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2014, Vol.15, No.4

  • 1.

    Carbon-allotropes: synthesis methods, applications and future perspectives

    P. S. Karthik | A. L. Himaja | Surya Prakash Singh | 2014, 15(4) | pp.219~237 | number of Cited : 1
    The element carbon has been used as a source of energy for the past few hundred years,and now in this era of technology, carbon has played a significant and very prominent rolein almost all fields of science and technology. So as an honour to this marvellous element,we humans should know about its various forms of existence. In this review article, weshed light on all possible carbon-allotropes; similarities in their synthesis techniques and thestarting materials; their wide range of possible availability; and finally, future perspectivesand applications. A brief introduction is given on the types, structures, and shapes of the allotropesof carbon for a better understanding.
  • 2.

    Overlook of carbonaceous adsorbents and processing methods for elemental mercury removal

    Kyong-Min Bae | Byung-Joo KIM | PARK SOOJIN | 2014, 15(4) | pp.238~246 | number of Cited : 1
    People have been concerned about mercury emissions for decades because of the extreme toxicity, persistence, and bioaccumulation of methyl Hg transformed from emitted Hg. This paper presents an overview of research related to mercury control technology and identifies areas requiring additional research and development. It critically reviews measured mercury emissions progress in the development of promising control technologies. This review provides useful information to scientists and engineers in this field.
  • 3.

    Modification of isotropic coal-tar pitch by acid treatments for carbon fiber melt-spinning

    우미정 | 고효준 | Yun-Soo Lim and 1other persons | 2014, 15(4) | pp.247~254 | number of Cited : 5
    In this work, thermal treatment accompanied with different acid treatments was applied toa commercial coal tar pitch (CTP) to obtain a spinnable precursor pitch for carbon fiber. In the case of thermal treatment only, a relatively high reaction temperature of between380°C and 400°C was required to obtain a softening point (SP) range of 220°C-260°C andmany meso-phase particles were created during the application of high reaction temperature. When nitric acid or sulfuric acid treatment was conducted before the thermal treatment, theprecursor pitch with a proper SP range could be obtained at reaction temperatures of 280°C-300°C, which were about 100°C lower than those for the case of thermal treatment only. With the acid treatments, the yield and SP of the precursor pitch increased dramatically andthe formation of meso-phase was suppressed due to the lower reaction temperatures. Sincethe precursor pitches with acid and thermal treatment were not spinnable due to the inhomogeneityof properties such as molecular weight distribution and viscosity, the CTP was mixedwith ethanol before the consecutive nitric acid and thermal treatments. The precursor pitcheswith ethanol, nitric acid, and thermal treatments were easily spinnable, and their spinningand carbon fiber properties were compared to those of air blowing and thermal treated CTP.
  • 4.

    Properties of multi-walled carbon nanotube reinforced epoxy composites fabricated by using sonication and shear mixing

    Koo, Minye | 신헌정 | 김원석 and 1other persons | 2014, 15(4) | pp.255~261 | number of Cited : 4
    Multi-walled carbon nanotube reinforced epoxy composites were fabricated using shearmixing and sonication. The mechanical, viscoelastic, thermal, and electrical properties of thefabricated specimens were measured and evaluated. From the images and the results of themeasurements of tensile strengths, the specimens having 0.6 wt% nanotube content showedbetter dispersion and higher strength than those of the other specimens. The Young’s moduliof the specimens increased as the nanotube filler content was increased in the matrix. As theconcentrations of nanotubes filler were increased in the composite specimens, their storageand loss moduli also tended to increase. The specimen having a nanotube filler content of0.6 wt% showed higher thermal conductivity than that of the other specimens. On the otherhand, in the measurement of thermal expansion, specimens having 0.4 and 0.6 wt% fillercontents showed a lower value than that of the other specimens. The electrical conductivitiesalso increased with increasing content of nanotube filler. Based on the measured andevaluated properties of the composites, it is believed that the simple and efficient fabricationprocess used in this study was sufficient to obtain improved properties in the specimens.
  • 5.

    Novel reforming of pyrolized fuel oil by electron beam radiation for pitch production

    정진영 | 박미선 | 김민일 and 1other persons | 2014, 15(4) | pp.262~267 | number of Cited : 9
    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.
  • 6.

    Electromagnetic interference shielding characteristics for orientation angle and number of plies of carbon fiber reinforced plastic

    Kim Hong-Gun | Hee Jae Shin | Kwang Choul Kim and 3other persons | 2014, 15(4) | pp.268~276 | number of Cited : 1
    Recently, methods that usea carbon-based filler, a conductive nanomaterial, have been investigated to develop composite fillers cont7aining dielectric materials. In this study, we added geometric changes to a carbon fiber, a typical carbon-based filler material, by differentiating the orientation angle and the number of plies of the fiber. We also studied the electrical and electromagnetic shield characteristics. Based on the orientation angle of 0°, the orientation angle of the carbon fiber was changed between 0, 15, 30, 45, and 90°, and 2, 4, and 6 plies were stacked for each orientation angle. The maximum effect was found when the orientation angle was 90°, which was perpendicular to the electromagnetic wave flow, as compared to 0°, in which case the electrical resistance was small. Therefore, it is verified that the orientation angle has more of an effect on the electromagnetic interference shield performance than the number of plies.
  • 7.

    Effects of phosphorus content and operating temperature on the electrochemical performance of phosphorus-doped soft carbons

    김은희 | Jung Yongju | 2014, 15(4) | pp.277~281 | number of Cited : 0
    A series of high capacity soft carbons with different phosphorus contents were successfullyprepared by carbonizing petroleum cokes treated with hypophosphorous acid at 900°C. Theeffect of phosphorus content on the electrochemical performance of the soft carbons wasextensively investigated. The P-doped soft carbons exhibited greatly enhanced dischargecapacities and outstanding rate capabilities with increasing phosphorus content. In addition,the influence of temperature on the electrochemical behaviors of the soft carbons wasinvestigated in a wide temperature range of 25°C to 50°C. Surprisingly, the electrochemicalproperties of the pristine and P-doped soft carbons were highly sensitive to the operatingtemperature, unlike conventional graphite. The pristine and P-doped soft carbons exhibitedsignificantly high discharge capacities of 470 and 522 mAh/g, respectively, at a high temperatureof 50°C.
  • 8.

    Thermal properties in strong hydrogen bonding systems composed of poly(vinyl alcohol), polyethyleneimine, and graphene oxide

    최수아 | 황덕군 | LEE HEON SANG | 2014, 15(4) | pp.282~289 | number of Cited : 1
    Blends of poly(vinyl alcohol) (PVA), polyethyleneimine (PEI), and graphene oxide (GO) were prepared by solution casting method. Calorimetric thermal properties of the blends were investigated. The Tgs of PVA/PEI blends were higher than the Tgs of either of the component polymers at low concentrations of PEI. These abnormal increases of Tgs may be due to the negative entropy of mixing which is associated with strong hydrogen bonding between PVA and PEI. The degree of depression of s was not reduced by the negative entropy of mixing, since strong hydrogen bonding also causes an increase in the magnitude of negative c between PVA and PEI. The Tg of PVA was increased significantly by adding 0.7 wt.% GO into PVA. The magnitude of negative c was increased by adding GO into the blends of PVA and PEI.
  • 9.

    Effects of comonomer with carboxylic group on stabilization of high molecular weight polyacrylonitrile nanofibrous copolymers

    Danyun Lei | Kesavan Devarayan | Xiangdan Li and 3other persons | 2014, 15(4) | pp.290~294 | number of Cited : 0
    New precursors, poly(acrylonitrile-co-crotonic acid) (poly(AN-CA)) and poly(acrylonitrile-co-itaconic acid-co-crotonic acid) (poly(AN-IA-CA)) copolymers, for the preparation of carbon fibers, were explored in this study. The effects of comonomers with acidic groups, such as crotonic acid (CA) and/or itaconic acid (IA), on the stabilization of nanofibrous polyacrylonitrile (PAN) copolymers were studied. The extent of stabilization, evaluated by Fourier transform infrared spectroscopy, revealed that the CA comonomer could retard/control the stabilization rate of PAN, in contrast to the IA comonomer, which accelerated the stabilization process. Moreover, the synthesized PAN copolymers containing CA possessed higher Mv than those of the IA copolymers and also showed outstanding dimension stability of nanofibers during the stabilization, which may be a useful property for improving the dimensional stability of polymer composites during manufacturing.
  • 10.

    A study on elemental mercury adsorption behaviors of nanoporous carbons with carbon dioxide activation

    Kyong-Min Bae | PARK SOOJIN | 2014, 15(4) | pp.295~298 | number of Cited : 2
    In this work, nanoporous carbons (NPCs) were prepared by the self-assembly of polymericcarbon precursors and block copolymer template in the presence of tetraethyl orthosilicateand colloidal silica. The NPCs’ pore structures and total pore volumes were analyzed by referenceto N2/77 K adsorption isotherms. The porosity and elemental mercury adsorption ofNPCs were increased by activation with carbon dioxide. It could be resulted that elementalmercury adsorption ability of NPCs depended on their specific surface area and micropore fraction.