• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.200-204
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• 2008

The curing kinetics of diglycidyl ether of bisphenol F (DGEBF) with an asymmetric cycloaliphatic amine curing agent were examined by thermal analysis in both isothermal and dynamic curing conditions. From the residual curing of the samples partially cured in isothermal condition and from the dynamic curing with various heating rates, it was found that there exist two kinds of reactions such as at low temperature and at high temperature regions. It was thus also found that the cure parameters obtained from the isothermal curing kinetic model hardly estimate experimental results for a degree of cure larger than 0.6. The activation energies and frequency factors of these two kinds of reactions were obtained from the dynamic curing experiments with various heating rates. From the curing analysis, it was verified that the total cure kinetics for low degrees of cure is dominated by the cure reaction in the low temperature region.

• Polymer(Korea)
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• v.37 no.2
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• pp.240-248
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• 2013

The curing behaviors of diglycidyl ether of bisphenol A (DGEBA) with mercaptan hardener were studied by the comparison with amine-adduct type hardener. Curing behaviors were evaluated by DSC at dynamic and isothermal conditions. In the DSC, the dynamic experiments were based on the method of Kissinger's equation, and the isothermal experiments were fitted to the Kamal's kinetic model. Activation energy of epoxy/amine-adduct type hardener was ca. 40 kcal/mol. As the functional group of mercaptan hardener, -SH increased, on epoxy/mercaptan hardeners, the activation energies decreased from 28 to 19 kcal/mol. Epoxy/amine-adduct type hardener was initiated at $90^{\circ}C$ or higher. However, epoxy/mercaptan hardeners reduced the initiation temperatures below $80^{\circ}C$ and shortened the durations of curing reaction within 10 min. We found out that the reaction kinetics of epoxy with mercaptan hardener followed the autocatalytic reaction models, and the maximum reaction rates were shown at the conversions of 20~40%.

• Applied Chemistry for Engineering
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• v.5 no.4
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• pp.731-736
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• 1994

Cure kinetics of DGEBA/MDA/MN system with and without HQ were studied by Fractional life method and Kissinger equation. And the effect of HQ as a catalyst was studied. As cure temperature increased, the reaction rate increased and reaction order was almost constant. The activation energy of the system with HQ was lower about 13% and the reaction rate was higher than that of the system without HQ. It was because hydroxyl group of HQ formed a transition state with epoxide group and amine group and opened the epoxide ring easily and rapidly.

• Applied Chemistry for Engineering
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• v.5 no.3
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• pp.517-523
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• 1994

The effects of cure kinetics and mechanism of DGEBA(diglycidyl ether of bisphenol A)/MDA(4,4'-methylene dianiline) with SN(succinonitrile) and HQ(hydroquinone) as an additive and accelerator were investigated. Cure kinetics was evaluated by Kissinger equation and fractional-life method through DSC analysis. The activation energy has hydroxyl group as an accelerator, the activation energy and the starting cure-temperature were lower than those of DGEBA/MDA/SN system. Cure mechanism of those systems was investigated through FT-IR according to the various SN contents. The ratio was SN : HQ = 4 : 1. It has been known that the cure reactions of an epoxy-diamine system are composed of primary amine-epoxy reaction, secondary amino-epoxy reaction and epoxy-hydroxyl group reaction. But in DGEBA/MDA/SN system, primary amino-CN group reaction and CN group-hydroxyl group reaction were added to the above mentioned reactions. These reactions attributed to the long main chain and the low crossliking density. And in DGEBA/MDA/SN/HQ system, hydroxyl group of HQ formed a transition state with epoxide group and amime group and also opened the ring of the epoxide group rapidly, then amino-epoxy reaction took place easily.

• 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.

• Korean Journal of Materials Research
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• v.6 no.3
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• pp.291-296
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• 1996

Diglycidy1 ether of bisphenol A (DGEBA)/4, 4' -methylene dianiline(MDA)에 hydroquinonepheny1 glycidy1 ether(HQ-PGE)를 첨가한 계의 경화반응 메카니즘 FT-IR을 이용하여 연구하였다. 15$0^{\circ}C$에서 경화반응이 일어날 경우 반응기간이 증가할 때 에폭시기와 히드록시기는 감소하였고, 에테르기는 증가하였다. 그리고, HQ-PGE의 함량이 증가함에 따라 에폭시기의 소모량이 증가하였고, 유리 전이 온도가 감소하였다. 이로부터 HQ-PGE는 반응에 참여할 때 사슬 확장제와 반응 가속제로 작용함을 할 수 있었다.

• Korean Journal of Materials Research
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• v.5 no.5
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• pp.606-610
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• 1995

Diglycidyll ether of bisphenol A(DGEBA)/4, 4'-methylene dianiline(MDA)계에 반응성 첨가제 malononitrile(MN)을 첨가하면 내충격성은 크게 향상되나 반응속도는 감소하게 된다. 에폭시 수지의 경화반응은 에폭시기가 개환되어 생성되는 히드록시기가 촉매로 작용하는 자촉매 반응이며, 외부에서도입된 히드록시기도 같은 효과를 나타낸다. 따라서 본 연구에서는 DGEBA/MDA/MN 계의경화 반응속도를 증가시키기 위해 히드록시기를 가진 촉매로서 hydroquinone(HQ)을 도입하였고 이들 계의경화특성 및 열적성질을 고찰하였다. HQ가 첨가됨으로 인해 활성화 에너지는 감속하고 속도상수는 증가하였으며, 발열곡선에서 반응 시작온도가 낮아졌다. 이 결과로부터 HQ가 반응 가속제로 작용하고 있음을 알 수 있다.

• Journal of Adhesion and Interface
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• v.16 no.4
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• pp.146-151
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• 2015

Raw sap of essential oil in Korean Dendropanax lacquer was extracted with ethanol, and which was cured by using ROMP (ring opening metathesis polymerization, one of olefin metathesis). Curing behavior with subsequent film properties were studied and compared with conventional curing (under ambient conditions) and UV photo curing. The compositional changes of major ingredients in the lacquer before and after curing were studied by using GC-MS (gas chromatography mass spectrometry). ROMP-cured coating film showed higher gel contents (40%) as compared to those of conventional (8%) and UV curing (25%). ROMP curing with 2 wt% Grubbs' catalyst at $100^{\circ}C$ completed curing reaction within 2 h, which was much faster than that of conventional curing. The quality of coating film prepared with ROMP was more homogeneous and wrinkle-free as compared with that with UV curing. It was found that major ingredients of sesquiterpenes, such as ${\alpha}$-selinene, ${\beta}$-selinene, and ${\delta}$-cadinene were reacted in ROMP, as well as polyacetylenes.

• Polymer(Korea)
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• v.24 no.1
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• pp.105-112
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• 2000

Using a commercial epoxy/carbon fiber composite prepreg (DMS 2224) as a model system, the cure kinetics of vitrifying thermoset system were analyzed by isothermal and dynamic-heating experiments. Focusing on the processing condition of high performance composite systems, a phenomenological kinetic model was developed by using differential scanning calorimetry (DSC) and reaction kinetics theories. The model system exhibited a limited degree of cure as a function of isothermal temperature seemingly due to the diffusion-controlled reaction rates. The diffusion-controlled cure reaction was incorporated in the development of the kinetic model, and the model parameters were determined from isothermal experiments. The first order reaction was confirmed from the characteristic shape of isothermal cure thermograms, and the activation energy wes 78.43 kJ/mol. Finally, the proposed model was used to predict a complex autoclave thermal condition, which was composed of several isothermal and dynamic-heating stages.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.504-507
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• 2017

The polybutadiene-based HTPB used as the propellant main binder influences the curing reaction rate of the binder and propellant depending on the synthetic batch. The properties of HTPB synthesized in different batches were analyzed and applied to propellants to evaluate the curing reaction rate and mechanical properties. Finally this reaction can also affect mechanical properties of propellant. And the results suggest that proper degree of curing reaction is necessary to obtain better mechanical properties of propellant.