• Bulletin of the Korean Chemical Society
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• 제35권10호
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• pp.2974-2978
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• 2014

$Mn_3O_4$/multi-walled carbon nanotube (MWCNT) composites are prepared by chemically synthesizing $Mn_3O_4$ nanoparticles on a MWCNT film at room temperature. Structural and morphological characterization has been carried out using X-ray diffraction (XRD) and scanning and transmission electron microscopies (SEM and TEM). These reveal that polycrystalline $Mn_3O_4$ nanoparticles, with sizes of about 10-20 nm, aggregate to form larger nanoparticles (50-200 nm), and the $Mn_3O_4$ nanoparticles are attached inhomogeneously on MWCNTs. The electrochemical behavior of the composites is analyzed by cyclic voltammetry experiment. The $Mn_3O_4$/MWCNT composite exhibits a specific capacitance of $257Fg^{-1}$ at a scan rate of $5mVs^{-1}$, which is about 3.5 times higher than that of the pure $Mn_3O_4$. Cycle-life tests show that the specific capacitance of the $Mn_3O_4$/MWCNT composite is stable up to 1000 cycles with about 85% capacitance retention, which is better than the pure $Mn_3O_4$ electrode. The improved supercapacitive performance of the $Mn_3O_4$/MWCNT composite electrode can be attributed to the synergistic effects of the $Mn_3O_4$ nanoparticles and the MWCNTs, which arises not only from the combination of pseudocapacitance from $Mn_3O_4$ nanoparticles and electric double layer capacitance from the MWCNTs but also from the increased surface area, pore volume and conducting property of the MWCNT network.

• 한국항공우주학회지
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• 제33권11호
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• pp.24-32
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• 2005

본 연구의 목표는 X-band에서 하중지지가 가능한 전자파 흡수 구조(RAS)를 제작하는 것이다. 본 연구에서는 하중을 지지할 수 있도록 비강성비강도가 우수한 유리섬유/에폭시 평직 복합재료에 손실을 일으킬 수 있는 MWNT를 첨가한 재료를 제작하였으며, 미세구조의 관찰과 유전율 측정을 통해 흡수 재료로의 적합성을 확인하였다. 유전자 알고리즘과 다층형 RAS의 전자파 반사/투과 이론을 적용하여 그 복합재료로 이루어진 RAS에 대한 최적설계를 수행하였다. RAS의 제작을 통해 복합재료의 층당 두께가 층수와 MWNT의 함량에 따라 변함을 확인하였다. 이를 고려한 제작 공정을 제안하고 적용하여 설계된 RAS를 제작하였고, 그것의 반사손실의 예측치와 실험치가 잘 일치함을 확인하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.468-470
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• 2004

CNT pastes with different inorganic binder such as glass frit and spin on glass (SOG) were synthesized by using multi-walled nanotube (MWNT) grown by CVD. The uniformity of cathode layer after firing was enhanced and the emission current density at an applied field of 7.95V/${\mu}m$ increased from 133${\mu}A$/$cm^2$ to 265${\mu}A$/$cm^2$ when inorganic binder changed from glass frit to SOG. The emission properties of CNT pastes with SOG were stable and uniform although firing was carried out at relatively high temperature of 450$^{\circ}C$ under air. It is concluded that SOG is more suitable inorganic binder than glass frit for field emission application.

• Fibers and Polymers
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• 제7권4호
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• pp.323-327
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• 2006

Poly(vinyl alcohol) (PVA)/multi-walled carbon nanotube (MWNT) composite films were prepared by casting a DMSO solution of PVA and MWNTs, whereby the MWNTs were dispersed by sonication. A significant improvement in the mechanical properties of the PVA drawn films was achieved by the addition of a small amount of MWNTs. The initial modulus and the tensile strength of the PVA drawn film increased by 30 % and 45 %, respectively, with the addition of 1 wt% MWNTs, which are close to those calculated from the rule of mixtures, and were strongly dependent upon the orientation of the PVA matrix. The mechanical properties, however, were not improved with a further increase in the MWNT content. The orientation of MWNTs in the composite was not well developed compared to that of the PVA matrix. This result suggests that the improvement of the molecular orientation of the PVA matrix plays a major role in the increase of the mechanical propeties of the drawn PVA/MWNT composite films.

• Composites Research
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• 제30권1호
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• pp.7-14
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• 2017

In this paper, the inter-lamina shear strength (ILSS) of multi-wall carbon nanotube (MWNT) reinforced carbon fiber reinforced plastics (CFRP) and thin-ply composites were verified under low earth orbit (LEO) space environment. CFRP, MWNT reinforced CFRP, thin-ply CFRP and MWNT reinforced thin-ply CFRP were tested after aging by using accelerated ground simulation equipment. The used ground simulation equipment can simulate high vacuum ($2.5{\times}10^{-6}torr$), atomic oxygen (AO, $9.15{\times}10^{14}atoms/cm^2{\cdot}s$), ultraviolet light (UV, 200 nm wave length) and thermal cycling ($-70{\sim}100^{\circ}C$) simultaneously. The duration of aging experiment was twenty hours, which is an equivalent duration to that of STS-4 space shuttle condition. After the aging experiment, ILSS were measured at room temperature ($27^{\circ}C$), high temperature ($100^{\circ}C$) and low temperature ($-100^{\circ}C$) to verify the effect of operation temperature. The MWNT and thin-ply shows good improvement of ILSS at ground condition especially with the thin-ply. And after LEO exposure large degradation of ILSS was observed at MWNT added composite due to the thermal cycle. And the degradation rate was much higher under the high temperature condition. But, at the low temperature condition, the ILSS was largely recovered due to the matrix toughening effect.

• Carbon letters
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• 제10권1호
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• pp.14-18
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• 2009

We measured the degree of macrodispersion of the various single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) using UV-VIS-NIR absorption spectroscopy. CNTs were dispersed with SDS of 2 wt % in deionized water using the homogenizer and then were further centrifugated at 6000 g for 10 min. The degree of macrodispersion, expressed by $D_m({\lambda})=A_a({\lambda})/A_b({\lambda})^*100$ (%), where ${\lambda}$ is the wavelength and $A_a({\lambda})$ and $A_b({\lambda})$ are the absorbance of the sample after and before centrifugation, respectively. In the case of MWCNTs, we evaluated the degree of macrodispersion by the average degree of macrodispersion ($D_m({\lambda})$) between 1000 and 1200 nm. The degree of macrodispersion of SWCNTs was evaluated at the wavelength in which van Hove singularity-related transition regions were excluded, i.e., the range was chosen between ${E_{11}}^S$ and ${E_{22}}^S$ peaks. We have estimated six samples with the same method. The standard deviation of each sample was lower than 5. Therefore, we presented a reliable evaluation method for the macrodispersion of CNTs for standardization.

• 드라이브 ㆍ 컨트롤
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• 제13권1호
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• pp.43-48
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• 2016

This paper presents a preliminary study on the pressure sensing characteristics of smart nano composites made of MWCNT (multi-walled carbon nanotube) to develop a novel pressure sensor. We fabricated the composite pressure sensor by using a solution casting process. Made of carbon smart nano composites, the sensor works by means of piezoresistivity under pressure. We built a signal processing system similar to a conventional strain gage system. The sensor voltage outputs during the experiment for the pressure sensor and the resistance changes of the MWCNT as well as the epoxy based on the smart nano composite under static pressure were fairly stable and showed quite consistent responses under lab level tests. We confirmed that the response time characteristics of MWCNT nano composites with epoxy were faster than the MWCNT/EPDM sensor under static loads.

• Advances in nano research
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• 제14권5호
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• pp.435-442
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• 2023

Sports activities, including playing tennis, are popular with many people. As this industry has become more professionalized, investors and those involved in sports are sure to pay attention to any tool that improves athletes' performance Tennis requires perfect coordination between hands, eyes, and the whole body. Consequently, to perform long-term sports, athletes must have enough muscle strength, flexibility, and endurance. Tennis rackets with new frames were manufactured because tennis players' performance depends on their rackets. These rackets are distinguished by their lighter weight. Composite rackets are available in many types, most of which are made from the latest composite materials. During physical exercise with a tennis racket, nanocomposite materials have a significant effect on reducing injuries. Materials as strong as graphite and thermoplastic can be used to produce these composites that include both fiber and filament. Polyamide is a thermoplastic typically used in composites as a matrix. In today's manufacturing process, materials are made more flexible, structurally more vital, and lighter. This paper discusses the production, testing, and structural analysis of a new polyamide/Multi-walled carbon nanotube nanocomposite. This polyamide can be a suitable substitute for other composite materials in the tennis racket frame. By compression polymerization, polyamide was synthesized. The functionalization of Multi-walled carbon nanotube (MWCNT) was achieved using sulfuric acid and nitric acid, followed by ultrasonic preparation of nanocomposite materials with weight percentages of 5, 10, and 15. Fourier transform infrared (FTIR) and Nuclear magnetic resonance (NMR) confirmed a synthesized nanocomposite structure. Nanocomposites were tested for thermal resistance using the simultaneous thermal analysis (DTA-TG) method. scanning electron microscopy (SEM) analysis was used to determine pores' size, structure, and surface area. An X-ray diffraction analysis (XRD) analysis was used to determine their amorphous nature.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2003년도 기술심포지움 논문집
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• pp.22-26
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• 2003

Electrical conductivity of the oxidized MWNT(Multi walled nanotubes)/polymer composites were investigated with respect to various oxidative conditions of acid concentration, treatment temperature, and treatment time. To remove the impurities existing in MWNT-deposites, liquid-phase oxidation was performed using the $HNO_3/HSO_4$ mixtures. Secondary effects occurred by the oxidation of MWNTs such as the damages of MWNTs and the introduction of functionalities were analyzed through measuring FT-IR, TEM, and zeta potential, All the oxidized NWNTs were functionalized with carboxylic groups and the conditions of oxidation of the MWNTs could have a certain influence on the degree of functionalization, damages, and dispersion of the MWNT. The electrical properties of MWNT composites strongly depend on the oxidative conditions of MWNTs. The conductivity of the composites filled with the proper oxidized MWNT showed the highest percolation threshold.

• 한국건축시공학회지
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• 제24권2호
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• pp.203-213
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• 2024

본 연구에서는 내열성, 화학적 안정성 등 다양한 특성으로 인해 산업 분야에서 자기감지, 균열 감지 등의 용도로 활용되고 있는 MWCNT를 활용하여 진행하였다. 하지만 MWCNT는 전기적 특성을 활용한 자기감지 및 스마트 센서에 대한 연구에 집중되어 있다. 또한, 연구자의 기술 및 장비의 차이로 인해 정량적 분산이 어렵고, 과도한 분산은 기계적 성능 저하로 이어질 수 있다. 따라서 본 연구에서는 일정 시간 초음파 분산과 분산 효과가 입증된 PCE 계면활성제를 활용하여 섬유보강 시멘트복합체 시험편을 제조하고, 각 시험편에 대해 강도 시험, 인발 시험, 직접 인장 시험을 수행하여 기계적 물성을 평가하였다. Micro-CT 촬영과 압축, 휨, 인장 강도 시험 결과 초음파 분산과 분산제를 사용한 시험체인 U-A0.5와 분산제만을 사용한 N-A0.5가 다른 시험체에 비해 높은 강도를 보이는 것을 확인하였으며 분산 방법에 따라 MWCNT의 분산 효율이 섬유보강 시멘트복합체의 기계적 성능 향상에 미치는 영향을 조사하였다.