• Macromolecular Research
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• 제11권4호
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• pp.267-272
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• 2003

The isothermal cure reactions of blends of epoxy (DGEBA, diglycidyl ether of bisphenol A)/anhydride resin with polyamide copolymer (poly(dimmer acid-co-alkyl polyamine)) or PEI were studied using differential scanning calorimetry (DSC). Rheological measurements have been made to investigate the viscosity and mechanical relaxation behavior of the blends. The reaction rate and the final cure conversion were decreased with increasing the amount of thermoplastics in the blends. Lower values of final cure conversions in the epoxy/thermoplastic blends indicate that thermoplastics hinder the cure reaction between the epoxy and the curing agent. Complete miscibility was observed in the uncured blends of epoxy/thermoplastics up to $120^{\circ}C$ but phase separations occurred in the early stages of the curing process at higher temperatures than $120^{\circ}C$. According to the rheological measurement results, a rise of G' and G" at the onset of phase separation is seen. A rise of G' and G" is not observed for neat epoxy system since no phase separation is seen during cure reaction. At the onset of phase separation the rheological behavior was influenced by the amount of thermoplastics in the epoxy/thermoplastic blends, and the onset of phase separation can be detected by rheological measurements.

• Korea-Australia Rheology Journal
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• 제12권1호
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• pp.77-81
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• 2000

Rheological behavior of thermoset/thermoplastic blends of epoxy/polyethersulphone (PES) was monitored during curing of the epoxy resin. During the isothermal curing of the mixture, a fluctuation in viscosity just before the abrupt viscosity increase was observed. This fluctuation is found to be due to the phase separation of PES from the matrix epoxy resin during the curing. The experimentally observed viscosity fluctuation is simulated with a simple two phase suspension model in terms of the increase in domain size. The viscosity profiles obtained experimentally at different isothermal curing temperatures are in good agreement with the predictions from the simple model taking into account the viscosity change due to the growth of PES domain and the network formation of the epoxy matrix.

• Carbon letters
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• 제19권
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• pp.47-56
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• 2016

In this study, the fracture behavior of a thermoplastic-modified epoxy resin reinforced with continuous carbon fibers for two levels of fiber-matrix adhesion was performed. A carbon fiber with commercial sizing was used and also treated with a known silane, (3-glycidoxy propyl trimethoxysilane) coupling agent. Toughness was determined using the double cantilever test, together with surface analysis after failure using scanning electron microscope. The presence of polysulfone particles improved the fracture behavior of the composite, but fiber-matrix adhesion seemed to play a very important role in the performance of the composite material. There appeared to be a synergy between the matrix modifier and the fiber-matrix adhesion coupling agent.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.688-693
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• 2002

Adhesive bonding is becoming one of the popular joining techniques in metal industries, since it has some advantages over other techniques such as welding and diffusion bonding, e.g., any dissimilar metals are easily adhesive-bonded together. In this study, the experiments were carried out in order to provide the statistical data with strength evaluation methods: tension, shear and four-point bending tests for thermoplastic epoxy resin based adhesive-bonded metal joints. We should certificate on the probability of the adhesive strength that has the tendency of brittle fracture, the adhesive bonding strength between metals with thermoplastic adhesive has the best probability at four-point bending test. The strength testing method that has higher probability is four-point bending test, shear test and tensile test in order.

• Carbon letters
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• 제25권
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• pp.43-49
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• 2018

This study suggests the novel thermoplastic toughening agent, which can be applied in the monomer forms without increasing the viscosity of the epoxy resin and polymerized during the resin curing. The diazide (p-BAB) and dialkyne (SPB) compounds are synthesized and mixed with the epoxy resin and the carbon fiber reinforced epoxy composites are prepared using vacuum infusion process (VIP). Then, flexural and drop weight tests are performed to evaluate the improvement in the toughness of the prepared composites to investigate the potential of the novel toughening agent. When 10 phr of p-BAB and SPB is added, the flexural properties are improved, maintaining the modulus as well as the toughness is improved. Even with a small amount of polytriazolesulfone polymerized, due to the filtering effect of the solid SPB by the layered carbon fabrics during the VIP, the toughening and strengthening effect were observed from the novel toughening agent, which could be added in monomer forms, p-BAB and SPB. This suggests that the novel toughening agent has a potential to be used for the composites prepared from viscosity sensitive process, such as resin transfer molding and VIP.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1995년도 추계 학술발표 강연 및 논문개요집
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• pp.57-57
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• 1995

• Composites Research
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• 제30권6호
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• pp.365-370
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• 2017

탄소섬유 강화 열가소성 수지 복합재료(Carbon fiber reinforced thermoplastic composites; CFRTPs)의 물성은 다양한 요인들에 영향을 받는다. 그 중에서도 탄소섬유 표면에 Sizing되어 있는 에폭시(Epoxy) 층은 열가소성 수지와 상호 작용(Interaction)이 없어 매우 취약한 계면을 형성하며, 열가소성 수지의 높은 용융 점도(Melting viscosity)는 탄소섬유 다발(Bundle) 사이로 함침(Impregnation)이 어려워 탄소섬유 강화 복합재료 내부에 기공(Void)를 형성한다. 이와 같이 탄소섬유와 열가소성 수지 간의 낮은 계면전단강도(Interfacial shear strength)은 탄소섬유강화 열가소성 복합재료(Carbon fiber reinforced thermoplastic composites; CFRTPs)의 기계적 물성을 저하시키는 가장 중요한 요인 중 하나이다. 따라서, 본 연구에서는 열가소성 수지와의 상호작용이 없는 탄소섬유 표면의 에폭시 층을 열풍을 통해 제거하고, 열가소성 수지의 점도를 낮춰 함침도를 향상시키기 위해서 용액형 열가소성 수지를 제조하여 탄소섬유 표면에 Sizing 처리 함으로써 CFRTPs의 물성을 향상시켰다. CFRTPs의 층간전단강도(Interlaminar shear strength; ILSS) 및 굽힘 강도(Flexural strength)를 통해 이를 검증하였으며, 수지의 함침도는 기공률(Void content)의 계산을 통해 분석하였다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.237-240
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• 2002

Amino terminated polyetherimide(ATPEI) has been synthesized by bisphthalic anhydride arid m-phenylenediamine, after that characterized by differential scanning calorimetry(DSC), thermogravimetric analyzer(TGA). Fourier transform (FT-IR) spectroscopy and gel permeation chromatography(GPC). ATPEI was blend to improve the toughness of bisphenol-A type epoxy resin which was cured by nadic methyl anhydride(NMA). The fracture toughness and the molphology of the toughened epoxy resin was evaluated. The toughness of ATPEI modified epoxy resin was higher than that of the PEI modified epoxy resin. In addtion, carbon fiber/ATPEI modified epoxy resin composites were fabricated and the mechanical properties of the resulted composites were investigated.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.207-208
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• 2007

Recently, high performance microelectronic devices are designed in multi-layer structure in order to make dense wiring of metal conductors in compact size. Imprint lithography have received significant attention due to an alternative technology for photolithography on such devices. In this work, we synthesized dielectric composite materials based on epoxy resin, and investigated their thermal stabilities and dynamic mechanical properties for thermal imprint lithography. In order to enhance the mechanical properties and toughness of dielectric material, various modified polyetherimide(PEI) was applied in the resin system. Curing behaviours, thermal stabilities, and dynamic mechanical properties of the dielectric materials cured with various conditions were studied using dynamic differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA), and Universal Test Method (INSTRON).

• 공업화학
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• 제2권4호
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• pp.301-310
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• 1991

대표적인 열가소성 수지인 에폭시 수지는 그 용도 및 응용분야가 광범위하지만, 경화 후 수지의 brittleness와 고온 및 습윤하에서 물성이 좋지 않아 시용에 제한을 받고 있다. 본고에서는 수지의 최대결점인 brittleness 개선과 고온 습윤 특성의 향상 방법에 대해 고찰하였다. Brittleness 개선 방법으로는 rubber 및 열가소성 수지를 에폭시 수지에 도입하여, 이에 따른 toughness 향상 정도를 중점적으로 다루었으며, 고온 습윤 특성을 향상시키기 위해 에폭시 수지의 molecular design 및 열가소성 수지의 응용방법에 대해 기술하였다.