• 대한기계학회논문집A
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• 제31권8호
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• pp.862-869
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• 2007

The compressive and torsional buckling behavior of carbon nanotube bundles at room temperature is examined with classical molecular dynamics simulation. The critical compressive load and stiffness of a single carbon nanotube in the bundle are found to be similar to those of individual carbon nanotubes. However, the critical torsional moment and stiffness of a single carbon nanotube in the bundle are found to be higher than those of individual carbon nanotubes. In addition, this study demonstrates that van der Waals interactions between the nanotubes in the bundle significantly affect the critical compressive load of the nanotube bundle.

• Composites Research
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• 제33권4호
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• pp.198-204
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• 2020

본 연구에서는 탄소나노튜브 다발을 포함하는 나노복합재료의 열-기계적 특성을 정량적으로 예측하기 위하여 분자동역학 전산모사와 유한요소 기반 균질화 기법을 적용하였다. 응집된 탄소나노튜브의 수가 증가함에 따라 동일한 탄소나노튜브의 체적분율에도 불구하고, 면내 영률 및 면내 전단계수는 감소하였고, 면내 열팽창계수는 증가함을 확인할 수 있었다. 계면의 두께를 조사하기 위하여 밀도의 반경 방향 분포(Radial density distribution)을 조사하였으며, 계면의 두께는 탄소나노튜브의 수와는 거의 무관함을 확인할 수 있었다. 기지와 계면은 등방성 재료로 가정하였으며, 예측한 계면의 열-기계적 특성에 따르면, 응집된 탄소나노튜브의 수가 증가함에 따라 계면의 영률 및 전단계수는 감소하였으며, 열팽창계수는 반대로 증가하였다. 이를 토대로, 탄소나노튜브 다발을 포함하는 PLA 나노복합재료의 열-기계적 특성 예측을 위한 멀티스케일 균질화 모델을 개발하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.381-381
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• 2011

The influence of the water vapor on the growth of single-walled carbon nanotubes (SWCNTs) was investigated. SWCNTs were synthesized by catalytic chemical vapor deposition of acetylene over Fe-Mo/MgO catalyst with injection of water vapor. The morphologies and structures of the water-assisted SWCNTs were investigated according to the growth conditions such as water vapor concentrations, flow rate of the gas, furnace temperature, and growth time. Water-assisted SWCNTs exhibited large bundle morphological features with well-alignment of each CNT, while SWCNTs synthesized in the absence of water vapor showed entangled CNT with the random orientation. We also found that the diameter of the SWCNT bundle could be controlled by the growth condition. In our optimal growth condition, the product yield and the purity were 300 wt. % and 75%, which were 7.5 and 2.5 times higher than those of SWCNTs synthesized without water vapor, respectively. More detail discussion will be offered at the poster presentation.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1535-1538
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• 2005

We present a mass productive and reproducible assembly technique of a single bundle of single-walled carbon nanotubes (sb-SWNTs) using dielectrophoresis (DEP). Gold electrodes with 10 gaps made via microlithography were used to align the carbon nanotubes (CNTs). The magnitude and type of applied electric field were investigated to verify their effects on CNT assembly. The optimum assembling conditions in which sb-SWNTs could be positioned at a desired site were experimentally identified, and the characteristics of the assembled sb-SWNTs were evaluated from AFM, Raman spectroscopy, and I-V curve. This assembly method has potential for applications such as gas sensors or electronic devices.

• Advances in aircraft and spacecraft science
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• 제2권3호
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• pp.263-273
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• 2015

Carbon nanotube strain sensors, or so called "fuzzy fiber" sensors have not yet been studied sufficiently. These sensors are composed of a bundle of fiberglass fibers coated with CNT through a thermal chemical vapor deposition process. The characteristics of these fuzzy fiber sensors differ from a conventional nanocomposite in that the CNTs are anchored to a substrate fiber and the CNTs have a preferential orientation due to this bonding to the substrate fiber. A numerical model was constructed to predict the strain response of a composite with embedded fuzzy fiber sensors in order to compare result with the experimental results obtained in an earlier study. A comparison of the numerical and experimental responses was conducted based on this work. The longitudinal sensor output from the model matches nearly perfectly with the experimental results. The transverse and off-axis tests follow the correct trends; however the magnitude of the output does not match well with the experimental data. An explanation of the disparity is proposed based on microstructural interactions between individual nanotubes within the sensor.

• Composites Research
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• 제29권3호
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• pp.104-110
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• 2016

본 논문은 층간 삽입 반응을 이용하여 그래핀을 박리하는 동시에 탄소나노튜브를 개별 분산시키고 이를 복합 필름으로 제조한 결과를 보고한다. 일반적으로 그래핀과 탄소나노튜브의 경우 흑연과 탄소나노튜브 번들로부터의 개별적 박리를 통해 제조될 수 있으나 장시간의 공정 시간을 요구하게 된다. 본 연구에서는 그래핀과 탄소나노튜브의 동시 박리 및 분산을 위해 흑연 및 탄소나노튜브 번들 내로 포타슘 소듐 타르트레이트를 삽입했으며 XRD 분석을 통해 흑연 층간 거리 및 탄소나노노튜브 번들 내 거리의 증가를 확인했다. 제조된 층간삽입화합물로부터 박리된 그래핀 및 탄소나노튜브의 경우 매우 낮은 산화도(< 8.3 at%)를 나타냈으며 제조된 물질을 여과 장치 및 스프레이 전사를 통해 복합 필름으로 제조한 결과 그래핀 및 탄소나노튜브의 단일 필름에 대비하여 복합 필름의 경우 전도성의 향상을 보였다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권8호
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• pp.451-454
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• 2000

We have grown vertically aligned carbon nanotubes in a large area of Co-Ni codeposited Si substrates by the thermal CVD usign $C_2H_2$ gas. Since the discovery of carbon nanotubes, growth of carbon nanotubes has been achieved by several methods such as laser vaporization, arc discharge, and pyrolysis. In particular, growth of vertically aligned nanotubes is important to flat panel display applications. Recently, vertically aligned carbon nanotubes have been grown on glass by PECVD. Aligned carbon nanotubes can be also grown on mesoporous silica and Fe patterned porous silicon using CVD. In this paper, we demonstrate that carbon nanotubes can be vertically aligned on catalyzed Si substrate when the domain density of catalytic particles reaches a certain value. We suggest that steric hindrance between nanotubes at an initial stage of the growth forces nanotubes to align vertically and each nonotubes are grown in bundle.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
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• pp.1536-1537
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• 2005

We have made point electron sources using carbon nanotubes (CNTs). For the fabrication of point electron sources, CNTs were dispersed in a solution and attached on electrochemically etched W tips using electrophoresis. In our study, we have utilized various CNTs such as single-walled CNT (SWCNT), multiwalled CNT (MWCNT), and thin-MWCNT and threshold current, turn-on voltage, filed enhancement factor of each emitter have been studied upon a tube/bundle diameter and length. In addition, fieldemitted electron energy distribution of various CNT emitters is characterized.

• Journal of Ceramic Processing Research
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• 제20권5호
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• pp.464-469
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• 2019

In this study, the electrical conductivity of multi-walled carbon nanotubes (MWCNTs) and polyethylene synthesized by an extrusion process was evaluated. The MWCNTs used exhibited differences in their dispersion characteristics depending on the type of catalyst or synthesis gas used. Thus, the choice of catalyst or synthesis gas significantly affect the physicochemical state of the final MWCNTs and MWCNT-based composites. In this investigation, the characteristics of MWCNTs were analyzed in four cases by introducing ethylene and propylene gas to each catalyst synthesized using deposition precipitation and spray drying methods. The MWCNT-based composites synthesized using the catalyst prepared by deposition precipitation and the ethylene synthesis gas showed the best electrical conductivity. In principle, the morphologies of the MWCNTs indicate that the smaller the aggregate size and bundle thickness, the better the electrical conductivity of the MWCNT composites. This implies that the network is well-formed.

• Korean Chemical Engineering Research
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• 제55권1호
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• pp.115-120
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• 2017

현재 세계적인 이슈가 되고 있는 나노과학과 기술은 탄소나노튜브(CNTs)를 기반으로 한 바이오센서 성능 향상에 주력하고 있다. 다양한 기능성을 가진 CNTs는 높은 안정성과 바이오 수용체와 같은 생체물질과의 높은 적합성으로 이를 이용한 바이오 전극 기술에 힘입어 의학, 식품 및 환경에서 이슈가 되는 물질들을 검출하기 위한 산업적 응용 연구가 주목받고 있다. 본 연구에서는 이러한 CNTs를 이용한 전기화학적 바이오센서에 있어서 시료가 액체 상태로 검출이 예상되는데 그 시료의 화학적 특성에 따른 금 전극 사이에 고정화된 CNTs의 전자전달현상을 조사하였다. 그 결과, 시료가 극성인 경우와 무극성인 경우 고정화된 CNTs의 전자전달 현상이 다르게 나타났으며, 극성의 세기가 증가할수록 전자의 이동에 방해를 받는 것으로 확인되었다. 이는 CNTs의 양끝에 존재하는 극성 작용기와의 상호작용에 의한 것으로서 센서 디바이스 전체를 시료 용액에 침투시켜 전자이동을 관찰한 결과와 달리 안정적으로 저항값을 나타내는 것으로 확인되었다. 향후 민감도가 높은 CNTs 기반 나노바이오센서 개발 시 시료의 효과적인 전처리 공정에서 이러한 용매의 극성을 고려한 최적화 연구가 필요하다.