• Title/Summary/Keyword: aggregated CNT

Search Result 7, Processing Time 0.02 seconds

Fabrication of Biofuel Cell Roll Using Flexible CNT Nanosheet Substrate (유연한 CNT Nanosheet 기판을 이용한 생체연료전지 Roll 제작)

  • Sung, Jungwoo;Lim, Geunbae
    • Journal of Sensor Science and Technology
    • /
    • v.23 no.6
    • /
    • pp.388-391
    • /
    • 2014
  • The most promising application of the biofuel cells is implantable devices, so the biofuel cells should have an appropriate shape for the vascular vessel. We demonstrated the biofuel cell roll for using in tubes. MWNTs were aggregated by vacuum filtration on a nitrocellulose membrane filter, which was biocompatible and flexible. The MWNT aggregated nitrocellulose membrane used the electrodes of the biofuel cells because it was conductive as well as nanostuructured. Then, the membrane was rolled into the roll shape. The maximum power density of the biofuel cell roll was $7.9{\mu}W/cm^2$ at 153mV and 50 mM glucose. Also, the power density is expected to increase in its practical application if there is flow in the tube, which makes the transportation of fuel easy. The biofuel cell roll contacts with the wall of the tube, so flow in the tube does not disturb. Also, the biofuel cell roll has multi-layers offering more electroactive area.

Prediction of Percolation Threshold for Electrical Conductivity of CNT-Reinforced Cement Paste (CNT 보강 시멘트 페이스트의 전기전도에 관한 침투임계점 예측)

  • Lee, Seon Yeol;Kim, Dong Joo
    • Journal of the Korean Recycled Construction Resources Institute
    • /
    • v.10 no.3
    • /
    • pp.235-242
    • /
    • 2022
  • The percolation threshold of the CNT-reinforced cement paste is closely related to the optimal CNT amount to maximize the sensing ability of self-sensing concrete. However, the percolation threshold has various values depending on the cement, CNT, and water-to-cement ratio used. In this study, a percolation simulation model was proposed to predict the percolation threshold of the CNT-reinforced cement paste. The proposed model can simulate the percolation according to the amount of CNT using only the properties of CNT and cement, and for this, the concept of the number of aggregated CNT particles was used. The percolation simulation consists of forming a pre-hydrated cement paste model, random dispersion of CNTs, and percolation investigation. The simulation used CNT-reinforced cement paste with a water-cement ratio of 0.4 to 0.6, and the simulated percolation threshold point showed high accuracy with a simulation residual ratio of up to 7.5 % compared to the literature results.

Modeling of rheological behavior of nanocomposites by Brownian dynamics simulation

  • Song Young Seok;Youn Jae Ryoun
    • Korea-Australia Rheology Journal
    • /
    • v.16 no.4
    • /
    • pp.201-212
    • /
    • 2004
  • Properties of polymer based nanocomposites depend on dispersion state of embedded fillers. In order to examine the effect of dispersion state on rheological properties, a new bi-mode FENE dumbbell model was proposed. The FENE dumbbell model includes two separate ensemble sets of dumbbells with different fric­tion coefficients, which simulate behavior of well dispersed and aggregated carbon nanotubes (CNTs). A new parameter indicating dispersion state of the CNT was proposed to account for degree of dispersion quantitatively as well as qualitatively. Rheological material functions in elongational, steady shear, and oscillatory shear flows were obtained numerically. The CNT/epoxy nanocomposites with different dis­persion state were prepared depending on whether a solvent is used for the dispersion of CNTs or not. Dis­persion state of the CNT in the epoxy nanocomposites was morphologically characterized by the field emission scanning electronic microscope and the transmission electron microscope images. It was found that the numerical prediction was in a good agreement with experimental results especially for steady state shear flow.

Effects of Minute Pirate Bug, Orius strigicollis (Hemiptera: Anthocoridae) on Control of Thrips on Hot Pepper in Greenhouse (하우스고추에서 Orius strigicollis Poppius를 이용한 총채벌레류 방제효과)

  • 송정흡;강상훈;이광석;한원탁
    • Korean journal of applied entomology
    • /
    • v.40 no.3
    • /
    • pp.253-258
    • /
    • 2001
  • Biological control of thrips with Orius strigicollis Poppius was evaluated in a hot pepper greenhouse. To study the biological control strategy of thrips on hot pepper grown in greenhouse, three plots were established: natural enemy removed plot(CNT), pesticide treated plot(PAT) and O. strigicollis released plot with no pesticide application (NRT). The nymphs of O. strigicollis were found on the leaves of lower stratum in CNT and NRT at 13 days after the first release. The density of thrips was suddenly dropped and maintained at low level since 15 day after transplanting in NRT. The densities of thrips on hot pepper flowers was also maintained at much less level in NRT than in CNT. The thrips and O. strigicollis, which were aggregated in flowers, may have resulted in improved predator searching. Average damage indices of CNT, PAT and NRT were 0.31, 0.05 and 0.08 and the percentage of damaged fruit were 80.0, 17.1 and 24.8% respectively. The damage index and percentage of damaged fruit of NRT was slightly higher than PAT, but very lower than CNT. The introduction of the adults of O. strigicollis, which was the biological control agent for the control of thrips, was effective on hot pepper.

  • PDF

On the mechanics of nanocomposites reinforced by wavy/defected/aggregated nanotubes

  • Heidari, Farshad;Taheri, Keivan;Sheybani, Mehrdad;Janghorban, Maziar;Tounsi, Abdelouahed
    • Steel and Composite Structures
    • /
    • v.38 no.5
    • /
    • pp.533-545
    • /
    • 2021
  • What is desirable in engineering is to bring the engineering model as close to reality as possible while the simplicity of model is also considered. In recent years, several studies have been performed on nanocomposites but some of these studies are somewhat far from reality. For example, in many of these studies, the carbon nanotubes (CNTs) are assumed completely straight, flawless and uniformly distributed throughout the matrix but by studying nanocomposites, we find that this is not the case. In this paper, three steps have been taken to bring the presented models for nanocomposites closer to reality. One is that assuming the straightness of nanotubes is removed and the waviness is considered. Also, the nanotubes are not considered to be pristine and the influence of defect is included in accordance with reality. In addition, the approximation of uniform distribution of nanotubes is ignored and according to experimental observations, the effect of nanotube aggregation is considered. As far as we know, this is the first study on these three topics together in an article. Moreover, we also include the size effects in our models for nanocomposites. To show the accuracy of our models, our results are calibrated with experimental results and compared with theoretical model. For numerical examples, we present the buckling behaviors of nanocomposites including the size effects using nonlocal theory and compare the results of our models with the results of models with above-mentioned approximations.

Field emission properties of Ag-Cu-alloy coated CNT-emitters (Ag-Cu합금 코팅된 탄소나노튜브의 전계방출 특성)

  • Lee, Seung-Youb;Ryul, Dong-Heon;Hong, Jun-Yong;Yeom, Min-Hyeng;Yang, Ji-Hoon;Choi, Won-Chel;Kwon, Myeng-Hoi;Park, Chong-Yun
    • Journal of the Korean Vacuum Society
    • /
    • v.16 no.4
    • /
    • pp.291-297
    • /
    • 2007
  • The field emission properties of CNT-emitters coated with Ag-Cu alloy have been investigated. The vertical aligned multi-walled CNTs were synthesized by dc-plasma enhanced chemical vapor deposition (dc-PECVD) and the Ag-Cu alloy was coated by using dc-magnetron sputter. The morphology of alloy-coated and un-coated CNT-emitters was observed by using SEM and their field emission properties were also measured. Annealing the AgCu-coated CNTs at temperature more than ${\sim}700^{\circ}C$, the Ag-Cu alloy was diffused to and aggregated on the top of the CNT as a Q-tip. A significant progress on the field emission was not observed with coating Ag-Cu alloy on the CNTs, but a certain improvement in a resistance against oxygen gas was made confirmation. It seems to be due to inertness of Ag-Cu alloy on the CNTs.

Effect of Fillers on Dispersion of Carbon Nanotubes in a Twin-Screw Extruder (이축압출기에서 카본나노튜브의 분산에 대한 충전제 효과)

  • Hong, Seung Soo;Shin, Ji Hee;Song, Kwon Bin;Lee, Kwang Hee
    • Polymer(Korea)
    • /
    • v.37 no.3
    • /
    • pp.342-346
    • /
    • 2013
  • In this study, it was attempted to disperse carbon nanotubes (CNTs) in a polymer matrix using a twin-screw extruder which was good for dispersing fillers of micron sizes but not suitable for dispersing nanometer-sized materials. Improved dispersion of CNTs could be achieved by the addition of inorganic fillers with different geometrical shapes. An increase in the matrix viscosity provided a high shear stress on aggregated CNTs, leading to a good dispersion of CNTs. The presence of the inorganic fillers was supposed to suppress the re-aggregation of CNTs in the regions where a lower shear stress was applied. As a result, the CNTs dispersion was well stabilized.