• Applied Chemistry for Engineering
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• v.22 no.3
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• pp.319-322
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• 2011

N,N'-Dicyclohexylcarbodiimide (DCC) known as powerful dehydrating reagent in amide or ester synthesis is converted into N,N'-dicyclohexylurea (DCU) during the reaction. In the paper, DCU was recovered from the reaction for the synthesis of the hydrophilic derivative of ${\beta}$-sitosterol, and the purification of the recovered DCU and the dehydration of DCU into DCC were investigated. In the presence of tosyl chloride, (TsCl) and triethylamine (TEA), DCU was converted into DCC, and the optimum molar ratio of [DCU] : [TsCl] : [TEA] was found to be 1.0 : 1.5 : 3.0. Pure DCC was obtained with a 46% yield by the sublimation after the purification process, and characterized by GC/MS, FT-IR and $^{13}C-NMR$.

• Korean Chemical Engineering Research
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• v.51 no.2
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• pp.279-284
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• 2013

The phenolic beads in macrosize range were obtained by suspension polymerization at $98^{\circ}C$ from phenol and formaldehyde in the presence of basic catalyst with a phenol to formaldehyde (P/F) range of 1:1~1:4, and they were carbonized to spherical carbon beads under nitrogen at $700^{\circ}C$. Thermal analysis on spherical phenolic beads obtained by suspension polymerization showed that the postcuring process is essential. In order to optimize the suspension polymerization, the effects of the P/F molar ratio, the pH of catalyst, and the molecular weight of stabilizer on the size distribution and yield of spherical phenol beads were examined separatively. The particle size was increased whereas the yield was decreased with P/F molar ratio. The increasing basicity of catalyst made the particle size to increase, while the molecular weight of stabilizer had more effect on the yield rather than on the particle size distribution. The thermal stability of the spherical phenolic beads obtained through postcure was also examined by TGA. The phenol beads of high P/F ratio still showed the weight loss at $220^{\circ}C$ even after postcure due to the high possibility of dibenzyl ether, while those of low P/F ratio showed the steady decrease in weight during $220^{\circ}C$ to $400^{\circ}C$, which showed that the optimal P/F ratio was 1:2.

• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.76-81
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• 1998

Physical adsorption on a silica gel(pore size of 80 nm, particle size of $10{\mu}m$)has been studied for binary mixture of acetone diluted in $CO_2$ by use of a FTIR transmission technique and we have compared the result of FTIR transmission technique with that of a chromatographic technique. Measurements were made at 313.2 K and under pressures up to 15MPa. As the pressure increases from 0.1MPa, the IA(Integral Absorbance) of the hydrogen-bonded OH groups interacting with acetone and adsorbed amount by use of a chromatographic technique increases at first, and reaches a maximum at a pressure below the critical pressure of $CO_2$, and then the intensities decrease gradually with increasing pressure. It is found that the pressure dependency of the chromatographic isotherm is a little larger than that of spectroscopic isotherm in the supercritical fluid region. This difference might be attributable to the weaker van der Waals force and relatively stronger hydrogen-bonding force influencing the adsorption of acetone on the sllica gel. The unique spectroscopic characteristics of amine group which vibrational frequencies of hydroxyl groups on the silica gel surface shift downward to about $1300cm^{-1}$ were measured from experimental result of triethylamine diluted in $CO_2$ or $N_2$.

• Journal of the Korean Applied Science and Technology
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• v.36 no.4
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• pp.1128-1135
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• 2019

In this study, different types of polyether amines and H₁₂MDI were used to synthesize water dispersed urea resins, which can be applied to coating material on the concrete slabs for bicycle road using the ordinary application equipments. The concentrations of several polyether amines with different molecular weights and the number of amine functionality were varied to set up the optimal condition for water dispersed urea resin preparation with both an excellent tensile strength and an elongation. In addition, the effect of DMPA[2,2-Bis(hydroxymethyl)propanoic acid] concentration on the storage stability of the water dispersed urea resin was also investigated. The formation of urea bonds from isocyanate and polyether amines was confirmed through FT-IR ATR spectroscopy. From the mechanical properties of urea resins, PU-4 and PU-6, which were prepared with both diamines and triamine of different molecular weights and number of functionality, showed the tensile strength of 10.5 N/㎟ and 12.7 N/㎟, respectively and the elongation of 1165 % and 969%, respectively. Among the water dispersed urea resin synthesized with different contents of DMPA, PU-6 showed the highest mechanical properties, a tensile strength of 14.2 N/㎟ and an elongation of 993%. In addition, the water dispersion state of this PU-6 was the most stable even after 8 weeks.

• Korean Journal of Heritage: History & Science
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• v.44 no.4
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• pp.130-141
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• 2011

This paper examined the bleaching effect of the two types of gel made with neutralizing agent such as sodium meta silicate gel & triethylamine gel mixed with carbopol resin 940 & 934 which has thickness effect in broad pH region and mixed with 10% hydrogen peroxide. Sodium meta silicate gel(1.6g included) provided pH 10, the most suitable environment for bleaching. The result of comparison of the baseline colour changes(${\Delta}E*ab$) and colour changes according to time(${\Delta}E*ab$) is as following. Group1(carbopol 940, sodium meta silicate, Urea Hydrogen Peroxide) showed 112% efficiency at CS-2; 63.3% at CS-4; 87.4% at CS-6. Group2(carbopol 934, sodium meta silicate, Urea Hydrogen Peroxide) showed 77.3%, 67.3%, 109.6% at CS-8, CS-10, CS-12 respectively; CT-1, CT-3, CT-5 of Group3(carbopol 940, triethylamine, Urea Hydrogen Peroxide) showed 36.8%, 73.2%, 74%; In Group4(carbopol 934, triethylamine, Urea Hydrogen Peroxide), efficiency of CT-6, CT-8, and CT-10 was 81.7%, 95.4%, and 95.7%. The paper showed that various concentration of neutralizing agent such as sodium meta silicate and triethylamine have bleaching effect. Viscosity of the gel including sodium meta silicate was higher than the gel including triethylamine. High viscosity helps the bleaching gel sit on the smooth slope of the ceramics. As a result, sodium meta silicate is considered to provide thickening and bleaching effect required in producing 10% hydrogen peroxide gel.