• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.1
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• pp.111-116
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• 2010

The treatment of heavy metal, in the waste ash from incinerator and mine solid waste, by using alkali-soluble acrylic copolymer emulsion, that is effective in the absorption of heavy metal has been studied. It seemed that alkali soluble acrylic copolymer emulsion was very effective in the absorption of Hg, Pb, Cd and Cu in this test. Also, eco-friendly thixotropic grout, using alkali soluble acrylic copolymer emulsion, that is effective in the absorption of heavy metal, for the recycling of waste ash from incinerator and mine solid waste has been tested. It was observed that waste ash could be used as a raw material of eco-friendly thixotropic grout mortar due to the effectiveness of alkali soluble acrylic copolymer emulsion in the fixation of heavy metals including $Cr^{6+}$ from waste ash in this test.

• Polymer(Korea)
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• v.24 no.4
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• pp.437-444
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• 2000

Propylene polymerizations were carried out by using rac-Et(Ind)$_2$ZrCl$_2$ (Zirconocene catalyst) and a commercial third generation Ziegler-Natta catalyst in a semibatch reactor. From the polymerization reactions, the optimum reaction conditions and the physical properties of polymers produced from each catalyst system were investigated. The optimum reaction temperatures of rac-Et(Ind)$_2$ZrCl$_2$ and Ziegler-Natta catalyst were 5$0^{\circ}C$, 4$0^{\circ}C$, respectively. On the basis of the results for the produced polymer particle size distributions and the catalytic activities of polymerization reaction, the reaction temperature should be considered as an important factor for the successful polymerization reactions. Especially, the polymer was conglomerated in the higher reaction temperature. It was found that there was an upper limitation to co-catalyst concentration. Reaction rates and polymer yields rather decreased with increasing the concentration of to-catalyst, i.e., MAO and TEAl affected only polymerization activities, but the PEEB in Ziegler-Natta catalyst system affected isotactic indexes of produced polymer as well as activities. Based on these observations, the production yield seems to exhibit a first order lineal relationship to the partial pressure of monomer.

• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.930-934
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• 1998

The modified poly(ethylene terephthalate) (PET) was synthesized by copolymerizing dimethyl terephthalate with ethylene glycol, polyethyleneglycol, and dodecylbenzene sulfonate as a surfactant. After characterization of viscosity, color, and contant angle, hydrophilic characteristics of the modified PET depending on additives was discussed.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.5
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• pp.67-73
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• 2012

Failure mechanisms for a solid propellant were discussed, and the stip-yield and the inherent flaw models were applied to them. Then, failure assessment diagram methods were investigated by means of modified two models. Fracture toughness tests using CCT(center-cracked tension) specimens made of a solid propellant were conducted to generate the failure assessment diagrams. The failure assessment diagram of the inherent flaw model was normalized in order to compare with that of the modified strip-yield model. From the comparison of two failure assessment diagrams, it was found that the failure assessment diagram of the modified inherent flaw model more conservatively assesses the failure than that of the modified strip-yield model.

• Radiation Oncology Journal
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• v.20 no.3
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• pp.264-273
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• 2002

Purpose : Three-dimensional radiation dosimetry using magnetic resonance imaging of polymer gel was recently introduced. This dosimetry system is based on radiation induced chain polymerization of acrylic monomers in a muscle equivalent gel and provide accurate 3 dimensional dose distribution. We planned this study to evaluate the clinical value of this 3-dimensional dosimetry. Materials and Methods: The polymer gel poured into a cylindrical glass flask and a spherical glass flask. The cylindrical test tubes were for dose response evaluation and the spherical flasks, which is comparable to the human head, were for isodose curves. T2 maps from MR images were calculated using software, IDL. Dose distributions have been displayed for dosimetry. The same spherical flask of gel and the same irradiation technique was used for film and TLD dosimetry and compared with each other. Results : The R2 of the gel respond linearly with radiation doses in the range of 2 to 15 Gy. The repeated dosimetry of spherical gel showed the same isodose curves. These isodose curves were identical to dose distributions from treatment planning system especially high dose range. In addition, the gel dosimetry system showed comparable or superior results with the film and TLD dosimetry. Conclusion : The 3-dimensional dosimetry for conformal radiation therapy using MRI of polymer gal showed stable and accurate results. Although more studies are needed for convenient clinical application, it appears to be a useful tool for conformal radiation therapy.

• KSBB Journal
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• v.14 no.1
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• pp.82-90
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• 1999

In order to eventually fabricate an analytical system for infectious microorganisms, we synthesized major immunochemical components, utilized them for the construction of model system, and investigated an assay concept for bacterial whole cells. For the preparation of system components, a polyclonal antibody, against Salmonella thompson as model analyte, purified by immuno-affinity chromatography was used to chemically link to streptavidin or an enzyme, horseradish peroxidase(HRP). The antibody and streptavidin was modified with sulfosuccinimidyl 4-[N-maleimidomethyl]cyclohexane-1-carboxylate and N-succinimidyl-3-[2-pyridyldithio]propionate(subsequently activated by dithiotheritol), respectively. The modified components were reacted to synthesize antibody-streptavidin conjugates which were then purified on a two-layer chromatography column of diaminobiotin gel and Sephadex G-100. For antibody-HRP conjugates, HRP molecules were activated by $NalO_4$ oxidation and then coupled to immunoglobulin. After stabilizing with ($NaCNBH_3$, the conjugates were purified by size exclusion chromatography on Biogel A5M column. To devise a model system, such produced components were combined with a dot-blotter in which a nitrocellulose membrane($12{\mu}m$ pre size) with immobilized biotin was already located. The analyte (S. thompson cells) was reacted with the both antibody conjugates in a liquid phase, and the complexes formed were captured on the membrane surfaces by applying vacuum in the bottom compartment of the blotter to invoke biotin-streptavidin reaction. Under optimal conditions, the system enabled to identify the analytical concept for bacterial whole cells, and the lower limit of detection was approximately $1{\mu}g/m{\ell}$($10^5-10^6$ cells/m$m{\ell}$). The controlling factors were the concentrations of each antibody conjugate that caused agglutination in the presence of analyte as they increased.

• Journal of the Korean Chemical Society
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• v.34 no.2
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• pp.197-202
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• 1990

Polyethylene glycol (PEG) grafted poly γ-benzyl L-glutamate (PBLG) were prepared from esterification or substitution reaction of PBLG with PEG having hydroxyl group at one end or primary amino groups at both ends. The viscosity of these polymer solution was decreased with decrease of polymer concentration. But in more dilute solution the viscosity was increased with decrease of polymer concentration. PEG-grafted PBLG polymers showed smaller water contact angles than PBLG homopolymer, and the water contact angles of the surface of PEG-grafted PBLG polymers were largely dropped by reacting with aminoethanol, resulting in hydrogel surfaces.

• Journal of the Korean Chemical Society
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• v.31 no.6
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• pp.590-600
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• 1987

Silicone-containing polyamide-imides were prepared from bis(p-chlorocarbonylphenyl)diphenylsilane (BCCDPS), pyromellitic dianhydride(PMDA) and diamines. The thermal characteristics of the above polymers had been carefully studied using a thermogravimetric analyzer. The thermal stability of polymer was decreased with increasing contents of bis(p-carbonylphenyl)diphenylsilane units(BCDPS). The effect of diamine on thermal stability of polymer led benzidine > m-phenylenediamine> 4,4'-diaminodiphenyl ether > 4,4'-diaminodiphenyl sulfone. The activation energy of degradation of polymer obtained by Friedman method increased as the contents of BCDPS in the polymer decreased. The degradation temperature of polymers generally increased as the activation energy increased. The solubility of polymer increased as the content of BCDPS increased except polymers prepared with benzidine.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.682-689
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• 1999

In this study, binary PA 6,6/EPM(or EPM-g-MA) blends and ternary PA 6,6/EPM/EPM-g-MA blends were fabricated according to the variation in elastomer content and composition ratio of blend, and mixing temperature and rate so as to investigate the degree of influence of elastomer content and average particle size, morphology, and distribution of dispersed elastomer on properties of blends. As results, under the constant mixing rate(250 rpm) and different five section temperature profiles(270-265-265-255-$255^{\circ}C$) in extruder, high notched Izod impact strength was the property of PA 6,6/EPM-g-MA(70/30) blend among binary blends. Notched Izod impact strength of this blend was 25 times improvement compared with that of polyamide 6,6. In addition, elastomer average particle size of ternary PA 6,6/EPM/EPM-g-MA(70/15/15) blend was $0.56{\mu}m$, which was fine distribution, and notched Izod impact strength of that blend was the highest of all blends prepared with the variation in elastomer content. But the properties of this ternary blend were decreased remarkably at the diverse mixing temperatures and mixing rates.

• Elastomers and Composites
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• v.34 no.1
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• pp.20-30
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• 1999

In this study, binary polyamide 6,6(PA 6,6)/ethylene-propylene rubber(EPM) or EPM-g-maleic anhydride(EPM-g-MA) blends and ternary PA 6,6/EPM/EPM-g-MA blends with various elastomer content were prepared in order to investigate the degree of influence of elastomer content and average particle size, morphology, and distribution of dispersed elastomer on mechanical and thermal properties of blends. According to the results, notched Izod impact strength and relative crystallinity of binary blends modified with EPM-g-MA as well as average particle size and distribution of dispersed elastomer in such blends were more improved than those of binary blends modified with EPM. Notched Izod impact strength of blend whose composition ratio(wt % ) was 70:30(PA 6,6 : EPM-g-MA) was the highest among the binary PA 6,6/EPM-g-MA blends. The impact strength was increased by 25 times and its relative crystallinity was increased by 7 times when compared with those of polyamide 6,6. In the case of ternary PA 6,6/EPM/EPM-g-MA blend of which composition ratio was 70:15:15(PA 6,6:EPM:EPM-g-MA), the elastomer was finely distributed with the average particle size of $0.56{\mu}m$. The Izod impact strength of this blend was the highest of all blends prepared with different elastomer content.