• Korean Journal of Materials Research
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• v.5 no.6
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• pp.667-672
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• 1995

Cure kinetics of DGEBA(diglycidyl ether of bisphenol A)/MDA(4, 4'-methylene dianiline)/SN(succinonitrile) system and DGEBA/MDA/SN/HQ(hydroquinone) system was studied by Kissinger equation and Fractional life method through DSC in the temperature range of 85∼150$^{\circ}C$. As cure temperature was increased, reaction rate increased and reaction order was almost constant. The reaction rate of the system with HQ as a catalyst was more higher and activation energy of that was lower about 20% than those of the system without HQ. Starting temperature of cure reaction for DGEBA/MDA/SN/HQ system decreased about 30$^{\circ}C$ than that of DGEBA/MDA/SN system.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.4
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• pp.41-48
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• 2010

To improve the pot life of one-part in-house anisotropic conductive paste (ACP) formulations, 2-methyl imidazole curing accelerator powders were encapsulated with five agents. Through measuring the melting point of the five agents using DSC, it was confirmed that a encapsulation process with liquid-state agents is possible. Viscosity of ACP formulations containing the encapsulated imidazole powders was measured as a function of storage time from viscosity measurements. As a result, pot life of the formulations containing imidazole powders encapsulated with stearic acid and carnauba wax was improved, and these formulations indicated similar curing behaviors to a basic formulation containing rare imidazole. However, the bondlines made of these formulations exhibited low average shear strength values of about 37% level in comparison with the basic formulation.

• Applied Biological Chemistry
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• v.36 no.2
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• pp.93-98
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• 1993

The purpose of this study is to determine the physicochemical properties in soybean oil during the hydrogenation by addition of phosphorus compounds and sulfur compounds is increased in soybean oil, decreased oleic acid and increased linoleic acid and stearic acid contents were found. When the sulfur compounds content is increased, solid fat content is increased at $10.0^{\circ}C$ and $21.1^{\circ}C$ and gradually decreased at $33.3^{\circ}C$ and $37.8^{\circ}C$. Higher melting point in hydrogenated soybean oil is observed on addition of phosphorus compounds compared to addition of sulfur compounds. When the sulfur compounds content is increased, conditions of selective hydrogenation are observed. Lead and arsenic are detected at a concentration of 0.01 ppm in a few kinds at each step of the refining process of soybean oil.

• Elastomers and Composites
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• v.35 no.3
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• pp.205-214
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• 2000

The polyurethane resin was prepared by the reaction of tolylenediisocyanate(TDI) and polypropyleneglycol(PPG). Physical properties of the resin were investigated experimentally. Charging catalyst before TDI-dropping induced the rapid increase of viscosity. On the other hand, charging catalyst after TDI-dropping resulted in mild stability without immoderate generation of heat on reaction. The use of phosphoric acid as catalyst led to low viscosity by restraining side-reaction such as forming of branch-chain, buret reaction and allopanate reaction, but it showed low cross-link density and slow drying. The curing speed was more influenced by structures of molecules rather than NCO/OH ratio. Including PPG 400 over 30 wt % showed excellent adhesive strength due to increase of crosslink density.

• Applied Chemistry for Engineering
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• v.10 no.7
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• pp.1046-1051
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• 1999

Cure behavior and thermal stability of the different ratio of diglycidylether of bisphenol A(DGEBA)/trimethylolpropane triglycidylether(TMP) epoxy blends initiated by 1 wt % N-benzylpyrazinium hexafluoroantimonate (BPH) as a cationic latent catalyst were studied using DSC and TGA, respectively. Latent properties were performed by measurement of the conversion as a function of temperature using dynamic DSC. Dynamic DSC thermograms of DGEBA/TMP blends revealed that the weak peak was formed by complex formation between the hydroxyl groups in DGEBA and BPH, and between epoxides and BPH in low temperature ranges. The strong peak was considered as an exothermic reaction by the formation of three-dimensional network in high temperature ranges. Isothermal DSC revealed that the reaction rate of the blends was found to be higher than that of the neat TMP. The thermal stabilities in the cured resins were increased with increasing the DGEBA content. These results could be interpreted in terms of the stable aromatic structure, existence of hydroxyl group and high molecular weight of DGEBA.

• Polymer(Korea)
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• v.27 no.3
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• pp.176-182
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• 2003

The fluorine-containing epoxy resin, 2-trifluorotoluene diglycidylether (FER) was prepared by reaction of 2-chloro-${\alpha}$,${\alpha}$,${\alpha}$-trifluorotoluene with glycerol diglycidylether in the presence of pyridine catalyst. Curing behavior of FER/DDM system was investigated using dynamic and isothermal DSC. Cure activation energy (Ea) was determined by Flynn-Wall-Ozawa's equation. The rheological properties of FER/DDM system were studied under isothermal condition using a rheometer. Cross-linking activation energy (Ec) was determined from the Arrhenius equation based on gel time and curing temperature. As a result, the chemical structure of FER was confirmed by FT-IR, $\^$13/C NMR, and $\^$19/F NMR spectroscopy. The cure activation energy of FER/DDM system was 55.4 kJ/mol and conversion and conversion rate were increased with the curing temperature. The cross-linking activation energy of FER/DDM system was 41.6 kJ/mol and gel time was decreased with the curing temperature.

• Polymer(Korea)
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• v.25 no.2
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• pp.168-176
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• 2001

The effect of novel N-crotyl-N,N-dimethyl-4-methylanilinium hexafluoroantimonate (CMH) curing agent as a thermal latent initiator on thermal behaviors, rheological properties, and thermal stability of diglycidylether of bisphenol A (DGEBA) epoxy cationic system was investigated. From DSC measurements of DGEBA/CMH system, it was shown that this system exhibits an excellent thermal latent characteristic at a given temperature. The conversion and conversion rate of DGEBA/CMH system increased with increasing the concentration of initiator, due to high activity of CMH. Rheological properties of the system were investigated under isothermal condition using a rheometer The gelation time was obtained from the analysis of storage modulus (G'), loss modulus (G"), and damping factor (tan $\delta$). As a result, the reduction of gelation time was affected by high curing temperature and concentration of CMH, resulting in high degree of network formation in cationic polymerization, due to difference of activity. The thermal stability of the cured epoxy resin was discussed in terms of the activation energy for decomposition and thermal factors determined from TGA measurements.ents.

• Polymer(Korea)
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• v.26 no.4
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• pp.501-507
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• 2002

In this work, diglycidylether of bisphenol-S (DGEBS) epoxy resin was prepared by alkaline condensation of bisphenol-S (BPS) with epichlorohydrin (ECH) in the presence of NaOH catalyst. The structure of the synthesized DGEBS epoxy resin was confirmed by IR, NMR spectra, and elemental analysis. The curing reaction and glass transition temperature ($T_g$) of DGEBS epoxy resin cured with phthalic anhydride (PA) and tetrahydrophthalic anhydride (THPA) at curing agents were studied by dynamic differential scanning calorimetry (DSC). The thermal stability of the cured specimen was investigated by thermogravimetric analysis (TGA). As a result, the activation energy ($E_a$) of DGEBS/PA system was higher than that of DGEBS/THPA system, whereas $T_g$, initial decomposed temperature (IDT), and decomposition activation energy ($E_t$) of DGEBS/PA were lower than those of DGEBS/THPA. This was probably due to the fact that the crosslinking density of DGEBS/THPA was increased by ring strain of curing agent.

• Journal of Adhesion and Interface
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• v.19 no.1
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• pp.13-18
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• 2018

At ruthenium (Ru) catalyst was exposed from the atmosphere, the degree of catalyst activation decreased. The change of catalyst activity with the number of days of exposure to air for the Ru catalyst was confirmed using the surface tension method quantitatively. Mechanical properties and surfactant change after polymerization by DCPD using Ru catalyst for each air exposure day was evaluated. The Ru catalyst mixed with a dilution agent was exposed in the air and color was monitored for each day. Surface tension was measured using Wilhelmy and PTFE and associated with different catalyst activities. Heat was measured in real time during polymerizing DCPD with Ru catalyst. After polymerization, tensile strength was measured for p-DCPD and the change of material property was measured. Interfacial properties were also evaluated via microdroplet pull-out tests between glass fiber and p-DCPD. The surface tension was stable until the 4 days (33 dyne/cm) whereas the surface energy increased at the 10 days (34 dyne/cm), which could be correlated with oxidation of the catalyst. Tensile property and interfacial shear strength (IFSS) was also stable until the 4 days (tensile strength: 38 MPa and IFSS: 26 MPa) whereas the mechanical property decrease at 10 days (tensile strength: 15 MPa and IFSS: 3 MPa) dramatically.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.144.2-144.2
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• 2010

Bipolar plate는 고분자 전해질 연료전지(PEMFC)에서 핵심 부품 중의 하나이고, 전해질 막이나 촉매 등에 비해서는 상대적으로 쉽게 접근할 수 있기 때문에 많은 연구가 수행되고 있다. Bipolar plate를 제조하는 기술은 크게 금속을 프레스 가공하는 방법, graphite 판을 직접 밀링하는 방법 및 고분자/카본계의 press molding 법 등 3가지로 분류되며, 본 연구에서는 3번째 방법에 의해서 bipolar plate를 대량 생산하는 방법에 대해 연구하였다. 고분자 매트릭스는 에폭시계 수지를 사용하였고, 카본계 재료는 graphite 분말과 carbon nanotube를 사용하였다. 이들 재료들을 일정한 비율로 혼합한 후 differential scanning calorimetry(DSC)를 사용하여 열분석 하였고, 그 결과를 Kissinger equation에 대입하여 경화반응 속도론을 연구하였다. 또한, 경화된 에폭시/탄소 복합재료의 전기전도도, 유리전이온도, 표면에너지 특성 등을 분석하였다.