• Proceedings of the Korean Fiber Society Conference
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• 2001.10a
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• pp.171-174
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• 2001

초임계유체(supercritical fluid, SCF)는 친환경적 용매로서 고분자 합성과 기능화를 비롯하여 RESS(rapid expansion of supercritical solution)와 초임계염색 등의 섬유공정 분야에서 연구자들의 흥미로운 관심을 받아 오고 있다. 초임계유체는 기체와 액체의 중간적인 특성을 가지면서도 가스와 같이 우수한 확산력을 가지며 또한 아주 낮은 점도를 갖는다. SCF 중에서 비교적 온화한 조건(31.1℃의 임계온도, 73.8기압의 임계압력, Figure 1)에서 초임계상태를 가질 수 있는 이산화탄소가 가장 많이 이용되고 있는데 이는 자원이 풍부하며 쉽게 회수하여 사용할 수 있어 응용 면에서 유리하다. (중략)

• Nuclear Engineering and Technology
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• v.40 no.2
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• pp.133-138
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• 2008

The use of Supercritical Fluids(SCF) has been proposed for numerous power cycle designs as part of the Generation IV advanced reactor designs, and can provide for higher thermal efficiency. One particular area of interest involves the behavior of SCF during a blowdown or depressurization process. Currently, no data are available in the open literature at supercritical conditions to characterize this phenomenon. A preliminary computational analysis, using a homogeneous equilibrium model when a second phase appears in the process, has shown the complexity of behavior that can occur. Depending on the initial thermodynamic state of the SCF, critical flow phenomena can be characterized in three different ways; the flow can remain in single phase(high temperature), a second phase can appear through vaporization(high pressure low temperature) or condensation(high pressure, intermediate temperature). An experimental facility has been built at the University of Wisconsin to study SCF depressurization through several diameter breaks. The preliminary results obtained show that the experimental data can be predicted with good agreement by the model for all the different initial conditions.

• Journal of the Korean Ceramic Society
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• v.41 no.6
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• pp.481-484
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• 2004

TiO$_2$ and TiO$_2$-CdS powders which were expected to be highly activated photocatalysts were prepared using supercritical fluid method (SCF). The prepared photocatalyst TiO$_2$ powders were crystalline of anatase and ultrafine spherical powders with large specific surface area. When photodecompositoion reaction was done with TiO$_2$ powders prepared by SCF as a photocatalyst in DCA (Dichloroactic Acid) solution, a hazardous organic compound, the photocatlyst, properties of TiO$_2$ powders prepared by SCF were better than that of commercial TiO$_2$ powders.

• Applied Biological Chemistry
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• v.41 no.5
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• pp.363-366
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• 1998

Supercritical fluid(SCF) carbon dioxide was used to extract safflower yellow pigments from Carthamus tinctorius L. In this work, supercritical fluid extractions were performed at various conditions; pressure (2000, 3000, 4000, 5000 psig), temperature $(40,\;50,\;60,\;70,\;80^{\circ}C)$ and co-solvent $(0,\;3,\;6,\;10,\;14\;wt%\;H_2O)$. Total concentrations of safflower yellow pigments extracted were determined by spectrophotometric method. A maximum yield of yellow pigments was obtained at 4000psig, $60^{\circ}C$ and 10% co-solvent. The extraction yield of pigments was also closely related to moisture content of the raw material. Extraction yield of safflower yellow pigments by SCF extraction at optimized conditions was 6% higher than that by solvent extraction. Supercritical carbon dioxide was proved to be suitable for the extraction of safflower yellow pigments from Carthamus tinctorius L.

• Journal of the Korean Wood Science and Technology
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• v.33 no.5 s.133
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• pp.50-56
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• 2005

The effect of wood material type on biocide retention and distribution during supercritical fluid impregnation was assessed using three different wood types including solid wood, plywood and oriented strand board (OSB). The result revealed that biocide treatability differed with structural composition and permeability of the various materials. Low treatability of plywood might be attributed to interferences of glue line limiting fluid movement. OSB samples showed higher biocide retentions, resulting from the presence of interconnecting gaps permitting more open flow.

• Carbon letters
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• v.11 no.2
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• pp.107-111
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• 2010

We prepared the amine epoxy adducts (AEA)/thin multiwalled carbon nanotubes (TWCNTs) composite particles using nonsolvent based methods including dry mechano-chemical bonding(MCB) process and supercritical fluid (SCF) process. The resulting TWCNTs/AEA composite particles have been used as curing agents for urethane modified bispheol A type epoxy resin. The thermal, thermomechanical properties of the epoxy resins cured with TWCNTs/AEA composite particles were measured by DMA and the dispersion of CNT was characterized by SEM. Because of high degree of CNT dispersion, thermal and mechanical properties of the epoxy resin cured with TWCNTs/AEA composite particles prepared by SCF process are better than those cured with mechano-chemically prepared TWCNTs/AEA composite particles.

• Journal of the Korean Society of Safety
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• v.7 no.1
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• pp.13-19
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• 1992

Supercritical fluid technology was applied to the regeneration of industrial catalyst contaminated with toxic materials. The regeneration process of activated loaded with phenol was proposed, then the adsorphon tower was packed with the activated carbon-bed. Phenol diffuses into supercritical carbon dioxide(SCC) through the micro-pore and voldge of the activated carbon. The saturated solubility of phenol in SCC depended on the density of SCC varing with temperature and pressure conditions. Therefore, the fasile phase equilibrium calculation model of dxpanded liquid One was proposed, and equilibrium solubility of phenol in SCC was calculated using the model theoretically. The regeneration mechanism of activated carbon was analysed by degree of saturation of phenol and diffusion in SCC. The solubility prediction was more satisfactory for the wide range of SCC density than the dense gas model and the desorption of phenol depended on the degree of saturation of phenol in SCC.

• Polymer(Korea)
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• v.39 no.3
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• pp.453-460
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• 2015

Engineering the polylactide via stereocomplexation with supercritical fluid (SCF) technology paved way to fabricate polymers with enhanced thermal and mechanical properties. We aimed to establish a SCF medium with excellent solubility for PLA without any additional solvent/co-solvent. We, therefore, employed supercritical dimethyl ether to synthesize 100% stereocomplex polylactide from high molecular weight homopolymers with an excellent yield. The remarkable solubility of the homopolymers in dimethyl ether is the key for quick conversion to s-PLA. This study proves a rapid synthesis route of dry s-PLA powder with sc-DME at 250 bar, $70^{\circ}C$ and 1.5 h, which are reasonably achievable processing parameters compared to the conventional methods. The degree of stereocomplexation was evaluated under the effect of pressures, temperatures, times, homopolymer-concentrations and molecular weights. An increment in the degree of stereocomplexation was observed with increased temperature and pressure. Complete conversion to s-PLA was obtained for PLLA and PDLA with $M_n{\sim}200kg{\cdot}mol^{-1}$ with a total homopolymer to total DME ratio of 6:100% w/w at prescribed reaction conditions. The degree of stereocomplexation was determined by DSC and confirmed by XRD. Considerable improvement in thermo-mechanical properties of s-PLA was observed. DSC and TGA analyses proved a $50^{\circ}C$ enhancement in melting transition and a high onset temperature for thermal degradation of s-PLA respectively.

• Archives of Pharmacal Research
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• v.28 no.7
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• pp.866-874
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• 2005

The objective of this study was to elucidate the feasibility to improve the solubility and bioavailability of poorly water-soluble itraconazole via solid dispersions by using supercritical fluid (SCF). Solid dispersions of itraconazole with hydrophilic polymer, HPMC 2910, were prepared by the aerosol solvent extraction system (ASES) under different process conditions of temperature/pressure. The particle size of solid dispersions ranged from 100 to 500 nm. The equilibrium solubility increased with decrease (15 to 10 MPa) in pressure and increase (40 to $60^{\circ}C$) in temperature. The solid dispersions prepared at $60^{\circ}C$/15 MPa showed a slight increase in equilibrium solubility (approximately 27-fold increase) when compared to pure itraconazole, while those prepared at $60^{\circ}C$/10MPa showed approximately 610-fold increase and no endothermic peaks corresponding to pure itraconazole were observed, indicating that itraconazole might be molecularly dispersed in HPMC 2910 in the amorphous form. The amorphous state of itraconazole was confirmed by DSC/XRD data. The pharmacokinetic parameters of the ASES-processed solid dispersions, such as $T_{max},\;C_{max},\;and\;AUC_{0-24h}$ were almost similar to $Sporanox_{\circledR}$ capsule which shows high bioavailability. Hence, it was concluded that the ASES process could be a promising technique to reduce particle size and/or prepare amorphous solid dispersion of drugs in order to improve the solubility and bioavailability of poorly water-soluble drugs.