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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Korean Chemical Engineering Research
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Journal DOI :
The Korean Institute of Chemical Engineers
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Volume & Issues
Volume 46, Issue 6 - Dec 2008
Volume 46, Issue 5 - Oct 2008
Volume 46, Issue 4 - Aug 2008
Volume 46, Issue 3 - Jun 2008
Volume 46, Issue 2 - Apr 2008
Volume 46, Issue 1 - Feb 2008
Selecting the target year
Directed Assembly of Block Copolymers for Defect-Free Nanofabrication
Shin, Dong-Ok ; Jeong, Seong-Jun ; Kim, Bong-Hoon ; Lee, Hyung-Min ; Park, Seung-Hak ; Xia, Guodong ; Nghiem, Quoc Dat ; Kim, Sang-Ouk ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 1~6
copolymers spontaneously assemble into various nanoscale structures such as spheres, cylinders,and lamellar structures according to the relative volumn ratio of each macromolecular block and their overall molecularweights. The self-assembled structures of block copolymer have been extensively investigated for the applications suchas nanocomposites, photonic crystals, nanowires, magnetic-storage media, flash memory devices. However, the natu-rally formed nanostructures of block copolymers contain a high density of defects such that the practical applications fornanoscale devices have been limited. For the practical application of block copolymer nanostructures, a robust process todirect the assembly of block copolymers in thin film geometry is required to be established. To exploit self-assembly ofblock copolymer for the nanotechnology, it is indispensible to fabricate defect-free self-assembled nanostructure over anarbitrarily large area.
Technical Status of Carbon Nanotubes Composites
Lee, Jong-Il ; Jung, Hee-Tae ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 7~14
Carbon nanotubes are considered as the most ideal nano filler in the field of composites with their excellent electrical, mechanical, and thermal properties. Therefore carbon nanotubes composites are increasingly utilized in conductive materials, structural material with high strength and low weight and multifunctional material. This review article describes recent research trend of carbon nanotubes synthesis, modification, various properties of the carbon nanotubes composites and their application. Furthermore the future development direction for the commercialization of carbon nanotubes composites is proposed.
Polyolefin Block Copolymer Thermoplastic Elastomer
Koo, Chong-Min ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 15~22
block copolymer has been taking a great deal of attention due to their great potential in polymerindustry since a new metallocene catalytic method for producing polyolefin block copolymer was developed by DowChemicals. However, so far, there was no systematic study of olefin block copolymer. In this review, Linear polyolefinblock copolymers, containing semicrystalline poly (ethylene) (E) blocks and a rubbery block as a thermoplastic elas-tomer, were investigated in the viewpoint of microphase separation mode, microstructure, deformation behavior, andmolecular architecture.
Comprehending Polymer-Clay Nanocomposites and Their Future Works
Choi, Yeong-Suk ; Chung, In-Jae ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 23~36
Polymer-clay nanocomposites, a novel organic-inorganic hybrid, attract much attention from both scientific fields and engineering fields due to their balanced improvements in mechanical properties as well as diffusion behaviors, including flame-retarding and barrier properties, with small amounts of clay. Preparation of polymer-clay nanocomposites, summarized as a process for uniform dispersion of hydrophilic layered clays in hydrophobic polymer matrixes, includes several technologies and scientific phenomena, such as surface-modifications of clay layers, physical properties of clays in liquids and dried states, polymer synthesis, polymer rheology, behaviors of polymer solutions/or monomers in the confined geometry, mechanical properties of polymers and clays. To comprehend complicated physical/chemical phenomena involved in the fabrication of nanocomposites, we reviewed physical properties of clays, structures of clays in nanocomposites, characterization of nanocomposites, the relation between morphology and physical property of nanocomposites, surveyed recent research trends, and then suggested a few strategies or methods for fabrication of nanocomposites reflecting future research directions.
Preparation of Polysilicon for Solar Cells
Kim, Hee-Young ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 37~49
rapid progress in the photovoltaic industry has seriously been retarded by limited supply of poly-silicon used as the feedstock for silicon wafer-based solar cells. It is thus believed that development of a competitiveprocess for preparing polysilicon with the quality required for solar cells can greatly enhance the competitiveness andextent of the photovoltaic application. Technologies currently available for preparing the silicon feedstock are reviewedwith the recent fluidized bed silicon deposition process being discussed in more details in terms of key technical barriers.
The Effects of Substrate Temperature on Properties of Carbon Nanotube Films Deposited by RF Plasma CVD
Kim, Dong-Sun ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 50~55
Nanotube (CNT) films were deposited with varying deposition temperature by RF plasma CVD onFe catalysts deposited onto SiO2 films grown thermally on the silicon wafer using C2H2 and H2 gases. The Fe catalystson silicon oxide film were made by RF magnetron sputtering. The grounded grid mesh cover on the substrate holder wasused for depositing CNT thin films with high purity. The surface morphologies and chemical structure of deposited CNTfilms were characterized using SEM, Raman, XPS and TEM. It was observed that deposited CNTs films were carbonfiber type having Bamboo-like multiwall structure and CNT film grown at 600 C was more dense than that at 550 C,but become less dense at 650oC.
Characteristics of Heat Transfer in Three-Phase Swirling Fluidized Beds
Son, Sung-Mo ; Shin, Ik-Sang ; Kang, Yong ; Cho, Yong-Jun ; Yang, Hee-Chun ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 56~62
Characteristics of heat transfer were investigated in a three-phase swirling fluidized bed whose diameter was 0.102 m and 2.5 m in height. Effects of gas and liquid velocities, particle size and liquid swirling ratio (RS) on the immersed heater-to-bed overall heat transfer coefficient were examined. The heat transfer characteristics between the immersed heater and the bed was well analyzed by means of phase space portraits and Kolmogorov entropy(K) of the time series of temperature difference fluctuations. The phase space portraits of temperature difference fluctuations became stable and periodic and the value of Kolmogorov entropy tended to decrease with increasing the value of liquid swirling ratio from 0.1 to 0.4. The value of Kolmogorov entropy exhibited its minimum with increasing liquid swirling ratio. The value of overall heat transfer coefficient (h) showed its maximum with the variation of liquid velocity, bed porosity or liquid swirling ratio, but it increased with increasing gas velocity and particle size. The value of K exhibited its maximum at the liquid velocity at which the h value attained its maximum. The overall heat transfer coefficient and Kolmogorov entropy were well correlated in terms of dimensionless groups and operating variables.
Decrosslinking of Cross-linked Polyethylene using Supercritical Methanol
Hong, Soon-Man ; Cho, Hang-kyu ; Koo, Chong-Min ; Lee, Jang-Hoon ; Park, Wan-Yong ; Lee, Hong-Shik ; Lee, Youn-Woo ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 63~68
We investigated the recycling method to re-plasticize cross-linked polyethylene by using supercritical methanol. The cross-linked polyethylene is successfully fragmented to thermoplasticized polyethylene with little degradation reactions in supercritical fluids. The thermo-plasticization reaction was accelerated with increase in temperature in the range from 360 ℃ to 400 ℃, resulting in decrease in crosslinking density, molecular weight and mechanical properties. However, the thermoplasticized polyethylene at 360 ℃ showed comparable tensile strength and impact strength with a raw resin of crosslinked polyethylene. Chemical structure of main chain of polyethylene was not affected by reaction condition.
Electrochemical Properties of
Prepared by Mechanochemical Process
Cho, Byung-Won ; Lee,, Joong-Kee ; Lee, Jae-Ryong ; Kim, Su-Jin ; Lee, Kwan-Young ; Na, Byung-Ki ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 69~75
Abstract − Discharge capacity of LiCoO2 in preparation by mechanochemical process decreased remarkably over 4.3V. However, Zr coating of LiCoO2 showed very stable electrochemical properties up to 4.5V. Zr coating of LiCoO2 in this experiment showed the discharge capacity of 197 mAh/g at 3.0-4.5V, and it maintained 96% of the initial discharge capacity after 50 cycle of charge/discharge.
Adhesive and Removable Characteristics of UV Curable Adhesive
Kim, In-Beom ; Lee, Myung-Cheon ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 76~81
UV curable pressure sensitive adhesive (PSA) was made by blending the di-functional or hexa-functional urethane-acrylate oligomer with synthesized acrylic PSA. The change of adhesive property and removability were investigated at various oligomer contents under each oligomer. As the content of oligomer increased, the peel strength was increased before UV irradiation, but it was decreased after UV irradiation. Also, it was observed that the peel strength increased with decrease of storage modulus (G'), and that loss factor (tan δ) of the adhesive material affected the adhesive properties and removability.
Decomposition Characteristics of Dual Bed Mixed Metal Oxide Catalytic System
Lee, Nan-Young ; Woo, Je-Wan ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 82~87
N2O decomposition characteristics of dual bed mixed metal oxide catalytic system was investigated. The partial oxidation of methane at first reactor of dual bed catalytic system was performed over Co-Rh-Al (1/0.2/1) catalyst under the optimized condition of 8,000 h-1 GHSV, gas ratio (CH4:O2=5:1) at 500 ℃. In the dual bed system investigated herein, the second catalyst bed was employed for the N2O decomposition using product of partial oxidation of methane at first bed. An excellent N2O conversion activity even at lower temperature (<250 ℃) was obtained with Co-Rh-Al (1/0.2/1) or Co-Rh-Zr-Al (1/0.2/0.3/1) catalyst by combining Co-Rh-Al (1/0.2/1) hydrotalcite catalyst for the partial oxidation of methane in a dual-bed system. The N2O conversion activity is drastically reduced in the presence of oxygen in second bed of a dual-bed system over Co-Rh-Al (1/0.2/1) catalyst at 300 ℃.
Correlation Between Crystal Structure and Properties in Polymer Solar Cells
Kim, Jung-Yong ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 88~93
The bulk-heterojunction polymer solar cell based on regioregular P3HT (poly(3-hexylthiophene)) and PCBM (methanofullerene [6,6]-phenyl C61-butyric acid methyl ester) was fabricated. Annealing effects on the crystal structure of polymer.fullerene blends as well as the UV-VIS electronic absorption spectroscopy were investigated. The correlation between the crystal organization of bulk-heterojunction film and the power conversion efficiency of solar cell was studied. Resultantly, the polymer solar cell annealed on 150 ℃ for 30 min, showed both the enhanced molecular interactions and the optimized crystal structure and displayed the power conversion efficiency of 3.2 %.
Supercapacitive Properties of Carbon-Nano Fiber/
Lee, Byung-Jun ; Yoon, Yu-Il ; Ko, Jang-Myoun ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 94~98
In order to improve the specific capacitance of amorphous hydrous manganese oxide (MnO2) for supercapacitors, it is made into composites with vapour-grown carbon nanofibers (VGCF) having the VGCF ratio as 40 wt% in the composites. The electrochemical properties of these composites are investigated in 1.0 M Na2SO4 by cyclic voltammetry (CV), impedance measurements and chronopotentiometric charger/discharger. The composite with 40 wt% VGCF shows the superior electrochemical performance, whose specific capacitance (based on the mass of MnO2, 0.8 mg/cm2) is 380 F/g at 20 mV/s and 230 F/g at 500 mV/s. Also, the cycle-life testing of this electrode carried out for 3,000 charge/discharge cycles at 2.0 mA/cm2 shows 97% capacitance retention.
Preparation of Core-Shell Structured
Powder Via Coating of
Kwon, Byung-Soo ; Lee, Hye-Un ; Jang, Jung-Yoon ; Lee, Sang-Kil ; Chung, In Jae ; Cho, Young-Sang ; Park, Tae-Jin ; Choi, Guang-Jin ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 99~105
Core-shell structured BaTiO3 powders were produced via nano-coating of Cr2O3 and Mn2O3 to barium titanate powder system for MLCCs. From preliminary experiments, the optimal solution reaction condition employing using KMnO4, K2Cr2O4 and sulfur was established. Not only powders of Cr2O3 and Mn2O3 were synthesized but also their coating on BaTiO3 powders were peformed under the same reaction condition. The coating was carried out in two ways, one-step and two-step, and its results were characterized for comparison. Conclusively speaking, two oxide additives were coated onto the BaTiO3 powder surface with high quality and excellent reaction yield even under mild condition, which indicates that the contents as well as the properties of additive shell layer can be precisely controlled with rather ease.
Effect of the Starch Content on the Silicate Dispersion and Rheological Properties of Polypropylene/Starch/Silicate Composites
Kim, Youn-Cheol ; Lee, Chang-Young ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 106~111
Polypropylene (PP)/corn starch master batch (starch-MB)/silicate composites with different corn starch compositions of 10, 20, 30, 40 and 50 were prepared by melt compounding at 200 ℃, using lab scale Brabender mixer. The content of silicate was fixed at 5 wt%. The composition of starch-MB in composites was confirmed by the existence of hydroxy group and peak intensity in fourier-transform-infrared (FT-IR) spectrum. The thermal properties of the PP/starch-MB/silicate composites were investigated by differential scanning calorimetry (DSC), and thermogravimetric analyzer (TGA). There was no district change in melting temperature, and TGA curve indicates a decrease in degradation temperature with the increase of starch-MB content. The silicate dispersion of the composites was measured by X-ray diffraction (XRD) and transmission electron microscope (TEM). The degree of silicate dispersion in PP/starch-MB/silicate composites depended on the content of starch-MB. There was detectable change in d-spacing and peak intensity of the composite when the content of starch-MB was higher than 20 wt%. The rheological behavior of the composites was explained by both shear thinning effect and elastic property with the starch-MB amount. These effects were remarkable when the content of starch-MB was higher than 20 wt%. These were confirmed by an oscillatory viscometer at 200 ℃.
Preparation of Photochromic Coating Films Containing Spiropyran by Sol-Gel Method
Jeong, Sang-Hyeok ; Cho, Kyung-In ; Song, Ki-Chang ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 112~117
Organic-inorganic hybrid solutions were prepared via sol-gel method using glycidoxypropyl trimethoxysilane (GPTMS) and methyl triethoxysilane (MTES) as starting precursors at a molar ratio of 1:1. The photochromic coating solutions were prepared by mixing the solutions of photochromic dye (spiropyran) dissolved in ethylacetate (EA) with the organic-inorganic hybrid solutions. Photochromic films were prepared on polycarbonate substrate by spin coating and cured for 2 h at 100 ℃. The resulting films exhibited a reversible color change upon irradiation with UV light. The photochromic properties of the films showed that the color-fading speed increases with increasing the EA content in the coating solutions.
An Oxyfluorination Effect of Carbon Nanotubes Supports on Electrochemical Behaviors of Platinum Nanoparticle Electrodes
Kim, Seok ; Lee, Jae-Rock ; Park, Soo-Jin ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 118~123
In the present study, the effect of oxyfluorination treatment on multi-walled nanotubes (MWNTs) supports was investigated by analyzing surface functional groups. The surface characteristics were determined by Fourier transformed-infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). After the deposition of platinum nanoparticles on the above treated carbon supports, a crystalline size and a loading level had been investigated. Electrochemical properties of the treated MWNTs-supported Pt (Pt/ MWNTs) catalysts were analyzed by current-voltage curve measurements. From the results of surface analysis, an oxygen and fluorine-containing functional group had been introduced to the surface of carbon supports. The oxygen and fluorine contents were the highest value at the treatment of 100 temperature. The Pt/100-MWNTs showed the smallest particle crystalline size of 3.5 nm and the highest loading level of 9.4% at the treatment of 100 temperature. However, the sample treated at the higher temperature showed the larger crystalline size and the lower loading level. This indicated that the crystalline size and the loading level could be controlled by changing the temperature of oxyfluorination treatment. Accordingly, an electrochemical activity was enhanced by increasing the temperature of treatment upto 100, and then decreased in the case of 200 and 300. The highest specific current density of 120 mA/mg had been obtained in the case of Pt/100-MWNTs.
Modification of PLA by Irradiation of Electron Beam in the Presence of Functional Monomer: Rheological and Thermal Properties
Kang, Kyoung-Soo ; Shin, Boo-Young ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 124~130
In order to fabricate a modified poly (lactic acid) (PLA) for applications requiring high melt strength, a PLA has been irradiated in the presence of functional monomer of glycidyl methacrylate (GMA). Samples were prepared with various contents of GMA and irradiation dosages, and were characterized by observing their thermal and melt viscoelastic properties and gel faction. The complex viscosity and storage modulus of the modified PLA without GMA were lower than those of the original PLA. Those of the modified PLA decreased with increasing dosage. In the case of the modified PLA containing 0.1 phr or 0.3 phr of GMA, their changing tendency with dosage was similar to the irradiated PLA without GMA. However, the 5 kGy irradiated PLA containing 0.5 phr of GMA showed the greatly enhanced complex viscosity and storage modulus, which were about 3 and 10 times higher than those of the original PLA at a frequency of 0.1 rad/s, respectively.
Charge-Discharge Characteristics of Lithium Metal Polymer Battery Adopting PVdF-HFP/(
) Polymer Electrolytes Prepared by Phase Inversion Technique
Kim, Jin-Chul ; Kim, Kwang-Man ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 131~136
Abstract − Silica- or titania-filled poly (vinylidene fluoride-co-hexafluoropropylene)-based polymer electrolytes were prepared by phase inversion technique using N-methyl-2-pyrrolidone and dimethyl acetamide as solvent and water as non-solvent. The polymer electrolytes were adopted to the lithium metal polymer battery using high-capacity cathode Li[Ni0.15Co0.10Li0.20Mn0.55]O2 and lithium metal anode. After the repeated charge-discharge test for the cell, it was proved that the cell adopting the polymer electrolyte based on the phase-inversion membrane containing 40~50 wt% silica showed the highest discharge capacity (180 mAh/g) until 80th cycle and then abrupt capacity fade was just followed. The capacity fade might be due to the deposition of lithium dendrite on the polymer electrolyte, in which the capacity retention was no longer sustainable. Key words: Lithium Rechargeable Battery, Polymer Electrolyte, Phase Inversion, Charge/Discharge, Filler Inclusion
Copolymerization of Ethylene and
-olefins with Embedded
Shin, Dong-Min ; Chung, Jin-Suk ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 137~141
of ethylene and α-olefin using rac-Et[Ind]2ZrCl2/MAO catalyst embedded onto polysty-rene was examined. The embedded catalyst was prepared by polymerizing a small amount of styrene with rac-Et[Ind]2ZrCl2. The catalytic activities of the embedded catalyst were higher than those of the homogeneous catalystregardless of comonomer type and the characteristic of the active sites of the embedded catalyst was not affected duringthe embedding process. Based on the DSC and NMR analyses of the produced copolymers, it was thought that theembedded catalyst had similar or slightly better comonomer incorporation ability. Furthermore, the copolymers pro-duced by the embedded catalyst had higher bulk densities and better particle morphology than those by the homoge-neous catalyst.
A Kinetic Study of Allylchloride Epoxidation using Titanium Silicalite-1 Catalyst
Yang, Seung-Tae ; Choi, Jung-Sik ; Kwon, Young-Chul ; Lee, Sang-Wook ; Ahn, Wha-Seung ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 142~146
Titanium silicalite-1 catalyst was prepared using a SiO2-TiO2 xerogel and applied to allylchloride (ALC) epoxidation by H2O2 as oxidant in a batch reactor. The reaction temperature was varied from 25 to 55 ℃, and the concentrations of ALC and H2O2 were changed from 0.2 to 3 M and from 0.2 to 1.5M, respectively. The kinetic data obtained were applied to the power rate law, Eley-Rideal, and a Langmuir-Hinshelwood model, and power rate law fits the experimental data best. Activation energy was 27.9 kJ/mol, and the reaction orders with respect to H2O2 and ALC were determined to be 0.41 and 0.52, respectively.
OOUS : An Educational System for the Optimal Operation of Utility Plants
Oh, Sang-Hun ; Yeo, Yeong-Koo ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 147~155
economics of most chemical plants are heavily dependent upon the management of the utilities used inthe plants. The utilities are supplied by the centralized utility system of the plant. Among the various utilities the steam isby far the most important energy source and the management of the electricity and the process water are greatly affectedby the steam. Therefore it is necessary to educate students and new employees the basic concepts about the effective dis-tribution of the utilities and the fundamental strategies to apply the concepts in actual plant operations. The OOUS(Optimal Operation of Utility System) is an GUI educational system designed to educate the effective generation of thesteam and the optimal steam distribution schemes within short period. The OOUS deals with various utility equipmentsand processes and shows how to save operation costs by displaying the optimal operation conditions based on the pro-cess models and the operational knowledgebase.
Management of Change in the Chemical Industries Based on Risk Assessment
Yoo, Jin Hwan ; Lee, Heon-Seok ; Choi, Jeong-Woo ; Seo, Jae-Min ; Ko, Jae-Wook ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 156~163
Process change and modification, which are caused by process failure, equipment life cycle and economic environment, have been generated in the chemical plants. And the MOC (management of change) base on the reasonable process safety technology such as change judgment, hazard identification by accurate technical references and risk assessment. But it is difficult to carry out the MOC because of lack of experience, shortage of knowledge and none of process safety specialists. In this study, the MOC system which could make enhancement of safety by finding and complementing weakness of MOC in chemical facilities was developed. This developed MOC system based on QRA was recommended the obvious standard for decision-making process, MOC procedure based on risk assessment and risk estimation of the process modification. The study based on the above way sought the enhancement of safety by performing Risk Based MOC for chemical plants.
Separation of Propylene/Propane using SPEEK-
Facilitated Transport Membrane
Lee, Jung-In ; Jang, Seong-Cheol ; Choi, Do-Young ; Bang, Jun-Ha ; Kim, Hoon-Sik ; Choi, Dae-Ki ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 164~169
In this study, the facilitated transport membranes, poly (ether ether)ketone (SPEEK)-Ag salts layers on top of polycarbonate supports membrane, were prepared and tested for the separation of propylene/propane. SPEEK was synthesised using PEEK and H2SO4. Experiments were porformed at room temperature and feed pressures up to 30 psig. The SPEEK-Ag salt membranes showed good selectivity for propane over propylene. With increasing the concentration of SPEEK in MeOH, 5~20 wt%, the thickness of SPEEK membrane on the polycarbonate increased. The selectivity and permeance of SPEKK-Ag membrane for propylene/propane were changed by membrane thickness and concentration of Ag salts.
P(VDF-HPF)-Based Polymer Electrolyte Filled with Mesoporous ZnS
Seo, Young-Ju ; Cha, Jong-Ho ; Lee, Huen ; Ha, Yong-Joon ; Koh, Jeong-Hwan ; Lee, Chul-Haeng ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 170~174
Abstract − ZnS-polymer gel films were prepared with incorporating mesoporous ZnS synthesized by surfactantassisted templating process and poly (vinylidene fluoride)-hexafluoropropylene copolymer (P(VDF-HFP)) in order to observe the variation of ionic conductivities according to the various weight ratios between ZnS and P(VDF-HFP). Ionic conductivities for each gel electrolyte were measured with increasing temperature. As a result, ionic conductivities increased with increasing the amount of ZnS and temperature. In particular, the films with 20 and 25 wt% ZnS were found that they possessed the high ionic conductivity of approximately 10-4 Scm-1 at room temperature. However, above 20 wt% of ZnS, the enhancement of ionic conductivity was not observed. For the characterization of ZnS and the gel electrolyte, XRD (x-ray diffractometer), DSC (differential scanning calorimetry), TGA (thermogravimetric analysis), FT-IR (fourier transform-infrared spectrometer), SEM (scanning electron microscopy) and TEM (transmission electron microscopy) were employed. Ionic conductivities were measured by a.c. impedance method.
Pure and Binary Gases Adsorption Equilibria of
on Li-X Zeolite
Park, Ju-Yong ; Yang, Se-il ; Choi, Do-Young ; Jang, Seong-Cheol ; Lee, Chang-Ha ; Choi, Dae-Ki ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 175~183
Adsorption equilibria of the gases CO2, CO, CH4 and H2 and their binary mixtures on Li-X zeolite (UOP) were obtained by static volumetric method in the pressure range of 0 to 20 bar at temperatures of 293.15, 303.15, and 313.15 K. Using the parameter obtained from single-component adsorption isotherm. Multicomponent adsorption equilibra could be predicted and compared with experimental data. Extended Langmuir isotherm, Extended Langmuir-Freundlich isotherm (L-F) and dual-site Langmuir isotherm (DSL) were used to predict the experimental results for binary adsorption equilibria of H2/CO2, H2/CO, and H2/CH4 on Li-X Zeolite. Extended Langmuir-Freundlich isotherm predicted equilibria of CH4 and H2 better than any other isotherm. One the other hand DSL isotherm predicted equilibria of CO2 and CO very well.
Fabrication of Chemical Sensors for the Detection of Acidic Gas using 1,3-bisdicyanovinylindane
Song, Hwan-Moon ; Park, Young-Min ; Son, Young-A ; Lee, Chang-Soo ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 184~188
Abstract − This study presented simple and efficient fabrication of chemical sensors for the detection of acidic gas using 1,3-bisdicyanovinylindane as an indicator because it can be promising materials having property of the rapid color change according to the variation of pH. The dissociation of proton and dye in acidic condition as changing of ion pairs give rise to dramatically change the absorbance intensity of 1,3-bisdicyanovinylindane, which can be easily applied to the development of chemical sensors. In addition, indicator dyes having negatively charge in aqueous phase can be easily fabricated using layer-by-layer (LBL) methods by way of electrostatic interaction. For the proof of concept, we demonstrated the abrupt presentation of skeleton symbol on the chemical sensor, which could be resulted from the reaction of 1,3-bisdicyanovinylindane as background color with acidic gas. Thus, the rapid appearance of symbol will induce user’s caution under the emergency condition. The presented chemical gas sensor using 1,3-bisdicyanovinylindane have strong advantages. First, the fabrication process of gas sensor was very simple and low-cost. Secondly, sensors reacted by acidic gas could be reused for several times. Finally, the chemical gas sensor would be environmentally friend, which can be a basic tool for the realization of eco-organic sensor device.
Biodiesel Production with Zinc Aluminate Catalysts in a High-Pressure-Fixed-Bed-Reactor
Vu, Khanh Bao ; Phan, Thuy Duong Nguyen ; Kim, Sun-Wook ; Shin, Eun-Woo ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 189~193
In this study, the effect of reaction conditions on the transesterification of soybean oil and methanol was investigated in a high-pressure-fixed-bed-reactor-system with zinc aluminate catalysts. Without catalysts, high-pressurereaction at 300 ℃ and 1,200 psi brought 19% yields of methyl esters, which was caused by the approach of reaction condition to supercritical point of methanol. However, except the specific reaction condition, the yields in the reaction with no catalyst were very low below 4.5%. The zinc aluminate was prepared as catalyst by coprecipitation and characterized with N2 gas adsorption/desorption and X-ray diffraction. With catalyst, the effect of the reaction parameters such as temperature, pressure, and molar ratio of reactants on biodiesel production was demonstrated. The higher temperature, pressure, and methanol molar ratio to soybean oil, the more yields of methyl esters. It was proved that among the reaction parameters, the reaction temperature be the most influential variable on methyl ester yields.
Optimization of Esterification of Jatropha Oil by Amberlyst-15 and Biodiesel Production
Choi, Jong-Doo ; Kim, Deog-Keun ; Park, Ji-Yeon ; Rhee, Young-Woo ; Lee, Jin-Suk ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 194~199
Abstract − In this study, the effective method to esterify the free fatty acids in jatropha oil was examined. Compared to other plant oils, the acid value of jatropha oil was remarkably high, 11.5 mgKOH/g. So direct transesterification by a base catalyst was not suitable for the oil. After the free fatty acids were esterified with methanol, jatropha oil was transesterified. The activities of four solid acid catalysts were tested and Amberlyst-15 showed the best activity for the esterification. After constructing the experiment matrix based on RSM and analyzing the statistical data, the optimal esterification conditions were determined to be 6.79% of methanol and 17.14% of Amberlyst-15. After the pretreatment, jatropha biodiesel was produced by the transesterification using KOH in a pressurized batch reactor. Jatropha biodiesel produced could meet the major specifications of Korean biodiesel standards; 97.35% of FAME, 8.17 h of oxidation stability, 0.125% of total glycerol and 0 oC of CFPP.
Cure Behavior of a DGEBF Epoxy using Asymmetric Cycloaliphatic Amine Curing Agent
Kim, Hong-Kyeong ;
Korean Chemical Engineering Research, volume 46, issue 1, 2008, Pages 200~204
The curing kinetics of diglycidyl ether of bisphenol F (DGEBF) with an asymmetric cycloaliphatic amine curing agent were examined by thermal analysis in both isothermal and dynamic curing conditions. From the residual curing of the samples partially cured in isothermal condition and from the dynamic curing with various heating rates, it was found that there exist two kinds of reactions such as at low temperature and at high temperature regions. It was thus also found that the cure parameters obtained from the isothermal curing kinetic model hardly estimate experimental results for a degree of cure larger than 0.6. The activation energies and frequency factors of these two kinds of reactions were obtained from the dynamic curing experiments with various heating rates. From the curing analysis, it was verified that the total cure kinetics for low degrees of cure is dominated by the cure reaction in the low temperature region.