Papers by Keyword: Single-Walled Carbon Nanotube (SWCNT)

Abstract: Stress transfer in the carbon nanotube reinforced nanocomposites is investigated in this work. The model consists of two concentric cylinders, namely, a single-walled carbon nanotube cylinder (SWCNT) and a matrix cylinder, as the representative volume element (RVE). The stress analysis is performed using the shear lag model for the axisymmetric RVE. Analytical solutions for the axial normal stresses in the SWCNT and matrix, and the interfacial shear stress across the SWCNT/matrix interface are obtained. Numerical results show that using a large volume fraction improves the efficiency of the stress transfer from the matrix to the carbon nanotubes.

Abstract: This paper studies the thermal effect on dynamic stability of single-walled carbon nanotubes (SWCNTs) embedded in polymer matrix in low and high temperatures under impact loads. To this end, we present a nonlocal elastic shell model including thermal and small-size effects. Further, numerical calculations are presented for SWCNTs. Results show that the increasing in temperature field has the effect of increasing the dynamic buckling loads at low or room temperature. However, this effect leads to decrease the dynamic buckling loads at high temperature. In addition, it is observed that nonlocal dynamic buckling loads increase by an increase in the Neperian frequency.

Abstract: In this paper, a solid-state dye sensitized solar cell (DSSC) based on carbon nanotubes by inserting N719 dye molecules has been designed for operating at 300oK and 330oK temperatures. The role of carbon nanotubes as hole and electron conducting agents and dye molecules as absorber of solar radiation and hole-electron pair producing agents has been discussed. After inserting N719 dye, parameters of the cell such as absorption coefficient of both layers (ZNO+SWNT, P3HT+SWNT), current density of solar cell , internal and external quantum efficiency of P3HT+SWNT layer have been obtained at 300oK and 330oK, numerically. Then, improvement value of energy conversion efficiency of the cell has been compared after inserting carbon nanotubes.

Abstract: Grafting copolymerization method was used to synthesize copolymer of polyethylene with single-walled carbon nanotubes (SWNTs). Firstly, SWNTs were functionalized along their side walls with 1-alkene organic groups using the 1, 3-dipolar cycloaddition reaction. Then, a metallocene catalyst C2H4[(tert-H)Ind]ZrCl2 was used to synthesize polyethylene grafted from SWNTs (PE-g-SWNTs) copolymers by copolymerization with ethylene. SWNTs can be used to compound PE-g-SWNTs nanocomposites by a grafting copolymerization approach. The results show that PE covalently grafted from organic functionalized SWNTs forming a strong interface between the SWNTs and the PE matrix. The microstructure of the obtained copolymers was characterized. The SWNTs were dispersed well in the copolymers due to covalent linkage of functionalized SWNTs with polyethylene. Thermal stability of PE-g-SWNTs is better than those of pure PE and PE/SWNTs physical mixture. It indicates that the addition of SWNTs by the grafting copolymerization approach is mainly due to the delay of the thermal decomposition temperature in PE matrix.

Abstract: Molecular dynamics simulations are used to investigate the junction formation of two crossed single-walled carbon nanotubes (SWCNTs) with or without preexisting structural defects by heat welding. The junction formation of the chiral SWCNTs by heat welding is discussed. Furthermore, both the single vacancy defects and double vacancy defects are introduced in SWCNTs to explore the effect on junction formation by heat welding. We found the single vacancy defects and double vacancy defects pairs distributed on both crossed SWCNTs will accelerate the heat welding process and make the junction easier, and the required temperature for junction formation will be significantly reduced.

Abstract: The field emission properties of single-wall carbon nanotubes with purity higher than 70%,which were produced by dc arc discharge evaporation of a carbon electrode including 1% Fe catalyst in H2-Ar mixture gas was studied.The single-wall carbon nanotubes that were produced by this method possess high a ‘clean’ surface since the coexisting Fe catalyst nanoparticles can be completely eliminated by a two-step purification process.The field emission properties was verified by measuring the emission current density(J) versus the applied electric field(E), the corresponding Fowler-Nordheim(F-N) plot for the sample.Through looking at the emission photos, the uniformity of field emission is found to be excellent.

Abstract: The functionalization of single-walled carbon nanotubes (SWCNTs) by noncovalent approach turned to be an effect strategy. Porphyrin and its derivatives are ideal materials for the decoration of SWCNTs. In this work, 5-(4-carboxypheny1)-10,15,20-triphenylporphyrin (H2CPTPP) was synthesized and covalently combined to the chitosan. The prepared chitosan/H2CPTPP composite was further conjugated with the oxidized SWCNTs to form chitosan/H2CPTPP/SWCNTs ternary composite. The results indicated that the carboxyl group of H2CPTPP was successfully introduced into the chitosan, which was confirmed by Fourier Transform infrared (FT/IR) spectroscopy, Raman shift and X-ray photoelectron spectroscopy (XPS). The solution of chitosan/ H2CPTPP/SWCNTs composite displays fluorescence quenching effect compared with that of chitosan/H2CPTPP composite at 615 nm and 654 nm upon excitation at 425nm.

Abstract: In this study, we report a facile electrochemical method to obtain polyaniline/single-wall carbon nanotubes (PANI/SWCNTs) composite electrodes by combining the electroreduction of diazonium salts and electropolymerization of conductive polymers. In a first step, the SWCNTs are covalently functionalized with diphenyl amine through the electrochemical reduction of the 4-aminodiphenylamine diazonium salt in order to provide anchors for the subsequent polymer electrodepostion. The aniline oxidation remains possible on this grafted layer and PANI can easily be deposited on the diphenyl amine-modified electrodes. The electrochemically deposited PANI/SWCNTs composites exhibit excellent electrochemical charge storage properties making them promising electrode materials for high power supercapacitors.

Abstract: In this paper, nonlocal Euler-Bernoulli beam theory is applied to investigate the dynamical behavior of a single-walled carbon nanotube (SWCNT) with an extra added nanoparticle. The SWCNT is assumed to be embedded on a Winkler-type elastic foundation with cantilever boundary condition. This configuration can be used as a nano-mass sensor which works on the basis of the changing the natural frequencies. The results show that the added mass causes an obvious increase in sensitivity of SWCNT-based nano-mass sensor, especially for stiff mediums, small nonlocal parameters, and stocky SWCNTs.

Abstract: Nanocomposites of single-walled carbon nanotubes modified polypyrrole (PPy/SWNTs) were synthesized successfully by in situ oxidative polymerization method in the FeCl₃·6H₂O solution. The morphological structure, electrical conductivity and thermal stability of the nanocomposites were characterized by TEM, SEM, FTIR and TGA. The PPy/SWNTs were 50-100 nm in diameter of PPy coating uniformly on the surface of the SWNTs. FTIR spectra revealed the presence of covalently interaction between the PPy and the carbon nanotubes. The electrical conductivity of PPy/SWNTs composite and pure PPy were 93 and 8.0×10^-3 S/cm, respectively. Meanwhile, the PPy/SWNTs composites possessed higher thermal stability (65.9 wt. % weight loss at 600 °C) compared to pure PPy (81.2 wt. % weight loss at 600 °C), the content of SWNTs was 15.3 wt. %.