• 한국건축시공학회지
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• 제17권5호
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• pp.465-471
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• 2017

본 연구에서는 그래핀 나노플레이트릿(Graphene nanoplatelet ; GNP)의 분산에 대한 문제를 해결하고자 질산으로 이를 산화시켜 GO를 제조하였다. 이렇게 제조한 GO를 에폭시 도료에 혼입하기 전, 푸리에변환적외선분광법(Fourier transform infrared spectroscopy; FT-IR)을 이용한 화학조성 분석과 용매에서의 분산안정성을 확인하였다. 그 후, GNP, GO를 에폭시 도료에 0.1, 0.3, 0.5, 1.0wt.% 혼입하여 GNP/Epoxy, GO/Epoxy 도료를 제조하고 역학적 특성을 평가하였다. 실험 결과, FT-IR 분석을 통해 GO에서 하이드록시기, 에폭시기, 카르복시기 기능기가 생성된 것을 확인할 수 있었다. 또한, GO는 GNP보다 증류수와 에탄올에서 분산안정성이 향상되는 것을 확인하였다. 한편, GO/Epoxy 도료는 Neat Epoxy, GNP/Epoxy에 비해 역학적 특성이 향상되었으며, 특히 0.3wt.% 혼입률에서 높은 역학적 특성을 나타내었다. 따라서 GO를 에폭시 수지에 강화제로써 혼입할 경우 에폭시 도료의 역학적 특성을 향상시키는데 효과적인 것으로 판단된다.

• 한국재료학회지
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• 제19권11호
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• pp.576-580
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• 2009

$BaTiO_3$/epoxy composites have been widely investigated as promising materials for embedded capacitors in printed circuit boards. It is generally known that the dielectric constant (K) of the $BaTiO_3$/epoxy composites increases with improvement of the dispersion of $BaTiO_3$ particles in the epoxy matrix that comes from adding surfactant. The influences of surfactant addition on the dielectric properties of the $BaTiO_3$/epoxy composites are reported in the present study. The dielectric constant of the $BaTiO_3$/epoxy composites is not significantly affected by the surfactant addition. However, the temperature coefficient of capacitance increases and the peel strength decreases as the amount of added surfactant increases. The influences of surfactant addition on the dielectric properties of the neat epoxy are also very similar to those of the $BaTiO_3$/epoxy composites. The residual surfactant in the $BaTiO_3$/epoxy composites affects the temperature coefficient of capacitance and the peel strength of the epoxy matrix, which in turn affects the temperature coefficient of capacitance and the peel strength of the $BaTiO_3$/epoxy composites.

• 한국조명전기설비학회지:조명전기설비
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• 제2권1호
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• pp.75-82
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• 1988

각종 전기설비용 절연재료로 주목받는 Epoxy는 경화제와의 가교반응으로 전기절연특성이 우수한 경화물질을 얻을 수 있으며, 경화제의 종류와 격자 형성에 형태에 따라 경화된 Epoxy의 특성이 결정된다. 본 연구는 Epoxy의 경화시 분위기의 온도를 변화시켜 격자형성의 진행형태를 변화시키고, 경화된 Epoxy의 제반특성을 조사하여 전기절연특성이 가장 우수하게 되는 경화온도를 얻고자 한다. Epoxy를 분위기 온도 $20~50[^{\circ}C]$사이에서 $5^[{\circ}C]$ 간격으로 변화하면서 경화시킨 결과, 분위기 온도 $30[^{\circ}C]$에서 경화된 Epoxy의 전기절연특성 및 기계적 강도가 가장 우수하다고 판명되었다.

• Transactions on Electrical and Electronic Materials
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• 제16권2호
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• pp.74-77
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• 2015

The cure kinetics of a neat epoxy system and epoxy/silica composite were investigated by DSC analysis. A cycloaliphatic type epoxy resin was diglycidyl 1,2-cyclohexanedicarboxylate and curing agent was anhydride type. To estimate kinetic parameters, the Kissinger equation was used. The activation energy of the neat epoxy system was 88.9 kJ/mol and pre-exponential factor was 2.64×10¹² min⁻¹, while the activation energy and pre-exponential factor for epoxy/silica composite were 97.4 kJ/mol and 9.21×10¹² min⁻¹, respectively. These values showed that the silica particles have effects on the cure kinetics of the neat epoxy matrix.

• 한국해양공학회지
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• 제11권2호
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• pp.48-56
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• 1997

This work has been investigated in order to study the influence of the moisture absorption on the mechanical pf the glass fiber/epoxy resein composites and the carbon fiber/epoxy resein composites. The types of glass fiber used in the glass fiber/epoxy resein composites were randomly oriented fiber and plain fabric fiber. And carbon fiber.epoxy resein composites was laminated with fabric prepreg which was formed with carbon fiber and epoxy resein. Both composites were immersed up to 100 days in distilled water at $80^{\circ}C$, and then dried up to 3 days in an oven at 80$80^{\circ}C$. Both composites were measured for the weight gain of water(wt.%) and tensile strength through immersion and dry time. Consequently, it was found that the tensile strength of thw glass fiber/epoxy resein composites and the carbon fiber/epoxy resein composites were reduced proportionally to the moisture absortion rate. Also, the tensile strength of glass fiber composites was decreased more than that of the carbon fiber composites. Additionally, it was found that the tensile strength of all composites which decreased by moisture absorption were partly recovered by drying in an oven at 80$80^{\circ}C$.

• 한국생산제조학회지
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• 제21권4호
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• pp.588-592
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• 2012

This study concentrates the effect of hybridisation on the collapse mode and energy absorption for composite cylinders. The static collapse behavior of laminated(Al/CFRP/GFRP) circular-cylindrical composite shell under quasi-static axial compressive load has been investigated experimentally. Eight different hybrids of laminated(Al/CFRP/GFRP) circular-cylindrical composite shell were fabricated by autoclave. Eight types of composites were tested, namely, Al/carbon fiber/epoxy, Al/glass fiber/epoxy, Al/carbon-carbon-glass/epoxy, Al/carbon-glass-carbon/epoxy, Al/carbon-glass-glass/epoxy, Al/glass-glass-carbon/epoxy, Al/glass-carbon-glass/epoxy and Al/glass-carbon-carbon/epoxy. Collpase modes were highly dominated by the effect of hybridisation. The results also showed that the hybrid member with material sequence of Al-glass-carbon-carbon/epoxy exhibited good energy absorption capability.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.663-667
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• 2005

Surface modified carbon nanotubes were applied into the epoxy composites to investigate its tribological property. Carbon nanotubes reinforced epoxy composites were fabricated by casting. Effects to the tribological property of loading concentrations and types of surface modification of carbon nanotubes were investigated under sliding condition using linear reciprocal sliding wear tester. The results show that the small amount of carbon nanotubes into the epoxy exhibited lower weight loss than the pure epoxy. It is concluded that the effect of an enormous aspect ratio of carbon nanotubes surface area which wider than conventional fillers that react as interface for stress transfer. As increased the contents of carbon nanotubes, the weight loss from the wear test was reduced. And the surface modified carbon nanotubes show better tribological property than as produced carbon nanotubes. It is due that a surface modification of carbon nanotubes increases the interfacial bonding between carbon nanotubes and epoxy matrix through chemical bonding. Changes in worn surface morphology are also observed by optical microscope and SEM for investigating wear behaviors. Carbon nanotubes in the epoxy matrix near the surface are exposed, because it becomes the lubricating working film on the worn surface. It reduces the friction and results in the lower surface roughness morphology in the epoxy matrix as increasing the contents of the carbon nanotubes.

• 한국재료학회지
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• 제9권1호
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• pp.65-72
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• 1999

In order to minimize flexible printed circuit(FPC), which is used in computer, communication, medical facility, aviation space industry, it is required to improve the interfacial adhesion of polymide/epoxy or polyimide/polyimide consists of FPC. In this study, it was considered to improve the adhesion strength of polyimide/epoxy joint by introducing functional group on polyimide film and improving mechanical property of epoxy. Functional group on polyimide film was introduced by changing polyimide film surface to polyamic acid in KOH aqueous solution. The optimum conditions for surface modification were the concentration of 1M KOH and treatment time of 5min. Also, the optimum adhesion strength of polyimide/epoxy joint was obtained using rubber modified epoxy and polyamic acid as a base resin and curing agent of epoxy adhesive, respectively. The degree of surface modification of polyimide film examined with contact angle measurement of FTIR, thus modification of polyimide to polyamic acid was identified. Fracture surface of plymide/epoxy joint was analyzed by scanning electron microscopy, and modified polyamic acid reimidezed to polymide as increasing curing temperature.

• 한국농공학회논문집
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• 제58권1호
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• pp.19-26
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• 2016

This study was performed to evaluate the strength and durability properties of modified epoxy composites with waste tire chip, recycled coarse aggregate, filler and modified epoxy to improve elongation and elasticity of epoxy. Additionally, for comparing to modified epoxy and unsaturated polyester resin as a binder, unsaturated polyester resin composites were developed in the same condition. The mix proportions were determined to satisfy the requirement for the workability and slump according to aggregate size and binder content. Tests for the compressive and flexural strength, freezing and thawing and durability for 20 % sulfuric solution were performed. The compressive and flexural strength of modified epoxy composites were in the range of 34.9~61.6 MPa and 10.2~18.3 MPa at the curing 7 days, respectively. Also, the compressive and flexural strength of unsaturated polyester resin composites were in the range of 44.2~77.8 MPa and 11.3~20.8 MPa at the curing 7 days, respectively. After 300 cycles of freezing and thawing, weight decrease ratio and durability factor of modified epoxy composites were in the range of 0.8~1.9 % and 95~98, respectively. Accordingly, modified epoxy composites will greatly improve the durability of concrete.

• Carbon letters
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• 제10권4호
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• pp.314-319
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• 2009

The surface treatment effects of reinforcement filler were investigated based on the dynamic mechanical properties of mutiwalled carbon nanotubes (MWCNTs)/epoxy composites. The as-received MWCNTs(R-MWCNTs) were chemically modified by direct oxyfluorination method to improve the dispersibility and adhesiveness with epoxy resins in composite system. In order to investigate the induced functional groups on MWCNTs during oxyfluorination, X-ray photoelectron spectroscopy was used. The thermo-mechanical property of MWCNTs/epoxy composite was also measured based on effects of oxyfluorination treatment of MWCNTs. The storage modulus of MWCNTs/epoxy composite was enhanced about 1.27 times through oxyfluorination of MWCNTs fillers at $25^{\circ}C$. The storage modulus of oxyfluorinated MWCNTs (OF73-MWCNTs) reinforced epoxy composite was much higher than that of R-MWCNTs/epoxy composite. It revealed that oxygen content led to the efficient carbon-fluorine covalent bonding during oxyfluorination. These functional groups on surface modified MWCNTs induced by oxyfluorination strikingly made an important role for the reinforced epoxy composite.