• Composites Research
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• v.24 no.5
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• pp.34-38
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• 2011

Carbon nanotubes (CNTs) have been widely investigated as reinforcements of CNT/polymer nanocomposites to enhance mechanical and electrical properties of polymer matrices since their discovery in the early 90's. Furthermore, the number of studies about incorporating CNTs into carbon fiber reinforced plastics (CFRP) to reinforce their polymer matrices is increasing recently. In this study, single-walled carbon nanotubes (SWNT) were dispersed in epoxy with 0.2 wt.% and 0.5 wt.%. Then, the SWNT/epoxy mixtures were processed to carbon fiber composites by a vacuum assisted resin transfer molding (VARTM) and a wet lay up method. The processed composite samples were tested for the interlaminar shear strength (ILSS). The relationship between the interlaminar shear strengths and processing, and the reinforcement mechanism of carbon nanotubes were investigated. CNT/epoxy nanocomposite specimens showed the increased tensile properties. However, the ILSS of carbon fiber composites was not enhanced by reinforcing the matrix with CNTs because of processing issues caused by increased viscosity of the matrix due to addition of CNTs particularly for a VARTM method.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.457-457
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• 2011

단일벽 탄소나노튜브(SWNTs)는 직경 및 키랄(chiral)특성에 따라 반도체성 튜브와 금속성 튜브로 구분되며, 작은 직경의 SWNTs는 큰 직경의 튜브에 비하여 일반적으로 기계적 특성이 뛰어나다고 알려져 있다. 따라서, 합성하는 단계에서 SWNTs의 직경 및 chiral 특성의 제어가 가능 하게 된다면 전자소자로의 응용을 한층 앞당길 수 있을 것으로 예상하고 있다. 이와 더불어 SWNTs의 수평배향성장은 SWNTs의 집적(integration)을 용이하게 할 수 있기 때문에 향후 나노전자소자 개발을 목표로 최근 많은 연구결과들이 보고되고 있다. 하지만 현재는 SWNTs가 고밀도로 합성되기 때문에, 우수한 개별 (individual) SWNT의 전기적 특성보다는 집단적(ensemble) 특성을 얻고 있다. 따라서, 합성기판 위에서 개별적인 SWNT를 낮은 밀도로 수평배향 성장하는 일은 향후 나노튜브기반의 고성능 전자소자 개발에 중요한 과제이다. 나아가, 수평배향 성장 된 개별 SWNT의 직경 및 키랄 특성까지 함께 제어할 수 있다면 곧바로 응용에 적용할 수 있는 획기적인 기술이 될 것이다. 본 연구에서는, SWNTs의 수평배향도 및 직경을 제어하여 성장시키는 것을 목표로 하였다. 합성기판은 퀄츠를 이용하였고, 합성촉매로는 나노입자의 밀도를 비교적 쉽게 제어할 수 있고, 균일한 크기를 갖는 페리틴 단백질을 이용하였다. 단분산(monodispersion) 된 촉매 나노입자를 얻기 위해서 스핀코팅 조건과 페리틴 용액농도를 조절하여 퀄츠기판 위에 분산시킨 후, 아르곤 분위기 하에 열처리를 통하여 촉매 나노입자의 크기 감소를 유도하였다. 그 결과 열처리 시간이 증가함에 따라 촉매 나노입자의 크기가 감소하는 것을 알 수 있었고, SWNTs의 직경 또한 감소하는 것을 확인하였다. 또한 퀄츠기판 위에 직경제어 합성 된 수평배향 SWNTs를 다른 기판으로 전사하는 기술을 확립함으로써, 향후 SWNTs기반의 소자 제작기술의 바탕을 마련하였다.

• Polymer(Korea)
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• v.35 no.5
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• pp.451-457
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• 2011

The effect of latex particle size on rheological and electrical properties of latex-blended polystyrene (PS)/multi-walled carbon nanotube (MWCNT) nanocomposites was investigated. Mono-dispersed PS particles synthesized either by emulsifier-free emulsion polymerization or by dispersion polymerization were mixed with MWCNTs under ultrasonication, and freeze-dried to prepare the nanocomposites. As the MWCNT content increased, storage modulus, complex viscosity and electrical conductivity were substantially increased. The increase of storage modulus and complex viscosity was higher for larger PS particles. The effect of particle size on electrical properties was different depending on MWCNT content. With lower MWCNT content, the nanocomposite prepared by smaller PS particles showed higher electrical conductivity, but the opposite result was given as the content increased.

• Composites Research
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• v.24 no.6
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• pp.1-6
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• 2011

A new water-soluble and self-doped poly(styrenesulfonic acid-graft-aniline), PSSA-g-PANI, for dispersing carbon nanotubes (CNTs) in water was synthesized and its ability to stabilize aqueous CNT dispersions was examined. It was observed that the PANI in PSSA-g-PANI, which has benzoid and quinoid structure, was strongly adsorbed onto the nanotube surface via a strong ${\pi}-{\pi}$ interaction, and thus only gentle sonication causes exfoliation of CNT ropes to small bundles and the long-term stability of their resulting dispersions was much better than commercial surfactants. Furthermore, when thin films of PSSA-g-PANI/CNT are prepared from aqueous dispersion and their electrical conductivities are measured by the four probe technique, it is observed that their conductivities are in the range of 1.5-2.5 S/cm.

• Journal of the Korean Electrochemical Society
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• v.24 no.1
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• pp.7-12
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• 2021

In this study, we investigated the formation of the metal oxide nanostructure by anodization of aluminum 3104H18 alloy. The anodization was performed in pyrophosphoric acid (H4P2O7) electrolyte. By the control of anodization condition such as concentration of electrolyte, anodization temperature and applied voltage, nanoporous or nanofiber structures were obtained. The optimal anodization condition to form nanofiber structures are 75 wt% of H4P2O7 at 30 V and 20℃. When anodization was performed at over 40 V, nanoporous structures were formed due to accelerated dissolution reaction rate of nanofiber structures or increasing thickness of channel wall.

• Journal of the Korean Applied Science and Technology
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• v.33 no.3
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• pp.593-598
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• 2016

We report on the preparation of reduced graphene oxide (rGO)/single-walled carbon nanotubes (SWNTs) electrodes deposited onto flexible polyethylene terephthalate (PET) via spray coating technique. The highest capacitance value of the unbent rGO/SWNTs electrode was $82Fg^{-1}$ in 1 M $H_2SO_4$ at $100mVs^{-1}$, which decreased to $38Fg^{-1}$ after 500 bending cycle. Further characterization, including galvanostatic charge/discharge measurements and electrochemical impedance spectroscopy (EIS), showed that the rGO/SWNTs electrode retained a well-defined capacitive response after repetitive bending cycle. Overall, the rGO/SWNTs composite electrode showed reasonable electrochemical properties even prolonged bending cycle. Approximately 50% of the initial capacitance for the rGO/SWNTs composite electrode is remained after 500 bending cycle, making the electrode a potential option for flexible energy storage applications.

• The Journal of the Korea Contents Association
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• v.17 no.10
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• pp.300-306
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• 2017

The purpose of this study was to investigate the antibacterial effect of functional multiwall carbon nanotube (MWCNT) on the conventional glass ionomer cement(GIC). The MWCNT was incorporated into a commercial powder at 0.125, 0.25, 0.5 and 1.0 wt%. Specimens for vickers hardness(VHN) disks(Ø$10mm{\times}2mm$) each were prepared. Indention were made using a load of 200 N and 20 s dwell on four specimens for each distilled water storage time 1d, 7d, and 14days. The antibacterial effects using agar diffusion test with S. mutans and S. aureus. The diameters of the inhibition zones produced around the materials were measured. The results revealed that all the vickers hardness values were increase significantly with incubation time(p<0.05). Regarding the antibacterial effect for S. mutans, all the tested groups showed a slightly higher value not significantly with the control group(p<0.05). However S. aureus statistical analysis indicated a significant difference for antibacterial agents between control and MWCNT containing 0.25 wt%(p<0.05). These results of this study provide that the conventional GIC with containing MWCNT show good antibacterial effect against and favorable mechanical properties. Further this study on the efficient functionalization of multiwall carbon nanotube will be needed.

• Tribology and Lubricants
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• v.30 no.5
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• pp.278-283
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• 2014

Carbon nanotubes (CNTs) are used in various composite materials to enhance electrical, thermal and mechanical properties of composite materials. In this study, we investigate the wear characteristics of polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) blends containing multi-walled carbon nanotubes (MWCNTs). PC/ABS blends are commonly used in many industrial applications such as cellular phones and display cases and MWCNTs have been added to the PC/ABS blends to improve their electromagnetic interference shielding (EMS). We performed wear tests on PC/ABS blends containing MWCNTs under reciprocating linear sliding conditions with chrome steel balls as a counterpart material. The normal loads were 10, 30, 50, 70, 100 N, the sliding speed was 10 mm/s, the stroke length was 15 mm, and the tests lasted 900 s. The MWCNTs included in the PC/ABS blends lower the wear volume and friction coefficient of the composites. We analyzed the wear debris collected from the composites during the tests in terms of the MWCNT concentration using inductively coupled plasma optical emission spectroscopy. The results show that the quantity of MWCNTs in the debris is proportional to the concentration of MWCNTs in the composite, indicating that the exposure of the MWCNTs to environments by wear could be increased with their concentration in the composite.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1209-1215
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• 2010

The effects of multi-walled carbon nanotube (MWCNT) content, carbon black (CB) content, atmospheric-pressure flame plasma (APFP) treatment, and acid treatment on the mechanical properties of elastomeric composites were investigated. For pure or filled rubbers with the given amount of CB (20 and 40 phr), the tensile strength and modulus of the elastomeric composites increase similarly with the MWCNT content. A composite with APFP-treated MWCNTs shows a hardening effect (high strength, high modulus, and high ductility) unlike the one with untreated MWCNTs. On the other hand, a composite with APFP-treated CB shows a softening effect (high strength, low modulus, and high ductility), which is unlike a composite with untreated CB. As the refluxing time increases from 1 h to 2 h and the sulfuric acid concentration increases from 60% to 90%, the tensile strength and modulus of a composite decrease. Thus, it is found that the MWCNT content, CB content, APFP treatment, sulfuric acid concentration, and refluxing time have an important effect on the mechanical properties of NBR composites.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.237-238
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• 2009

1999년 Zwilling 등은 타이타늄과 타이타늄 합금위에 불산을 포함하는 산성 전해질에서 양극산화 방법에 의해 $TiO_2$ 나노튜브를 형성시켰다. 그러나 HF의 강한 용해성으로 인해 튜브의 길이를 500 nm이상 성장 시킬 수 없다는 문제점을 가지고 있었고 그 후에 HF대신에 전해질에 $NH_{4}F$를 혼합하여 pH를 조절하는 방법으로 $TiO_2$가 용해되는 속도를 감소시켜 약 $2{\sim}4$배 더 크게 성장 시킬 수 있다고 보고한 바 있지만 수 ${\mu}m$ 이상의 길이로는 성장 시킬 수 없다는 한계를 가지고 있었다. 최근에는 불소이온을 포함하는 점액질의 유기전해질에서 높은 종횡비, 40-60 nm의 작은 기공직경과 매끄러운 튜브벽을 가지는 수 um이상의 나노튜브를 성장 시키는 보고가 있으나 $TiO_2$ 나노튜브의 제조에 영향을 미치는 파라메타에 대한 연구가 아직 많지 않은 실정이다. 따라서 본 연구에서는 전해질의 구성, 전압, 양극산화 시 교반의 영향에 대해 조사하였다. 불산과 에틸렌글리콜 전해질에서 형성된 $TiO_2$ 나노튜브의 비 표면적의 차이를 조사했고 튜브의 길이와 기공크기도 양극산화 시 인가전압과 전해질 구성에 따라 다른 것을 확인할 수 있었다. 이는 포어 바닥에서 국부적인 산성화를 유발하는 타이타늄의 가수분해와 $TiO_2$의 용해는 산화피막층의 용해작용을 증가시키는 수소이온의 농도를 증가시고 그에 따라 인가접압이 증가함에 따라 전해질 내의 이온수송을 활발하게 하기 위한 구동력이 증가해 전류밀도가 높아지는 것으로 확인되었단. 또한 양극산화 동안 전해질을 교반 한 경우 그런지 않은 경우에 비해 전해질 내의 유속(mass flow)를 증가시켜 더 긴 나노튜브를 얻을 수 있었다.