• Korean Journal of Metals and Materials
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• v.46 no.1
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• pp.13-19
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• 2008

To develop a recycling process of magnesium alloy scrap, a fundamental study on the distillation of magnesium alloy melt was carried out. Melt temperature, vacuum degree and reaction time were considered as experimental variables. The amount of vaporized magnesium melt per unit surface area of melt increases with the increase of melt temperature, reaction time and vacuum degree. The vapor condensed at the tip of water cooling Cu-condenser as a form of pine cone. Magnesium and zinc were vaporized easily from the melt. However, It's difficult to separate magnesium and zinc by vacuum distillation because vapor pressure of zinc is similar to one of magnesium. The contents of aluminum, manganese and iron, etc. in residual melt increase due to the decrease of magnesium and zinc content after the distillation of magnesium alloy.

• Journal of the Korean Ceramic Society
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• v.27 no.5
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• pp.677-683
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• 1990

Melt-textured growth of the YBa2Cu3O7-x phase from a supercooled melt created locally aligned, barshaped grains of the orthorhombic 1-2-3 phase. Based on all the observed phenomena, the gross mechanism of the melt-textrued growth of YBa2Cu3O7-x on the (100) plane of MgO was delineated by three basic patterns of reactions. These are : (ⅰ) formation of the aligned 1-2-3 phase and the Y-rich 2-1-1 phase at the bulk region away from the (100) plane of MgO ; (ⅱ) formation of the Cu-richprecipitates at the interfacial region by the selective interface-induced precipitation of the liquid phase ; (ⅲ) condensation reaction of the entrapped Cu-rich vapor with Mg atoms during the initial stage of rapid cooling from 130$0^{\circ}C$ to 98$0^{\circ}C$.

• Fibers and Polymers
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• v.4 no.4
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• pp.156-160
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• 2003

Poly(ethylene 2,6-naphthalate) (PEN)/Poly(ethylene glycol) (PEG) copolymers were synthesized by two step reaction during the melt copolymerization process. The first step was the esterification reaction of dimethyl-2,6-naphthalenedicarbox-ylate (2,6-NDC) and ethylene glycol (EG). The second step was the condensation polymerization of bishydroxyethylnaphthalate (BHEN) and PEG. The copolymers contained 10 mol% of PEG units with different molecular weights. Structures and thermal properties of the copolymers were studied by using $^1{H-NMR}$, DSC, TGA, etc. Especially, while the intrinsic viscosities of PEN/PEG copolymers increased with increasing molecular weights of PEG, but the glass transition temperature, the cold crystallization temperature, and the weight loss temperature of the copolymers decreased with increasing molecular weights of PEG. Consequently, the hydrophilicities by means of contact angle measurement and moisture content of the copolymer films were found to be significantly improved with increasing molecular weights of PEG.

• Elastomers and Composites
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• v.45 no.3
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• pp.156-164
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• 2010

Thermoplastic elastomers (TPEs) exhibit both elastomeric behaviors at used temperature range and melt processibility. Polyamide based thermoplastic elastomers (TPAEs) are segmented block copolymers with hard blocks consisting of polyamide segments, while the soft blocks usually consist of flexible segments having a low glass transition temperature. The TPAE is one of the engineering TPEs possessing high thermal stability, excellent mechanical performances, chemical resistance and excellent processibility. And they showed wide range of physical and functional properties depending upon the structure of each segment and their relative contents and the hybridization with various inorganic particles. In this review, synthesis, properties, and possible applications of TPAEs are summarized.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.6
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• pp.98-104
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• 2018

Deflected 4-way panels of ceiling air conditioners produced by injection molding process have caused dew condensation at the edge of products. In order to prevent this drawback with reducing weight and deformation, this study proposed renovated process adopting microcellular foaming. According to results from 2-sample t-test and analysis of variance(ANOVA), the critical factors affecting weight were melt temperature and injection speed. In addition, the vital effects on deformation were structure at the edge, mold temperature and cooling time. Optimal conditions of these parameters were derived by regressive analysis with CAE and response surface method(RSM), and then applied to an actual design and process stage to analyze performance. As a results, it clearly showed that new process improved process capability as well as reduced both weight and deformation by 18.8% and 71.9% respectively compared to the conventional method.

• Journal of the Korean Ceramic Society
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• v.41 no.7
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• pp.555-559
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• 2004

Ceramic foams were prepared by a self-blowing process of a polysiloxane with A1$_2$O$_3$ as a filler. The release of water and ethanol vapor during the condensation reaction of the polymer triggered the pores in the polymer melt. The size. interconnectivity and shape of the pores in the ceramic foams were strongly dependent on the viscosity of the polymer melt, which could be varied by the content and size oi the filler. When the content of the filler inceased and the size of the filler decreased. the size of the pores were decreased and the thickness between the pores were increased. In the addition, the viscosity of polymer melt increased by the pretreatment at 130$^{\circ}C$ for Ire intermolecular cross linking thereby stabilizing the foam structure. The density and compressive strength of the ceramic foams were affected by the heating rate during the blowing process.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.335-336
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• 2003

The synthesis of poly(trimethylene terephthalate) (PTT), whose application is being expanded very rapidly to new apparel and carpet materials, was investigated by melt condensation polymerization using 1,3-propanediol (PDO) and terephthalic acid (TPA). No catalyst was used in the 1st step reaction (esterification), but tetrabutyl titanate(TBT) was used as a polyesterification catalyst ranging from 25 to 75 ppm based on the weight of TPA used in the 2nd step reaction (polyesterification). The molar ratio of PDO to TPA was set as 2.2:1. The effect of reaction conditions on the color and intrinsic viscosity of the final product was investigated. (omitted)

• Elastomers and Composites
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• v.54 no.3
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• pp.182-187
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• 2019

To improve the mechanical properties of glass-fiber-reinforced polypropylene (PP) composites through interfacial adhesion control between the PP matrix and glass fiber, the surface of the glass fiber was modified with PP-graft-maleic anhydride (MAPP). Surface modification of the glass fiber was carried out through the well-known hydrolysis-condensation reaction using 3-aminopropyltriethoxy silane, and then subsequently treated with MAPP to produce the desired MAPP-anchored glass fiber (MAPP-a-GF). The glass-fiber-reinforced PP composites were prepared by typical melt-mixing technique. The effect of chemical modification of the glass fiber surface on the mechanical properties of composites was investigated. The resulting mechanical and morphological properties showed improved interfacial adhesion between the MAPP-a-GF and PP matrix in the composites.

• Polymer(Korea)
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• v.35 no.6
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• pp.593-598
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• 2011

The IPA-co-HDO-co-(TPA/MA) copolymers for all-vanadium redox flow battery were synthesized by melt condensation polymerization using isophthalic acid(IPA), 1,6-hexandiol (HDO), terephthalic acid(TPA) and maleic anhydride(MA). The amination of chloromethylated IPA-co- HDO-co-(TPA/MA)(CIHTM) copolymer was carried out using trimethylamine, and the anion exchange membrane was also prepared by UV crosslinking reaction. The structure and thermal stability of IHTM copolymers were confirmed by FTIR, $^1H$ NMR, and TGA analysis. The anion membrane properties such as water uptake, ion exchange capacity, electric resistance and electrical conductivity, were measured by gravimetry, titration and LCR meter. The efficiency of the all-vanadium redox flow battery was analyzed. The ion exchange capacity, electric resistance and electrical conductivity were 1.10 meq/g, $1.98{\Omega}{\cdot}cm^2$, and 0.009 S/cm, respectively. The efficiency of charge-discharge, voltage, and energy for the allvanadium redox flow battery were 96.5, 74.6, 70.0%, respectively.

• Journal of Adhesion and Interface
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• v.17 no.4
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• pp.136-140
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• 2016

In this study, a series of dimer acid-based polyamides with different diamines were synthesized by condensation polymerization and the polyamides were characterized by Fourier transform infrared spectroscopy (FT-IR). Effects of diamine structures on mechanical and thermal properties of polyamides were investigated. The tensile strength and lap shear adhesion strength of aromatic-based polyamide (DAP) were higher than those of aliphatic-based polyamide (DAH). In DSC thermogram, DAP has a high $T_g$ and $T_m$ compared with DAH. DAP's and DAH's softening point were $112-115^{\circ}C$ and $98-121^{\circ}C$, respectively.