxyl, quinone, and phenol were introduced to ACFs-BQ surface after steam activation. Methylene blue decolorization and iodine adsorption capacity of ACF-BQ increased linearly with the increase of specific surface area and was larger than that of ACF-Kureha at the same specific surface area.
Conversion of Carbon Fiber into Silicon Carbide Fiber by Pack-Cementation
Joo, Hyeok-Jong ; Kim, Jung-Il ; Lee, Jum-Kyun ;
Carbon letters, volume 1, issue 1, 2000, Pages 12~16
Carbon fiber was reacted with gaseous silicon monoxide which is produced from pack-powder mixture at elevated temperature. As a result of the reaction, two kinds of SiC fiber were obtained. The first one was SiC fibers which were converted from carbon fiber. The fiber is constituted with polycrystal like fine grains or monolithic crystals that have a size from sub-micron to
. Their size depends on the temperature during the conversion reaction. The second one was ultra-fine SiC fibers that were found on the surface of the converted SiC fibers. The ultra-fine fibers have diameters from 0.08 to
and their aspect ratio were larger than 100. The chemical composit ion of the ultra-fine fibers was analyzed using an Auger electron spectroscopy. In result, the fibers consist of 51% silicon, 38% carbon and 11% oxygen by weight.
NO Reduction and Oxidation over PAN based-ACF
Kim, Je-Young ; Lee, Jong-Gyu ; Hong, Ik-Pyo ;
Carbon letters, volume 1, issue 1, 2000, Pages 17~21
Catalytic reduction and oxidation of NO over polyacrylonitrile based activated carbon fibers (PAN-ACF) under various conditions were carried out to develop removal process of NO from the flue gas. The effect of temperature, oxygen concentration and the moisture content for the reduction of NO with ammonia as a reducing agent was investigated. The reduction of NO increased with the oxygen concentration, but decreased with the increased temperature. The moisture content in the flue gas affects the reduction of NO as the inhibition of the adsorption of the other components and the reaction on the surface of ACE For the oxidation of NO to
over PAN-ACF without using a reducing gas, it showed the temperature and the oxygen concentration of the flue gas are the important factors for the NO conversion in which the conversion increased with oxygen concentration and decreased with the temperature increase and might be the alternative option for the selective catalytic reduction process.
Raman Spectroscopical Evaluations of Carbonization and Graphitization of Coal Tar Pitch
Kim, Y.M. ; An, K.L. ; Kim, C. ; Choi, Y.O. ; Park, S.H. ; Yang, K.S. ; Lee, W.E. ;
Carbon letters, volume 1, issue 1, 2000, Pages 22~26
Raman spectroscopy has been used to investigate the structure of coal tar pitch heat-treated up to
by using 514.5 run Ar ion laser line. Four critical temperature ranges were found on pyrolyzing coal tar pitch, which correspond to four distinct processes from disordered carbons to the well-ordered graphite structure. The range of heat treat temperature (HTT) below
corresponds to gas evolution during the pyrolysis of coal tar pitch. Above the HTT are correlated to rearrangements of enlarged molecules, growth of the molecules along the direction of plane, finally stacking in the normal direction of the plane, in the respective HTT ranges of 1000-2000, above 2000 and
Characteristics of DMFC Using High Porous Active Carbon as an Uncatalysed Diffusion Layer in Anode Electrode
Jung, Doo-Hwan ; Shin, Dong-Ryul ;
Carbon letters, volume 1, issue 1, 2000, Pages 27~30
Performance of direct methanol fuel cell using high porous active carbon as an uncatalysed diffusion layer in anode (composite electrode) has been evaluated. Effects of porous active carbon in anode were investigated by galvanostatic method and Fourier Transform Infrared spectroscopy. The single cell was operated with 2.5 M methanol at temperature of
and showed performance of
at 0.4V. By replacing conventional electrode with composite electrode, the increment of
in current density was obtained at
and 0.4V. The potential decay of the single cell was about 14.5% for 20 days operation.
and NO on the Carbon-bed by Microwave
Kim, Dong-Sik ; Lee, Dong-Kyu ;
Carbon letters, volume 1, issue 1, 2000, Pages 31~35
]and NO gases that come from the flue gases of most of all industrial combustion processes are harmful to everything include person and industrial facilities. For the simplification of the environmental clean-up processes, we studied the decomposition process by microwave. The microwave can destroy molecules into elementary atoms and offers energy to the atoms to react with carbons. Since the microwave is not absorbed into quartz tube and metallic chamber, the air pollution gases can be removed with much lower energy than in the case of conventional methods. We studied the decomposition of
and NO gases on the carbon beds by microwave. In the microwave field, the gases can be decomposed to form other compounds, such as elementary sulfur, nitrogen, carbon monoxide and carbon dioxide. It was found that CO gas is formed at higher temperature than is
gas, so it needs to control the bed temperature depend on products that we want to get.
Initial Electrochemical Insertion/Desertion of Lithium into Hard Carbon
Doh, Chil-Hoon ; Moon, Seong-In ; Yun, Mun-Soo ; Jin, Chang-Soo ; Jin, Bong-Soo ; Eom, Seung-Wook ;
Carbon letters, volume 1, issue 1, 2000, Pages 36~40
The initial irreversible capacity (IIC) of a hard carbon during the charge/discharge reaction is strongly affected by both the initial irreversible capacity on the carbon surface
and the initial irreversible lithium insertion into carbon
. The initial coulombic efficiency of the insertion and the desertion of lithium (IIE) can be used as a performance to classify
of the carbon. The
was proportional to the specific discharge capacity with a slope,
- 1. The IIE of hard carbon had four regions.
for the region of 0~95 mAh/g of
for the regions of 95~172 mAh/g and 172~308 mAh/g had 84.9% and 91.5%, respectively.
was appeared above 308 mAh/g. But, the
was reduced to 82.1% compared with
. These IIE might be corresponding to lithium desertion from carbon at the region of 0~172 mAh/g range, lithium desertion from the micropore of carbon at the region of 172~308 mAh/g range, and to the lithium stripping of the plated lithium for the region above 308 mAh/g, respectively.