• Carbon letters
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• 제13권3호
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• pp.157-160
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• 2012

In this work, iron oxide ($Fe_3O_4$) nanoparticles were deposited on multi-walled carbon nanotubes (MWNTs) by a simple chemical coprecipitation method and $Fe_3O_4$-decorated MWNTs (Fe-MWNTs)/polypyrrole (PPy) nanocomposites (Fe-MWNTs/PPy) were prepared by oxidation polymerization. The effect of the PPy on the electrochemical properties of the Fe-MWNTs was investigated. The structures characteristics and surface properties of MWNTs, Fe-MWNTs, and Fe-MWNTs/PPy were characterized by X-ray diffraction and X-ray photoelectron spectroscopy, respectively. The electrochemical performances of MWNTs, Fe-MWNTs, and Fe-MWNTs/PPy were determined by cyclic voltammetry and galvanostatic charge/discharge characteristics in a 1.0 M sodium sulfite electrolyte. The results showed that the Fe-MWNTs/PPy electrode had typical pseudo-capacitive behavior and a specific capacitance significantly greater than that of the Fe-MWNT electrode, indicating an enhanced electrochemical performance of the Fe-MWNTs/PPy due to their high electrical properties.

• Carbon letters
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• 제14권3호
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• pp.131-144
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• 2013

The carbon nanotube (CNT) represents one of the most unique inventions in the field of nanotechnology. CNTs have been studied closely over the last two decades by many researchers around the world due to their great potential in different fields. CNTs are rolled graphene with $SP^2$ hybridization. The important aspects of CNTs are their light weight, small size with a high aspect ratio, good tensile strength, and good conducting characteristics, which make them useful as fillers in different materials such as polymers, metallic surfaces and ceramics. CNTs also have potential applications in the field of nanotechnology, nanomedicine, transistors, actuators, sensors, membranes, and capacitors. There are various techniques which can be used for the synthesis of CNTs. These include the arc-discharge method, chemical vaporize deposition (CVD), the laser ablation method, and the sol gel method. CNTs can be single-walled, double-walled and multi-walled. CNTs have unique mechanical, electrical and optical properties, all of which have been extensively studied. The present review is focused on the synthesis, functionalization, properties and applications of CNTs. The toxic effect of CNTs is also presented in a summarized form.

• 한국광학회지
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• 제15권5호
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• pp.449-454
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• 2004

광 리미터는 입사광의 세기가 커질때 투과율을 줄여서 눈과 센서를 보호하는 광소자이다. 최근에 높은 효율의 광 리미터 재료로 알려진 다중벽 탄소 나노튜브 분말을 증류수, 클로로포름, 에탄올, 에틸렌 글리콜과 같은 용매에 각각 섞어 현탁액을 만들고 실온에서 용매의 끓는점까지 온도를 변화시키면서 광 리미팅 효율의 변화를 관측하였다. 광원으로는 펄스폭이 6 ns이고 파장이 1064 nm인 Q-스위칭된 Nd:YAG 레이저 펄스를 사용하였다. 관측 결과, 다중벽 탄소 나노튜브 현탁액의 온도가 증가할수록 광 리미팅 효율이 나빠졌고 현탁액 용매의 끓는점, 점도 그리고 표면장력 값이 낮을수록 광 리미팅 효율이 좋아짐을 확인하였다.

• Safety and Health at Work
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• 제2권1호
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• pp.65-69
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• 2011

Objectives: Carbon nanotubes are an important new class of technological materials that have numerous novel and useful properties. Multi-walled carbon nanotubes (MWCNTs), which is a nanomaterial, is now in mass production because of its excellent mechanical and electrical properties. Although MWCNTs appear to have great industrial and medical potential, there is little information regarding their toxicological effects on researchers and workers who could be exposed to them by inhalation during the handling of MWCNTs. Methods: The generation of an untangled MWCNT aerosol with a consistent concentration without using surfactants that was designed to be tested in in vivo inhalation toxicity testing was attempted. To do this, MWCNTs were dispersed in deionized water without the addition of any surfactant. To facilitate the dispersion of MWCNTs in deionized water, the water was heated to $40^{\circ}C$, $60^{\circ}C$, and $80^{\circ}C$ depending on the sample with ultrasonic sonication. Then the dispersed MWCNTs were atomized to generate the MWCNT aerosol. After aerosolization of the MWCNTs, the shapes of the NTs were examined by transmission electron microscopy. Results: The aerosolized MWCNTs exhibited an untangled shape and the MWCNT generation rate was about 50 $mg/m^3$. Conclusion: Our method provided sufficient concentration and dispersion of MWNCTs to be used for inhalation toxicity testing.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.29-32
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• 2003

Multi -walled carbon nanotube(MWNT)/poly(methyl methacrylate) composites were fabricate d through film casting. Manufacturing process was established using a ultrasonic cleaner and a homogenizer. Acetone was used as a solvent to melt PMMA and mix with MWNT. The ultrasonic cleaner performed an important role in producing MWNT/MMA nanocomposites. Ultrasonic energy was utilized to disperse MWNT in acetone. Also, melting PMMA in acetone and mixing MWNT and PMMA were achieved using the homogenizer. It was confirmed that the nanohlbes were well dispersed in PMMA according to SEM images.

• Carbon letters
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• 제11권4호
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• pp.298-303
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• 2010

A method of functionalization of multi-walled carbon nanotube (MWNT) at room temperature using dry ozone gas is described. The resulting MWNT were characterized by Fourier transform infrared, x-ray photoelectron spectroscopy, and scanning electron microscopy. Combined to these analyses and solubility in liquids, it could be concluded that the dry ozone gas exposure introduces polar functional groups such as carboxylic groups to MWNT similar to acidic modification of MWNT. Particularly, the stable dispersion of MWNT in water after ozone treatment above a critical level could be obtained, implying potential bio-application. The hydrophilic functional groups on the MWNT introduced by ozone oxidation were helpful in improving the interaction with functional groups in PA6 such as $-NH_2$ and -CONH- resulting in improved mechanical properties.

• 반도체디스플레이기술학회지
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• 제10권1호
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• pp.107-111
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• 2011

Polypropylene(PP)/carbon fiber(CF)/multi-walled carbon nanotube(MWCNT) nanocomposites along with various CF and MWCNT contents were prepared in a Twin screw extruder. Electrical, mechanical property and morphology were investigated with a variation of CF and MWCNT contents. From the surface resistance of PP/CF/MWCNT composites, MWCNT can increase the conductivity of composites compared with PP/CF composites without MWCNT. It is suggested that MWCNT and CF can make the conductive network in the polymer matrix. Flexural modulus and Izod impact strength of the PP/CF/MWCNT composites were improved with the increase of CF contents. Morphology showed that length of CF in polymer matrix was shortened by torque during melt mixing with MWCNT. As a result of this phenomenon, the impact strength of composites was somewhat decreased.

• Carbon letters
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• 제13권2호
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• pp.88-93
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• 2012

Polypyrrole (PPy)/multi-walled carbon nanotubes (MWCNTs) composites were prepared by in situ polymerization of pyrrole on the surface of MWCNTs templates to improve the ammonia gas sensing properties. PPy morphologies, formed on the surface of MWCNTs, were investigated by field emission scanning electron microscopy. The thermal stabilities of the PPy/MWCNTs composites were improved as the content of MWCNTs increased due to the higher thermal stability of the MWCNTs. PPy/MWCNTs composites showed synergistic effects in improving the ammonia gas sensing properties, attributed to the combination of efficient electron transfer between PPy/MWCNTs composites and ammonia gas, and the reproducible electrical resistance variation on PPy during the gas sensing process.

• Korean Chemical Engineering Research
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• 제51권1호
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• pp.73-79
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• 2013

Polycarbonate diol (PCD), isophorone diisocyanate (IPDI)와 dimethylol propionic acid (DMPA)를 출발물질로 하여 수분산 폴리우레탄(waterborne polyurethane dispersion, WPUD)을 합성하였다. WPUD에 아크릴 단량체인 methyl methacrylate (MMA)를 첨가하여 수분산 아크릴 폴리우레탄(waterborne acrylic polyurethane dispersion, AUD)을 합성하였다. 이 AUD와 물에 분산되어 있는 multi-walled carbon nanotube (MWCNT)를 혼합하여 전도성 코팅 용액을 제조한 후 polycarbonate 시트 위에 도포하여 코팅 도막을 형성하였다. AUD 중의 MMA의 첨가량이 증가될수록 코팅 도막의 연필경도, 내마모성 및 내약품성은 향상되었으나 전기 전도도는 감소하였다. 반면에 전도성 코팅 용액 중의 MWCNT의 첨가량이 증가될수록 코팅 도막의 연필경도, 내마모성 및 내약품성은 감소되었으나 전기 전도도는 증가하였다.

• Advanced Composite Materials
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• 제18권3호
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• pp.209-219
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• 2009

Carbon nanotubes (CNTs) have shown great potential for the reinforcement of polymers or fiber-reinforced composites. In this study, mechanical properties of multi-walled carbon nanotube (MWNT)-filled plain-weave glass/epoxy composites intended for use in radar absorbing structures were evaluated with regard to filler loading, microstructure, and fiber volume fraction. The plain-weave composites containing MWNTs exhibited improved matrix-dominant and interlaminar fracture-related properties, that is, compressive and interlaminar shear strength. This is attributed to strengthening of the matrix rich region and the interface between glass yarns by the MWNTs. However, tensile properties were only slightly affected by the addition of MWNTs, as they are fiber-dominant properties.