• 폴리머
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• 제38권6호
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• pp.767-773
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• 2014

응고 침전법으로 제조한 폴리스티렌(PS)/탄소나노튜브(CNT) 나노복합재료의 유변물성 및 전기적 물성을 고찰하였다. CNT의 분산성 향상을 위해 도입하는 일반적인 방법인 화학적 개질이나 계면활성제 도포 방법은 CNT의 고유 물성을 저하시킬 수 있다. 이를 방지하기 위해 본 연구에서는 PS와 CNT를 dimethylformamide에 분산시킨 후 증류수에 응고 침전시키는 방법으로 나노복합재료를 제조하였다. 응고 침전법에 의한 CNT의 분산은 매우 효과적이어서 제조한 나노복합재료는 우수한 전기 전도도를 나타내었다. 또한 PS 매트릭스에 poly(styrene-co-divinylbenzene) 가교 입자를 첨가하여 가교 입자 첨가가 유변물성과 전기적 물성에 미치는 영향을 고찰하였다. 가교 입자를 첨가한 나노복합재료의 경우 CNT의 전기적 임계점이 0.25 wt%로 감소되었고 전기 전도도는 더욱 증가하였다. 이는 가교입자가 차지하는 부피 내의 CNT가 전기적 통로를 형성하는데 추가적으로 기여했기 때문으로 판단된다.

• Fibers and Polymers
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• 제7권1호
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• pp.85-87
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• 2006

The tensile-recoil compressional behavior of the carbon nanotube reinforced mesophase pitch (MP)-based composite carbon fibers (CNT-re-MP CFs) was investigated by using Instron and SEM. The CNT-re-MP CFs exhibited improved, or at least equivalent, compressive strength as compared with commercial MP-based carbon fibers. Particularly, when CNT of 0.1 wt% was reinforced, the ratios of recoil compressive strengths to tensile strength of CNT-re-MPCFs were much higher (the difference is at least 10 % or higher) than those for the commercial counterparts and even than those for PAN-based commercial carbon fibers. FESEM micrographs showed somewhat different fractography from that of a typical shear failure as the CNT content increased.

• 전기학회논문지
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• 제62권6호
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• pp.782-785
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• 2013

Multi-walled carbon nanotubes were synthesized on Ni catalyst using thermal chemical vapor deposition. By introducing ammonia gas during the CNT synthesis process, clean and vertically aligned CNTs without impurities could be prepared. As the ammonia gas increased a partial pressure of hydrogen in the mixed gas during the CNT synthesis process, we could control the CNT synthesis rate appropriately. As the ammonia gas has an etching ability, amorphous carbon species covering the catalyst particles were effectively removed. Therefore catalyst particles could maintain their catalytic state actively during the synthesis process. Finally, we could obtain clean and vertically aligned CNTs by introducing $NH_3$ gas during the CNT synthesis process.

• Steel and Composite Structures
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• 제22권2호
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• pp.277-299
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• 2016

In this paper, free vibration, forced vibration, resonance and stress wave propagation behavior in nanocomposite plates reinforced by wavy carbon nanotube (CNT) are studied by a mesh-free method based on first order shear deformation theory (FSDT). The plates are resting on Winkler-Pasternak elastic foundation and subjected to periodic or impact loading. The distributions of CNTs are considered functionally graded (FG) or uniform along the thickness and their mechanical properties are estimated by an extended rule of mixture. In the mesh-free analysis, moving least squares (MLS) shape functions are used for approximation of displacement field in the weak form of motion equation and the transformation method is used for imposition of essential boundary conditions. Effects of CNT distribution, volume fraction, aspect ratio and waviness, and also effects of elastic foundation coefficients, plate thickness and time depended loading are examined on the vibrational and stresses wave propagation responses of the nanocomposite plates reinforced by wavy CNT.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.1594-1597
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• 2008

Carbon nanotube (CNT) cathodes were fabricated using nano-sized silver powders as a bonding material. The effects of powder size on the field emission properties for the CNT cathode were investigated The better emission properties of CNT cathodes using smaller particles are due to a low sintering temperature of the bonding materials.

• 한국전자통신학회논문지
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• 제5권1호
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• pp.88-92
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• 2010

본 연구에서는 기존의 반도체 공정을 이용하여 bottom gate, top gate구조의 탄소나노튜브 트랜지스터를 제작하였다. 게이트 특성에 따른 특성을 연구하기 위하여 열화학 기상 증착법(CVD)으로 탄소나노튜브를 디바이스에 직접 성장시키고, 탄소나노튜브의 성장 특성 및 I-V동작 특성을 분석하였다. 제작된 탄소나노튜브 FET는 p-type, 즉 hole이 다수 캐리어로 존재하는 트랜지스터이며 구동전압에 따라 conductance 변화하는 특성을 보였다.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1169-1173
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• 2015

This paper presents vertical carbon nanotube (CNT) field effect transistors (FETs). For the first time, the author successfully fabricated vertical CNT-based FETs on an anodized aluminum oxide (AAO) template by using atomic layer deposition (ALD). Single walled CNTs were vertically grown and aligned with the vertical pores of an AAO template. By using ALD, a gate oxide material (Al₂O₃) and a gate metal (Au) were centrally located inside each pore, allowing the vertical CNTs grown in the pores to be individually gated. Characterizations of the gated/vertical CNTs were carried and the successful gate integration with the CNTs was confirmed.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.152-155
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• 2009

A novel two-step surface treatment was developed and demonstrated for the carbon nanotube (CNT) cathode with highly efficient backlight unit application. An adhesive taping method was applied firstly and then followed by a post-heat treatment for the CNT cathode. During the postheat treatment process, some residues covering the CNTs were burned out. The post-heat treatment enhanced the emission current of the CNT cathode around 20% compared with that of no heat-treated sample.

• Coupled systems mechanics
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• 제1권3호
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• pp.269-283
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• 2012

In the present paper, a multilevel approach for the local nanobuckling analysis of carbon nanotube (CNT) based composite materials is proposed and described. The approach comprises four levels, all of them at nanoscale. The first level aims to propose the potential that describes the interatomic forces between carbon atoms. In the second level, molecular dynamics simulations are performed to extract the elastic properties of the CNT. The third level aims to determine the stiffness of the material that surrounds the CNT (matrix), using the annular membrane analysis. In the fourth level, finite strip analysis of the CNT elastically restrained by the matrix is performed to calculate the critical strain at which the CNT buckles locally. In order to achieve accurate results and take the CNT-matrix interaction into account, the $3^{rd}$ and $4^{th}$ steps may be repeated iteratively until convergence is achieved. The proposed multilevel approach is applied to several CNTs embedded in a cylindrical representative volume element and illustrated in detail. It shows that (i) the interaction between the CNT and the matrix should be taken into account and (ii) the buckling at nanoscale is sensitive to several types of local buckling modes.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권12호
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• pp.570-575
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• 2006

In this paper, we have investigated thermal properties by changing the content of carbon nanotube, which is component part of semiconductive shield in underground power transmission cable. Heat capacity (${\Delta}H$), glass transition temperature (Tg) and melting temperature (Tm) were measured with the samples of eight, through DSC (Differential Scanning Calorimetry), and the measurement ranges of temperature selected from $-100[^{\circ}C]\;to\;100[^{\circ}C]$ with heating temperature selected per $4[^{\circ}C/min]$ Also, high temperature, heat degradation initiation temperature, and heat weight loss were measured by TGA (Thermogravimetric Analysis) in the temperature from $0[^{\circ}C]\;to\;700[^{\circ}C]$ with rising temperature of $10[^{\circ}C/min]$. As a result, the Glass transition temperatures of the sample were showed near $-20[^{\circ}C]{\sim}25[^{\circ}C]$, and the heat capacity and melting temperature from the DSC was increased according to increasing the content of carbon nanotube, while, thermal diffusivity was increased according to increasing the content of carbon nanotube. Also, heat degradation initiation temperature from the TGA results was increasing according to increasing the content of carbon nanotube with CNT/EEA. Therefore, heat stabilities of EVA, which contained the we VA (vinyl acetate), showed the lowest.