• Clean Technology
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• v.15 no.4
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• pp.233-238
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• 2009

Supercritical fluid processes have gained great attention as a new and environmentally-benign method of preparing the microparticles of energetic materials like explosives and propellants. In this work, RDX (cyclotrimethylenetrinitramine) was selected as a target explosive. The microparticle formation of RDX using supercritical anti-solvent (SAS) recrystallization process was performed and the effect of operating variables on the size and morphology of prepared particles was observed. N,N-Dimethylformamide was used as organic solvent for dissolving the RDX. The size of the RDX particles decreased remarkably up to less than $10\;{\mu}m$ by SAS recrystallization. In the range of operating conditions of the SAS process studied in this work, the finest RDX particles were obtained at 313.15K, 150 bar, and 15wt% RDX concentration in feed solution.

• Clean Technology
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• v.15 no.2
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• pp.69-74
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• 2009

A high-dose ion-implanted photoresist (HDIPR) was stripped off from the surface of a semiconductor wafer by using a mixture of supercritical carbon dioxide and a co-solvent. The additional ultrasonication improved the stripping efficiency remarkably and thus reduced the stripping time by supplying physical force to the substrate. We investigated the effect of co-solvents, co-solvent concentration, and stripping temperature and pressure on the stripping efficiency. The wafer surfaces before and after stripping were analyzed by scanning electron microscopy and by an energy dispersive X-ray spectrometer. The HDIPR could be stripped off completely in 3 min with 10%(w/w) acetone/sc$C0_2$ mixture at 27.6 MPa and 343 K.

• Bulletin of the Korean Chemical Society
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• v.13 no.5
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• pp.486-491
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• 1992

The rate constants for the reactions of p-nitrophenyl acetate with 6 different aryloxides and 2 benzohydroxamates have been measured spectrophotometrically in water containing various concentrations of cetyltrimethylammonium bromide (CTAB). The reactivity of the nucleophiles has been demonstrated to be significantly enhanced as the concentration of the surfactant increases up to a certain point. When the basicities of the aryloxides are comparable, the rate enhancement is more prominent for the aryloxide having larger binding constant to the micellar aggregate. Benzohydroxamates exhibitis significantly large ${\alpha}$-effect in the absence of the surfactant, although, the ${\alpha}$-effect nucleophiles are considered to be more solvated in water than the corresponding normal nucleophile. Thus, the solvation effect does not appear to be solely responsible for the ${\alpha}$-effect. Interestingly, the large ${\alpha}$-effect disappears in the presence of the surfactant. Therefore, one might attribute the disappearance of the ${\alpha}$-effect to solvent effect. However, a structural change of the reactive ${\alpha}$ -effect nucleophile into unreactive ones would also be considered to be responsible for the absence of the ${\alpha}$-effect in the present system.

• Proceedings of the Korean Fiber Society Conference
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• 2002.04a
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• pp.321-324
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• 2002

Recently, organic-inorganic nanocomposites have attracted great interest from researchers since they frequently exhibit unexpected hybrid properties synergistically derived from two components[1]. The addition of highly dispersed inorganic nano-sized fillers permits improvement of certain properties of polymers as compared with conventional particulate composites; increase of modulus and strength, improved barrier properties, increase in solvent and heat resistance, and good optical properties[2]. (omitted)

• Proceedings of the Korean Fiber Society Conference
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• 2007.11a
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• pp.193-194
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• 2007

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• Textile Coloration and Finishing
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• v.5 no.3
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• pp.188-193
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• 1993

Aqueous polyurethanes(APU) were prepared from polypropylene glycol(PPG), dimethylol propionic acid(DMPA), and isophoron diisocyanate(IPDI) following a prepolymer mixing process. APUs were applied as binder for nonwoven fabrics processing. APU treated nonwoven fabrics generally showed better tear and tensile strength as compared with the untreated ones. In addition, depending on the soft segment length and crosslinking density of the PU, tear strength of APU treated fabrics was favorably compared with solvent type treated one. Similar results were obtained with microfiber nonwoven fabrics, however, the effect was less significant.

• Textile Coloration and Finishing
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• v.4 no.2
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• pp.55-63
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• 1992

The effects of benzyl alcohol on the properties of dyeing kinetic of silk fibroin were studied. The acid dye used was C.I. Acid Red 114. The half dyeing time is shorten by addition of benzyl alcohol. The diffusion activation energy is higher with the increase of the solvent. The rate of dyeing at benzyl alcohol addition to the purified silk fibroin is faster than that of the unpurified one.

• Journal of the Korean Chemical Society
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• v.12 no.4
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• pp.160-162
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• 1968

Rate constants and activation parameters have been petermined for the chloride exchanges of benzyl chloride in 60, 70, 80 and 90 vol.% ethanol-water solutions. Results showed a good linearity when appiled to our general equation. The significance of this linear fit has been discussed in conjunction with the Dewar's relation which was derived from the PMO method.

• Textile Coloration and Finishing
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• v.10 no.2
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• pp.29-36
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• 1998

Poly(L-lactide) microcapsules containing hydrophilic penetrate were prepared by interfacial precipitation method through solvent evaporation from w/o/w emulsion. Effect of four determinative process parameters on the particle size distributions, morphologies, and release properties of microcapsules coated with poly(L-lactide) was investigated. Moreover, susceptible functional cotton fabrics treated with the mentioned microcapsules were prepared and laundry test up to 15 times were done to determine fastness properties. As a result, the prepared poly(L-lactide) microcapsules with a more sharp-distributive, rounder, and more permeable membranes could be prepared by means of protective colloid concentration, solution volume and stirring rate.

• YAKHAK HOEJI
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• v.33 no.3
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• pp.206-210
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• 1989

Bromolactonization of 2-Substituted-1-cyclohexenyl-1-acetic acid (1) with 1,3-dibromo-5,5-dimethylhydantoin (dibromantin) in N,N-dimethylformamide gave the corresponding ${\gamma}-bromo-{\beta}-lactone$ (2) and ${\beta}-bromo-{\gamma}-lactone$ (3). The effect of the substituents, the reaction temperature, and the solvent on the regioselectivity was discussed.