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pISSN : 1976-4251 / eISSN : 2233-4998

2020 KCI Impact Factor : 0.33
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2020, Vol.30, No.3

  • 1.

    Evaluation of composite PAN fibers incorporated with carbon nanotubes and titania and their performance during the microwave-induced pre-oxidation

    Elagib Tienah H. H. | Hassan Elwathig A. M. | Liu Baihua and 2other persons | 2020, 30(3) | pp.235~245 | number of Cited : 0
    Abstract
    The composite PAN fbers which incorporated with CNTs and Titania were prepared by mean of wet spinning. These fbers were then pre-oxidized with microwave heating in an air atmosphere. A combination of characterizations was carried out to study the impact of nanoparticles fllers on the properties of as-spun fbers and their performance during the microwave pre-oxidation. The addition of an equal amount of fllers made obvious changes in the chemical and crystalline structure, consequently improves the strength, and this could lower the capability to creep over a wide range of temperatures in the subsequent processes. FTIR and NMR analyses results of the pre-oxidized fbers exhibited clear changes in the PAN structure, where the dehydrogenation reaction and the degree of cyclization were investigated. Additional confrmation of the occur�rence of cyclization reaction was achieved by XRD and thermal analysis. According to the TGA results, the pre-oxidized CNT1 /Ti-PAN fbers exhibit greater thermal stability suggesting high carbon content and good quality could result in the dependent carbon fbers.
  • 2.

    Microstructure and electrical properties of carbon short fiber reinforced copper composites fabricated by electroless deposition followed by powder metallurgy process

    Daoush Walid M. | Alkhuraiji Turki S. | Khamis Moath A. and 1other persons | 2020, 30(3) | pp.247~258 | number of Cited : 0
    Abstract
    Carbon short fbers/copper composites with diferent carbon short fber contents up to 15 wt.% as reinforcements are prepared to investigate the infuence of the carbon short fber surface coating on the microstructure, density, and electrical properties of the carbon short fbers/copper composites. The carbon short fbers were surface treated by acid functionalization followed by alkaline treatment before the coating process. It was observed from the results that coated type copper nanoparticles were deposited on the surface of the carbon short fbers. The surface treated carbon short fbers were coated by copper using the electroless deposition technique in the alkaline tartrate bath by using formaldehyde as a reducing agent of the copper sulfate. The produced coated carbon short fbers/copper composite powders were cold compacted at 600 MPa, and then sintered at 875 °C for 2 h under (hydrogen/nitrogen 1:3) atmosphere. A reference copper sample was also prepared by the same method to compare between the properties of pure copper and the carbon short fbers/copper composites. The phase composition, morphology, and microstructure of the prepared carbon short fbers/copper composite powders as well as the correspond�ing carbon short fbers/copper composites were investigated using X-ray difraction analysis (XRD) and scanning electron microscope (SEM) equipped with an energy-dispersive spectrometer (EDS), respectively. The density and the electrical resistivity of the sintered composites were measured. It was observed from the results that the density was decreased; how�ever, the electrical resistivity was increased by increasing the carbon short fbers wt.%.
  • 3.

    Structural characteristics and sodium penetration behaviors in anthracite cathodes: a combination study using Monte Carlo and molecular dynamics simulations

    Daoush Walid M. | Li Jiaqi | Zhang Hongliang and 2other persons | 2020, 30(3) | pp.259~269 | number of Cited : 0
    Abstract
    In aluminum electrolysis, sodium penetration into carbon cathodes is considered as the main cause of cell failure and ef�ciency loss, but the detailed mechanism is still not defnitely clear. Since the macroscopic properties of material depend on the microscopic structures, a large-scale atomistic model of anthracite cathodes was constructed to represent several important structural characteristics. Combined with Monte Carlo and molecular dynamics simulations, the adsorption and difusion behaviors of sodium were investigated, respectively. The results suggest that sodium adsorption mainly occurs in the larger micro-pores with the range of 10–19 Å, while it accords well with to type-I Langmuir adsorption model. The sodium is found to be preferentially adsorbed in arch-like structures with 5- or 7-membered rings or around heteroatom, especially oxygen. Moreover, the movements of sodium through carbon matrix mainly depend on the continuous difusive motion while most sodium particles tend to be trapped in voids with small mobility. The calculated transport difusion coefcient is equal to 6.132 × 10−10 m2 /s, which is in outstanding agreement with experimental results. This fundamental research would contribute to the understanding of sodium penetration mechanism and the optimization of cathode industry in the f
  • 4.

    Fracture mechanism characteristics of ultra-thin chopped carbon fiber tape-reinforced thermoplastics hat-shaped hollow beam under transverse static and impact loadings

    Guo Qitao | Xiao Bohan | Ohsawa Isamu and 1other persons | 2020, 30(3) | pp.271~280 | number of Cited : 0
    Abstract
    This paper aims to experimentally and numerically explore fracture mechanism characteristics of ultra-thin chopped carbon fber tape-reinforced thermoplastics (UT-CTT) hat-shaped hollow beam under transverse static and impact loadings. Three distinct failure modes were observed in the impact bending tests, whereas only one similar progressive collapse mode was observed in the transverse bending tests. The numerical model was to incorporate some hypothetical inter-layers in UT-CTT and assign them with the failure model as cohesive zone model, which can perform non-linear characteristics with failure criterion for representing delamination failure. The dynamic material parameters for the impact model were theoretically predicted with consideration of strain-rate dependency. It shows that the proposed modeling approach for interacting damage modes can serve as a benchmark for modeling damage coupling in composite materials.
  • 5.

    Trichloroethylene adsorption from aqueous solutions by activated carbons

    Krasnova Tamara A. | Belyaeva Oxana V. | Gorelkina Alena K. and 3other persons | 2020, 30(3) | pp.281~287 | number of Cited : 0
    Abstract
    We studied trichloroethylene (TCE) adsorption from aqueous solutions in equilibrium conditions by activated carbons (AC). They difer in raw materials, porous structure characteristics and chemical state of the surface. TCE adsorption isotherms were found to have a concave shape, which is characteristic of a sorbent—sorbate weak interaction. It can be a result from electrostatic repulsion of organic matter molecule from polar groups on carbon surface and adsorbed water molecules. The basic parameters of adsorption were calculated by the Dubinin–Radushkevich equation. We determined that for AG-OV-1 and SKD-515 in the coordinates of the Dubinin–Radushkevich equation, there are two linear plots suggesting adsorption in pores of diferent sizes or reorientation of adsorbate molecules on the activated carbon surface. The efciency of TCE removal by the activated carbons was evaluated. To reduce the TCE to the maximum allowable, the lowest sorbent consumption was observed for AC with the highest values of surface area and micropore volume. However, the high cost and hydrophobicity of these adsorbents make it impractical to use them in adsorption columns with a fxed layer. We ofered an adsorbent that reasonably combines extraction efciency, ease of operation and economic feasibility.
  • 6.

    Low thermal conductivity carbon material from electrospinning and subsequent chemical activation

    Gbewonyo Spero | Xiu Shuangning | Shahbazi Abolghasem and 1other persons | 2020, 30(3) | pp.289~296 | number of Cited : 1
    Abstract
    Low thermal conductivity carbon fbers from polyacrylonitrile (PAN) are currently being explored as an alternative for tradi�tional rayon-based carbon fbers with a thermal conductivity of 4 W/m K. Compared to multiple component electrospinning, this research demonstrated another feasible way to make low thermal conductivity carbon fbrous material by electrospinning PAN followed by carbonization and alkali activation. The efects of activation condition on microstructure, pore formation, and thermal conductivity of the resultant carbon nanofbrous material were investigated. The processing-structure-thermal conductivity relationship was revealed and mechanism of thermal conductivity reduction was discussed. The overall thermal conductivity of the prepared carbon nanofbrous material is a result of combined efects from factors of carbon structure and number of pores rather than volume of pores or specifc surface area. The activated carbon nanofbrous materials showed thermal conductivity as low as 0.12 W/m K, which is a reduction of~99% when compared to that of solid carbon flm and a reduction of~95% when compared to that of carbon nanofbrous material before activation.
  • 7.

    Facile preparation of activated carbon with optimal pore range for high butane working capacity

    Lee hye-min | Lee Byeong-Hoon | An Kay-Hyeok and 2other persons | 2020, 30(3) | pp.297~305 | number of Cited : 0
    Abstract
    In this work, the correlation between the pore characteristics of activated carbon (AC) and the adsorption/desorption charac�teristics of evaporated fuel was studied. AC was prepared by various physical re-activation methods using coconut-derived commercial AC. Pore characteristics of the re-activated AC were investigated using N2/77 K adsorption isotherms. The structural characteristics of the AC were observed by X-ray difraction and Raman spectroscopy. The butane working capacity was observed according to ASTM D5228. From the results, the specifc surface area and total pore volume of the ACs were determined to be 1380–2040 m2 /g and 0.60–0.96 cm3 /g, respectively. It was also observed that various pore size distributions were found to be dependent on the functions of the activation method and time. A close relationship between butane activity/ retentivity and micropore/mesopore volumes was found. In addition, it was inferred that the volume fraction of micropores and sub-mesopores with diameters between 1.5 and 3.0 nm primarily controls butane activity.
  • 8.

    Synthesis and characterization of activated carbon produced from waste human hair mass using chemical activation

    Bal Altuntaş Derya | Nevruzoğlu Vagif | Dokumacı Meryem and 1other persons | 2020, 30(3) | pp.307~313 | number of Cited : 0
    Abstract
    In this study, hair waste was converted into active carbon for the frst time and its characteristics were analyzed. As chemi�cal activation tool, zinc chloride (ZnCl2) was impregnated and then carbonized under diferent temperatures (250–300 °C). Scanning Electron Microscope (SEM) images showed an increase in the pore density, radius and volume of pores. X-ray difraction analysis (XRD) showed that the samples had an amorphous structure. In Fourier-transform infrared (FT-IR) spec�troscope analysis, C=C and N–H vibrations observed in 1515–1520 cm−1 wave number of protein molecules were found to disappear with the increase in temperature. With Raman spectroscopy, the behaviors of D peak at 1344 cm−1 wave number and G peak at 1566 cm−1 wave number expressing structure layout in carbonized structures were analyzed depending on the temperatures. Between these intensities, (ID/IG) the rate was found to difer in direct proportion to temperature. XRD spectrums showed that the samples are converted into a more irregular crystal structure. All these results implied that the waste hair mass could be used as an adsorbant material.
  • 9.

    Preparation and electrochemical properties of self-doped nitrogen porous carbon derived from Zn-MOFs

    Zhang Dongqiang | Zhang Chi | Wang Qian and 3other persons | 2020, 30(3) | pp.315~324 | number of Cited : 0
    Abstract
    Metal–organic frameworks (MOFs) are network-like frameworks composed of transition metals and organic ligands con�taining oxygen or nitrogen. Because of its highly controllable composition and ordered porous structure, it has broad appli�cation prospects in the feld of material synthesis. In this work, Zn4(PYDC)4(DMF)2∙3DMF (ZPD) was synthesized via a hydrothermal method. Self-doped nitrogen porous carbon ZPDC-T was then prepared by one-step carbonization. The results show that the self-doped nitrogen porous carbon ZPDC-850 has a micro/mesoporous structure with a specifc surface area of 1520 m2 g−1 and a nitrogen content of 6.47%. When a current density is 1.0 A g−1, its specifc capacitance is 265.1 F g−1 . After 5000 times of constant current charging and discharging, the capacitance retention rate was 79.2%. Thus, self-doped nitrogen porous carbon ZPDC-850 exhibits excellent electrochemical properties and good cyclic stability. Therefore, the self-doped nitrogen porous carbon derived from MOFs can be a promising electrode material for superc
  • 10.

    A complementary analysis of the porous structure of biochars obtained from biomass

    Kwiatkowski Mirosław | Kalderis Dimitrios | 2020, 30(3) | pp.325~329 | number of Cited : 0
    Abstract
    This paper presents the results of the analysis of the porous structure of biochars produced from biomass, namely eucalyptus, wood chips, pruning waste and rice husk. The structural analysis was carried out using the BET, the t-plot, the NLDFT and the LBET methods, which yielded not only complementary information on the adsorptive properties of obtained biochars from these materials, but also information on the usefulness of the structural analysis methods in question for the research into an effect of the technology of carbonaceous adsorbent preparation.
  • 11.

    Heteroatoms in situ-doped hierarchical porous hollow-activated carbons for high-performance supercapacitor

    Yan Rui | Wang Kai | Tian Xiaodong and 6other persons | 2020, 30(3) | pp.331~344 | number of Cited : 0
    Abstract
    Heteroatoms in situ-doped hierarchical porous hollow-activated carbons (HPHACs) have been prepared innovatively by pyrolyzation of setaria viridis combined with alkaline activation for the frst time. The micro-morphology, pore structure, chemical compositions, and electrochemical properties are researched in detail. The obtained HPHACs are served as outstand�ing electrode materials in electrochemical energy storage ascribe to the particular hierarchical porous and hollow structure, and the precursor setaria viridis is advantage of eco-friendly as well as cost-efective. Electrochemical measurement results of the HPHACs electrodes exhibit not only high specifc capacitance of 350 F g−1 at 0.2 A g−1, and impressive surface specifc capacitance (Cs) of 49.9 μF cm−2, but also substantial rate capability of 68% retention (238 F g−1 at 10 A g−1) and good cycle stability with 99% retention over 5000 cycles at 5 A g−1 in 6 M KOH. Besides, the symmetrical supercapacitor device based on the HPHACs electrodes exhibits excellent energy density of 49.5 Wh kg−1 at power density of 175 W kg−1 , but still maintains favorable energy density of 32.0 Wh kg−1 at current density of 1 A g−1 in 1-ethy-3-methylimidazolium tetrafuoroborate (EMIMBF4) ionic liquid electrolyte, and the excellent cycle stability behaviour shows the nearly 97% ratio capacitance retention of the initial capacitance after 10,000 cycles at current density of 2 A g−1. Overall, the results indicate that HPHACs derived from setaria viridis have appealing electrochemical performances thus are promising electrode materi�als for supercapacitor devices and large-scale applications.
  • 12.

    Influence of oxyfluorinated graphite on fluorinated ethylene–propylene composites as bipolar plates

    Lee Moon Hee | Kim Ho Young | Kim Ji Wook and 3other persons | 2020, 30(3) | pp.345~352 | number of Cited : 1
    Abstract
    Numerous studies have reported that good adhesion and fuorination of carbon materials in a fuoropolymer matrix enhance their electrical and mechanical properties. However, a composite reinforced with oxyfuorinated graphite has not been reported for improving mechanical properties. This paper discusses the fabrication of conductive fuorinated ethylene–pro�pylene (FEP)/oxyfuorinated graphite (f-graphite) composite bipolar plates (BPs) via compression molding. To investigate the efects of fuorinating graphite, graphite with a large particle size of 500 μm was mixed with FEP powder with a small particle size of 8 μm through ball milling. The FEP/graphite composites exhibited high anisotropic electrical conductivity with the in-plane conductivity much higher than the through-plane conductivity because of the planar orientation of the graphite sheets. Therefore, the mechanical properties of the composites such as fexural strength tended to deteriorate with increasing graphite content. In particular, the FEP/f-graphite composites exhibited excellent fexural strength of 12 MPa, much higher than that of FEP/graphite composites at 9 MPa with a graphite content of 80 wt%. The interfacial interaction between FEP and f-graphite led to improved physical compatibilization, which contributed to enhance the mechanical properties of these composites. Our results are a step toward developing BPs for use in high-temperature fuel cells and heat-sink components. Graphic abstract