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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 16, Issue 4 - Oct 2015
Volume 16, Issue 3 - Sep 2015
Volume 16, Issue 2 - Apr 2015
Volume 16, Issue 1 - Jan 2015
Selecting the target year
Preparation and characterization of carbon fiber-reinforced thermosetting composites: a review
Jin, Fan-Long ; Park, Soo-Jin ;
Carbon letters, volume 16, issue 2, 2015, Pages 67~77
DOI : 10.5714/CL.2015.16.2.067
Carbon fibers (CFs) have a unique combination of properties which allow them to be widely used as reinforcing materials in advanced polymer composites. The mechanical properties of CF-reinforced polymer composites are governed mainly by the quality of interfacial adhesion between the CFs and the polymer matrix. Surface treatments of CFs are generally carried out to introduce chemical functional groups on the fiber surfaces, which provide the ability to control the surface characteristics of CFs. In this study, we review recent experimental studies concerning various surface treatment methods for CFs. In addition, direct examples of the preparation and properties of CF-reinforced thermosetting composites are discussed.
Activated carbons prepared from mixtures of coal tar pitch and petroleum pitch and their electrochemical performance as electrode materials for electric double-layer capacitor
Lee, Eunji ; Kwon, Soon Hyung ; Choi, Poo Reum ; Jung, Ji Chul ; Kim, Myung-Soo ;
Carbon letters, volume 16, issue 2, 2015, Pages 78~85
DOI : 10.5714/CL.2015.16.2.078
Activated carbons (ACs) were prepared by activation of coal tar pitch (CTP) in the range of
for 1-4 h using potassium hydroxide (KOH) powder as the activation agent. The optimal activation conditions were determined to be a CTP/KOH ratio of 1:4, activation temperature of
, and activation time of 3 h. The obtained ACs showed increased pore size distribution in the range of 1 to 2 nm and the highest specific capacitance of 122 F/g in a two-electrode system with an organic electrolyte, as measured by a charge-discharge method in the voltage range of 0-2.7 V. In order to improve the performance of the electric double-layer capacitor electrode, various mixtures of CTP and petroleum pitch (PP) were activated at the optimal activation conditions previously determined for CTP. Although the specific capacitance of AC electrodes prepared from CTP only and the mixtures of CTP and PP was not significantly different at a current density of 1 A/g, the AC electrodes from CTP and PP mixtures showed outstanding specific capacitance at higher current rates. In particular, CTP-PP61 (6:1 mixture) had the highest specific capacitance of 132 F/g, and the specific capacitance remained above 90% at a high current density of 3 A/g. It was found that the high specific capacitance could be attributed to the increased micro-pore volume of ACs with pore sizes from 1 to 2 nm, and the high power density could be attributed to the increased meso-pore volume.
Characterization and influence of shear flow on the surface resistivity and mixing condition on the dispersion quality of multi-walled carbon nanotube/polycarbonate nanocomposites
Lee, Young Sil ; Yoon, Kwan Han ;
Carbon letters, volume 16, issue 2, 2015, Pages 86~92
DOI : 10.5714/CL.2015.16.2.086
Multi-walled carbon nanotube (MWCNT)/polycarbonate (PC) nanocomposite was prepared by direct melt mixing to investigate the effect of the shear rate on the surface resistivity of the nanocomposites. In this study, an experiment was carried out to observe the shear induced orientation of the MWCNT in the polymer matrix using a very simple melt flow indexer with various loads. The compression-molded, should be eliminated. MWCNT/PC nanocomposite sample exhibited lower percolation thresholds (at 0.8 vol%) and higher electrical conductivity values than those of samples extruded by capillary and injection molding. Shear induced orientation of MWCNT was observed via scanning electron microscopy, in the direction of flow in a PC matrix during the extrusion process. The surface resistivity rose with increasing shear rate, because of the breakdown of the network junctions between MWCNTs. For real applications such as injection molding and the extrusion process, the amount of the MWCNT in the composite should be carefully selected to adjust the electrical conductivity.
Effect of surface modification of carbon felts on capacitive deionization for desalination
Lee, Jong-Ho ; Ahn, Hong-Joo ; Cho, Donghwan ; Youn, Jeong-Il ; Kim, Young-Jig ; Oh, Han-Jun ;
Carbon letters, volume 16, issue 2, 2015, Pages 93~100
DOI : 10.5714/CL.2015.16.2.093
Surface modified carbon felts were utilized as an electrode for the removal of inorganic ions from seawater. The surfaces of the carbon felts were chemically modified by alkaline and acidic solutions, respectively. The potassium hydroxide (KOH) modified carbon felt exhibited high Brunauer-Emmett-Teller (BET) surface areas and large pore volume, and oxygen-containing functional groups were increased during KOH chemical modification. However, the BET surface area significantly decreased by nitric acid (
) chemical modification due to severe chemical dissolution of the pore structure. The capability of electrosorption by an electrical double-layer and the efficiency of capacitive deionization (CDI) thus showed the greatest enhancement by chemical KOH modification due to the appropriate increase of carboxyl and hydroxyl functional groups and the enlargement of the specific surface area.
Functionalization of graphene nanoplatelets using sugar azide for graphene/epoxy nanocomposites
Bose, Saswata ; Drzal, Lawrence T. ;
Carbon letters, volume 16, issue 2, 2015, Pages 101~106
DOI : 10.5714/CL.2015.16.2.101
We report a covalent functionalization of graphene nanoparticles (GnPs) employing 2,3,4-Tri-O-acetyl-
-D-xylopyranosyl azide followed by fabrication of an epoxy/functionalized graphene nanocomposite and an evaluation of its thermo-mechanical performance. Successful functionalization of GnP was confirmed via thermal and spectroscopic study. Raman spectroscopy indicated that the functionalization was on the edge of the graphene sheets; the basal plane was not perturbed as a result of the functionalization. The epoxy/functionalized GnP composite system exhibited an increase in flexural modulus (~18%) and glass transition temperature (
) compared to an un-functionalized GnP based epoxy composite.
The effects of stacking sequence on the penetration-resistant behaviors of T800 carbon fiber composite plates under low-velocity impact loading
Ahmad, Furqan ; Hong, Jung-Wuk ; Choi, Heung Soap ; Park, Soo-Jin ; Park, Myung Kyun ;
Carbon letters, volume 16, issue 2, 2015, Pages 107~115
DOI : 10.5714/CL.2015.16.2.107
Impact damages induced by a low-velocity impact load on carbon fiber reinforced polymer (CFRP) composite plates fabricated with various stacking sequences were studied experimentally. The impact responses of the CFRP composite plates were significantly affected by the laminate stacking sequences. Three types of specimens, specifically quasi-isotropic, unidirectional, and cross-ply, were tested by a constant impact carrying the same impact energy level. An impact load of 3.44 kg, corresponding to 23.62 J, was applied to the center of each plate supported at the boundaries. The unidirectional composite plate showed the worst impact resistance and broke completely into two parts; this was followed by the quasi-isotropic lay-up plate that was perforated by the impact. The cross-ply composite plate exhibited the best resistance to the low-velocity impact load; in this case, the impactor bounced back. Impact parameters such as the peak impact force and absorbed energy were evaluated and compared for the impact resistant characterization of the composites made by different stacking sequences.
Mechanisms of Na adsorption on graphene and graphene oxide: density functional theory approach
Moon, Hye Sook ; Lee, Ji Hye ; Kwon, Soonchul ; Kim, Il Tae ; Lee, Seung Geol ;
Carbon letters, volume 16, issue 2, 2015, Pages 116~120
DOI : 10.5714/CL.2015.16.2.116
We investigated the adsorption of Na on graphene and graphene oxide, which are used as anode materials in sodium ion batteries, using density functional theory. The adsorption energy for Na on graphene was -0.507 eV at the hollow sites, implying that adsorption was favorable. In the case of graphene oxide, Na atoms were separately adsorbed on the epoxide and hydroxyl functional groups. The adsorption of Na on graphene oxide-epoxide (adsorption energy of -1.024 eV) was found to be stronger than the adsorption of Na on pristine graphene. However, the adsorption of Na on graphene oxide-hydroxyl resulted in the generation of NaOH as a by-product. Using density of states (DOS) calculations, we found that the DOS of the Na-adsorbed graphene was shifted down more than that of the Na-adsorbed graphene oxide-epoxide. In addition, the intensity of the DOS around the Fermi level for the Na-adsorbed graphene was higher than that for the Na-adsorbed graphene oxide-epoxide.
Stabilization of pitch-based carbon fibers accompanying electron beam irradiation and their mechanical properties
Park, Mi-Seon ; Ko, Yoonyoung ; Jung, Min-Jung ; Lee, Young-Seak ;
Carbon letters, volume 16, issue 2, 2015, Pages 121~126
DOI : 10.5714/CL.2015.16.2.121
Carbon fibers are prepared by stabilizing pitch fibers accompanying electron beam (E-beam) irradiation. The carbon fibers pretreated by E-beam irradiation achieve a higher stabilization index than the carbon fibers that are only heat-stabilized. In addition, the carbon fibers subjected to E-beam irradiation in the stabilization step exhibit a comparable tensile strength to that of general purpose carbon fibers. The carbon fibers pretreated with an absorbed dose of 3000 kGy have a tensile strength of 0.54 GPa for a similar fiber diameter. Elemental, Fourier-transform infrared spectroscopy, and thermogravimetric analyses indicate that E-beam irradiation is an efficient oxidation and dehydrogenation treatment for pitch fibers by showing that the intensity of the aliphatic C-H stretching and aromatic
bending (out-of-plane) bands significantly decrease and carbonyl and carboxylic groups form.
Hydrogen storage capacity of highly porous carbons synthesized from biomass-derived aerogels
Choi, Yong-Ki ; Park, Soo-Jin ;
Carbon letters, volume 16, issue 2, 2015, Pages 127~131
DOI : 10.5714/CL.2015.16.2.127
In this work, highly porous carbons were prepared by chemical activation of carbonized biomass-derived aerogels. These aerogels were synthesized from watermelon flesh using a hydrothermal reaction. After carbonization, chemical activation was conducted using potassium hydroxide to enhance the specific surface area and microporosity. The micro-structural properties and morphologies were measured by X-ray diffraction and scanning electron microscopy, respectively. The specific surface area and microporosity were investigated by
/77 K adsorption-desorption isotherms using the Brunauer-Emmett-Teller method and Barrett-Joyner-Halenda equation, respectively. Hydrogen storage capacity was dependent on the activation temperature. The highest capacity of 2.7 wt% at 77 K and 1 bar was obtained with an activation temperature of
Changes in the porosity of bulk graphite according to the viscosity of resin for impregnation
Lee, Sang-Min ; Kang, Dong-Su ; Kim, Hye-Sung ; Roh, Jea-Seung ;
Carbon letters, volume 16, issue 2, 2015, Pages 132~134
DOI : 10.5714/CL.2015.16.2.132
When manufacturing bulk graphite, pores develop within the bulk during the carbonization process due to the volatile components of the fillers and the binders. As a result, the physical properties of bulk graphite are inferior to the theoretical values. Impregnants are impregnated into the pores generated in the carbonization process through pressurization and/or depressurization. The physical properties of bulk graphite that has undergone impregnation and re-carbonization processes are outstanding. In the present study, a green body was manufactured by molding with natural graphite flakes and phenolic resin at 45 MPa. Bulk graphite was manufactured by carbonizing the green body at 700 and it was subsequently impregnated with impregnants having viscosity of 25.0 cP, 10.3 cP, and 5.1 cP, and the samples were re-carbonized at
. The above process was repeated three times. The open porosity of bulk graphite after the final process was 22.25%, 19.86%, and 18.58% in the cases of using the impregnant with viscosity of 25.0 cP, 10.3 cP, and 5.1 cP, respectively.