Contribution Of Carbon Nanotubes Research Articles

The formation mechanisms and mechanical effects of lattice defects in carbon nanotube reinforced 2024Al composite

Lattice defects significantly affect the mechanical performance of metallic materials. In this study, lattice defects of a carbon nanotube reinforced 2024 aluminum alloy (CNT/2024Al) composite were systematically investigated and the contribution of carbon nanotubes was illustrated. The results showed that dislocations and grain boundaries were closely related to the deformation behavior and lead to discontinuous yielding phenomena. Moreover, the carbon nanotubes reduced the stacking fault energy, which was conducive to forming stacking faults and a small number of twins in the composite. The stacking faults, twin boundaries, and intragranular Al4C3 phases hindered dislocation motion, thus enhancing the mechanical properties of the composite. In addition, the novel formation mechanism of the 9R structure was revealed: the Σ3(11‾1)/(151) incoherent twin boundary may dissociate into two tilt walls bounding a 9R structure (zone axis: [1‾01]), which enriches understanding of the relationship between Σ3 twin boundaries and the 9R structure.

A comprehensive proposed model for gas separation prediction of mixed matrix membranes containing tubular fillers

AbstractIn this study, a comprehensive model based on composite modulus prediction model named Takayanagi is rendered which can reasonably describe gas performance of tubular filler contained mixed matrix membrane (MMMs) by considering any possible interfacial morphology. Interphase thickness (t), interphase permeability (Pi), and percolation threshold concept are included in proposed model to accurate description of the MMM performance. Since tubular fillers can be in different surface area with the same chemistry, mechanical properties are useful for determination of interphase thickness based on Pukanszky approach. On the other hand, the maximum separation potential of tubular filler can be estimated by the proposed model. In order to examine the proposed model, polyvinylidene fluoride based MMMs containing pristine and acid modified multiwalled carbon nanotube are fabricated and characterized. The interphase morphology and contribution of carbon nanotubes in gas permeability of the constructed MMMs are interpreted in details by the proposed model.

Development of a Novel Multifunctional Cementitious-Based Geocomposite by the Contribution of CNT and GNP.

In this study, a self-sensing cementitious stabilized sand (CSS) was developed by the incorporation of hybrid carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) based on the piezoresistivity principle. For this purpose, different concentrations of CNTs and GNPs (1:1) were dispersed into the CSS, and specimens were fabricated using the standard compaction method with optimum moisture. The mechanical and microstructural, durability, and piezoresistivity performances, of CSS were investigated by various tests after 28 days of hydration. The results showed that the incorporation of 0.1%, 0.17%, and 0.24% CNT/GNP into the stabilized sand with 10% cement caused an increase in UCS of about 65%, 31%, and 14%, respectively, compared to plain CSS. An excessive increase in the CNM concentration beyond 0.24% to 0.34% reduced the UCS by around 13%. The addition of 0.1% CNMs as the optimum concentration increased the maximum dry density of the CSS as well as leading to optimum moisture reduction. Reinforcing CSS with the optimum concentration of CNT/GNP improved the hydration rate and durability of the specimens against severe climatic cycles, including freeze–thaw and wetting–drying. The addition of 0.1%, 0.17%, 0.24%, and 0.34% CNMs into the CSS resulted in gauge factors of about 123, 139, 151, and 173, respectively. However, the Raman and X-ray analysis showed the negative impacts of harsh climatic cycles on the electrical properties of the CNT/GNP and sensitivity of nano intruded CSS.

High active and ultra-stable bifunctional FeNi/CNT electrocatalyst for overall water splitting

Efficient non-noble metal catalysts are desirable to greatly improve the efficiency of anodic oxygen evolution and cathodic hydrogen evolution reactions. Herein, iron-nickel/carbon nanotube composites are synthesized as efficient bifunctional electrocatalysts for water splitting. The catalyst is homogeneously distributed, while the formation of iron-nickel alloy is confirmed. Because of the synergism of iron and copper and the contribution of carbon nanotubes, the Fe–Ni/CNT electrocatalyst shows excellent oxygen evolution reaction performance with the overpotential of 221 mV at 10 mA cm−2 and maintains stable at 0.48 V for 150 h. It expedites overall water splitting at 10 mA cm−2 with 1.50 V and show excellent stability at 20 mA cm−2 for 65 h, providing great potential for large-scale applications.

Carbon Nanotube Elastomer Composites

Composites of multi walled carbon nanotubes and several synthetic rubbers as well as natural rubber were investigated regarding their mechanical properties, electrical and thermal conductivity and vulcanization properties. The composites were prepared by a melt mixing process. Induction and cure times obtained from rheometer curves exhibited a considerable decrease with increasing filler loading and kinetic investigations using a first order model indicated a distinct reduction of the activation energy. An examination of the crosslink density by equilibrium swelling and hysteresis tensile testing showed a strong increase with carbon nanotube content. The analysis of the thermal conductivity revealed the presents of a considerable interfacial thermal resistance which restricts the contribution of carbon nanotubes to the composite thermal conductivity. The electrical percolation thresholds of the melt compounded composites depend on processing procedure as well as elastomer and CNT type. At least a partial exfoliation of the CNT aggregates was reached.

Removal of micropollutants and NOM in carbon nanotube-UF membrane system from seawater

One of the main problems for seawater reverse osmosis desalination is membrane fouling associated with natural organic matter. Bisphenol-A (BPA) and 17alpha-ethinylestradiol (EE2) are well-known endocrine-disrupting compounds that have been detected in wastewater and seawater. In this study, the contribution of carbon nanotubes (CNTs, single-walled carbon nanotubes) to membrane fouling control and the potential adsorption mechanisms of BPA and EE2 were investigated using artificial seawater (ASW) in a bench scale ultrafiltration (UF) membrane coupled with CNTs. For high ionic strength ASW, UVA254 nm is a good alternative for highly aromatic dissolved organic carbon (DOC) determination, with a very strong linear relationship (R2 > or = 0.99) with increasing DOC concentrations. Approximately 80% of DOC in ASW was rejected by the CNT-UF system where 31% of DOC was removed due to adsorption by CNTs. The presence of CNTs shows a 20% increase in membrane flux in ASW. A strong linear correlation between retention and adsorption of BPA and EE2 was obtained. The percentage of adsorption/retention of BPA and EE2 in UF-CNTs follows the order: 94.0/96.6 (DI + CNTs, EE2) > 86.2/90.0 (ASW + CNTs, EE2) > 73.6/78.9 (DI + CNTS, BPA) > or = 74.1/77.3 (ASW + CNTS, BPA) > 29.8/29.8 (ASW, EE2) approximately equal to 27.3/27.3 (ASW, BPA) > or = 25.3/25.3 (DI, EE2) approximately equal to 24.8/24.8 (DI, BPA). This indicates that retention by the UF-CNT system is mainly due to adsorption. Overall, EE2 adsorption was greater than BPA during the UF-CNT experiments, presumably due to the higher hydrophobicity of EE2 than BPA.

A review on carbon nanotubes in an environmental protection and green engineering perspective

Recent developments in nanotechnologies have helped to benchmark carbon nanotubes (CNTs) as one of the most studied nanomaterials. By taking advantages of CNTs extraordinary physical, chemical and electronic properties, a wide variety of applications has been proposed in various engineering fields. In this short review, the contribution of CNTs is addressed in terms of sustainable environment and green technologies perspective, such as waste water treatment, air pollution monitoring, biotechnologies, renewable energy technologies, supercapacitors and green nanocomposites. Consideration of CNTs for large scale application from the aspect of cost and potential hazards are also discussed. Based on the literature studied, CNTs pose a great potential as a promising material for application in various environmental fields.

Review of two microwave applications of carbon nanotubes: nano-antennas and nano-switches

This paper provides an overview of two potential applications of carbon nanotube devices in microwave technology. Firstly, the main structural, mechanical, thermal and electronic properties of carbon nanotubes are briefly reviewed. Then, the possibilities offered by metallic carbon nanotubes as nano-antennas in the E- and W-bands and further are investigated: comparison with macroscopic wire antennas is made, the major advantages brought by nanotubes but also technical issues to be addressed are discussed. Finally, the integration of carbon nanotubes in nano-electro-mechanical-systems (NEMS) is studied through nano-switches: the contribution of carbon nanotubes is detailed, state-of-the-art is described, as well as our future approaches for such nano-devices. To cite this article: S. Demoustier et al., C. R. Physique 9 (2008).