• Journal of the Korean Applied Science and Technology
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• v.34 no.1
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• pp.83-90
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• 2017

The polyurethane resin used for the garment skin leather surface coating was synthesized by varying the content of polyethylene glycol (PEG) in [NCO] / [OH] mole % ratio. The mechanical properties of the synthesized polyurethane resin were analyzed by SEM, FT-IR, UTM. As the [NCO] / [OH] mole % ratio of nonionic poly ethylene glycol (PEG) increased, there was no change in flexural resistance (dry, wet) and abrasion resistance and tensile strength measurement value were lowered. In contrast, the elongation property values were increased. The result of viscosity measurement showed that the viscosity became thinner with increasing [NCO] / [OH] mole % of PEG.

• Clean Technology
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• v.5 no.2
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• pp.37-44
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• 1999

The influence of the reactant composition on the surface free energy and on the dispersity in water was investigated by using the fluorine-containing water-soluble polyurethane synthesized with the fluorine-containing diol and hydrophilic diol. The diol donating ionic characteristics was more effective than polyol, and stable emulsion with the diameter of 610~310 nm was obtained in the range of 0.3~0.7 molar ratio of the diol to polyol. According to the increment of fluorine-containing compound up to 10 wt %, the surface free energy of polyurethane was dramatically decreased from 22.3 to 12.6 dyn/cm, and the diameter of water dispersed polyurethane increased from 380 to 860 nm due to the strong interaction between polymer molecules because fluorine segments are arranged on the surface of molecules. The macromonomer with perfluoroalkyl group was more effective in complement of the weak point of water-soluble polyurethane, which is a decrease of hydrophobicity, because of strong hydrophobicity.

• Applied Chemistry for Engineering
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• v.10 no.6
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• pp.809-813
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• 1999

D phase emulsification has been developed and elucidated the emulsification mechanism by using phase diagrams. The process of D phase emulsification begins with the formation of isotropic surfactant solution, follows by formation of oil-in-surfactant (O/D) gel emulsion by dispersion of octamethylcyclotetra siloxane(OMCS) in the surfactant solution. Polyols were essential components for this experiments. To understand the function of polyols, the solution behaviors of nonionic surfactant/oil/water/polyol systems were investigated by the ternany phase diagrams of polyoxyethylene oleyl ether/OMCS/propylene glycol(PG) aqueous solutions. The solubility of oil in the isotropic surfactant phase was increased with the addition of PG. D phase emulsion was formed in the range of 70~90% of OMCS and 2.0~3.0 dyne/cm of interfacial tension and the structure was homogenious spherical and O/W type and its diameter was about $10{\mu}m$.

• Applied Chemistry for Engineering
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• v.31 no.3
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• pp.267-276
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• 2020

Poly(epichlorohydrin) copolyol series (PECH copolyols) were synthesized via cationic ring-opening copolymerization (ROCP) of oxirane-based monomers and effects of reaction temperature, solvent type, and initiator were studied. As a comonomer, two types of alkylene oxides were used, and polymerization conditions were conducted both with diethylene glycol (DEG) as an initiator in methylene chloride (MC) solvent and tripropylene glycol (TPG) in toluene solvent. In order to induce the active monomer (AM) mechanism in the ring-opening copolymerization reaction, the monomer was injected by an incremental monomer addition (IMA) method using a syringe pump, and the polymerization was performed at -5 ℃. PECH copolyol, a synthesized ephichorohydrin (ECH)-based copolyol, was converted to glycidyl azide-based energy-containing copolyol (GAP copolyol) by azadizing the ECH unit through a substitution reaction. It was confirmed that the synthesized azide copolyol had little effects on changes of the solvent and the initiator. Also, the molecular weight increased 500 after the azide reaction, thereby the GAP copolyol was polymerized as designed. As the content of the comonomer increased, both the T_g and viscosity tended to decrease due to the influence of the alkyl chain length. It is possible to fundamentally prevent CH₃N₃ amount produced in the azide reaction process, and it is expected that a large-scale process could be achievable.

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.435-441
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• 2012

The direct conversion of cellulose into polyols in $H_2$ was examined over Pt catalysts supported on various zeolites, viz., mordenite, Y, ferrierite, and ${\beta}$. For comparison, Pt catalysts supported on ${\gamma}-Al_2O_3$, $SiO_2-Al_2O_3$, and $SiO_2$ were also tested. The physical properties of the catalysts were probed with $N_2$ physisorption. The surface acidity was measured with temperature programmed desorption of ammonia ($NH_3$-TPD). The Pt content was quantified with inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The Pt dispersion was determined with CO chemisorptions and transmission electron microscopy (TEM). The conversion of cellulose appeared to be mainly dependent on the reaction temperature and reaction time because it depends on the concentration of $H^+$ ions reversibly formed in hot water. Pt/H-mordenite (20) showed the highest yield to polyols among the tested catalysts. Pt/H-zeolite was superior to Pt/Na-zeolite for this reaction. The polyol yield was dependent on the surface acid density and the external surface area.

• Applied Chemistry for Engineering
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• v.8 no.4
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• pp.617-623
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• 1997

In this study, the mechanism on the phase behavior of polysorbate nonionic surfactants was investigated. In the ternary system containing water, hexanol as a polar oil and surfactant, the phase behaviors ranging from micellar region to occurrence of liquid crystal phase were observed by crossed microscope. As results, fine mosaic texture of liquid crystal phase and other phases were examined in the range of 20~70 wt%. This range if thought to give information about the basic data for the formulation of more stable emulsifying systems or dispersed systems. According to the alkyl chain length, three phase region diminished, whereas two phase range increased without an observation of the anisotropic liquid crystalline phase.

• Journal of the Korean Applied Science and Technology
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• v.36 no.2
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• pp.434-447
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• 2019

Polyethylene glycol (PEG) is widely used in cosmetics as a surfactant, detergent and emulsifier. During the manufacturing process, 1,4-dioxane, which is toxic to humans, can be produced as a by-product by dimerization of ethylene oxide. As consumers' interest in cosmetic ingredients has increased, the need for safe emulsion research without PEG ingredients in the personal care market has increased. With increasing consumer interest in cosmetic ingredients, the need for safer emulsion research without the PEG ingredient in the personal care market has increased. In this study, we aimed to develop and stabilize nanoemulsion formulation without PEG. Response Surface Methodology (RSM) was used to develop optimized nanoemulsion formulations. Surfactant content (2~4%), oil content (4~8%) and polyol content (12~24%) were set as independent variables as a result of preliminary experiments for determining independent variables and ranges. The particle size, zeta potential, turbidity, and polydispersity index of the formulation were measured as response variables. As a result of measurement of the prepared nanoemulsion by FIB (Focused ion beam), spherical particles were found to have a size distribution of 100 to 200 nm. The stability of each formulation was evaluated for 30 days at each temperature ($4^{\circ}C$, $25^{\circ}C$, and $45^{\circ}C$). The optimal formulation considering the optimum particle size, turbidity, polydispersity index and zeta potential was found to be surfactant (2%), oil (8%) and polyol (24%).

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.463-466
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• 2006

직접 알콜 연료전지는 액체인 알콜을 직접 연료전지에 공급하여 연소시킴으로써 높은 효율을 갖는 휴대용전원으로 주목받는 장치이다. 직접 알콜 연료전지에 담지체로 사용되는 탄소 소재는 넓은 표면적과 우수한 전기전도도를 가지고 있다는 장점 있으나 금속 촉매와의 상호작용이 약하여 촉매 활성에 영향을 주지 못한다. 산화물을 담지체로 사용할 경우 이러한 금속-담지체 간의 상호작용으로 인한 촉매활성 증가 및 입자성장 억제의 효과를 기대할 수 있다. 본 연구에서는, 안티몬 도핑된 주석산화물 (Sb-doped SnO2 : ATO nanoparticle)을 직접 메탄올 연료전지용 담지체어 적용하였으며 합성 과정은 다음과 같다. SnC14 5H2O SbC13, NaOH, HCl 수용액 혼합물을 삼구 플라스크에 넣고 $100^{\circ}C$ 온도에서 환류(reflux) 시킨 후 세척 및 건조하여 Air 분위기에서 열처리하였다. 합성된 산화물 수용액에 폴리올 방법으로 합성된 백금 콜로이드를 담지하였으며, 세척과 건조를 통하여 산화물에 담지된 백금 촉매를 촉매를 합성하였다. 촉매의 구조분석을 위해 XRD, TEM을 사용하였으며, 전극촉매로서의 활성을 평가하기 위해 cyclic voltammetry을 평가하였다. 본 연구에서는 백금의 담지량에 따른 Costripping voltammetry특성과 메탄올 및 에탄올 산화 반응 특성에 대하여, 탄소를 담지체로 사용한 Pt/C 촉매와 비교 평가하였다. 알콜 산화반응 평가결과, 주석산화물에 담지한 촉매가 탄소를 담지체로 사용한 촉매보다 우수한 활성을 나타내었으며 활성증가는 메탄올에 비해 에탄올 산화 반응의 경우 크게 증가하였다. 막과 비교해 보았다. $ZrO_2$ 입자는 전도성이며 동시에 친수성을 나타내기 때문에 상용 막에 비하여 함수율 및 수소이온 전도도가 우수하게 나타났다. 복합막의 이러한 물성은 $100^{\circ}C$이상의 고온에서 전해질 막 내의 물 관리를 용이하게 한다. 단위 전지 운전 온도 $130^{\circ}C$, 상대습도 37%의 운전 조건에서도 상당히 우수한 전지 성능을 보임에 따라 고온/저가습 조건에서 상용 Nafion 112 막보다 우수한 막 특성을 나타냄을 확인하였다.소/배후방사능비는 각각 $2.18{\pm}0.03,\;2.56{\pm}0.11,\;3.08{\pm}0.18,\;3.77{\pm}0.17,\;4.70{\pm}0.45$ 그리고 $5.59{\pm}0.40$이었고, $^{67}Ga$-citrate의 경우 2시간, 24시간, 48시간에 $3.06{\pm}0.84,\;4.12{\pm}0.54\;4.55{\pm}0.74 $이었다. 결론 : Transferrin에 $^{99m}Tc$을 이용한 방사성표지가 성공적으로 이루어졌고, $^{99m}Tc$-transferrin의 표지효율은 8시간까지 95% 이상의 안정된 방사성표지효율을 보였다. $^{99m}Tc$-transferrin을 이용한 감염영상을 성공적으로 얻을 수 있었으며, $^{67}Ga$-citrate 영상과 비교하여 더 빠른 시간 안에 우수한 영상을 얻을 수 있었다. 그러므로 $^{99m}Tc$<

• Korean Journal of Food Science and Technology
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• v.53 no.1
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• pp.12-18
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• 2021

The in vitro antioxidant activity of oregano seed fractions, fractionizing with 80% ethanol, n-hexane, ethyl acetate, n-butanol, and water, was evaluated, and their effects on edible oils were determined in corn oil at 180℃. The ethyl acetate fraction had the highest radical-scavenging activity. The ferric reducing antioxidant power activity and total phenol content of the ethyl acetate fraction were determined as 6,130 µmol ascorbic acid equivalents/g extract and 770 µmol tannic acid equivalents/g extract, respectively, which were significantly higher than those of the other fractions (p<0.05). Primary and secondary oxidation products in corn oil added with the ethyl acetate fraction of oregano seed significantly decreased by 1.5 and 1.26 times, respectively, compared with those in the control groups. The major volatile ingredients in the ethyl acetate fraction of oregano seeds were determined to be carvacrol, thymoquinone, and 3-cyclopentylcyl-cyclopentan-1-one. Ethyl acetate is a suitable solvent for extracting antioxidant compounds from oregano seeds and can be used as a natural antioxidant.