• Applied Chemistry for Engineering
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• v.5 no.5
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• pp.904-909
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• 1994

Cure kinetics of DGEBA(diglycidyl ether of bisphenol A)/MDA(4,4'-methylene dianiline)/GN(glutaronitrile) system with and without HQ(hydroquinone) as a catalyst was studied by Kissinger equation and Fractional life method. The activation energy of the system with HQ was somewhat lower and the pre-exponential factor of that was higher by about 30% than those of the system without HQ. As 1.25phr of HQ was added, reaction rates increased about 1.8 times.

• Korean Journal of Materials Research
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• v.4 no.5
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• pp.574-580
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• 1994

This study is about cure kinetics of DGEBA/MDA/MN(malononitrile) system by Barrett method and Integral method using DSC dynamic run. Curing behavior was shown through DSC and the heat change involved in a reaction could be measured directly with DSC. The kinetic parameters such as activation energy, pre-exponential factor and reaction order were given by Barrett method and Integral method obtained in an assumption that the area of DSC enthalpic analysis curve was propotional to the enthalpic change.

• The Korean Journal of Rheology
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• v.10 no.2
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• pp.92-97
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• 1998

열잠재성 경화제인 N-benzylpyrazinium hexafluoroantimonate (BPH)를 이용하여 함 량에 따른 DGEBA계 에폭시 수지의 경화반응에서의 유변학적 특서 및 반응속도를 연구하 였다. 경화시의 활성화 에너지를 Barrett 방법을 이용한 동적 DSC 측정방법으로 조사 하였 다. DSC 실험 결과 BPH의 함량이 증가할수록 활성화 에너지는 감소함을 알수 있었다. Rheomter를 이용하여 DGEBA/BPH 계의 유변학적 특성을 등온경화와 tdmdhsrud화 조건하 에서 살펴보았다. BPH의 함량이 증가함에 따라 겔화점 도달시간 빠르게 나타나는데 이는 낮아진 활성화 에너지에 기인한 것으로 사료된다. 두 번째 damping 피크를 이용하여 유리 화점을 측정하여 Time-Temperature-Transformation (T-T-T) cure diagram을 작성한 결 과 열잠재성 경화제의 특성인 일정온도 이상에서 활성이 나타남을 확인할수있었다.

• Elastomers and Composites
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• v.27 no.1
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• pp.20-26
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• 1992

Reactions between chlorinated or brominated poly(isobutylene-isoprene) (CIIR and BIIR, respectively) and 3-mercaptopropyltrimethoxysilane(MPS) were kinetically studied by gas chromatography in solution state. CIIR and BIIR were mixed with MPS and dibutyltin dilaurate as catalyst on roll mill and then the compounds were cured in hot water or atmosphere. From the gas chromatography, reaction order, activation energy, and frequency factor were determined. Crosslinking density and physical properties of moisture-cured CIIR and BIIR were measured. CIIR and BIIR were effectively moisture-cured and physical properties of these rubbers were comparatively good.

• 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.

• Polymer(Korea)
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• v.37 no.1
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• pp.41-46
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• 2013

The glass transition temperature ($T_g$) and conversion (${\alpha}$) were measured for a diglycidyl ether of bisphenol A (DGEBA) epoxy/aromatic amine system incorporated with an organic-inorganic hybrid molecule, polyhedral oligomeric silsesquioxane (POSS). Samples isothermally cured at varying cure temperatures and times were analyzed by differential scanning calorimetry (DSC). $T_g$ vs. ln (time) data at an arbitrary reference were superposed by time-temperature shifts for the kinetically controlled reaction, and the shift factors were used to calculate an Arrhenius activation energy. Influence of POSS was investigated from $T_g$ vs. ${\alpha}$ data, which in turn were fitted with DiBenedetto equation.

• Journal of the Korean Chemical Society
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• v.47 no.5
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• pp.472-478
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• 2003

In this work, the zeolite/diglycidylether of bisphenol A(DGEBA) systems were investigated in terms of the cure kinetics and mechanical interfacial properties of the composites. The 4, 4-diamino diphenyl methane(DDM) was used as a curing agent for epoxy. Two types of zeolite(PZ) were prepared with 15 and 35 wt% KOH treatments(15-BZ and 35-BZ, respectively) for 24 h, and their surface characteristics were studied by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction(XRD). Cure kinetics of the composites were examined in the context of differential scanning calorimetry(DSC), and mechanical interfacial properties were investigated in critical stress intensity factor($K_{IC}$) and critical strain energy release rate($G_{IC}$). In the results of XPS and XRD, sodium ion(Na) of zeolite was exchanged for potassium ion(K), resulting from the treatment of KOH. Also, $Si_{2p}/Al{2p}$ composition ratios of the treated zeolite were increased, which could be attributed to the weakening of Al-O bond in framework. Cure activation energy($E_a$) of 15-BZ composites was decreased, whereas KIC and $G_{IC}$ were increased, compared with those of the pure zeolite/DGEBA composites. It was probably accounted that the acidity of zeolite was increased by surface treatments and the cure reaction between zeolite and epoxy was influenced on the increased acidity of zeolite.

• 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%.

• Journal of Adhesion and Interface
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• v.3 no.2
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• pp.30-39
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• 2002

The effect of cure accelerator content on the change in crosslink density by thermal aging was studied for silica-filled natural rubber (NR) vulcanizates. Influence of silane coupling agent was also investigated. N-tert-Butyl-2-benzothiazole sulfenamide (TBBS) and bis-(3-(triethoxysilyl)-propyl)-tetrasulfide (TESPT) were used as a cure accelerator and a silane coupling agent, respectively. The crosslink density increased by thermal aging and the increasing level became larger as the aging temperature increased. The degree of crosslink density change of the vulcanizates without the silane coupling agent was larger than that of the vulcanizates containing the silane coupling agent. For the vulcanizates silane coupling agent, the activation energy for the crosslink density change decreased with increase of the cure accelerator content in the vulvanizate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1661-1667
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• 2009

Post-cure characteristics of a silicone rubber material which is widely used for a LCD lamp holder were investigated using thermogravimetric analysis (TGA). Research was especially focussed on searching for the optimum post-cure conditions in relation to the practical operation environments. The results showed that incipient volatile temperature(Ti) during the process was considered as the most important factor and, thereby, post-curing for 2hrs at $250^{\circ}C$seemed to be a reasonable condition in the practical view-point. Arrhenius plot of shift factors which were empirically determined from the time-temperature-superposition-principle showed good linearity, exhibiting the post-cure mechanism might be proceeded through single mechanism with activation energy of 108.25kJ/mol.