碳纳米管的表面修饰及其对碳纳米管/氟橡胶复合材料导电性能的影响

分别采用混酸和四氟化碳(CF4 ) 等离子体处理技术对碳纳米管(MWCNTs) 进行了表面修饰, 将处理前后的碳纳米管进行了XPS 和SEM 测试, 获得了处理后前的表面形貌和结构, 并采用溶液浇注的方式制备了MWCNTs/氟橡胶(FE) 复合材料, 探讨了不同碳纳米管状态(未处理、混酸处理、CF4等离子体处理) 的导电性能, 结果表明两种表面处理方式可以使MWCNTs 表面接上极性官能团。而且在相同的碳纳米管添加量下(质量分数分别为0. 1 %、0. 5 %、1. 0 %、2. 0 %) , 酸处理MWCNTs/ FE 的渗流阈值最小, 达0. 5 %。      

Modeling carbon nanotube reinforced composite materials with the cylindrical method of cells

Micromechanics modeling, utilizing a cylindrical method of cells (CMOC) model, is employed to obtain the effective mechanical properties of an elastic transversely isotropic, isothermal material system consisting of a hollow carbon nanotube (CNT) embedded in an isotropic polymeric material matrix. It is shown that weak interfacial bonding between the CNT and polymeric matrix, which is characteristic of this type of material system, can be modeled with the CMOC. Numerical solutions of the effective independent material constants are obtained, based upon appropriate values of the properties of the carbon nanotube and epoxy matrix. The numerical results are presented graphically and compared with corresponding classical closed‐form solutions. Copyright © 2015 John Wiley & Sons, Ltd.     

Embedded Fin‐Like Metal/CNT Hybrid Structures for Flexible and Transparent Conductors

In this paper, an embedded fin‐like metal‐coated carbon nanotube (Fin‐M/CNT) structure is demonstrated for flexible and transparent conductor wire applications. Embedded in a polydimethylsiloxane polymeric substrate, Fin‐M/CNT wires with a minimum width of 5 μm and a minimum pitch of 10 μm have been achieved. Direct current resistances of single Fin‐M/CNT wires, where the supporting CNT structures have been covered by Ti/Al/Au metal coatings of different thicknesses, have been measured. The high aspect ratio of the fin‐like structures not only improves the adhesion between the wires and the polymeric substrate, but also yields a low resistance at a small surface footprint. In addition, transparent Fin‐M/CNT grid lines with hexagonal patterns, with a sheet resistance of as low as 45 Ω sq^?1, have been achieved at an optical transmittance of 88%. The robustness of the Fin‐M/CNT structures has been demonstrated in bending tests up to 500 cycles and no significant changes in wire resistances are observed.     

Characterization of the uncertainties in the constitutive behavior of carbon nanotube/cement composites

This paper addresses the uncertainties associated with using carbon nanotubes (CNTs) as reinforcement for cement. These uncertainties emerge mainly from the CNTs’ wide range of mechanical properties and their interfacial behavior with cement. This study sheds light on the basis of choosing the optimal combinations of CNTs mechanical and interfacial parameters to improve the structural strength and ductility of CNT-reinforced cementitious composites. The finite element method (FEM) is employed to study the individual and interactive effects of five parameters, including interfacial shear (bond) strength, allowable slip, CNT Young’s modulus, residual bond stress and aspect ratio. Numerical results show that the parameters, at certain ranges of values, interact substantially and greatly alter the mechanical properties of the composite. It is also found that the governing parameter is the CNT Young’s modulus, which determines whether the composite is ductility critical or strength critical. Furthermore, the level of residual bond stress substantially influences the effect of other parameters, especially in the case of composite ductility.     

Characterization of the uncertainties in the constitutive behavior of carbon nanotube/cement composites

Abstract

This paper addresses the uncertainties associated with using carbon nanotubes (CNTs) as reinforcement for cement. These uncertainties emerge mainly from the CNTs’ wide range of mechanical properties and their interfacial behavior with cement. This study sheds light on the basis of choosing the optimal combinations of CNTs mechanical and interfacial parameters to improve the structural strength and ductility of CNT-reinforced cementitious composites. The finite element method (FEM) is employed to study the individual and interactive effects of five parameters, including interfacial shear (bond) strength, allowable slip, CNT Young’s modulus, residual bond stress and aspect ratio. Numerical results show that the parameters, at certain ranges of values, interact substantially and greatly alter the mechanical properties of the composite. It is also found that the governing parameter is the CNT Young’s modulus, which determines whether the composite is ductility critical or strength critical. Furthermore, the level of residual bond stress substantially influences the effect of other parameters, especially in the case of composite ductility.     

High-performance photoconductive channels based on (carbon nanotube)-(CdS nanowire) hybrid nanostructures

A photoconductive channel based on hybrid nanostructures comprising carbon nanotubes (CNTs) and CdS nanowires is fabricated by a directed assembly strategy and catalyst-assisted chemical vapor deposition (CVD). The photoconductive channels simultaneously exhibit large photocurrent and fast response speed. Furthermore, it can be easily applied to surfaces that are not flat, such as a glass tube. This is a simple but efficient strategy for various optoelectronic applications.     

Application of carbon nanotube in wireless sensor network to monitor carbon dioxide

Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure. Over the years, new discoveries have led to new applications, often taking advantage of their unique electrical properties, extraordinary strength and efficiency in heat conduction. Since industrialisation, human activities have resulted in steadily increasing concentrations of the greenhouse gases. Excess amount of carbon dioxide (CO₂) in living environment is toxic and unsuitable for human consumption. Thus, a need exists for accurate, inexpensive, long-term monitoring of environmental contaminants using sensors that can be operated on site. Over the past decade, many wireless sensor network (WSN)-based monitoring applications have been proposed. This article reviews the developments of sensing elements to monitor CO₂ in the environment. The cylindrical carbon molecules have novel properties that make them potentially useful in many applications in nanotechnology, electronics, optics and other fields of materials science, as well as potential sensing element in wireless sensor technology. They exhibit extraordinary strength and unique electrical properties, and are efficient thermal conductors. The unique properties of CNT makes it a potential sensing element in the WSN technology.     

Fabrication of Highly Stretchable Conductors via Morphological Control of Carbon Nanotube Network

Stretchable conductors, which can keep their excellent electrical conductivity while highly stretched, have been investigated extensively due to their wide range of applications in flexible and stretchable electronics, wearable displays, etc.; however, their preparation is often complicated and expensive. Herein, an efficient method to prepare high performance stretchable conductors through morphological control of conductive networks formed with carbon nanotubes (CNTs) in an elastomer matrix is reported. It is observed that an interface‐mediated method could be used to align randomly oriented filler during stretching and to induce buckling of CNTs during relaxation. Further morphological studies indicate the possible formation of a wavy CNT structure induced by cyclic pre‐straining. Subsequent thermal annealing is observed to collapse the oriented network and improve the local contacts between conductive networks. Through such a simple procedure, a conductivity of nearly 1000 S m^?1 and a stretchability of 200% can be achieved for composites containing 20 wt% CNTs. CNTs are observed to buckle over a large area in polymer bulk, and the combination of pre‐straining and thermal annealing modifies the conductive network in the elastomer matrix. As a general method, this could be used for easy fabrication of high‐performance stretchable conductors for arbitrary‐shaped objects on a large scale.     

CVD法工业化生产纳米碳管的研究

以乙炔为原料气,用工业化生产炉代替小型实验研究炉批量制备出了纳米碳管,产量为150g/h。TEM图和Raman光谱结果表明,纳米碳管管径均匀分布在20～30 nm间,具有很高的石墨化程度。同时,讨论了生产炉结构、工艺参数以及裂解温度、裂解时间和原料气流量对纳米碳管的影响。     

CVD法工业化生产纳米碳管的研究

以乙炔为原料气,用工业化生产炉代替小型实验研究炉批量制备出了纳米碳管,产量为150g/h.TEM图和Raman光谱结果表明,纳米碳管管径均匀分布在20～30 nm间,具有很高的石墨化程度.同时,讨论了生产炉结构、工艺参数以及裂解温度、裂解时间和原料气流量对纳米碳管的影响.