Different Amounts Of Carbon Nanotubes Research Articles

Sisal and jute composite containing carbon nanotubes for improved mechanical and thermal performance

Natural fiber composites are often sought after in industries, such as automotive and aerospace, due to their low density compared to traditional synthetic composites. Sisal and jute are renewable and biodegradable resources, making them attractive from a sustainability standpoint. The effect of carbon nanotube (CNT) insertion of a composed sisal and jute fiber composite material on the thermal and mechanical characteristics is investigated in this study. The primary objective of this research is to determine the exceptional mechanical strength and heat resistance that allows the composite-filled filling CNT to perform better than others. The methodical experimental approach was used to evaluate the effect of sisal and jute matrix and different amounts of CNTs’ mechanical and thermal properties. Thermal behavior is found by thermogravimetric analysis, and mechanical performance is used to qualify tensile strength, flexural strength, and impact resistance. The result suggests that CNTs may have reinforcing properties and significant tensile and flexural strength improvement. Impact resistance improved and increased the toughness of the composite material. The 7% CNT composite exhibited improvements in tensile strength of 63.9% and flexural strength of 46.6%, suggesting the synergistic reinforcing effect of CNTs. The high temperature from the use of need resistance shows promise for the composite material based on the tests of its capability for heat absorption and thermal stability. Various technical contexts are potentially useful in focusing on environmentally friendly material creation that exhibits exceptional thermal and mechanical properties.

Simultaneous enhancement of electrical conductivity and shape memory behavior of polystyrene/ethylene octene copolymer blend nanocomposites by CNTs through double percolation

The purpose of this paper is to investigate the effects of carbon nanotube (CNT) addition on the morphology as well as mechanical and electrical and shape memory properties of immiscible polystyrene/ethylene octene copolymer (PS/EOC) blends prepared by melt compounding. To prepare PS and EOC blends, weight percent of 80/20 and 50/50, different amounts of CNTs were varied between 0.05 and 1.5 phr. An investigation of the morphology of the PS/EOC blends using scanning electron microscopy revealed that when CNTs are added, the morphology of the blends changes from matrix-droplet to co-continuous. Based on the rheological results, blend nanocomposites exhibited solid-like behavior at low frequencies due to the formation of the 3D network of CNTs in mainly the PS phase. According to the electrical conductivity measurement, the electrical percolation thresholds for PS/EOC (80/20) and (50/50) samples were as low as 0.15 and 0.25 phr, respectively. Through the double percolation phenomenon, the electrical conductivity increased by 9 orders of magnitude by adding only 1.5 phr CNTs. Also, the shape fixity and recovery of PS/EOC/CNT (50/50/1.5) nanocomposite reached 100 % mainly contributed to increased interfacial elasticity and CNTs’ 3D network formation. The results showed that this method can be applied to produce materials with desirable electrical conductivity, shape memory, and mechanical properties.

Treatment of Water Contaminated with Diesel Using Carbon Nanotubes

The purpose of this research was to evaluate the adsorbent properties of carbon nanotubes by investigating, in particular, the possibility of their use in the purification of water contaminated with automotive diesel, caused, in most cases, as a result of spillage from underground tanks, leaks from pipelines, traffic accidents, etc. In particular, we investigated whether the high molecular weights of the hydrocarbon molecules present in diesel could influence the adsorption capacity of carbon nanotubes. Initial systems consisting of water and diesel were treated with different amounts of carbon nanotubes. The final post-adsorption phases were characterized using NMR analysis, FT-IR spectroscopy and TG-DTG-DTA thermal analysis. Carbon nanotubes showed great efficiency in the adsorption of diesel, the possibility of their reuse in several adsorption cycles and the consequent recovery of the adsorbed diesel and of the treated water.

Study on Mechanical Properties of Carbon Nanotube Reinforced Carbon Fiber/ Epoxy Resin Composites

Carbon nanotubes(CNTs) reinforced carbon fiber/epoxy resin composites with different amounts of carbon nanotubes were prepared by using carbon nanotubes as reinforcement. The effect of the amount of carbon nanotubes on the mechanical properties of the composites was studied. The results show that carbon nanotubes enhance the mechanical properties of carbon fiber resin composites to some extent. When the content of carbon nanotubes is 0.5%, the transverse tensile strength and modulus of the composites are increased by 32.7% and 9% respectively, and the flexural strength and modulus are increased by 12.8% and 16.4% respectively. When the content of carbon nanotubes is 0.3%, the compressive strength reaches the maximum and is increased by 28.7%.

The β Form in PVDF Nanocomposites with Carbon Nanotubes: Structural Features and Properties

Different amounts of carbon nanotubes (CNT) have been incorporated in materials based on poly(vinylidene fluoride) (PVDF) by solvent blending followed by their further precipitation. Final processing was performed by compression molding. The morphological aspects and crystalline characteristics have been examined, additionally exploring in these nanocomposites the common routes described in the pristine PVDF to induce the β polymorph. This polar β phase has been found to be promoted by the simple inclusion of CNT. Therefore, coexistence of the α and β lattices occurs for the analyzed materials. The real-time variable-temperature X-ray diffraction measurements with synchrotron radiation at a wide angle have undoubtedly allowed us to observe the presence of the two polymorphs and determine the melting temperature of both crystalline modifications. Furthermore, the CNT plays a nucleating role in the PVDF crystallization, and also acts as reinforcement, increasing the stiffness of the nanocomposites. Moreover, the mobility within the amorphous and crystalline PVDF regions is found to change with the CNT content. Finally, the presence of CNT leads to a very remarkable increase in the conductivity parameter, in such a way that the transition from insulator to electrical conductor is reached in these nanocomposites at a percolation threshold ranging from 1 to 2 wt.%, leading to the excellent value of conductivity of 0.05 S/cm in the material with the highest content in CNT (8 wt.%).

A novel Cu-carbon nanotube sheet composite manufactured via the ARB process: A microstructural and mechanical study

A Cu matrix composite was designed and produced successfully by adding carbon nanotubes (CNTs) as reinforcement particles. The accumulative roll bonding (ARB) process was used to introduce the material in the shape of the sheet. The process was repeated up to five ARB cycles to obtain a uniform composite with good mechanical properties. Different amounts of CNTs were added to the matrix of Cu in order to evaluate the behavior of the CNTs in the matrix of the Cu. Microstructural evaluations confirmed that by increasing the ARB cycles, a uniform distribution of the CNTs was achieved. However, for Cu-1%CNT considerable numbers of unbonded areas led to weak bonding. Also, the material responded differently to the applied tensile test during loading. For low amounts of CNT-contained composites, the ultimate tensile strength (UTS) was increased in each ARB pass, but, for Cu-1%CNT composite, the UTS was the lowest. Also, microscopy observations were used to study the distribution/configuration of CNTs. The weak bonding of the Cu layers in some spots was attributed to the agglomeration of CNTs between the layers. Fractography of the samples after the tensile test, also, showed remarkable separation between the unbonded layers.

Microstructures, thermal and mechanical properties of Al–Si-CNT composites for thermal management applications

In this work, a novel electronic packaging material, Al–Si-CNT composite, is fabricated by ball milling and hot extrusion of Al20Si powder blended with different amount of carbon nanotubes (CNTs). The influences of CNTs content on the microstructures, thermal properties and mechanical properties of the composites are investigated. The ball milling produces flake powders in which CNTs, accompanied by refined Si particles and in-situ formed k'-Al2O3, are uniformly dispersed in the Al matrix. The homogenous microstructures are subsequently inherited by the extruded composites. Compared to the Al20Si sample without CNT addition, the CNT-contained composites are more thermally stable and resistant to structural coarsening caused by Ostwald ripening effect. The composite with 2 wt % CNT content exhibits the best properties among all samples. It has a high tensile yield strength ∼235 MPa, and low thermal expansion coefficient ∼16.8 × 10−6 K−1 (at 50–400 °C) as well as acceptable thermal conductivity ∼102 Wm−1K−1 (at 50–400 °C). This study using hybrid reinforcements Si and CNTs to enhance the Al matrix composite is inspiring to design high performance thermal management materials.

Efeito de nanotubos de carbono em matrizes de cimento Portland

abstract: This study evaluates the effects of three carbon nanotubes with different geometric characteristics on the rheological behaviour and mechanical performance, as well as on the microstructure of mortars and cement pastes. For nanotube content ranging from 0.025 to 0.2 wt%, the yield stress and viscosity were determined by rotational rheometry, and mechanical performance was evaluated by flexural strength and dynamic modulus of elasticity. The microstructural analysis was performed by X-ray diffraction, thermo-gravimetric analysis and scanning electron microscopy (SEM). The obtained results showed that the yield stress presents a considerable increase as the carbon nanotube content increases. The viscosity was also influenced by the presence of carbon nanotubes. The flexural strength of mortars increases for different amounts of carbon nanotubes, and depending on the geometric characteristics of the carbon nanotubes, the material behaves like a composite. The microstructural analysis showed the nucleation of hydration products on the surface of the carbon nanotubes, and that the better mechanical performance of matrices containing carbon nanotubes is not related to the increase in hydration products.

Carbon Nanotubes Networking in Styrene‐Butadiene Rubber: A Dynamic Mechanical and Dielectric Spectroscopy Study

AbstractThe study of the reinforcement network in elastomer compounds is one of the most relevant issues for the application of these materials because their properties are strongly dependent on the obtained morphology. To this regard, the viscoelastic and dielectric behavior of vulcanized styrene butadiene rubber (SBR) reinforced with different amounts of carbon nanotubes (CNT) have been investigated and compared with the vulcanized unfilled SBR and the vulcanized SBR samples reinforced with a conventional amount of carbon black (40 phr). Differential scanning calorimetry (DSC) measurements have been carried out to highlight possible differences of the glass transition temperatures for all the reinforced compounds. The percolation threshold value of the nanocomposite samples has been estimated by dielectric analysis. Finally, dynamic mechanical analysis (DMA) measurements have been performed in tensile mode in the temperature range of −60 to 80 °C to obtain bothE′ andE′′. From these experimental data, the master curve for each sample has been estimated by using the time–temperature superposition principle in combination with the vertical shift approach. From the analysis of this latter, the activation energy, associated to the thermal movement of the reinforcement network, has been calculated to better elucidate the reinforcement mechanism in the nanocomposites.

Melt Spinning of Elastic and Electrically Conductive Filament Yarns and their Usage as Strain Sensors

Electrically conductive fibers are required for numerous fields of application in modern textile technology. They are of particular importance in the manufacturing of smart textiles and fiber composite systems with textile-based sensor and actuator systems. Elastic and electrically conductive filaments can be used as strain sensors for monitoring the mechanical loading of critical components. In order to produce such sensorial filaments, thermoplastic polyurethane (TPU) is compounded with carbon nanotubes (CNT) and melt spun. The mechanical performances of filaments produced at different spinning speeds and containing different amounts of CNT were tested. Furthermore, the correlation between the specific electrical resistance of the filaments and the mechanical strain were analyzed depending on the CNT-content and the spinning speed.

Broadband microwave absorbing materials for green electronics based on poly (lactic acid)/ethylene‐vinyl acetate copolymer blends loaded with carbon nanotube

AbstractPartially bio‐based conducting polymer nanocomposites constituted by poly(lactic acid) (PLA)/ethylene‐co‐vinyl acetate (EVA) (50:50 wt%) blend loaded with different amounts of carbon nanotube (CNT) were prepared for developing microwave absorbing materials. The effect of EVA characteristics and the mixing conditions on the electrical conductivity was investigated. The higher conductivity value was achieved using PLA@CNT master batch and EVA with 28% of VA. In fact, this system presented electrical percolation threshold of 7 × 10−4 volume fraction and a conductivity value of 3 × 10−3 S/m with the addition of 0.9 wt% (0.58 vol%) of CNT. A minimum reflection loss of −29 dB (electromagnetic (EM) attenuation of around 99.9%) at 11.7 GHz and the bandwidth (<−10 dB) of 4.9 GHz was observed with the presence of 0.58 vol% of CNT, whereas RL value of around −39.4 dB (EM attenuation of around 99.99%) at 14.7 GHz and a bandwidth of 4.6 GHz was observed for the composite loaded with 0.25 vol% of CNT. Due to the outstanding microwave absorption properties and wide absorption bandwidth with low amount of CNT, these composites are promising candidates for flexible materials suitable for shielding electronic devices in a wide frequency range.

Dynamic thermoelectromechanical characterization of carbon nanotube nanocomposite strain sensors

Recent advancements in materials science and bioinspired designs have led to the development of wearable strain sensors with high sensitivity and stretchability. However, the majority of strain sensors are simultaneously responsive to strain and temperature variations. Therefore, it is necessary to invent effective strategies to decouple this unwanted crosstalk for accurate and noise-free strain sensing in complex environmental conditions. Herein, a temperature-dependent 3D percolation model is presented capable of predicting the sensory response of stretchable strain sensors made of carbon nanotubes-elastomer nanocomposites under transient changes in strain and temperature. The nanocomposite strain sensors are fabricated by the vacuum filtration process, and their dynamic thermoelectromechanical properties are systematically investigated. The experimental results are then used to initiate, develop, and validate the proposed model. After the model validation, further studies are conducted to assess the dynamic response of strain sensors containing different amounts of carbon nanotubes at high temperatures, their signal-to-noise ratio, and temperature coefficient of resistance. Finally, to simulate a real-world scenario, virtual displacement and temperature profiles are generated, and the corresponding dynamic response of a strain sensor is predicted utilizing the modified 3D percolation model.

Fused filament fabrication of polyetheretherketone/multiwalled carbon nanotube nanocomposites: the effect of thermally conductive nanometric filler on the printability and related properties

AbstractFused filament fabrication is an additive layer manufacturing technique. It was extensively used at the beginning for the manufacturing of prototypes, and it has been adopted during the last few years for the manufacturing of fully functional components. Polyetheretherketone (PEEK) has been thoroughly investigated as a composite matrix because of its outstanding mechanical properties and thermal and chemical stability. This study is focused on PEEK nanocomposites with different amounts of carbon nanotubes (CNTs) (i.e. 3, 5, 10 wt%) produced in the form of a filament and successively 3D printed. The influence of the CNT presence on printability was studied and correlated to the nanocomposite feedstock thermal and microstructural properties, defining a substrate temperature processability window. Interestingly the addition of CNTs significantly limits the processability window due to the influence on the crystallization process and viscosity. Moreover, the thermal and mechanical properties of 3D printed bulk samples were investigated in view of the PEEK/CNT nanocomposite feedstock properties. © 2021 Society of Chemical Industry

Enhancing strength and ductility in carbon nanotubes reinforced zinc matrix composites by in-situ formation of ZnC8

Abstract To obtain a strong interfacial bonding between carbon nanotubes (CNTs) and zinc (Zn) matrix has always been a crucial issue for the preparation of high-performance CNTs-Zn composites. In the present study, a hot-pressed sintering process is used to fabricate the 27 wt% Al-containing Zn alloy composites with different amount of CNTs. The tensile strength and ductility are simultaneously improved by the addition of CNTs. The results of the interface characterization also indicate that the in-situ formed carbides, ZnC8, are formed between CNTs and Zn matrix. These carbides can lock the dispersed CNTs in place and improve the CNTs-Zn interface bonding. This study provides a novel approach to improve the load transfer efficiency of CNTs for fabricating CNTs reinforced Zn composites with high performance.

Effect of carbon nanotubes grown temperature on the fracture behavior of carbon fiber reinforced magnesium matrix composites: Interlaminar shear strength and tensile strength

The design of an interfacial structure is particularly important for load transfer in composites. In this paper, different amounts of carbon nanotubes (CNTs) were grafted onto the carbon fiber (CF) surface by adjusting grown temperature using injection chemical vapor deposition (ICVD). The prepared CF preform grafted with CNTs (CNTs-CF) were used to reinforce magnesium alloy by squeeze casting process. The microstructures were analyzed by means of optical microscope (OM) and scanning electron microscope (SEM), and the interlaminar shear strength (ILSS) and tensile strength of the composites were determined by double-notch shear test and tensile test. The results indicated that moderate ILSS was more conducive to improving the tensile properties of carbon fiber reinforced magnesium matrix (Cf/Mg) composites. Compared with Cf/Mg, the tensile strength of composite with CNTs increased by about 80%. For Cf/Mg composites grafted with CNTs, CNTs had the effects of delaying crack propagation and increasing energy consumption by the pull-out and bridging mechanism, which were the main reasons for improving the strength. The analysis of shear fracture surface showed that the crack propagation path can be optimized by adjusting the amounts of grafted CNTs. The presence of CNTs affects the stress distribution and consequently the crack initiation as well as the crack propagation.

Electrospun polyurethane/carbon nanotube composites with different amounts of carbon nanotubes and almost the same fiber diameter for biomedical applications.

The aim of this study was to investigate the net effect of raw carbon nanotube (CNTs) on the final properties of polyurethane (PU)/CNT composites considering their biomedical applications. So, neat PU and PU/CNT composites containing different amounts of CNTs (0.05%, 0.1%, 0.5%, and 1%) were prepared by electrospinning. Electrospinning parameters optimized to have a bead-free structure with no significant difference between their mean fiber diameter and porosity percentage. The results showed adding CNTs caused an increase in crystallinity percentage, water absorption ratio, young modulus, toughness, conductivity, degradation time in an accelerated medium, clotting time, and human umbilical vein endothelial cells adhesion. But a direct relationship between CNT percentage and the calcium adsorption was not detected. Moreover, no significant cytotoxicity was observed for 7-day extracts of all samples. These nanocomposites have a vast range of properties which make them a good candidate as neural, cardiovascular, osseous biomaterials or tendon, and ligament substitute.

Developed carbon nanotubes/gutta percha nanocomposite films with high stretchability and photo-thermal conversion efficiency

It is necessary to develop novel nanocomposite films for reducing soil pollution caused by the use of petroleum-based materials. In this paper, a simple solvent-cast method was used to fabricate gutta percha films with carbon nanotubes (CNTs) by homogeneously dispersing different amount of CNTs (0%, 0.5%, 1%, 1.5% and 2%, wt/%) through gutta percha matrix. The obtained nanocomposite films were characterized by Raman spectroscopy, atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Meanwhile, the wettability, mechanical properties, water vapor barrier properties, electromagnetic absorption of films as well as their photo-thermal conversion of the soil were investigated in detail. The results showed that the 1% loading of CNTs film significantly improved the mechanical properties of the nanocomposite films compared to the control: the tensile strength, elongation at break and Young's modulus were increased by 44.0%, 30.5% and 26.1%, respectively. In addition, the CNTs/gutta percha films demonstrated lower thermal stability, glass transition temperature (Tg), melting enthalpy (ΔHm) crystallinity and water vapor permeability (WVP) than the pristine gutta percha film. Especially, the WVP value of the film with 1% CNTs was the lowest. And finally, the soil warming experiments showed that the 1% CNTs film had the highest 83.73% photo-thermal conversion efficiency, compared to the 18.61% for control. This nanocomposite film has the potential for application in agriculture in arid regions because of its high stretchability and photo-thermal conversion efficiency, which could be potential application in agricultural mulch.

Molecular dynamics simulations of mechanical properties of swollen nitrile rubber composites by incorporating carbon nanotubes

AbstractMolecular models of pure and 10% and 20% swollen nitrile rubber matrices were developed. Different amounts of carbon nanotubes (CNTs) were incorporated into the swollen nitrile rubber matrices. The effects of the swelling behaviors and introduced CNTs on the mechanical properties of the nitrile rubber matrices were investigated using molecular dynamics simulations. The simulation results show that compared to the pure nitrile‐butadiene rubber (NBR) models, the elastic moduli and tensile strengths of the nitrile rubber matrices were reduced by ~31.72% and 20.10% (at a swelling ratio of 10%) and 68.28% and 36.82% (at a swelling ratio of 20%), respectively. Compared to those of the swollen NBR models without CNTs, after the introduction of one CNT, the elastic modulus and tensile strength improved by ~67.02% and 4.17% (at a swelling ratio of 10%) and 215.27% and 7.00% (at a swelling ratio of 20%), respectively. The mechanical properties of the nitrile rubber matrix improved when the content of CNTs increased. The radial distribution functions of the rubber materials, interfacial energies of the reinforced regions, and mean square displacements and diffusion coefficients of the solutions were analyzed. The introduced CNTs blocked the diffusion of the solute in the nitrile rubber matrix. This study elucidates the swelling behaviors of rubber materials from an atomic perspective and mechanical properties of carbon‐nanotube‐reinforced swollen rubber matrices.

Carbon-nanotube/TiO2 materials synthesized by a one-pot oxidation/hydrothermal route for the photocatalytic production of hydrogen from biomass derivatives

Hybrid photocatalysts containing different amounts of carbon nanotubes (CNTs) and TiO2 were synthesized by a one-pot oxidation/hydrothermal route and used for hydrogen production from aqueous solutions of methanol and glycerol under UV-LED irradiation. Platinum nanoparticles (1 wt%) were used as co-catalysts. Different techniques, namely X-ray diffraction, transmission electron microscopy, photoluminescence, electrochemical impedance, diffuse reflectance UV–vis spectroscopy, thermogravimetry and N2 adsorption were used to characterize the prepared materials. The presence of both CNTs and Pt has a great influence on the photocatalytic activity of CNT-Pt/TiO2 nanocomposites. The presence of CNTs extend the photo-response of TiO2 to the visible region, narrow its bandgap energy, enhance the charge mobility and reduce the electron/hole recombination. The hybrid material loaded with 1 wt% of CNT (1%CNT-Pt/TiO2), displayed the highest photoactivity for hydrogen production under UV-LED (384 nm) irradiation using both methanol and aqueous glycerol solutions, with 2327 and 2091 μmol g−1 of H2 produced at the end of 2 h of irradiation, respectively. Also, this material showed excellent photostability during at least three cycles.

Effect of fungal degradation on technological properties of carbon nanotubes reinforced polypropylene/rice straw composites

Effects of fungal decay period on the technological properties of polypropylene/rice straw composites reinforced with different amount of carbon nanotubes (CNTs) were evaluated in this research work. The composite specimens were prepared using an internal mixer followed by compression molding. The specimens were then subjected to the fungal decay using white-rot fungus ( Coriolus versicolor) for 1, 2, 3, and 4 months. The degree of fungal attack was recorded by determining the weight loss of the specimens. The physical and mechanical properties including water uptake, flexural strength, and impact strength (IS) were investigated. The results indicated that the weight loss of the specimens was significantly reduced by increasing the CNT loading levels. The weight loss ratio of the specimens with the CNT was lower than that of the specimens without the CNT. The modulus of rupture, modulus of elasticity, and IS of the specimens exposed to the fungal degradation increased in the presence of CNT. Furthermore, the decayed specimens without CNT had higher water uptake than those of the specimens with CNT. This was attributed to the decrease in the number of cavities on the surface of the composites containing CNT. Based on the findings obtained from the present study, it was concluded that the amount of the CNT should be considered according to the severity and duration of the fungal exposure.