Agglomeration Of Nanotubes Research Articles

Synthesis and characterization of surface modified MWCNTs reinforced PVA composite films.

Polymers have been ruling the packaging industry for decades due to their versatility, easy manufacturability, and low cost. The overuse of non-biodegradable plastics in food packaging has become a serious environmental concern. Multi-walled carbon nanotube (MWCNT) reinforced nanocomposites have exceptional electrical, thermal, and mechanical properties. However, a major difficulty in the synthesis of CNT-reinforced nanocomposites is the nanotube agglomeration, which results in poor dispersion and less interfacial bonding between reinforcements and matrix, limiting its advantages. Although acid treatment is effective, strong acids, treatment timing, and sonication power can lead to nanotube damage. This study introduces a novel approach to enhance PVA nanocomposite films' mechanical, thermal, optical, and antibacterial performance using polydopamine-coated CNTs, which are more effective than pristine or acid-treated CNTs, making them promising for food packaging applications. Pristine CNT reinforced polyvinyl alcohol (PVA) nanocomposite films were fabricated with varying concentrations of CNTs (0wt%, 0.5wt%, 1.0wt%, 1.5wt%, and 2.0wt%). These samples underwent mechanical, thermal, and optical characterization for the optimization of CNTs' concentration in the PVA matrix. Then the optimized amount of acid-treated and polydopamine-coated CNTs was used to fabricate PVA/CNT films. The mechanical, thermal, and optical characteristics of the resultant films were investigated. It was found that the polydopamine coating on CNTs improved the mechanical, thermal, and optical properties of the films as compared to those of pure PVA, PVA/pristine CNT, and PVA/acid-treated CNT films. Moreover, the resultant film also demonstrated good antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) in comparison to pure PVA.

Interfacial Characterization of Graphene Oxide and Carbon Nanotubes-Strengthened Aluminium Matrix Composites

Fast innovations and improvements in the manufacturing sector continuously demand new and reliable materials to create higher quality goods faster. Metal matrix composites (MMCs) are one of the most conspicuous materials to achieve vital jobs in the manufacturing industry. They are growing as critical materials owing to their unique properties, such as higher strength, superior abrasion and wear resistance, and lower constants of thermal enlargement while maintaining greater corrosion resistance. Aluminium (Al) matrix composites (AMCs) are the most important candidates to fabricate intricate shapes of apparatus in different sectors such as aerospace, automobile, and marine industries. On the other hand, its poor hardness and decreased abrasion resistance have limited its application in some crucial engineering sectors. On the other hand, carbon nanomaterials, including graphene oxide (GO) and carbon nanotubes (CNTs) are considered excellent reinforcement nanomaterials for strengthening AMCs. In this research, we add 0.5 wt. % GO or 0.5 wt. % CNTs to strengthen the AMC. This study fabricates the composites through the powder metallurgical method. This study conducts different analyses related to texture, chemical structure, porosity, interface and reinforcement structure, and Electron Backscatter Diffraction (EBSD) of developed composites. EBSD is used to determine the local crystal configuration and crystal orientation at the surface of a specimen. Pole figure maps are used to analyze the texture of the developed composite specimen. The Al/0.5 wt. % GO material demonstrated a more enhanced surface morphology than pure Al sample owing to the restraining properties of GO, which led to better mechanical characteristics. While, the Al/0.5 wt. % CNT material possessed the equal average particle size as the pure Al sample and revealed a reduced engineering stress. This phenomenon was characterized by a lower performance of load transfer from the Al material to the strengthening materials, due to the deficiency of chemical reactions at the boundaries and the extensive agglomeration of the carbon nanotubes.

Effect of surface-active substances on the macrodispersion behavior of thermal stress-modified multi-wall carbon nanotubes in cryogenic environments

In the preparation of nanocomposites, the agglomeration of multi-walled carbon nanotubes (MWCNTs) in the composite due to their low colloidal stability limits their use in industrial areas. To overcome these problems, it is important to develop simpler, economical, high-yield and non-hazardous techniques to replace existing techniques with low yields, expensive additional equipment or hazardous liquids. This study explores how surfactants affect the macrodispersion of thermal stress-modified MWCNTs in cryogenic environments, focusing on their application in polymer film preparation. Firstly, optimal conditions for modifying MWCNTs through thermal stress were identified using liquid nitrogen. Parameters assessed included the number of cycles (2, 4, and 6), duration in liquid nitrogen (10, 20, and 30 min), and subsequent waiting time at room temperature (5, 12, and 20 min). Results showed that the highest surface area was obtained with 2 cycles, 20 min in liquid nitrogen, and 5 min at room temperature. Analytical techniques such as Brunauer-Emmett-Teller (BET), X-Ray Diffraction (XRD), High Contrast Transmission Electron Microscopy (CTEM) and Raman spectroscopy were used to evaluate the functionalization process's effects on MWCNTs' internal graphitic structure and physicochemical properties. CTEM micrographs indicated that thermal stress reduced the length of MWCNTs, while Raman analysis showed improved graphite quality. The modification process, carried out with 100 % efficiency and no sample loss, increased the BET surface area from 297.551 m2/g to 397.295 m2/g. The study also investigated the impact of surfactants (polyethylene glycol sorbitan monooleate-Tween 80, sodium dodecyl sulfate-SDS, and hexadecyltrimethylammonium bromide-CTAB) on MWCNTs' macrodispersion degrees (DM%) and energy band gaps via UV–visible (UV–Vis) absorption spectroscopy. CTAB provided the highest and most stable macrodispersion, reducing the energy band gaps of MWCNTs from 5.65–5.75 eV to 3.53–3.60 eV. CTAB showed excellent colloidal stability with a zeta potential of 44.2 mV, while SDS had −49.9 mV. Polyvinyl alcohol (PVA) polymer films, created using MWCNT solutions with optimal macrodispersion, were confirmed by Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimeters (DSC), and BET surface area analyses to have successfully and homogeneously incorporated MWCNTs. In addition to the superior properties of MWCNTs modified with the functionalization technique developed within the scope of this study by increasing their specific surface area and porosity, the excellent colloidal stability provided may have various effects in many industrial areas. These advantages enable MWCNTs functionalized with the developed technique to have a wider range of applications in industrial applications and provide more efficient and sustainable solutions.

Revisiting the effects of carbon nanotube agglomerates in cement

Agglomerates of carbon nanotube (CNT) are typically considered as defects in cement matrix, yet without a clear physiochemical picture regarding why and how. By representing CNT agglomerates with CNT sponge powders (CNTSPPs), we discovered that hydrates can precipitate in the pores of CNTSPPs to form a CNT/hydrates nanocomposite shell, the thickness and compactness of which are dependent on the curing temperature. In contrast to the detrimental effects of CNTSPPs for the samples cured under standard condition, the addition of 0.05 wt % CNTSPPs increased the 28d compressive strength by ∼16 % compared to the reference sample under steam curing condition. This is because steam curing condition significantly improves the hydrophilicity of CNTSPPs, resulting in its absorption of pore solution and calcium ions, which eventually increase the CNT/hydrates nanocomposites shell thickness and microhardness. Such nanocomposites shell with high mechanical properties can screen the negative effects of the porous inner CNTSPPs.

In‐situ preparation of modified‐halloysite/thermoset nanocomposites via thiol‐epoxy click chemistry

AbstractIn the current study, thermoset nanocomposites including halloysite nanotubes (HNTs) have been prepared through thiol‐epoxy click reaction at ambient conditions. Naturally available HNTs are first modified separately by epoxy and thiol groups and used as nanofillers in a mixture of trimethylolpropane triglycidyl ether and trimethylolpropane tris(3‐mercaptopropionate) ranging from 0 to 5 wt%. Fourier transformed infrared (FT‐IR) spectroscopy has been used to observe the characteristic bands of the pure and modified halloysite, neat thermoset, and HNT/thermoset nanocomposites. Thermal properties of epoxide‐modified and thiol‐modified halloysite nanotubes and also final thermoset nanocomposites have been investigated using thermogravimetric analysis (TGA) by comparing pure halloysite and neat thermoset, respectively. The dispersion of HNT nanotubes in thermoset matrix has been examined with scanning electron microscopy (SEM). In addition to the agglomerated/non‐agglomerated distribution, the present of HNT has been proved by EDX. The effect of HNT‐Epoxide and HNT‐Thiol loadings on mechanical properties has been examined by tensile test. All nanocomposites were found to exhibit better tensile strength than that of neat thermoset, called as reference sample. The most enhanced mechanical properties have been detected in the nanocomposite with 3% modified‐HNTs by weight because of the best dispersion, which promotes effective interactions between the nanotubes and thermoset matrix. Tensile strength of thermoset nanocomposites increased by 43% and 62%, while elongation at break increased by 58% and 149% when 3 wt% HNT‐Epoxide and 3 wt% HNT‐Thiol were added to the matrix, respectively. Further increase of HNT added to the matrix causes agglomeration of nanotubes and thus deterioration of mechanical properties.Highlights Pure HNT was modified and successfully converted into HNT‐Epoxide and HNT‐Thiol. In‐situ preparation of thermoset nanocomposites with modified‐HNTs was effectively achieved via thiol‐epoxy click chemistry. Mechanical properties increased significantly with both HNT‐Epoxide and HNT‐Thiol loading ratio up to 3 wt%. The presence and agglomerated/non‐agglomerated dispersion of modified‐HNTs in the thermoset matrix were verified by SEM–EDX analysis.

Improved energy method and agglomeration influence of carbon nanotubes on polymer composites

In this paper, the geometric analysis of carbon nanotubes (CNTs) without external loading is carried out by energy method. Based on the theory of molecular mechanics, an improved mechanical model is proposed to predict the energy of armchair carbon nanotubes under stress-free conditions, and the diameter of CNTs is estimated according to the principle of minimum energy. The results show that the diameter obtained by the improved model is larger, but basically consistent with that obtained by conformal mapping. The inversion energy term is added to the modified model, and the inversion energy term related to atomic curvature is characterized by the conization angle. It can be seen from the error that the inversion energy of carbon nanotubes can not be neglected in the stress-free state, especially in the case of small diameter. The agglomeration of nanotubes is one of the important factors, which affects the effective elastic modulus of nanocomposites. Here, a new micro-mechanics model consisting of both agglomeration of CNTs and pure matrix is also presented to analyze its effect on the effective elastic modulus. It is noted from the results that the stiffness of nanocomposites is very sensitive to the CNTs agglomeration.

Bed structure of CNT agglomerates in gas–solid fluidized beds

In this study, the bed structure according to the flow regime of fine particles in gas–solid fluidized beds was studied by measuring the pressure drop and heat transfer coefficient. Two types of carbon nanotube (CNT) agglomerates with behavior similar to Geldart A and Geldart B and two types of glass bead (GB) particles corresponding to Geldart A and Geldart B classification were used. CNTs fluidized in the form of agglomerates, and in some CNT agglomerates, a homogeneous expansion regime with suppressed generation of bubbles, were observed. In the homogeneous expansion regime of CNT agglomerates, the relationship between superficial velocity and voidage was consistent with the Richardson–Zaki equation, and had a higher n value than that of Geldart A particles and fumed silica agglomerates. In this regime, small-diameter channels coexisted, and due to unstable fluidization at low superficial velocity, intermittent bed collapse occurred. In the homogeneous expansion regime of GB particles, the heat transfer coefficient remained constant, and as bubbles were generated, the heat transfer coefficient increased. On the other hand, as the superficial velocity increased, the heat transfer coefficient of CNT agglomerates continuously increased, regardless of the flow regime transition. In the homogeneous expansion regime of CNT agglomerates, unlike Geldart A particles, movement of agglomerates within the bed was confirmed, and a dynamic bed structure was present, in which the movement increased according to the superficial velocity.

Nonlinear Optimized PID Vibration Control of Thermal-Dependent FG Composite Porous Plates Reinforced by Agglomerated CNTs

This research study aims to delve into the effects of carbon nanotubes (CNTs) agglomeration on the dynamic characteristics of smart functionally graded (FG) porous sandwich plates. The structure of the sandwich plate comprises a core layer that incorporates dispersed CNTs within a polymer matrix. In addition, two layers are equipped with piezoelectric sensors and actuators. The agglomeration of CNTs is mathematically modeled using the Eshelby–Mori–Tanaka approach, accounting for both complete and partial agglomeration states. Moreover, the study takes into account the thermal-dependent behavior of CNTs. Subsequently, an optimal nonlinear proportional-integral-derivative (PID) control scheme based on the Bat optimization algorithm is applied to mitigate vibrations within the composite structure. Unlike the fixed gains of the classical PID, the nonlinear version dynamically adjusts its parameters in real time, ensuring enhanced responsiveness and stability. Furthermore, a comprehensive numerical investigation is conducted to assess the impact of several parameters on the natural frequencies in the frequency domain. These parameters encompass porosity distributions, porosity coefficients, reinforcement patterns, weight fractions of nanofillers, temperature, and the agglomeration of CNTs. The vibration attenuation performance of both nonlinear and classical PID controllers is evaluated through numerical simulations. The findings indicate the robustness and rapid disturbance rejection of the proposed control scheme.

Continuous iron spreading on carbon-shell composite nanotubes for electromagnetic wave absorption

Iron-based nanotubes are promising candidates for high performance electromagnetic wave absorbing fillers due to their high aspect ratio, light weight, high axial permeability and high saturation magnetization. Furthermore, the introduction of carbon can improve dielectric loss and block the agglomeration of iron nanotubes. Here, Fe@C composite nanotubes were prepared by introducing carbon onto the surface of precursor α-FeOOH’ fibers followed by hydrogen-thermal annealing. We find that Fe@C composite nanotubes retain the one-dimensional nanostructure of the precursor throughout the annealing. The well-developed lattice and nanostructure of Fe@C nanotubes endow high saturation magnetization, high anisotropy, suppressed eddy current effect and cross-particle exchange coupling as well, and thus contribute to an enhanced permeability. Coatings with Fe@C as fillers achieve a reflection loss of up to −69.34 dB at 3.37 GHz at the matching thickness of 3.97 mm. The Fe@C composite nanotubes developed here are a promising candidate for high performance electromagnetic wave absorbing fillers.

A comprehensive morphology study on the carbon nanotube agglomerations in cementitious composite

To comprehensively understand the fundamental role of carbon nanotubes (CNTs) in cementitious composites, three independent methods were employed to investigate the morphological characteristics of the composites. The embedding method and the depositing method controlled the direction of hydrate reactions by compulsorily segregating CNTs and cement grains, helping to more accurately deduce the formation process of various morphologies. The sectioning method used focused ion beam for precise cutting, enabling in-situ morphology information that cannot be observed through mechanical polishing. This study provides the first visual evidence to demonstrate that the micro-agglomerations of CNTs were sufficiently incorporated into the hydration products, indicating that CNT agglomerations may not be the primary cause for the decline in the mechanical properties of carbon nanotube cementitious composites. Furthermore, this study proposes the physical entrapment mechanism as a substitute for the ambiguous nucleation mechanism.

Non-linear stability characteristics of randomly distributed CNT-reinforced fiber composite beams under thermo-mechanical loadings

The aim of the present study is to elucidate the non-linear stability characteristics of randomly distributed carbon nanotube-reinforced fiber composite (RD-CNTRFC) beams subjected to thermo-mechanical loading. Effective material properties of RD-CNTRFC are estimated using the Eshelby-Mori-Tanaka approach and Halpin–Tsai micromechanical techniques. The material properties are considered to be temperature-dependent, and the influence of carbon nanotube (CNT) agglomeration is also incorporated in material properties estimation of hybrid matrix. The strain-displacement relations are assumed by incorporating the higher-order shear deformation theory and geometrical nonlinearity (von Kármán). The governing partial differential equations are obtained by minimizing the total potential energy of the beam. Buckling loads of beam subjected to in-plane compressive loads are estimated using Eigen value approach. Similarly, buckling temperatures are also determined by solving Eigenvalue problem iteratively due to temperature-dependent material properties. The non-linear equilibrium paths under thermal and mechanical loadings are traced through iterative Eigenvalue approach. Numerical results are presented to elucidate the influence of various parameters like CNT agglomeration, ply sequences, span-to-depth ratio, boundary conditions, and mass fraction of CNTs.

Supercapacitors Based on Spider Nest–Shaped Nickel Foam Electrodes Operating in Seawater

Abstract An environmental-friendly supercapacitor based on aqueous electrolyte was fabricated. Electrodes with conductive spider nest–shaped three-dimensional (3D) porous structures were prepared for the assembly of symmetric supercapacitors. The nickel foam was modified by multiwalled carbon nanotubes and β-cyclodextrin. The construction of the spider nest was stabilized via the chemical bond inside carbon nanotubes, π–π stack effects among carbon nanotubes, and physical adsorption between nickel foam and carbon nanotubes substrate. The role of β-cyclodextrin is a dispersant to prevent agglomeration of carbon nanotubes, thereby enhancing electroactive surface area of nickel foam and improving the specific capacitance of the electrodes. Furthermore, the electrodes exhibited excellent rate capability. The obtained symmetrical supercapacitors exhibited an excellent power density of 17,561.3 W kg−1, a good specific capacitance of 398.8 F g−1, and an energy density of 154.8 Wh kg−1 for 4000 cycles with outstanding cycling stability. In addition, the specific capacitance, energy density, and power density of the supercapacitor operating in seawater were found to be 100.2 F g−1, 17.8 Wh kg−1, and 2568 Wh kg−1, respectively, for 3000 cycles. Overall, our findings indicate that the supercapacitor could stably operate in seawater and shows potential for use as an ecofriendly power supply to marine engineering equipment.

Improving the fatigue life of composite by using multiwall carbon nanotubes

Abstract The fatigue life of polymer materials like epoxy can be improved by using stiffeners such as carbon fiber and/or adding multiwall carbon nanotubes (MWCNTs). This article studies the effect of adding MWCNTs with different ratios (0.5, 1, and 2 wt%) to epoxy and composite (epoxy + 30% carbon fibers). The experimental results of the fatigue test with fully reversed bending stress (with R = −1) showed a maximum increase of 788% in fatigue life when adding 1 wt% MWCNTs to epoxy, while the maximum improvement ratio reaches 2,500% when adding 1 wt% MWCNTs to composite. The best results of fatigue life improvement were observed for samples with MWCNTs of 1 wt%. The material will be transferred from low cycle fatigue (less than 105 cycles) to high cycle fatigue (more than 105 cycles) by adding 1 wt% of MWCNTs. At the same time, the ratio of MWCNTs of more than 1 wt% (such as 2 wt%) will decrease the fatigue life due to the agglomeration of nanotubes inside the resin and reduce the positive effect of it. These agglomeration points work as a barrier to load transfer and stress concentration points. The numerical model was built to simulate the fatigue test and compare the results with the experimental with a discrepancy value of 7.5%.

Fractal Approach to Dielectric Properties of Single Walled Carbon Nanotubes Reinforced Polymer Composites

In this paper, the internal structure and dielectric properties of unsaturated polyester resin-based neat and single-walled carbon nanotube reinforced composites were comprehensively evaluated with the fractal analysis using the Fast Fourier Transform (FFT). The greyscale images, bitmap (BMP) images and 3D tomographic images were obtained by converting the scanning electron microscope images of the materials. It was observed that the distributions of components in the resin for both materials are irregular and their surfaces exhibit anisotropic behaviors. The surface coating rate (SCR) and fractal dimensionality (FD) of the materials were also calculated using the power spectrum. It has been observed that the fractal dimensionality of the composites can be changed by the doping process and the fractalization of the nanotube doped sample increases compared to the pure material due to nanotube agglomeration, spatial distribution and the orientation. The increase in fractalization as a result of this agglomeration and orientation in carbon nanotubes explains the high dielectric constant values observed at low frequencies by increasing the number and size of carbon nanotubes clusters that act as micro capacitors in certain regions of the matrix. It has been reported that the calculations for the surface coverage ratios for both samples also support these results.

Insight into the carbon nanotube agglomeration deteriorated fire safety of epoxy

Carbon nanotube (CNT)/epoxy composite is a star lightweight structure material. However, the reason why well-dispersed CNTs retard the combustion of epoxy while CNT agglomerations always accelerate it instead seems still confusing, which severely limits the further understanding and design of the high-performance CNT/epoxy composite. Herein, with CNT agglomerations inside, 4coCNT/epoxy composite and 2coCNT0.5/epoxy composite were prepared to reveal the truth of the dramatically worsened flame retarding performances compared with their expected values. The void-rich CNT agglomerations were proved to be qualified candlewick-like fillers after directly observing the formations of micron-diameter fiber-like agglomerations by scanning electron microscope (SEM) and X-ray computed tomography (XCT); verifying the ability of CNT agglomerations to allow the epoxy melt to wet, spread, and flow on their surface. The thermogravimetric analysis (TG) and the limited oxygen index (LOI) results suggested that fire is necessary for the CNT agglomeration to worsen the thermostability of composites. With the presence of the liquid-phase combustible epoxy melt in the fire captured by a high-definition camera, all the requirements to induce the candlewick effect were satisfied. Ruling out a popular explanation that the agglomerated CNTs promote polymers' inflammability by cracking chars created during the combustion, a similar but distinct candlewick effect was then proposed and specially defined as “nano-candlewick effect” in the present study. The nano-candlewick effect defeated the flame-retarding free radical scavenging effect of the dangling bonds from coCNT and coCNT0.5, and further worsened the flame retardancy of the epoxy matrix. The detailed working mechanism of the nano-candlewick effect was described. The mechanism is supposed to be appropriate for polymer nanocomposites with candlewick-like fillers inside, and account for the dramatically accelerated combustion.

The effect of interphase and agglomeration on the mechanical properties of aluminum matrix nanocomposites reinforced with carbon nanotubes

The interphase phenomena are a critical problem for estimating the mechanical behavior of carbon nanotube-reinforced aluminum composites. In this research, the Aluminum-carbide (Al4C3) interphase and carbon nanotubes (CNTs) agglomeration effects on the mechanical properties of Aluminum /Carbon nanotubes composites are investigated using a numerical micromechanical model. Moreover, the impacts of the CNTs fraction, agglomeration, Al4C3 interphase, and their diameter on the elastic modulus of Aluminum (Al) composites are explored. The results demonstrated the effect of CNTs agglomeration and Al4C3 interphase on Young’s modulus of Al composites significantly when the CNT fraction increases; In addition, it observed that with increasing interphase thickness, Young’s modulus of Al composites increases and is changed with variation of agglomeration shape. The Literature’s experimental results validated the applicability of the present finite element (FE) model. The results of this study are hard evidence for CNT/ Aluminum composites creating potential applications in industry, especially for automobile and aircraft fields.

Study on Interfacial Interaction of Cement-Based Nanocomposite by Molecular Dynamic Analysis and an RVE Approach

There is an increased demand for cement nanocomposites in the twenty-first century due to their composition, higher strength, high efficiency, and multiscale nature. As carbon nanotubes (CNTs) possess extremely high strength, resilience, and stiffness, inclusion of carbon nanotubes in small quantities to the concrete mix makes them a multifunctional material. A molecular level understanding is significant to capacitate the macrolevel properties of these composites. In the proposed work, molecular dynamics (MD) simulations are used to understand the behaviour of the composites at the atomic level and continuum mechanics with representative volume element (RVE) homogenization modelling is carried out for interfacial interaction study of composites. The mechanical properties such as Young’s modulus, shear modulus, and poisons are evaluated using previous methods of simulations for different compositions of nanomaterials in cement matrix. The FORCITE module of MD simulation and square RVE model is used to determine the mechanical, electrical properties, and elastic constants of the cement nanocomposite. The MD simulation describes the linking effect of CNT into cement matric, and the RVE modelling study reveals the pull-out effect of CNT from matrix. From experimental and analytical studies, it is found that increase in CNT till 0.5% weight fraction increases the mechanical properties about 12% and further increasing of CNT weight fraction causes a reduction in mechanical properties about 5% due to the agglomeration of nanotubes. The density of states method in MD simulation indicates that mobility of the electrons increases with an increase in carbon nanotube proportion in the composites. The experimental test results substantiate the analytical studies, and the error obtained from both approaches is less than 20%. From the analytical study, the average maximum Young’s modulus, shear modulus, and bulk modulus are obtained as 46 GPa, 31 GPa, and 32 GPa for 0.5% weight fraction of CNT in cement matrix. Hence, it is concluded that 0.5% weight fraction of CNT is considered as optimum dosage to obtain better electrical and mechanical properties.

Simultaneously Encapsulating Co/Co2P Nanoparticles Inside and Growing Vertical Graphene Nanosheets Outside for N‐Doped Carbon Nanotubes as Efficient Sulfur Carriers for High‐Performance Lithium Sulfur Batteries

Agglomeration of carbon nanotubes (CNTs) extremely hampers utilization of active surface area and impedes sulfur loading, which limit their application in high–energy‐density lithium–sulfur (Li–S) batteries. Herein, N‐doped carbon nanotubes with Co/Co2P nanoparticles encapsulated inside and vertical graphene (VG) nanosheets grown outside (CCP@NCNT@VGs) are prepared as efficient sulfur carriers for Li–S batteries. The Co/Co2P nanoparticles encapsulated in the NCNTs could strongly anchor polysulfide and efficiently catalyze the conversion of polysulfides to Li2S, while the 3D hierarchical conductive network constructed by the vertical graphene nanosheets and NCNT quickly transfer electrons and improve the conversion kinetics of polysulfides. The as‐synthesized hierarchical structure combines conductivity with anchoring and catalysis, significantly elevating the electrochemical performance of the Li–S batteries. Hence, even at a high mass loading of 7 mg cm−2, the CCP@NCNT@VGs/S electrode with limited electrolyte/sulfur ratio (4 μL mg−1) exhibits a high areal capacity of 7 mAh cm−2, showing great application potential in the field of energy storage.

The effects of single-walled carbon nanotubes dispersion and agglomeration in aluminum matrix: Fabrication and finite element simulation

This paper provides novel research on the effect of full dispersion and agglomeration of single-walled carbon nanotubes (SWCNT) in the Aluminum (AL) matrix. The effect was investigated using the representative volume element (RVE) and finite element method (FEM). The acquired findings were compared to the experimental method (EXP) to assess the correctness of the employed method. In the investigation to anticipate the SWCNT rule in AL/SWCNT mechanical properties, RVE and FEM approach focused on two primary conditions: SWCNT complete dispersion and via agglomeration. Al/SWCNT was manufactured using powder technology. SEM images revealed that there were local SWCNT agglomerations within the composites at greater carbon nanotube concentrations, resulting in a decrease in the specimens' elastic modulus and mechanical strength. Based on RVE and EXP methods, the elastic modulus was increased until dispersed SWCNTs were added up to 2 wt%, after which the modulus was decreased as more SWCNTs were added. The elastic modulus with EXP was compared to the RVE curve cylinder SWCNT full dispersion and curve cylinder with SWCNT agglomeration results under periodic boundary conditions (PBC). The comparison demonstrated that EXP and RVE were in an acceptance agreement. In addition, AL-SWCNT RVEs were studied under damage condition.

Machine learning assisted nonlinear deflection analysis of agglomerated carbon nanotube core smart sandwich plate with three-phase magneto-electro-elastic skin

This research focuses on evaluating the combined effects of the interphase of the three-phase magneto-electro-elastic (TPMEE) composites and carbon nanotubes (CNTs) agglomeration on the nonlinear deflection of the multifunctional sandwich plate, using an artificial neural network (ANN) assisted finite-element (FE) approach. The data points collected from the in-house developed FE computational tool are used to train the ANN model. To this end, a backpropagation-based Levenberg–Marquardt algorithm is used. The core of the plate is made of agglomerated CNTs, and the facesheets are made of TPMEE composites. Two different agglomeration states, partial and complete, are considered for evaluation. Also, three variations of CNTs arrangement are assumed. On the other hand, the interphase effects are incorporated through its volume fractions and compositions. The plate kinematics is based on the higher-order shear deformation theory, and the nonlinearity is assumed to follow von Karman's strain-displacement relation. The equations of motion are derived using the total potential energy principle. Finally, the direct iterative method is used to arrive at the solutions. The numerical examples are also provided to understand the influence of coupling fields associated with the parameters, such as agglomeration, interphase volume fraction, interphase compositions and CNTs arrangement.