• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.701-706
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• 1999

The effect of siloxane oligomer content on thermal stability and internal stress of DGEBA epoxy resin was investigated. Siloxane-epoxy polymers having terminal epoxy group were prepared by reaction of siloxane-DDM prepolymer with DGEBA epoxy resin. Thermal stability was studied in terms of the initial decomposition temperature(IDT), temperature of maximum rate of weight loss($T_{max}$), integral procedural decomposition temperature(IPDT), and decomposition activation energy($E_t$) using TGA data. The thermal stability increased with increasing the siloxane oligomer content and showed a maximum value in the case of 5 wt% siloxane oligomer content in the blend system. While, the coefficient of thermal expansion(${\alpha}_r$) and the flexural modulus($E_r$) allowed us to study internal stress of the blend system. As the content of siloxane oligomer increases, the internal stress systematically decreases as decreasing both ${\alpha}_r$ and $E_r$.

• Polymer(Korea)
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• v.29 no.3
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• pp.231-236
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• 2005

Amino terminated polyetherimide (AP-PEI) has been synthesized using 2,2'-bis [4-(3,4-dicarboxyphenoxy)-phenyl]propane dianhydride (BPADA) and m-phenylenediamine. Polyetherimide containing pendant carboxy group (CP-PEI) has also been synthesized by the reaction of BPADA, m-phenylenediamine and 3,5-diaminobenzoic acid. The modified PEIs were used as toughening agent for diglycidyl ether of bisphenol-A epoxy resin which was cured with nadic methyl anhydride (NMA). Thermal properties, fracture toughness ($K_{IC}$) and solvent resistance of toughened epoxy resin were measured. The $K_{IC}$ of epoxy resin containing 20 phr of AT-PEI was 2.88$MPa{\cdot}m^{0.5}$ without sacrificing thermal properties. The $K_{IC}$ of epoxy resin which contained 20 phr of CP-PEI was 2.82$MPa{\cdot}m^{0.5}$.

• Macromolecular Research
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• v.10 no.1
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• pp.34-39
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• 2002

Cure behavior of an epoxy resin was investigated at different cure temperatures (110, 120, 130, 140, and 150 $^{\circ}C$) and cure times in the presence of 2 wt% of an N-benzylpyrazinium hexafluoroantimonate (BPH) cationic catalyst by means of differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The glass transition temperature ( $T_{g}$) and chemical conversion (x) at the different temperatures were determined from DSC thermograms. The $T_{g}$ and x vs. In time data were superposed up to $T_{g}$ = 10$0^{\circ}C$ and x = 0.70 by shifting horizontally at a reference temperature of $T_{g}$ = 13$0^{\circ}C$. It is interesting that the $T_{g}$ and x of the superposed data increase rather slowly in the early stage of cure and rapidly thereafter. Therefore, the increase of the $T_{g}$ and x can be divided into two regions; $R_{I}$= -18.4(= $T_{go}$ ) ~5$^{\circ}C$ and $R_{II}$ = 5 ~ 10$0^{\circ}C$ in $T_{g}$, and $R_{I}$ : 0~0.24 and $R_{II}$ : 0.24~0.70 in x. The $R_{I}$ is closely related to the initiation reactions between BPH and epoxy and between hydroxy group and epoxy in this epoxy/catalyst system. From the kinetic analysis of the $T_{g}$-shift, activation energy was 12.5 kcal/mol. The relationship between $T_{g}$ and x was also considered. The gelation and vitrification times for different cure temperatures were obtained from DMA curves.urves. DMA curves.urves.

• Journal of the Korean Applied Science and Technology
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• v.33 no.4
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• pp.615-626
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• 2016

In the paper, mild solvent soluble alkyl group modified epoxy resins were prepared via a three-step method; (1) the condensation reaction of dodecyl phenol (DP) and formaldehyde, (2) the crosslinking reaction of dodecyl phnol novolac compound (DPC) and bisphenol A diglycidyl ether, (3) the dodecyl phenol novolac epoxy resins containing fatty acid (DPFA) was prepared by introducing fatty acid to DPC. Equivalent ratios of DP and formaldehyde were 1.25~1.333/1.0. Equivalent ratio of DPC and bisphenol A diglycidyl ether (YD-128) was 1.0/2.0. Reactivity, viscosity, molecular weight, solvent solubility, and physical properties of DPFA were investigated. The result show that as the number of aromatic ring of DPFA increased, viscosity increased and solvent solubility improved. When we test the properties of coatings by blending the synthesized DPFA with a white pigment, DPFAC-5 using triphenylphosphine (TPP) as a ring-open catalyst showed optical performance for drying time, adhesion, hardness, impact resistance, acid resistance and storage stability.

• Macromolecular Research
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• v.14 no.6
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• pp.610-616
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• 2006

An azoinitiator linked to an epoxy oligomer, which could easily diffuse into the organoclay gallery and swell it, was used as an initiator to enhance the delamination of an organoclay, Cloisite 25A, in a matrix of styrenic polymers, poly(styrene-co-acrylonitrile) and polystyrene, during the preparation of a nanocomposite via an in-situ polymerization method. X-ray diffraction results and transmission electron microscopic observation of the morphology showed that the epoxy segment enhanced not only the delamination but also the extrication of ammonium cations from the organoclay gallery into the polymer matrix. The latter phenomenon induced the structural change of the alkyl group of ammonium cations in the gallery from a bilayer to monolayer structure, and also decreased the glass-rubber transition temperature as measured by a differential scanning calorimeter and dynamic mechanical analyzer.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.264-267
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• 2004

Cure monitoring and nondestructive characteristics of carbon fiber/epoxy composites were evaluated by the measurements of electrical resistance and acoustic emission (AE). Logarithmic electrical resistivity of the untreated single-carbon fiber composite increased suddenly to infinity when the fiber fracture occurred, whereas that of the electrodeposited composite increased relatively broadly up to infinity. As curing temperature increased. logarithmic electrical resistivity of steel fiber increased. On the other hand, electrical resistance of carbon fiber decreased due to the intrinsic electrical properties based on the band theory. The apparent modulus of the electrodeposited composite was higher than that of the untreated composite due to the improved interfacial shear strength (IFSS).

• Journal of the Korea Furniture Society
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• v.11 no.1
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• pp.25-29
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• 2000

This study was carried out to analyze the ultrasonic properties of sound board which was glued with various adhesives and to evaluate which adhesive is the best for the acoustic radiation of the musical instrument. The results are as follows: 1. Animal glue is the best adhesive for the sound board with respect to the acoustic radiation ratio of the musical instruments. Epoxy resin and polyvinyl acetate resin are the next group, urea formaldehyde resin and Hot melt are the third group, polychloroprene(CR) resin is the lowest. 2. Epoxy resin, animal glue and Titebond(PVA) give the highest shear strength and the highest wood failure relatively Hot melt and polychloroprene(CR) resin do not meet the standard because of low wood failure.

• Bulletin of the Korean Chemical Society
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• v.8 no.3
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• pp.162-165
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• 1987

The reduction rate of borohydride exchange resin (BER) was greatly enhanced in the presence of lithium salts. Thus 2-heptanone was reduced completely with BER-LiCl in 1 h at room temperature. However, no reduction was observed with BER alone under the same conditions. With this system, organic compounds containing various fuctional groups were examined in ethanol at room temperature. This study revealed that BER-LiCl system exhibits an excellent chemoselectivity for carbonyl group in the presence of other functional groups. Keto esters and epoxy ketones were reduced with BER-LiCl to give the corresponding hydroxy esters and epoxy alcohols with excellent yields. Selective reductions of carbonyl groups were also possible in the presence of other organic compounds containing functional groups such as 1-idooctane, 1-bromooctane, caproamide, hexanenitrile, nitrobenzene, n-butyl disulfide, dimethyl sulfoxide and 1-dodecene.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.162-163
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• 2021

To prepare the waterborne silicone acrylic resin coatings, acrylic resin was prepared by a radical polymerization. Glass transition temperature(Tg) of the acrylic copolymer was fixed at 30℃ and the contents of tertiary amine monomer(DMAEMA), were varied to be 5, 10, 15 and 20 wt%, hydroxyl monomer, and carboxyl monomer were fixed 10 wt%, and 4 wt% respectively. γ-Glycidoxypropyltrimethoxysilane(GPTMS) containing epoxy group was used for curing agents. The eqivalent ratio of amine to epoxy was 1:1. The prepared coatings exhibited excellent adhesion to various substrates, and various physical properties of the coatings were satisfactory. The gloss retension and color difference were improved at low tertiary amine concentration. The coatings containing 10wt% tertiary amine concentration have especially good weather resistant properties.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.164-165
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• 2021

To prepare the good-adherent and weather-resistant acrylic resin coatings, acrylic resin was prepared by a radical polymerization. Glass transition temperature(Tg) of the acrylic copolymer was fixed at 30℃ and the contents of tertiary amine monomer(DMAEMA) was varied to be 5, 10, 15, 20 wt% respectively. γ-Glycidoxypropyltrimethoxysilane(GPTMS) containing epoxy group was used for curing agents and di-n-butyltindilaurate(DBTDL) was used for drying accelerator. The equivalent ratio of amine to epoxy was 1:1. The prepared coatings exhibited excellent adhesion to various substrates, and various physical properties of the coatings were satisfactory. The gloss retention and color difference were improved at low tertiary amine concentration. The coatings containing 10wt% tertiary amine concentration have especially good weather resistant properties.