• Korean Journal of Materials Research
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• v.7 no.3
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• pp.244-250
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• 1997

본 연구에서는 에폭시/산무수물계에 경화촉진제를 첨가한 시료를 몰드(mold)내에서 등온 경화시킬 때 시료 내부의 온도변화를 측정하여 얻어진 온도-시간 곡선(temperature-time profile)을 조사하였다. 실험에 사용한 경화촉진제의 종류는 1-cyanoethy1-2-ethy1-4-methy1 imidazole(1E4MZ-CN), N,N-dimethy1 benzy1 amine(BDMA), 2,4,6-tris(dimethy1-aminomethy1)-phenol(DMP-30)이며 그들의 농도(c)는 1.0,1.5,2.0,2.5,phr그리고 경화온도(T$_{cure}$ )는 65,70,85,95$^{\circ}C$로 하였다. 경화가 진행되는 동안 시료내부의 온도는 초기에 경화온도로 상승한 후 본격적인 경화 반응이 일어나기 시작하여 온도가 급격히 상승하였다가 다시 감소하는 양상을 보였다. 온도-시간 곡선상에 나타나는 온도가 최고로 상승되는 시점(t$_{peak}$ )과 그 때의 온도(T$_{peak}$ )는 촉진제의 종류와 농도 그리고 경화온도에 의하여 영향을 받았다. 사용한 경화촉진제중에 DMP-30이 가장 짧은 t$^{peak}$ 값을 가져 가장 우수한 촉진 효과를 갖는 것으로 나타났으며, T$_{peak}$ 는 촉진제의 농도와 경화온도가 증가할수록 상승하였다. 그리고 경화촉진제의 농도와 경화온도의 변화에 따른 t$_{peak}$ 과 T$_{peak}$ 의 변화를 보면 촉진제 농도와 경화온도가 낮을 때 그 변화가 민감하여 2E4MZ-CN 이 가장 민감한 촉진제로 나타났으며 또한 T$_{peak}$ 에 영향을 주는 여러가지 요소들을 본 연구에서 얻어진 결과로부터 자세히 살펴보았다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.3822-3826
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• 2012

We have studied the effect of temperature and exposure time on the UV curing rate of Urethane Acrylate. UV dose has been modulated by changing the electric power, and temperature has been controled by coating rate and water temperature of the coating roll. Curing rate was evaluated by measuring gel fraction of the cured film. It has been found that effect of coating velocity on the gel fraction of the final film is predominant, but role of temperature of the UV chamber is negligible. These observations imply that exposure time of UV light is critical to have a fully cured film. To better understand the effect of design and operating condition of UV coater on the behavior of UV curing of Urethane Acrylate, we have also conducted heat-flux analysis of UV chamber.

• The Korean Journal of Rheology
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• v.6 no.1
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• pp.10-19
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• 1994

에폭시수지와 CFRP 복합체 구조물의 경화공정 중에 발생하는 잔류응력은 구조물의 기계적물성에 영향을 미친다. 따라서 잔류응력을 낮추기 위해 여러 가지 방법들이 발표되고 있다. 이연구에서는 잔류응력을 낮추는 방법으로 잔류응력의 발새mechanism을 이해하고 반 응속도식과 여러 가지 기초물성을 기초로 한 computer simulation pro-gram을 이용하여 에 촉시수지와 복합체 구조물의 잔류응력을 최소화하는 경화공정을 찾는 연구를 진행하였다. 경화과정에서는 대부분의 경화온도가 구조물의 유리전이온도보다 높기 때문에 잔류응력이 발생하지 않고 대부분의 잔류응력은 냉각과정에서 발생하였다. 잔류응력을 정량화하는 방법 으로 구조물의 표면이 유리전이온도에 도달하였을때 내부 비체적분초를 상대적인 잔류응력 이라 간주하였다. 컴퓨터모사에 의해 최종경화온도와 냉각속도를 바꾸면서 잔류응력을 모사 한 결과 최종경화온도가 낮을수록, 냉각속도가 작을수록 잔류응력이 작게 발생하였다.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.11b
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• pp.463-468
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• 1996

질소의 함량을 0.04%~0.15% 까지 변화시킨 316L 스테인레스 강으로 공기 중에서 저주기 피로시험을 수행하였다. 전체변형범위 1%, 변형속도 2$\times$$10^3$/sec, 삼각파로 상온 ~$600^{\circ}C$ 온도범위에서 시험을 수행하였다. 상온에서는 사이클이 진행됨에 따라서 연화가 계속해서 발생하지만 온도가 증가하면 초기에 경화가 발생한다. 피로시험 초기에 경화되는 정도와 saturation 응력은 온도가 증가하면 증가한다. 이러한 경화현상은 동적변형시효에 의해서 발생되는 것으로 판명되었다. 질소를 첨가하면 강도는 증가하지만 경화는 감소되었다. 질소에 의한 경화의 감소는 질소가 동적변형시효를 억제하기 때문이다.

• Korean Journal of Materials Research
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• v.7 no.10
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• pp.827-831
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• 1997

DGEBA/MDA/GN 계의 기계적 및 절연성질에 미치는 후기경화 조건의 영향을 연구하였다. 시편은 8$0^{\circ}C$에서 1.5시간 동안 경화한 후 15$0^{\circ}C$에서의 후기 경화시간과 경화온도를 다르게 하였다. 후기 경화온도가 증가함에 따라 인장강도, 절연파괴 강도 그리고 유리전이온도는 약간 증가하였으나 감소하였다. 4시간까지 후기경화되었을 때 인장강도와 유리전이온도는 증가하였으나 충격강도는 감소하였다. 그러나 4시간 후에는 거의 일정한 값을 나타내었다. 절연파괴 강도는 후기경화 시간에 관계없이 거의 일정한 값을 나타내었다.

• Applied Chemistry for Engineering
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• v.8 no.6
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• pp.973-978
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• 1997

The toughness and morphology of epoxy resin based on diglycidyl ether of bisphenol A(DGEBA) cured with of tris (dimethylaminomethy]) phenol(DMP-30) and castor oil (CO) as a toughening modifier have been studied. Mixtures of CO and an epoxy resin showed a higher miscibility than the classical CTBN modified epoxy resin. The glass transition temperature($T_g$) was decreased with the CO content and the cure temperature. It is interpreted that the networks of epoxy matrix obtained at high temperature are apparently looser and more flexible due to the lower crosslinking density. The toughness was slightly increased with the CO content at $40^{\circ}C$ of curing temperature. The toughness increased with increasing the cure temperature and CO content.

• Polymer(Korea)
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• v.24 no.6
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• pp.837-844
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• 2000

The cure behavior of commercial epoxy molding compounds (EMC) commonly used for IC package was studied at constant cure temperatures as well as at constant heating rates using differential scanning calorimetry (DSC), rheometer, and dielectric analyzer (DEA). The cure kinetics were obtained using autocatalytic reaction model according to the Ryan Dutta method after assuming m+n equal to 2. The prediction of reaction rates by the model equation corresponded well to experimental data at all temperatures except for 10$0^{\circ}C$. The phase transitions such as gelation and vitrification occurred during network formation. At each isothermal cure temperature, $T_{g}$ was measured in accordance with cure time, and the vitrification point was attained when $T_{g}$ was equal to $T_{cure}$. The temperature dependence of gel points and vitrification points showed good agreement with Arrhenius relation. DEA using parallel plate electrode was effective for the monitoring of EMC cure. we knew that if the resin systems are materials of comparable quality, $_{gel}$$T_{g}$ is constant regardless of accelerator concentration in TTT (Time-Temperature-Transformation) diagram.

• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.963-969
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• 1996

Cure characteristics of DGEBA(diglycidyl ether of bisphenol A)/dicy(dicyandiamide) system containing diuron(3-(3,4-dichloro phenyl) -1,1-dimethylurea) as an accelerator was investigated. The system has shelf life of six months because dicy is insoluble in liquid/solid resins at room temperature. It is generally known that dicy is an adequate curing agent for one component adhesive due to its highly latent property. With increasing the amount of added dicy, reaction heat of DGEBA/dicy system increased and degree of conversion was not varied. For DGEBA/dicy/diuron system, cure temperature decreased about $40^{\circ}C$ and cure reaction became fast by the addition of diuron which activates dicy. $T_g$ of the mixed resin decreased with the amount of accelerator. which was interpreated with molecular structure forming loose chain. Cure kinetics of DGEBA/dicy and DGEBA/dicy/diuron system were explained using Kamal's autocatalytic reaction model. The effect of acceleration was confirmed with that reaction model.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.2 no.1
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• pp.75-82
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• 1988

Epoxy, noticed as a new insulation material tor electrical installation, may become an excellent cured material from the crosslink reaction with some curing agents. The characteristics of cured Epoxy is determined by the kind of the curing agents and the method of lattice formation. The purpose of this paper, varing the process of lattice formation by various surrounding temperatures during the curing process, is to obtain the optimum curing temperature for electrical insulation from the results of investigation on the properties of cured Epoxy. In the experiment, Epoxy was cured at various temperatures between $20[^{\circ}C] and 50^[{\circ}C]$ which differ by $5^[{\circ}C]$, and then examined on the electrical insulation haracteristics as well as the thermal and mechanical stability. As a result, it is concluded that the optimum electrical insulation characteristis and mechanical strength of cured Epoxy can be obtained when cured at a surrounding temperature at $30[^{\circ}C]$.

• Composites Research
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• v.16 no.6
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• pp.33-40
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• 2003

The initial thermal degradation of polymer matrix composite is not observed easily. At the beginning of thermal degradation of polymer matrix composites, phase transformation such as chain scission, oxidation occur, and then micro delamination is produced in matrix and interface between matrix and fiber before blistering. Initial heat damage deteriorate mechanical properties of composites. We presented the detection method of the initial heat damage of composites conveniently using ultrasonic technique. Absorption coefficient and material velocity was measured with thermal degradation and degree of cure. The more thermal degradation was progressed, the more absorption coefficient was increased. When the cure temperature is more high, the absorption coefficient of cured composite is increased and material velocity is decreased. We concluded that cure temperature is more high, the defects such as void is increased and molecular structure cured at high temperature has cross-linking structure which is more absorb the ultrasonic waves.