• Journal of Adhesion and Interface
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• v.21 no.2
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• pp.65-70
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• 2020

Epoxy adhesive was mainly used to combine different composite materials. Epoxy adhesive was a typical thermosetting resin that can be bonded by changing from a linear structure to a three-dimensional network structure by curing reaction of epoxy and hardener. The curing conditions of epoxy adhesive were different with different types of hardener such as mixing ratio, curing time, and temperature. These curing conditions affected to the adhesive property of epoxy adhesive. In industry, it was difficult to proceed the applying epoxy adhesive and combining two parts immediately. The adhesive property decreased by humidity and pre-curing of epoxy adhesive in waiting time between two processes. In this paper, the glass fiber reinforced composite (GFRC) was combined with epoxy adhesive and adhesion property between epoxy adhesive and GFRCs was evaluated using single lap shear test. The different waiting times and humidity conditions were applied to epoxy adhesive in room temperature and adhesive property decreased as the waiting time increased. In small amount of humidity, the adhesive property increased because a small amount of moisture in the surroundings accelerated the curing reaction. In certain amount of humidity, however, the adhesion property decreased.

• Proceedings of the Korean Fiber Society Conference
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• 2002.04a
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• pp.451-454
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• 2002

최근 우주 항공 및 자동차 산업 등에서 기존의 금속재료를 대체하기 위하여 고강도 경량 구조 재료인 선진 복합재료 (advanced composite materials)의 개발에 관심이 모아지고 있다[1]. 선진 복합재료의 매트릭스 수지로서 가장 많이 사용되고 있는 에폭시는 수지 및 경화제의 종류에 따라 여러 가지 물성을 나타낼 수 있다. 에폭시 수지는 기계적 물성 및 내화학성이 우수하고 경화시 수축변형이 적은 장점이 있으나 높은 가교밀도 때문에 순간적인 충격에 취약하다는 단점을 지니고 있다. (중략)

• Composites Research
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• v.28 no.3
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• pp.99-103
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• 2015

This paper presents the cure kinetics studies on the cure reaction of thermosetting resin. Above all, change in degree of cure and specific heat capacity according to temperature are observed using DSC and MDSC. The results are analyzed by cure kinetics and specific heat capacity model. Glass transition temperature was also measured to apply to the specific heat capacity model. Model parameters were gained from the modeling result. As a result, behavior of specific heat capacity can be calculated mathematically.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.219-223
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• 2001

The on-line cure monitoring during the cure process of composite materials is important for better quality and productivity. The dielectric sensor for cure monitoring consists of base film and electrodes. Because the characteristic of dielectric sensor for the on-line cure monitoring is dependent on the base material, width and number of electrode, etc, the dielectric sensor should be standardized. And the selection of base film material of sensor is very important. In order to prevent the measuring errors generated from the increase of environmental temperature, the base film material should have stable dielectric constant with respect to environmental temperature. In this study, the newly developed dielectric sensor for cure monitoring was designed and the dissipation factor which is function of degree of cure was measured using the sensor. The relationship between the dissipation factor and degree of cure with respect to environmental temperature was investigated.

• 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 Dyers and Finishers Conference
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• 2012.03a
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• pp.20-20
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• 2012

최근, 수송기기 분야는 국제 환경규제 강화에 따른 CO2 절감, 연비향상, 경량화를 위한 기술적 수요가 증대되고 있으며, 그린카, 그린선박 등 친환경 수송기기에 대한 연구가 활발히 진행되고 있다. 하지만, 기존의 금속소재가 가지는 경량화의 한계를 극복하기 위해서는 CFRP, GFRP 등 금속대체 복합소재를 적용한 수송용 경량부품 개발에 대한 필요성이 요구되고 있다. 복합소재는 섬유사이에서 응력을 전달하는 기지(Matrix)와 하중을 전달하는 섬유(Fiber)의 종류와 양 및 적층 각도에 따라 수송용 부품에 적합한 기계적 특성을 얻을 수 있고, 높은 비강도와 비강성의 값을 갖게 되어 경량화가 용이한 장점이 있다. 반면, 섬유재의 종류, 성형방법, 경화온도 등에 따라 물리적 특성에 큰 변화가 발생하며, 수지의 경화조건에 따라 성형시간이 많이 소요되는 단점을 가지고 있다. 따라서, 본 연구에서는 자동차, 선박, 항공기, 철도차량 등 각종 수송기기의 경량화를 목적으로 생산성 향상 및 성형시간 절감을 위해 열가소성 수지, 저온속경화 수지를 적용하여, 경화 시간을 단축시키고, 3D-fabric 및 다층구조 직물을 Vacuum Infusion 공법으로 성형하여, 기존의 섬유재 적층시 소요되는 작업 공정을 간소화 할 수 있도록, 고속성형 복합소재를 적용한 수송용 경량부품 개발에 관한 연구를 수행하였다.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.3
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• pp.130-135
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• 2002

This study investigates the effect of curing method on the bonding strength of aluminum/CFRP composites. The surface of aluminum panel was treated by DC plasma. Lap shear tests and T-peel tests were performed based on the procedure of ASTM 906-94a and ASTMD1876-95, respectively. Test samples were fabricated by using the co-curing method and the secondary curing method. The results showed that the shear strength of test samples made by the co-curing method was 2.5 times greater than that of test samples made by the secondary curing method. The T-peel strength of the co-curing method case was almost 2 times greater than that of the secondary curing method case.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.11
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• pp.2853-2865
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• 2000

During the curing process of thick glass/epoxy laminates, a substantial amount of temperature lag and overshoot at the center of the laminates is usually experienced due to the large thickness and low thermal conductivity of the glass/epoxy composites. Also, it takes a longer time for full and uniform consolidation. In this work, temperature, degree of cure and consolidation of a 20 mm thick unidirectional glass/epoxy laminate were investigated using an experiment and a 3-dimentional numerical analysis. From the experimental and numerical results, it was found that the experimentally obtained temperature profile agreed well with the numerical one, and the cure cycle recommended by the prepreg manufacturer should be modified to prevent a temperature overshoot and to obtain full consolidation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05b
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• pp.15-18
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• 2004

피뢰기에 뇌 또는 이상전압과 같은 정격이상의 고장전류가 유입되어 발생하게 되는 순간적인 열 충격과 내부압력 상승은 폭탄이 내부에서 터지는 것과 같은 엄청난 양의 충격에너지이다. 본 연구에 있어서 폴리머 피뢰기의 제조에 사용된 모듈용 브레이드 복합재료는 압력해소 및 폭발 비산하지 않도록 하는 기능을 수행하도록 설계되어있다. 기존의 폴리머 피뢰기에 적용된 복합재료보다 충격에너지를 흡수하는 구조물에 유리한 브레이드 복합재료를 피뢰기 모듈의 제조에 도입한 것은 매우 의미 있는 일이라 판단된다. 따라서 본 연구에서는 열경화성 브레이드 복합재료를 제조하기 위하여 프리폼을 먼저 제작한 다음 금형에 삽입한 후 진공상태에서 수지를 주입하여 경화시키는 RTM공법을 이용하였다. 본 연구의 목적은 브레이드 패턴 및 방압개소 설계 등의 기초적인 자료조사 및 실험을 통하여 폴리머 피뢰기의 폭발 비산을 방지할 수 있는 압력해소 성능을 위한 기초 자료를 확보하고자 하는 것이다. 브레이드 복합재료의 기본적인 경화거동을 등온 및 동적 DSC를 이용하여 고찰하였고, 기본적인 전기적 특성을 평가하였으며, 방압개소를 가진 폴리머 피뢰기 모듈의 고장전류시험시 예상되는 열 충격에 대한 성능을 검증하기 위하여 열팽창계수를 측정하였다.

• Composites Research
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• v.24 no.5
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• pp.23-28
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• 2011

In this paper, the bonding strengths of co-cured T800 carbon/epoxy composite-aluminum single lap joints with and without additional pressures were investigated using the pressure information induced by the fiber tension during a filament winding process. The specimens of all the tests were fabricated by an autoclave vacuum bag de-gassing molding being controlled forming pressures (absolute pressures of 0.1MPa, 0.3MPa and 0.7MPa including vacuum). A special device which can act uniform additional pressures on the joining part of the single lap joint specimen was designed to measure the bonding strengths of composite-aluminum liners of type III hydrogen pressure vessel fabricated by a filament winding process. After the three different additional pressures (absolute pressures of 0.1MPa, 0.3MPa and 0.7MPa) were applied to the specimens the effect of the additional pressures on the bonding strengths of the co-cured single-lap joints were evaluated.