• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.32.1-32.1
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• 2009

현재 ITO를 대체할 재료로 투명 전도성 탄소나노튜브(carbon nanotube, CNT) 필름에 대한 연구가 진행 되고 있다. 이러한 연구에서 특히 CNT 필름의 투과도에 따른 전기저항을 향상시키기 위한 연구가 활발히 진행되고 있다. 본 연구에서는 단일벽 CNT (single-walled CNT)를 여러 가지 계면활성제로 최적 분산시킨 수용액으로부터 제조한 CNT 필름의 투과도에 따른 면 저항 (sheet resistance) 변화를 관찰하였다. 우선 계면활성제로 분산시킨 CNT 수용액을 알루미나 재질의 필터에서 정량적으로 진공 필터링하여 CNT 필름을 제조하였다. 알루미나 필터를 sodium hydroxide (NaOH) 수용액으로 용해시켜 제거함으로써 얻은 CNT 필름을 유리기판 위에 부착시켰다. 필름의 전기저항을 낮추기 위해 유리기판 위에 부착된 CNT 필름을 질산 (HNO3) 용액으로 처리하였다. Scanning electron microscopy, UV-Vis spectroscopy를 이용하여 각각 필름의 형상과 광 투과도를 분석하였고, 4-point probe로 면 저항을 측정하였다. 계면활성제로 분산시킨 CNT 필름 대부분의 면 저항은 질산 처리에 의해 감소하였다. 이는 CNT 표면에 코팅되어 있던 계면활성제가 질산에 의해 제거되었기 때문인 것으로 예상된다. 여러 계면활성제 중 sodium dodecyl benzenesulfonate로 분산시킨 CNT 필름이 산 처리 후에 가장 낮은 면 저항을 보였다. 그리고 Polyvinyl pyrrolidone (PVP)과 cetyltrimethylammonium bromide (CTAB)를 사용하여 제조한 CNT 필름의 면 저항이 가장 뚜렷한 감소를 보였다.

• Clean Technology
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• v.12 no.2
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• pp.107-111
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• 2006

Two types of mesoporous carbons, CMK-3 and CMK-5, were prepared using mesoporous silica as a removable template, and their hydrogen storage capacities were evaluated. For the purpose of comparison, MWCNT (multi-walled carbon nanotubes) was selected and the adsorption of hydrogen was measured. The amount of hydrogen adsorbed on carbon materials was found to be closely related to the surface areas of carbon samples: The higher the surface area of the carbon material, the larger amount of hydrogen was adsorbed. The hydrogen storage capacity increased in the order of CMK-5 > CMK-3 > MWCNT. In addition, hydrogen storage capacity was greatly enhanced by the Pd-doping onto CMK-5. When the metallic Pd was doped on the carbon material, the adsorption amount of hydrogen via a hydrogen spill-over mechanism was crucial to the hydrogen storage capacity of Pd-doped CMK-5.

• Korean Journal of Optics and Photonics
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• v.15 no.5
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• pp.449-454
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• 2004

The optical limiter is an optical component which reduces laser beam intensity for the protection of eyes and light sensors. Carbon nanotube is now known as a highly efficient optical limiting material. Optical limiting effect of the multi-walled carbon nanotube suspensions, in several kinds of solvents such as distilled water, chloroform, ethanol and ethylene glycol, were measured in the range from room temperature to near to the boiling points of the solvents. The pulsed Nd:YAG laser whose wavelength is 1064 nm and pulse duration is 6 ns was used as a light source. The experimental result shows that the limiting efficiency was reduced as the temperature increased, and the suspension which has lower boiling point, viscosity and surface tension has highest efficiency.

• Composites Research
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• v.28 no.3
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• pp.130-135
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• 2015

This study investigates the property of graphene filled polymer nanocomposites in LEO(Low Earth orbit) environment conditions. In order to improve compatibility with polymer matrices and resistance of carbon material against AO(Atomic oxygen) attack, silanization of graphene oxide with organosilane was carried out. The corresponding moieties were characterized through X-ray photoelectron spectroscopy (XPS). Graphene oxide filled nanocomposites were prepared using solution based processing methods. The sets of specimen series were tested in an accelerated LEO simulated space environment facility. Graphene oxide and silane treated graphene oxide reinforced nanocomposites were compared with neat epoxy. The comparison revealed that the silane treated graphene filled polymer composite shows inherent resistance against atomic oxygen attack while the lack of silane treatment resulted in a reduction in performance.

• Composites Research
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• v.29 no.4
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• pp.161-166
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• 2016

Carbon nanotube buckypaper (CNTs-BP)/thermoplastic polyurethane (PU) elastomer composites were successfully fabricated. The CNTs-BP/PU nanocomposites exhibited simultaneous improvements in both tensile modulus and strength by 1360 and 430%, respectively, as compared to pure PU. Possible reinforcing mechanisms were evidenced by SEM analyses and tensile tests. The CNTs-BP/PU nanocomposites can be potentially used as an inter-reinforcing agent in ultra-lightweight, high-strength aircraft, carbon-fiber-reinforced plastics, etc.

• 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.

• Polymer(Korea)
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• v.31 no.2
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• pp.117-122
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• 2007

In this work, the mechanical and electrical properties, and thermal stability of vapor-grown carbon nanofibers/polyimide (VGCNFs/PI) composite film synthesized by in-situ polymerization were investigated in terms of tensile properties, volume resistivity and thermogravimetric analysis (TGA), respectively. From the results, the addition of VGCNFs with a certain amount into polyimide led to obvious improvement in tensile strength. The volume resistivity of the films was decreased with increasing the VGCNFs content and the electrical percolation threshold appeared between 1 and 3 wt% of VGCNFs content, which was probably caused by the formation of interconnective structures among the VGCNFs in a composite system. The thermal stability of the film was higher than that of pure PI one. This result indicated that the crosslinking of VGCNFs/PI Composites was enhanced by well-distribution of YGCNFs in PI resin, resulting in the increase of the thermal stability of the resulting composites.

• Composites Research
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• v.23 no.3
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• pp.58-63
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• 2010

Tensile and flexural properties and electrical conductivity of MWCNT/epoxy composites with different aspect ratios of MWCNTs were compared. The MWCNT/epoxy mixtures were prepared by mechanical dispersion methods using a homomixer and a three-roll mill, and then composite samples were fabricated by compression molding process. The fractured surfaces of the samples were observed by SEM in order to evaluate the degree of dispersion of MWCNTs. The addition of MWCNTs into epoxy resin improved its tensile strength by 7.0% while its flexural strength increased slightly as compared with the one without MWCNTs. In the case of MWCNTs having highest aspect ratio, the mechanical properties of the composites were decreased. When the contents of CM-95 MWCNTs were varied, maximum of tensile and flexural strengths occurred at 1wt% and 0.5wt%, respectively. From the higher contents than these, tensile and flexural strengths of the composites decreased. Electrical conductivities of in-plane and thought-the-thickness directions of MWCNT/epoxy composites were measured using a two-point probe method. They increased with the increase of the aspect ratios and concentrations of MWCNTs in the epoxy matrix.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.61-61
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• 2010

니켈 니켈 와이어를 증류수 및 에탄올 등의 유기용매 중에서 펄스파워 기술을 이용하여 전기적으로 폭발 시켰다. 폭발에 의하여 생성된 입자들은 직경이 수 마이크로미터 에서 수 십 나노미터에 이르는 넓은 입도분포를 보였다. 본 연구에서는 원심분리기술을 이용하여 입자의 크기별로 분리 회수가 가능함을 증명하였다. 또한 유기용매 중에서 제조된 니켈분말에 탄소가 포함되어 있으며, 열처리를 통하여 제거가 가능함을 실험을 통하여 밝혔다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.193-194
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• 2020

Recently, as the use of high-performance concrete has become common, various problems related to high-performance concrete have become an issue. Among them, self-shrinkage of cement paste due to low water cement ratio is known to cause problems in the volume stability of concrete. To improve this, studies related to the mixing technology of cement-based materials and nano materials have been actively conducted. Looking at the results of prior research related to nano material mixing technology, generally, research results have been reported in which nano materials are incorporated into cement-based materials to improve material properties1). Among them, it was shown that the mechanical performance and various types of functionality of the cement composite are expressed. Among nano materials, carbon nanotubes (hereinafter referred to as CNTs) and graphenes are used in a mixture with cement-based materials. Accordingly, this study intends to compare the mechanical properties by incorporating various CNTs and graphene into cement paste.