• Applied Chemistry for Engineering
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• v.23 no.4
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• pp.405-408
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• 2012

$TiO_2$ particles with various shapes were synthesized by using a modified sol-gel method with binary ionic liquids. The structural properties of the particles were significantly affected by the composition of ionic liquids. This is mainly attributed to the interaction between the organic solvent and ionic liquid at the interface leading to the formation of particle structure. The photocatalytic activity of the prepared samples was also examined for the degradation of 4-chlorophenol. Among the particles, $TiO_2$ prepared with 1-octyl-3-methylimidazolium tetrafluoroborate and 1-octyl-3-methylimidazolium tetrafluoroborate showed the best photocatalytic performance.

• Applied Chemistry for Engineering
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• v.24 no.2
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• pp.165-170
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• 2013

An external gelation method in place of an internal gelation method applied to the fabrication process of an intermediated compound of Uranium Oxy-Carbide (UCO) kernel spheres for Very High Temperature Reactor (VHTR) fuel preparation is under development in Korea. For the preliminary experiments of the UCO kernel sphere preparation using an external gelation method, the carbon black dispersion experiments were carried out using a simulated broth solution. From the selection experiments of various kinds of carbon black through dispersion experiments in a viscous metal salt solution, Cabot G carbon black was selected owing to its dispersion stability, and the homogeneous dispersing state of carbon black particles in our system. For the effective dispersion of nano-size aggregated carbon black particles in a high viscous liquid, the carbon black particles in a metal salt solution were first de-aggregated with ultrasonic force. The mixed solution was then dispersed secondly by the use of the extremely high-speed agitation with a mechanical mixer of 6000 rpm after feeding the Poly Vinyl Alcohol (PVA) in the solution. This results in the broth solution with good stability and homogeneity alongside no further changes in physical properties.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.10a
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• pp.93-97
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• 1997

$CO_2$ gas를 초임계상태의 유체로하고 그 용매에 코팅물질인 파라핀을 용해시켜 초임계 분출법(RESS)에 의해 핵입자 코팅을하여 복합입자를 제조하였고 그 용출 특성을 고찰하였다. 핵입자로는 입도분포가 다른 Glassb eads, Brilliant Blue(이하 BB)를 피복한 Glass beads, 분무건조법으로 제조한 염기성 탄산마그네시아의 Microcapsule(이하 MHC MC)을 사용하였다. 제조된 복합분체 표면을 SEM으로 관찰하였고 FT-IR을 사용하여 표면의 성분분석을 하였다. BB로 피복시킨 Glass beads는 Spectrophotometer로 BB가 용출되는 시간을 측정하였고 AA로 MHC MC중 Mg2+ ion의 release time이 7min, 26min, 30min으로 반응부에서 포집한 시료의 용출특성이 제일 우수하였다.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1993.04a
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• pp.59-62
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• 1993

고품위의 동력전달 장치와 같은 고정밀 기능 부품들은 보다 높은 비강도, 고경도, 내마모성 및 내식성을 가져야 하며, 특히 소재의 마찰, 마모 특성은 기아제품 등의 수명, 정밀도 및 에너지 손실을 좌우하는 것으로서 물성의 열화를 극복할 수 있는 소재의 개발이 요구되고 있다. 지난 수년동안 금속기지에 $Al_2O_3$나 SiC등의 보강재를 첨가하여 복합재의 응착 및 연삭마모에 대한 저항성을 향상시키는 시도를 하고 있다. 주로 제조비용이 낮고 거의 등방적인 성질을 가지며 가공성이 좋은 입자 보강 복합재료에 대한 연구가 지배적이었지만, 입자 보강 복합재료의 경우 강도 및 탄성계수의 향상 정도가 적다는 단점을 지니고 있다. 본 연구에서는 분말야금법을 이용하여 금속기지에 세라믹상으로 SiC 입자 및 휘스커가 첨가된 복합재를 제조하여 제조공정변수에 따라 마모거동을 pin-on-disk 형태의 마모시험기에서 실험하였으며, 주사전자현미경으로 마모표면관찰 등으로 복합재의 마모기구를 연구하였다.

• Clean Technology
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• v.10 no.4
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• pp.215-220
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• 2004

Micronized acetaminophen was precipitated from ethanol solution using supercritical $CO_2$ as antisolvent. A coaxial nozzle was used to introduce the supercritical $CO_2$ and the acetaminophen/ethanol solution. The effects of pressure, temperature, $CO_2$ flow rate and solvent flow rate were studied in the constant pressure and temperature condition. The particle size and morphology were influenced by the variations of precipitation condition. The particle size and morphology were analyzed with scanning electron microscopy.

• Elastomers and Composites
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• v.45 no.1
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• pp.7-11
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• 2010

The acetylene black/silica composite particles were prepared by a simple and fast method using polyethylenimine (PEI) as a coupling agent. The composite particles were produced via the following two steps; adsorption of PEI on the surface of acetylene black particles and synthesis of silica by sol-gel process. The morphology of the composite particles was a core-shell, and a large number of micropores was created after silica was synthesized on the acetylene black surface.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2004.05a
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• pp.213-216
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• 2004

폐슬러지 실리콘과 흑연의 혼합물에 물을 주입하고 열처리하여, 마이크론 크기의 이산화 실리콘 구형입자를 제조하였다. 제조된 이산화 실리콘의 직경은 균일하고 약 $1.7\mu\textrm{m}$이다. 탄화 실리콘이 이산화 실리콘 구형입자와 함께 존재하였으며, 그 모양은 휘스커와 다면체였다. 폐슬러지 실리콘과 탄소의 혼합물을 고온에서 열처리하면 일산화 실리콘 기체가 생성된다. 물이 산소의 공급원으로 주입되면 일산화 실리콘 기체는 산소와 반응하여 이산화 실리콘 고체가 형성될 수 있다. 실리콘 공급원으로 일산화 실리콘이 반응기 내에 균일하게 분포하고 물을 주입하여 이산화 실리콘이 형성되는 메커니즘은 액상에서 수산화 실리콘 구형입자를 형성하는 메커니즘과 유사하다.

• Journal of the Korean Chemical Society
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• v.47 no.5
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• pp.479-486
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• 2003

In this study, poly(DL-lactide-co-glycolide) nanoparticles loaded with water-insoluble vitamins such as vitamin A (Retinol) and vitamin E acetate were prepared by the emulsification diffusion method. Polymer solution was prepared by the two water-miscible organic solvent, such as ethanol and acetone. Because of its biocompatible property, polyethyleneglycol-polypropyleneglycol diblock copolymer was used as surfactant and stabilizer. The influence of some preparative variables on the nanoparticle formation and on the loading efficiency of active agents, such as the type and concentration of stabilizing agent, the stirring methods, the water/oil phase ratio and the polymer concentration were investigated in order to control and optimize the process. After preparation of nanoparticles loaded with active agent, particle size and distribution were evaluated by the light scattering particle analyzer. The loading efficiency of active agents was evaluated by the UV-visible spectroscopy. As the results, particle size were 50-200 nm and dispersibility was monodisperse. The optimum loading efficiency of active agents was observed 50-60%. It was found that the appropriate of selections of binary solvent mixtures and polymeric concentrations in both organic and aqueous phases could provide good yield and favorable physical properties of PLGA nanoparticles.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.1
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• pp.47-56
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• 2023

This study describes the successful synthesize strategy for the silica nanoparticles utilizing various water sources, including tap, industrial, and stream waters without using deionized water. Also, as-synthesized silica nanoparticles are employed as dispersive materials for the electro-responsive smart fluid application. Specifically, homogeneous silica nanoparticles with sizes of 500-700nm are successfully prepared in large scale at once (ca. 12.0 g) with the described experimental method and showing similar structural and chemical characteristics with silica nanoparticles synthesized using the deionized water. The size of silica nanoparticles are varied according to the ion conductivity differences of tap, industrial, stream water, and deionized water. The size of silica nanoparticles decresed with the increased ion conductivity, indicating the ion suppression of growth of silica nanoparticles. Moreover, as-synthesized silica nanoparticles from various water sources of electro-responsive characteristic are investigated by the smart fluid application. The smart fluids containing silica nanoparticles synthesized by tap, industrial, and stream water exhibited higher shear stress compared to the deionized water, owing to the more rigid fibril-like structures formed by the smaller silica nanoparticles. Conclusively, uniform silica nanoparticles from various water sources without any purification are able to successfully prepared without usage of deionized water and resulting silica nanoparticles manifested higher electro-responsive performance.

• Polymer(Korea)
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• v.34 no.2
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• pp.144-149
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• 2010

Ag/polystyrene(PS) nanocomposites were prepared by in situ reduction of silver 2-ethylhexylcarbamate (Ag-CB) complex and follwing radical polymerization only by heating at 110 $^{\circ}C$. In contrast to this conventional heating method, the microwave irradiation afforded well-dispersed silver nanoparticles(NPs) in styrene monomer without polymerization. The synthesis of Ag NPs proceeded uniformly throughout the reaction vessel only under microwave irradiation, completing the reaction simultaneously in the whole reaction solution. Successive polymerization of the monomer containing the resultant NPs has successfully produced a hybrid of the silver NPs dispersed in PS matrix. Ag/PS (0.1/100) nanocomposites were prepared successfully by melt-mixing process using Ag/PS(4.0/100) as a master-batch. UV-VIS spectroscopy, TEM, and X-ray diffraction techniques were used to investigate the process of formation of Ag/PS nanocomposites.