• Ceramist
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• v.4 no.3
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• pp.122-127
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• 2001

나노복합재료는 기계적, 전기적, 전자기적 특성을 향상하거나 새로운 기능을 갖는 신소재를 제조할 수 있는 가능성으로 인하여 많은 주목을 받고 있다. 우수한 특성을 갖는 나노복합재료의 제조에 있어서 주의할 점은, 나노복합재료가 다른 세라믹재료에 비하여 제조공정에 민감하게 영향을 받는다는 것이다. 출발원료, 혼합방법, 건조방법 등의 선택에 따라서 특성이 향상될 수도 있고 역으로 저하될 수도 있다. 이러한 현상은, 초미립자의 비표면적이 크기 때문에 균일한 분산이 어렵고 응집이 발생하기 쉽기 때문이라 생각된다. $Si_3N_4/SiC$ 나노복합재료의 경우는 고온강도와 열피로에 대한 저항성이 획기적으로 향상되어 $1400^{\circ}C$ 이상에서도 사용할 수 있는 초고온재료로로서의 가능성을 갖고 있다. 그러나 이러한 나노복합재료의 실용화를 위해서는 제조공정이 단순하고, 경제성이 있는 신 공정의 개발과 GPS 소결 등에 관하여 보다 많은 연구가 필요하다. 그러나 계속적인 환경오염에 관한 국제적 규제의 강화, 국제 원유가의 상승 등은 열기관의 열효율 향상을 위해서 초고온에서 사용할 수 있는 나노복합재료와 같은 재료를 요구할 것이며, 또한 정보통신산업 발전에 따른 소형화, 고 기능화는 우수한 특성과 새로운 기능을 갖는 나노복합재료의 개발과 실용화를 앞당기는 계기가 될 것으로 생각된다.

• Composites Research
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• v.18 no.3
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• pp.1-6
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• 2005

Carbon nanofiber exhibits superior and of ien unique characteristics of mechanical, electrical, chemical and thermal properties. Despite of the excellent properties of carbon nanofiber, the properties of carbon nanofiber filled polymer composites were not increased largely. The reason is that it is still difficult to ensure the uniform dispersion of carbon nanofiber in a polymer matrix. In this study, for improvement of the mechanical properties of composites, carbon nanofiber reinforced hybrid composites was investigated. For the dispersion of carbon nanofiber. solution blending method using ultrasonic was used. Dispersion of carbon nanoifiber was observed by scanning electron microscope (SEH). Mechanical properties were measured by universal testing machine(UTM).

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.554-557
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• 2010

본 논문에서는 동일한 체적분율 가지는 탄소나노튜브 나노복합재의 기계적 특성을 규명하였다. 동일한 chirality를 가지는 서로 다른 크기의 탄소나노튜브를 이용하여 탄소나노튜브의 크기가 복합재의 물성에 미치는 영향을 규명하였다. 복합재료의 분자동역학의 결과 탄소나노튜브의 길이방향의 물성은 크게 증가하나, 전단특성의 물성 강화효과를 나타나지 않았다. 이는 통해 탄소나노튜브와 기지재료 사이의 상호작용력이 복합재료의 전단력을 전달하고, 변형을 유지할 만큼 강하지 않다는 것을 확인하였다. 이와 같은 분자동역학 결과를 바탕으로 멀티스케일 모델을 개발하여 복합재료에서 나타나는 현상을 묘사하였다. 제안된 멀티스케일 모델을 이용하여 다양한 조건의 복합재료에 대한 특성 예측이 가능하다.

• Composites Research
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• v.18 no.4
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• pp.21-26
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• 2005

Nondestructive damage sensing and load transfer mechanisms of carbon nanotube (CNT) and nanofiber (CNF)/epoxy composites have been investigated by using electro-micromechanical technique. The electrospun PVDF nanofibers were also prepared as a piezoelectric sensor. The electro-micromechanical techniques were applied to evaluate sensing response of carbon nanocomposites by measuring electrical resistance under an uniform cyclic loading. Composites with higher volume content of CNT showed significantly higher tensile properties than neat and low volume$\%$ CNT composites. CNT composites showed humidity sensing within limited temperature range. CNT composites with smaller aspect ratio showed higher apparent modulus due to high volume content in case of shorter aspect ratio. Thermal treated electrospun PVDF nanofiber showed higher mechanical properties than the untreated case due to crystallinity increase, whereas load sensing decreased in heat treated case. Electrospun PVDF nanofiber web also showed sensing effect on humidity and temperature as well as stress transferring. Nanocomposites and electrospun PVDF nanofiber web can be applicable for sensing application.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.2
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• pp.131-136
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• 2023

Nanocomposites have been considered innovative composite materials that have multi-functionality and high performance. Because the incorporation of nanoscale fillers may significantly improve the electrical, mechanical, and thermal properties of composites, numerous extensive studies on the characterization of nanocomposites with nanoscale fillers have been performed. In particular, the development of nanocomposites using carbon-based nanoscale fillers (e.g., carbon nanotubes, carbon black, graphene nanoplates) have attracted much interest in the composite field. This paper provides a review of recent advances in the electrical/mechanical characteristics of nanocomposites, which are essential for their practical applications. Furthermore, this paper revisits the recent research on multi-scale modeling, which is a promising approach for predicting the characteristics of nanocomposites. The current challenges and future development potentials for multi-scale modeling are also discussed.

• Composites Research
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• v.26 no.3
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• pp.147-154
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• 2013

Nanocarbons such as carbon nanotubes (CNT) and graphene are considered to be ideal fillers for polymer composites, because of their outstanding mechanical properties and high length-to-diameter ratio. There has been much effort to realize the implementation of their full potential, but a large number of unsolved problems still must be challenged, for example, effective processing for fabrication. This review deals with the progress that has already been made in the area of nanocarbon polymer composites using CNT and graphene. Mechanical reinforcement of various nanocarbon polymer composites is analyzed and compared, and future perspectives in research and development that need to be done are discussed.

• Composites Research
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• v.17 no.6
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• pp.1-7
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• 2004

The studies of particulate reinforced composites have been conducted for many years. The nanocomposites to be studied vigorously in recent years are one of them. We fabricated and studied multi-walled carbon nanotube(MWNT)/epoxy composites which may be useful as matrix for continuous fiber-reinforced composites. We investigated tensile properties of MWNT/epoxy composites as a function of MWNT concentration, which were prepared by the fabrication method established in this study. Tensile stiffness and strength increased 19% at 0.5 wt% and 12% at 0.2 wt%, respectively. We observed the reaggregation phenomenon of MWNTS during curing, which should be controlled to obtain higher tensile properties.

• Composites Research
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• v.27 no.6
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• pp.219-224
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• 2014

Nancomposites manufacture has been developed rapidly, because of reinforcing effects of CNT in terms of mechanical, electrical and thermal properties. In this study, 10 wt% CNT paste was fabricated with good dispersion state and easy processability. Damage sensing and reinforcing effect of CNT paste were investigated in nanocomposites. 10 wt% CNT paste exhibited better tensile and flexural properties than those of general 1 wt% CNT nanocomposites. To observe the healing effect of CNT paste, a crack was made artificially with 30wt% CF30wt%/PP composites, and the CNT paste was filled inside the crack. The damage sensing of CNT paste in CF30wt%/PP composites was investigated by electrical resistance measurement and mechanical tests. CNT paste exhibited good reinforcing effect in mechanical properties of CF30wt%/PP composites, and this reinforcing effect was getting better with larger cracks. The reason was because CNT paste had good interfacial adhesion with CF30wt%/PP composites to resist crack propagation. In electrical resistance measurement, there was a jump in electrical resistance signal at the adhesion interface. The jumping signal could be used to predict fracture of CF/PP composites. CNT nanocomposites for damage sensing had crack reducing effect and damage detection using electrical resistance method.

• Polymer(Korea)
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• v.28 no.4
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• pp.285-290
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• 2004

Nondestructive damage sensitivity of carbon nanotube(CNT) and nanofiber (CNF)/epoxy composites with their adding contents was investigated using electro-micromechanical technique. Carbon black (CB) was used only for the comparison with CNT and CNF. The fracture of carbon fiber was detected by acoustic emission (AE), which was correlated to the change in electrical resistance, ΔR under double-matrix composites (DMC) test. Stress sensing on carbon nanocomposites was performed by electro-pullout test under uniform cyclic loading. At the same volume fraction, the damage sensitivity for fiber fracture, matrix deformation and stress sensing were highest for CNT/epoxy composite, whereas for CB/epoxy composite they were the lowest among three carbon nanomaterials (CNMs). Damage sensitivity was correlated with morphological observation of carbon nanocomposites. Homogeneous dispersion among CNMs could be keying parameters for better damage monitoring. In this study, damage sensing of carbon nanocomposites could be evaluated well nondestructively by the electrical resistance measurement with AE.

• Polymer(Korea)
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• v.30 no.2
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• pp.129-134
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• 2006

Nanocomposites of polyurethane were prepared from inorganic nano particles, $Na^+-montmorillonite$ (MMT), silica, $CaCO_3$, and surface modified MMT and their properties were investigated. It was shown that the molecular weight and polydispenity of nanocomposites of polyurethane were 20000 to 28000 and 1.0 to 2.0, respectively. d-Spacing for nanocomposites of MMT were increased than that of pure MMT. Initial degradation temperature of nanocomposites were 250 to $280^{\circ}C$. And also, the range of weight loss for nanocomposites were decreased and the end of thermal degradation was observed at higher temperatures about $50^{\circ}C$. The elongation at break for $CaCO_3$ filled nanocomposites were the highest among the nanocomposites used in this study. studied. It was found that the tensile strength increased with increasing the filler contents while the silica nanocomposite exhibited the lowest increase and the $CaCO_3$ nanocomposite the highest.