• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.149-150
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• 2017

It is known that physical and chemical changes of cement hydrates cause problems in the volume stability of concrete. In order to overcome these problems, there is a growing interest in research on mixing technology of cement-based materials and nanomaterials. Among the nanomaterials, carbon nanotubes (CNTs) are attracting attention due to their excellent mechanical properties. The CNTs are made of cylindrically shaped graphene sheets. According to the number of sheets, single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) are classified. Although the SWCNT has superior mechanical properties, the research using MWCNT is vigorous due to the difficulty of marketability and manufacturing, but the research using SWCNT is insufficient. In this study, we investigate the effect of SWCNT on the formation of hydrate of cement paste by observing the microstructure of broken cement paste after measuring the flexural strength of cement paste with SWCNT dispersion.

• Journal of Power System Engineering
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• v.21 no.4
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• pp.94-99
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• 2017

Single walled carbon nanotubes were mixed with various metal powders by mechanical ball milling and sintered by spark plasma sintering processes. Two compositional (0.1 and 1 vol%) of the single walled carbon nanotubes were dispersed onto the pure aluminum, 5052 aluminum alloy, pure titanium, Ti6Al4Vanadium alloy, pure copper, and stainless steel 316L. Each composite powders were spark plasma sintered at $600^{\circ}C$ and well synthesized regardless of the matrices. Vickers hardness of the composite materials was measured and they exhibited higher values regardless of the carbon nanotubes composition than those of the pure materials. Moreover, single walled carbon nanotubes reinforced copper matrix composites showed highest enhancement between the other metal matrices system. We believe that low energy mechanical ball milling and spark plasma sintering processes are useful tool for fabricating of the carbon nanotubes-reinforced various metal matrices composite materials. The single walled carbon nanotubes-reinforced various metal matrices composite materials could be used as an engineering parts in many kind of industrial fields such as aviation, transportation and electro technologies etc. However, detail strengthening mechanism should be carefully investigated.

• Bulletin of the Korean Chemical Society
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• v.35 no.10
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• pp.3035-3040
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• 2014

A new efficient catalytic method for aza/thia-Michael addition reactions of amines/thiols with higher product yields has been developed. Combining single-walled carbon nanotubes (SWCNT) with triethylammonium hydrogen phosphate (TEAP) ionic liquid (IL) can work as a catalyst. We utilized Raman spectroscopy to gain insight into the interactions between IL and SWCNT. The interactions between SWCNT with TEAP were confirmed by the increasing intensity ratios and spectral shift in wavelength of the Raman D and G bands of SWCNT. Further, the morphology of the resulting composite materials of TEAP and SWCNT was determined by using scanning electron microscopy (SEM). Higher product yield in reduced reaction time is the key advantage of using bucky gel as a catalyst for Michael reaction.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.1
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• pp.47-53
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• 2011

From recent research, it has revealed that Electroacitve polymer(EAP) has a physical limitation. Carbon nanotube(CNT) is known as the promising material which has excellent electro-mechanical characteristics and is mostly defect-free. It is expected that a successful synthesis of CNT and Nafion known as a primary material for IPMC would make a great improvement on its electro-mechanic feature. In this paper, we suggest the method of synthesis of CNT with Nafion which improves electro-mechanical characteristic. Using mechanical dispersion with Nafion and Isopropyl Alcohol(IPA), we disperse Single-walled carbon nanotubes(SWCNT). For a uniformly layer of CNT, we used a spray gun on a hot plate by a simplified method. In the result, we fabricated a disperse SWCNT/Nafion composite uniformly.

• Carbon letters
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• v.10 no.1
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• pp.9-13
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• 2009

We propose an evaluation method of the relative content of single-walled carbon nanotubes (SWCNT) in SWCNT soot synthesized by arc discharge using UV-VIS-NIR absorption spectroscopy. In this method, we consider the absorbance of semiconducting and metallic SWCNTs together to calculate the relative content of SWCNTs with respect to a highly purified reference. Our method provides the more reliable and realistic evaluation of SWCNT content with respect to the whole carbonaceous content than the previously reported method.

• Steel and Composite Structures
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• v.11 no.1
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• pp.59-76
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• 2011

Dynamic analysis of an embedded single-walled carbon nanotube (SWCNT) traversed by a moving nanoparticle, which is modeled as a moving load, is investigated in this study based on the nonlocal Timoshenko beam theory, including transverse shear deformation and rotary inertia. The governing equations and boundary conditions are derived by using the principle of virtual displacement. The Galerkin method and the direct integration method of Newmark are employed to find the dynamic response of the SWCNT. A detailed parametric study is conducted to study the influences of the nonlocal parameter, aspect ratio of the SWCNT, elastic medium constant and the moving load velocity on the dynamic responses of SWCNT. For comparison purpose, free vibration frequencies of the SWCNT are obtained and compared with a previously published study. Good agreement is observed. The results show that the above mentioned effects play an important role on the dynamic behaviour of the SWCNT.

• Advances in nano research
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• v.12 no.5
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• pp.483-488
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• 2022

The present work is an attempt to study the vibration analysis of the single-walled carbon nanotubes (SWCNTs) under the effect of the surface irregularity using Donnell's model. The surface irregularity represented by the parabolic form. According to Donnell's model and three-dimensional elasticity theory, a novel governing equations and its solution are derived and matched with the case of no irregularity effects. To understand the reaction of the nanotube to the irregularity effects in terms of natural frequency, the numerical calculations are done. The results obtained could provide a better representation of the vibration behavior of an irregular single-walled carbon nanotube, where the aspect ratio (L/d) and surface irregularity all have a significant impact on the natural frequency of vibrating SWCNTs. Furthermore, the findings of surface irregularity effects on vibration SWCNT can be utilized to forecast and prevent the phenomena of resonance of single-walled carbon nanotubes.

• Journal of the Korea Institute of Building Construction
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• v.19 no.2
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• pp.113-121
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• 2019

Single walled carbon nanotube (SWCNT) has been used as a material for reinforcing various advanced materials because it has superior mechanical properties. However, pure SWCNT that does not have any functional group has a hydrophobic character, and exists as bundles due to the strong Van der Waals attraction between each SWCNT. Due to these reasons, it is very difficult to disperse SWCNTs in the water. In this work, in order to use SWCNT for production of cementitious composites, SWCNT was first dispersed in water to make an aqueous solution. Sodium deoxycholate (DOC) and Sodium dodecyl sulfate (SDS) were chosen as surfactants, and the dosage of DOC and SDS were 2wt% and 1wt%, respectively. Sonication and ultracentrifugation were applied to separate each SWCNT and impurities. Using such processed SWCNT solutions, cement paste was prepared and its shear stress vs. strain rate relationship was studied. The yield stress and plastic viscosity of cement paste were obtained using Bingham model. According to the results in this work, cement pastes made with DOC and SDS showed similar rheological behavior to that of air entrained cement paste. While cement paste made with DOC 2 wt.% SWCNT solution showed similar rheological behavior to that of plain cement paste, cement paste made with SDS 1 wt.% SWCNT solution showed different rheological behavior showing much less yield stress than plain cement paste.

• Journal of the Korean Vacuum Society
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• v.17 no.2
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• pp.170-174
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• 2008

We have studied, using Raman and photoluminescence (PL) spectroscopy, material property changes of single-walled carbon nanotubes (SWCNTs) dispersed in sodium dodecyl sulfate(SDS) aqueous solution by ultrasonication. Radial breathing mode Raman intensities of the dispersed SWCNTs shows different behavior depending on their chiralities as the sonication time increases. As the amount of SWCNTs dispersed in 1wt% SDS solution increases, both a downshift of the G-band Raman frequency and an enhancement in the PL intensity were observed.

• Korean Journal of Materials Research
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• v.23 no.8
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• pp.453-461
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• 2013

Controlling the stick and slip motions of the contact lines in a confined geometry comprised of a spherical lens with a flat substrate is useful for manufacturing polymer ring patterns. We used a sphere on a flat geometry, by which we could control the interfaces of the solution, vapor and substrate. By this method, hundreds of concentric ring-pattern formations of a linear conjugated polymer, poly [2-methoxy-5-(2-thylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), were generated with excellent regularity over large areas after complete solvent evaporation. Subsequently, the MEH-PPV ring patterns played a role as a directed template to organize highly regular concentric rings of single-walled carbon nanotubes(SWCNTs); when a droplet of the SWCNT suspension in water was casted onto the prepared substrate, hydrophobic polymer patterns confined the water dispersed SWCNTs in between the hydrophilicized $SiO_2/Si$ substrate. As the solvent evaporated, SWCNT-rings were formed in between MEH-PPV rings with controlled density. Finally, we used a lift-off process to produce SWCNT patterns by the removal of a sacrificial polymer template with organic solvent. We also fabricated a field effect transistor using self-assembled SWCNT networks on a $SiO_2/Si$ substrate.