• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.391-397
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• 2012

The depletion of conventional oil reserves and the increasing energy need in developing countries such as China and India result in exceeding oil demand over supply. As a solution of the problem, the efficient utilization of heavy oil has been receiving more and more interest. In order to utilize heavy oil, upgrading processes are required. Among the upgrading processes, thermal decomposition is thought to be relatively simple and economical. In this study, to understand basic characteristics of thermal decomposition of heavy oil, we conducted pyrolysis experiments of deasphalted oil (DAO) produced by a solvent deasphalting process. DAO is a mixture of many components and consists mainly of materials of carbon number 20~40. For the comparison with results of DAO pyrolysis, additional pyrolysis experiments with single materials of carbon number 30 ($C_{30}H_{62}$, $C_{30}H_{58}O_4S$, $C_{30}H_{63}O_3P$) were conducted. Pyrolysis experiments were carried out non-isothermally with variation of heating rate (10, 50, $100^{\circ}C$/min) in a thermogravimetric analyzer. Average pyrolysis activation energy determined by using Arrhenius method, Ingraham and Marrier method, and Coats and Redfern method was 72~99 kJ/mol. In the activation energy calculated by Ozawa-Flynn-Wall method, DAO had wider variation than other single materials.

• Membrane Journal
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• v.5 no.3
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• pp.119-128
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• 1995

The effects of coarsening on microstructure formation in polystyrene-cyclohexane solutions and membranes made from them were studied by scanning electron miccoscopy(SEM). Thermal analysis of the polymer solutions was carried out with a differential scanning calorimeter and the binodal curve was determined from the onset temperature of the heat of demixing peak. Using thermally induced phase separation(TIPS) and a freeze drying technique, it was demonstrated that polymer membrane microstructure can be changed significantly by controlling coarsening time and quench route. For systems undergoing phase separation by spinodal decomposition, resulting in a well interconnecmd, microporous structure with nearly uniform pore sizes, it was found that extending the phase separation time prior m freezing and solvent removal can result in a significant increase in pore or cell size which is highly dependent on both quench depth and coarsening time. Also this study has revealed the important role of polymer concentration in dictating the material continuity of the membranes.

• Korean Chemical Engineering Research
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• v.58 no.2
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• pp.313-318
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• 2020

Bi₂WO₆ were successfully synthesized using EGME, GL, EG and water as solvents by a conventional hydrothermal method. They were characterized by XRD, DRS, BET and SEM and we also investigated the photocatalytic activity of these materials for the decomposition of Rhodamin B under visible light irradiation. The XRD results revealed the successful synthesis well-crystallized Bi₂WO₆ crystals with Aurivillius structure when EGME and EG are used as solvents. In addition, the well-crystallized Bi₂WO₆ crystals showed the flower-like structure. The Bi₂WO₆ catalysts prepared at 180 ℃ using EGME as a solvent showed the highest photocatalytic activity. The Bi₂WO₆ catalysts prepared at mole ratio of H₂O/EGME more than 50% showed high photocatalytic activity.

• Journal of the Korean Electrochemical Society
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• v.17 no.3
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• pp.156-163
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• 2014

In this study, we tried to improve the cycling performance of lithium-ion batteries by suppressing decomposition of the electrolyte solution containing fluorsilane-based additive. Trifluoropropyltrimethoxysilane was electrochemically oxidized and reduced prior to the decomposition of the liquid electrolyte composed of lithium salt and carbonate-based organic solvent. Thus, the stable solid electrolyte interphase (SEI) layer on both negative electrode and positive electrode was formed, and it was confirmed that the cycling performance of lithium-ion batteries assembled with electrolyte solution containing 5 wt.% trifluoropropyltrimethoxysilane was the mostly enhanced. The products formed on electrodes were analyzed by the SEM and XPS analysis, and it was demonstrated that trifluoropropyltrimethoxysilane can be one of the promising SEI-forming additives.

• Textile Coloration and Finishing
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• v.33 no.2
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• pp.72-78
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• 2021

The purpose of this study, the purpose of this study is to activate the antibacterial effect on the Chlorinated polyvinyl chloride film by using Octadecyldimethyl (3-triethoxy silylpropyl) ammonium chloride antibacterial agent with Chlorinated polyvinyl chloride polymer, which is inexpensive and has excellent properties such as heat resistance and chemical resistance. The Chlorinated polyvinyl chloride polymer was dissolved in a dimethylacetamide solvent, and film samples were prepared by varying the ratio of Octadecyldimethyl (3-triethoxy silylpropyl) ammonium chloride to study the antibacterial performance. A Scanning Electron Microscope-Energy Dispersive X-ray Spectrometer and X-ray photoelectron spectroscopy were employed to confirm the elements in the samples. According to the initial decomposition temperature of the Chlorinated polyvinyl chloride film and the Chlorinated polyvinyl chloride/Octadecyldimet hyl (3-triethoxy silylpropyl) ammonium chloride(10%) film using a Thermogravimetric analyzer(TA-DTA), it was confirmed that the initial decomposition temperature was lowered due to the influence of Octadecyldimethyl (3-triethoxy silylpropyl) ammonium chloride. In addition, in order to measure the mechanical properties, Universal testing machine was used and the result showed that a strength of Chlorinated polyvinyl chloride/Octadecyldimethyl (3-triethoxy silylpropyl) ammonium chloride(10%) was 36.8 MPa. The antimicrobial properties of the Chlorinated polyvinyl chloride/Octadecyldimethyl (3-triethoxy silylpropyl) ammonium chloride(10%) film showed 99.9% antimicrobial properties.

• Bulletin of the Korean Chemical Society
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• v.26 no.11
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• pp.1776-1782
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• 2005

ZnSe/ZnS, UV-blue luminescent core shell quantum dots, were synthesized via a thermal decomposition reaction of organometallic zinc and solvent coordinated Selenium (TOPSe) in a hot solvent mixture. The synthetic conditions of the core (ZnSe) and the shell (ZnS) were independently studied at various reaction temperature conditions. The obtained colloidal nanocrystals at corresponding temperatures were characterized for their optical properties by UV-vis, room temperature solution photoluminescence (PL) spectroscopy, and further obtained powders were characterized by XRD, TEM, and EDXS analyses. The synthetic temperature condition to obtain the best PL emission intensity for the ZnSe core was 300 ${^{\circ}C}$, and for the optimum shell capping, the temperature was 135 ${^{\circ}C}$. At this temperature, solution PL spectrum showed a narrow emission peak at 427 nm with a PL efficiency of 15%. In addition, the measured particle sizes for the ZnSe/ZnS nanocomposite via TEM were in the range of 5 to 12 nm. Furthermore, we have synthesized water-soluble ZnSe/ZnS nanoparticles by capping the ZnSe/ZnS hydrophobic surface with mercaptoacetate (MAA) molecules. For the obtained aqueous colloidal solution, the UV-vis spectrum showed an absorption peak at 250 nm, and the solution PL emission spectrum showed a peak at 425 nm, which is similar to that for hydrophobic quantum dot ZnSe/ZnS. However, the calculated PL efficiency was relatively low (0.1%) due to the luminescence quenching by water and MAA molecules. The capping ligand was also characterized by FT-IR spectroscopy, with the carbonyl stretching peak in the mercaptoacetate molecule appearing at 1575 $cm ^{-1}$. Finally, the particle sizes of the MAA capped ZnSe/ZnS were measured by TEM, showing a range of 12 to 17 nm.

• Textile Coloration and Finishing
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• v.20 no.2
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• pp.1-8
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• 2008

Regenerated composite fibers are prepared from solution(styela clava tunics /poly vinyl alchol) using N-methylmorpholine-N-oxide(NMMO)/water(87/13)(wt/wt) as a solvent by dry-wet spinning. The chemical cellulose (94%, ${\alpha}$-cellulose content) used for this study is extracted from styela clava tunics (SCT, Midduck), which are treated in chemical process and mechanical grinding. The structure and physical properties of regenerated composite fibers were investigated through IR-spetra, DSC, TGA and SEM. The optimal blend ratio of SCT/PVA for spinning solution was 70/30 and the total weight was 4% concentrations in NMMO/water solvent system. The fiber density, moisture contents and the degree of swelling were $1.5(g/cm^3)$ 10.2(%) and 365(%), respectively. The crystallinity index of composite fibers are decreased as the PVA contents increased. Thermal decomposition of composite fibers took place in two stages at around $250^{\circ}C$ and $550^{\circ}C$. The best thermal stability was obtained with 30% PVA contents.

• Applied Chemistry for Engineering
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• v.2 no.3
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• pp.253-261
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• 1991

Polyamic acids, precursor polymers of polyimides have been obtained by the solution polycondensation of benzophenone tetracarboxylic dianhydride (BTDA) with 4, 4'-diamino diphenyl methane (MDA) and/or 3, 3'-dimethyl benzidine (OTB). The reaction was carried in two solvent systems such as m-cresol and m-cresol/xylene mixture. The results of TGA analysis showed that the polyimide films had good thermal stability with the initial decomposition temperature ranging from $540^{\circ}$ to $590^{\circ}$. According to DSC analysis of polymers, the glass transition temperature was over $340^{\circ}$. Polyimide film samples, showed good mechanical and electrical properties, had over $16Kg/mm^2$ of tensile strength and about 200 KV/mm of dielectric breakdown voltage. The properties of the copolymer from MAD/OTB were better than those of the homopolymer from MDA. And the polymer synthesized in m-cresol had lower properties than that obtained in m-cresol/xylene.

• Journal of the Korean Society of Tobacco Science
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• v.14 no.2
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• pp.159-167
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• 1992

It would be clear that the constituents of the leaf surface lipid is ye비 important as an evaluation index of tobacco leaf quality since the quality of tobacco specific aroma with leaf species depends on the contents of the lipid and the strength of the aroma is determined by the amounts of the lipid secreted. For the reason, a rapid and peproducible method to quantify DVT, which is a kind of lipid, has been studied. The biosynthesis procedure of DVT in leaf growing processes, and the volatile or decompositional characters of DVT in leaf drying processes were also discussed. In consequence, it might be possible to get the data available to the cultivation of better tobacco leaf and the manufacture of cigarettes with better aroma and taste. The results obtained from this study are as follows. 1. Chloroform/dichloromethane solvent was better than chloroform alone for DVT extraction. The extraction yields of the leaf surface lipid were about 5% 2. The extractives with dichloromethane were treated by silylation with BSTPa and the quantitative analysis of DVT was carried out using SE -54 fused silica capillary column. It was found that rapid and reproducible data could be obtained from these methods. 3. In flue - cured tobacco species, DVT contents were $30.3\mu\textrm{g}/cm^2$ in the beginning stage of leaf drying processes and $12.1\mu\textrm{g}/cm^2$ corresponded to 30% levels of the beginning stage, in the end stage. 4. DVT contents in Burley mere 2 times as large as those in fluecured tobacco. DVT in the upper stalk position of leaf was 3 times larger than that in the lower stalk position. 5. DVT of tobacco leaves was decomposed by $SO_2$ gas or the sun light. The decomposition rate was largest in the sample used methanol as a extraction solvent.

• Applied Chemistry for Engineering
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• v.5 no.4
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• pp.616-623
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• 1994

Conductive Polypyrrole films have been synthesized by electrochemical method in nucleophilic solvent such as N, N-dimetylformamide(DMF), dimethylsulfoxide(DMSO). The effect of protic acid as supporting electrolyte to decrease the nucleophilicity of the solvent was studied. Cyclic voltammetry, I-t transients were carried out to investigate the electrodeposition of conductive polypyrrole film on platinum electrode. Three peaks of 0.65V, 0.85V, and 1.2V vs. $Ag/AgNO_3$ indicated oxidation of monomer, oxidation of pyrrole to the platinum electrode and decomposition of polypyrrole film, respectively. With the I-t transients, nucleation process was confirmed and from obtained linear fits of I vs.t2resembles the metal film formation, and 2.15-2.26 of n-value could be calculated. As concentration of pyrrole or prolic acid was increased, the conductivity of polypyrrole film increased linearly. Tensile strength and elongation were investigated for comparing the mechanical properties and also SEM was performed for morphology investigation.