Influence Of Multi-walled Carbon Nanotubes Research Articles

Investigation of the Influence of Multi-Walled Carbon Nanotubes on Laminate Composites During Progressive Tensile Damage Using Acoustic Emission

Investigation of the Influence of Multi-Walled Carbon Nanotubes on Laminate Composites During Progressive Tensile Damage Using Acoustic Emission

On the early behavior and microstructure of oil well cement paste incorporating with carbon nanotubes cured at a high temperature

With the rapid development of shale gas/oil exploitation, hostile downhole condition asks for more flexible and ductile oil well cement paste (OWCP). This study is devoted to investigating the influence of multi-walled carbon nanotubes (MWCNTs) on the rheological behavior, early mechanical properties and volume stability of OWCP by means of different experimental methodologies. Multiple microstructural techniques are employed to further understand the reinforcing mechanism of MWCNTs on the performances of OWCP. The results show that the optimal dosage of MWCNTs is 0.6wt.‰. The rheological behavior of MWCNTs/OWCP slurry at low shearing rate is improved after the addition of 0.6wt.‰MWCNTs. The mechanical properties and autogenous shrinkage of MWCNTs/OWCP composites are enhanced after the addition of the optimal dosage of MWCNTs, MWCNTs/OWCP composites with addition of 0.6wt.‰MWCNTs exhibit more flexible and ductile than plain OWCP. The additional nucleation sites provided by MWCNTs, the role of bridging effect and pull-out effect by MWCNTs, and the high curing temperature are all responsible for the enhanced mechanical properties of MWCNTs/OWCP composites. Owing to the addition of MWCNTs, the relationship between the compressive strengths of MWCNTs/OWCP composites and gel/space ratios does not exhibit exponential form. However, the addition of MWCNTs does not alter the Avrami-type exponential relationship between the degree of hydration and curing ages, moreover, it does not alter the linear relationship between the mercury intrusion porosity and gel/space ratio.

Study on the interfacial contact behavior of carbon nanotubes and asphalt binders and adhesion energy of modified asphalt on aggregate surface by using molecular dynamics simulation

In this work, a comprehensive study has been conducted on the interfacial contact behavior of carbon nanotubes (CNTs) and asphalt binders as well as the influence of multi-walled carbon nanotubes (MWCNTs) embedded into asphalt on the adhesion ability of asphalt on aggregate surface at atomic scale. CNT/asphalt composite and asphalt-aggregate interface models were investigated by molecular dynamics (MD) simulations to evaluate the molecular interactions of materials. The interfacial adhesion characteristics of functionalized single-walled carbon nanotubes (SWCNTs) and MWCNTs with asphalt binders were investigated by performing pull-out simulations and the interactions of SWCNTs and asphalt components were analyzed. The obtained results showed that asphalt components with low molecular weight were more easily adsorbed by SWCNTs than higher weight components. For CNTs/asphalt composite model, Van der Waals (VdW) energy is much higher than electrostatic energy accounting for a great portion of interaction energy. Although functional groups on the surface of CNTs can increase interfacial interaction, this increase is far less than the enhancement of interaction energy and interfacial shear stress between MWCNTs and asphalt binders. Therefore, MWCNTs are regarded as a better additive to be inserted into asphalt binders to enhance the interfacial adhesion of CNTs/asphalt composites. In addition, the results of adhesion energy change of asphalt-aggregate interface models indicated that MWCNT addition into asphalt significantly increased the adhesion ability of asphalt on aggregate surface (especially for alkaline aggregates).

Impact of MWCNT in CFRP composite during end milling process

ABSTRACT Incorporation of nanofillers upto a certain weight percentage in polymeric matrix has been established to enhance the performance of composites. Machining is an integral part of any manufacturing process and the effect of machining on nanocomposites has been a subject of various studies. The present study investigates the influence of multi-walled carbon nanotube (MWCNT), spindle speed (SS), and feed rate (FR), on end milling performances, such as, delamination factor (DF) and surface roughness (Ra) by using the TOPSIS methodology. The investigation has showed that incorporation of MWCNTs in the CFRP composites optimizes the machining performances. The investigation, using multi-objective TOPSIS-based analysis of variance approach, showed that SS is the most governing factor, followed by FR and MWCNT wt%, which influence the overall performance of the composites. Field emission scanning electron microscope (FESEM) has been used to show the dispersion of MWCNT in the epoxy matrix. Improvisation on machining surface characteristics along with optimal performance parameters are accomplished successfully.

Influence of multi-walled carbon nanotubes on the fracture response and phase distribution of metakaolin-based potassium geopolymers

Influence of multi-walled carbon nanotubes on the fracture response and phase distribution of metakaolin-based potassium geopolymers

Platinum Nanoparticles Decorated IrO2@MWCNT as an Improved Catalyst for Oxygen Evolution Reaction

AbstractIn this paper, IrO2 nanoparticles supported on multi‐walled carbon nanotubes (MWCNTs) are synthesized via a facile hydrothermal method and calcination process at different temperature. Platinum nanoparticles decorated IrO2@MWCNT‐400 °C are prepared by chemical reduction method. The influence of MWCNTs and Pt on physicochemical properties and oxygen evolution reaction (OER) activity of IrO2@MWCNT composites were studied via transmission electron microscope (TEM), X‐ray diffraction (XRD), Raman spectra, thermogravimetric analysis (TGA), X‐ray photoelectron spectroscopic (XPS) and electrochemical methods. Among the samples, Pt/IrO2@MWCNT‐400 °C exhibits better catalytic activity with an overpotential of 270 mV at the current density of 10 mA cm−2 with a low Tafel slope of 85.1 mV dec−1. The outstanding OER performance of Pt/IrO2@MWCNT‐400 °C is ascribed to the introduction of the MWCNTs, which can not only act as a support to prevent agglomeration of IrO2 nanoparticles that produces high surface area of catalytic sites, but also facilitates electron transfer between IrO2 nanoparticles and MWCNTs. On the other hand, the Pt optimizes electronic structure for excellent electrocatalytic performance. Therefore, the Pt/IrO2@MWCNT‐400 °C catalyst is a good choice for application in OER.

Interfacial IMC evolution and shear strength of MWCNTs-reinforced Sn–5Sb composite solder joints: Experimental characterization and artificial neural network modelling

Abstract The continuous miniaturization of electronic products and the constantly rising functionality demand by final users necessitate major challenges for the academia and the industry to produce reliable lead-free solders for long-term service. In the present study, an analysis on the influence of MWCNTs (multi-walled carbon nanotubes) on the interfacial IMC (intermetallic compound) evolution and shear strength of Sn–5Sb solder joint was performed. The composite solder joint samples were developed through the reflow soldering process and thereafter subjected to isothermal aging at different temperatures (120 °C, 150 °C and 170 °C). Given the promising properties of MWCNTs, empirical findings showed that inhibited interfacial IMC evolution and enhanced shear strength were markedly achieved due to the presence of MWNCTs in the Sn–5Sb solder alloy. Artificial neural network (ANN) model was developed by making use of the experimental data to characterize the composite solder joints. Various influential parameters that affect the thickness of the IMC layer and the shear strength performance of the composite solder joints including the MWCNTs content, aging temperature and aging time were considered as the input parameters for the ANN model. Having used the statistical parameters such as the coefficient of determination (R2) and root mean square error (RMSE) to evaluate the model, the ANN model developed in this study adequately predicted the IMC layer thickness (R2 = 0.9913; RMSE = 0.0234) and shear strength (R2 = 0.9798; RMSE = 0.0314) of the composite solder joints.

Carbon nanotubes interaction with amorphous and semi‐crystalline domains of polypropylene in melt‐mixed composites: Influence of multiwall carbon nanotubes agglomerate and their modifications

AbstractPolypropylene (PP) and multi‐walled carbon nanotubes (MWCNTs) composites were prepared by melt‐mixing with two types of MWCNTs of varying agglomerate size. Agglomerate dominated dispersion was observed in the PP matrix, wherein N‐MWCNTs exhibit a finer dispersion as compared to D‐MWCNTs. Further, MWCNTs were encapsulated by Li‐salt of 6‐amino caproic acid in various proportions along with PP‐g‐maleic anhydride in order to achieve finer MWCNTs dispersion. Thermogravimetric analysis exhibited an increase in onset of degradation temperature and higher residual weight (%) at 500 °C of PP with increased MWCNTs concentration, which suggests the formation of a thicker “interphase.” Glass transition temperature of the PP phase was increased monotonically as a function of unmodified MWCNTs concentration, which suggests a strong interfacial interaction between PP and MWCNTs. An extensive analysis was carried out with modified MWCNTs based PP composites. Moreover, MWCNTs act as a strong hetero‐nucleating agent manifesting in smaller spherulite size of PP, wherein bulk crystallization temperature is increased to ~130 °C of the PP phase at 5 wt% MWCNTs content. The influence of unmodified and modified MWCNTs on the interaction between the PP chains and MWCNTs in the amorphous phase as well as in the crystalline domains are analyzed in PP/MWCNTs composites.

Free and Forced Vibration Characteristics of CNT Reinforced Composite Spherical Sandwich Shell Panels with MR Elastomer Core

In this work, the dynamic behavior of the spherical magnetorheological elastomer (MRE) sandwich shell panel with multiwalled carbon nanotubes (MWCNT) reinforced composite face sheets is studied. The governing differential equation of motion for the (doubly curved) spherical sandwich shell panel is derived based on the Higher-Order Shear Deformation Theory (HSDT) kinematics. In the finite element framework, nine noded iso-parametric elements with nine Degrees of Freedom (DOFs) at each node are considered for solving the numerical problem. The finite element model of the multifunctional MR elastomer core spherical sandwich shell panel is validated against the existing works in terms of natural frequencies on different boundary conditions and magnetic field environment. The influence of MWCNT in the face sheet of the MR elastomer spherical sandwich shell panel is also studied through the structural rigidity. Detailed parametric investigations are performed to study the stiffness and damping characteristics of the shell panel with respect to the magnetic field intensities, thickness ratio, aspect ratio, ply orientation, and boundary conditions on the multifunctional MR elastomer core spherical sandwich shell panel. Also, the transverse vibration study of the MWCNT reinforced spherical sandwich shell with MR elastomer is carried out for different magnetic field intensities and curvatures to assess their effects on the structural performance. This study shows the applicability of the MR elastomer in sandwich shell structure for control of vibration and damping.

Influence of multi-walled carbon nanotubes with different diameters and lengths on the tension, shear and bending performance of glass/epoxy laminates

Influence of multi-walled carbon nanotubes with different diameters and lengths on the tension, shear and bending performance of glass/epoxy laminates

Effect of using multiwall carbon nanotube reinforced epoxy adhesive in enhancing glass fiber reinforced polymer composite through cocure manufacturing technique

AbstractThe high‐performance epoxy‐based cocure manufacturing technique has been used to join composite structures such as wings, frames, and ribs in aerospace applications. The present study aims to examine the influence of multiwall carbon nanotubes (MWCNTs) addition on mechanical and free vibrational behavior of glass fiber reinforced polymer composites fabricated through cocure manufacture technique. The experimental results revealed that the addition of 1 wt.% of MWCNTs enriched the tensile and flexural properties of cocured composites by 27.8% (344 Mpa) and 26.16% (379.12 Mpa), respectively. Shear analysis depicted that 0.25 wt.% MWCNT reinforcement significantly enhanced the shear strength of cocured lap joints by 63.8% (16.79 MPa). The scanning electron microscopy and atomic force microscopy indicated that homogenous dispersion of MWCNTs enriched the interfacial bonding, deviated the crack path, and formed uneven surfaces. A comparison between the failure mode of neat and modified adhesive demonstrated the effective presence of MWCNTs in changing the adhesive failure mode of cocured composite to cohesive. Thus, it enhanced the failure strength of cocured composites. The experimental free vibrational analysis affirmed that addition of 1 wt.% MWCNTs enhanced the fundamental natural frequency whereas, lower wt.% MWCNT addition increased the cocured composites' inherent damping due to higher‐level formation of agglomeration area in the composite. Thus, it increased the stress level and minimized the bonding between fiber and matrix.

Influence of Multiwalled Carbon Nanotubes in the Structural Performance of the Curved Composite Beam

In this paper, Experimental investigation on the free vibration response bheavior of multi walled carbon nanotubes (MWCNT) reinforced curved composite beams have been accomplished to evaluate the structural integrity. To obtain the uniform distribution of MWCNTs in the matrix (epoxy), the ultra-sonication technique is carried out and the curved composite beams are fabricated with the incorporation of MWCNT with the curvature radius of 0.8 m then the free vibration analysis is performed at different boundary conditions. The structural performances of the curved composite beams are explored in the relation of modal natural frequencies and damping ratio. The effective structural integrity and vibration responses are achieved with respect to the enhancement of MWCNT in the curved composite structure.

MWCNTs filled high-density polyethylene composites to improve tribological performance

The water-lubricated stern tube bearings play a considerable role in the marine propulsion system. Due to poor mechanical properties and temperature resistance, polymer materials are prone to plastic deformation during friction under extreme conditions, which could induce frictional vibrations and noise. Reducing the coefficients of friction (COFs) and weakening the plastic deformation of the contact surface could significantly decrease its frictional vibrations and noise. A novel composite material composed of high-density polyethylene (HDPE) and multi-walled carbon nanotubes (MWCNTs) was prepared to investigate its tribological properties, which slid against ceramic balls under low velocity and heavy load. The influence of MWCNTs on wear behaviours was examined by comparing and analyzing the mechanical properties, scratch testing results, coefficients of friction (COFs), wear volumes, and wear morphologies. The results indicated that MWCNTs obviously enhanced the mechanical properties of HDPE and weakened the deformation behaviours on the friction interface, which resulted in reductions of COFs and wear volumes under dry and water-lubricated conditions. HDPE modified by 7.5 wt% MWCNTs presented the best COF reduction and wear resistance improvement, and the effect mechanism of the MWCNTs was revealed. The knowledge obtained in this research would be useful to develop polymer matrix composites with low COFs, and good deformation resistance and enhance the tribological properties and frictional vibration reduction ability of water-lubricated polymer bearings.

Prediction of influences of MWCNT fillers on the vibration characteristics of laminated hybrid honeycomb core sandwich GFRP composite plate

In this paper, the prediction of influences of multi-wall carbon nanotubes (MWCNT) fillers on the vibration characteristics of laminated hybrid honeycomb core sandwich GFRP composite plate has been performed based on the higher-order shear deformation theory using finite element formulations. The parametric study on the dynamic behavior of honeycomb sandwich composite plates hybrid with MWCNT with the influence of the weight percentage of CNTs for core material and upper and bottom skins with CCCC boundary conditions, different ply configuration was performed. The numerical study clearly shows that the bending frequency increase with an increase in the weight percentage of MWCNTs. It can be observed that the influence of MWCNT in the core is least contributing to increasing the stiffness with the influence of MWCNT in the skins on the bending characteristics. Finally, the ANN technique is used to predict effectively the dynamic characteristics of honeycomb sandwich composite plates hybrid with MWCNT with the influence of intermittent the weight percentage of CNTs for core material and upper and bottom skins which reduces the computational effort.

Investigating the influence of multi-walled carbon nanotubes on the mechanical and damping properties of ultra-high performance concrete

Abstract In this paper, the effects of multiwalled carbon nanotubes (MWCNTs) on the mechanical and damping properties of ultra-high performance concrete (UHPC) were investigated. The results show that the proper amount of MWCNTs can improve mechanical properties as well as the damping properties. For the mechanical properties, the compressive strength and flexural strength of the specimens increased with the increase of MWCNTs content in the range of 0~0.05% (mass ratio to cement). However, when the content of MWCNTs was more than 0.05wt.%, the mechanical properties of UHPC could not be improved continually because too many MWCNTs were difficult to disperse and agglomerated easily in UHPC. Similar laws also have been found for the damping property of UHPC. The loss factor of UHPC increased with the increase of MWCNTs content in the range of 0 ~ 0.05%. The incorporation of MWCNTs would introduce a large number of interfaces into UHPC, the friction and slip between interfaces were the main reasons for the improvement of the damping property of UHPC. However, when the content of MWCNTs was more than 0.05%, it was difficult to disperse effectively. As a result, the overall energy consumption efficiency of MWCNTs was decreased.

Novel multi-walled carbon nanotube reinforced glass-ionomer cements for dental restorations

Carbon nanostructures have been fascinating mankind since their discovery. Their excellent biocompatibility and toughening properties can virtually reinforce any material. Glass ionomer (GIC) dental cement is bestowed with numerous advantages like anti-caries action, adhesion to a tooth, etc. But, due to its low mechanical properties, it is not the material of choice to be used to fill the posterior teeth. In the present study, a composite of GIC and multi-walled carbon nanotubes (MWCNT) is studied to evaluate the potential use as posterior restorative types of cement. The MWCNT was mixed with GIC powder at 3 different proportions and cement pellets were formed by the usual mixing procedure followed in dentistry. The fabricated composites were characterized under XRD, Electron microscopy, FTIR, TGA and DSC. The setting time was evaluated. The composites were also analyzed for swelling and solubility properties. The pellets were placed in normal saline and were analyzed for compressive strength, hardness and wear. The results were statistically analyzed and the influence of MWCNT on the properties of composites were elucidated.

Effects of MWCNTs on the Tensile Properties and Thermal Conductivity of BaTiO3 /Epoxy Nanocomposites

This research studied the effects of modified BaTiO3 (BT) nanoparticles with coupling agent γ-APS (0.5wt. %) on the tensile and thermal conductivity of epoxy nanocomposites with respect to content (0.25, 0.5, 0.75, 1, 3 and 5wt. %). Multiwall carbon nanotubes (MWCNTs) at different concentration (0.2, 0.4, 0.8 and 1 wt. %) were added to the BaTiO3/epoxy nanocomposites. The influence of MWCNTs on the tensile properties and thermal conductivity was investigated. The tensile strength and Young’s modulus of BaTiO3/epoxy nanocomposites film were increased at up to 3 wt. % of added BT, but adding BT at more than 3 wt.% decreased the strength of epoxy. The tensile strength was increased with increasing MWCNTs content from 32 MPa for pure epoxy to the value 56.8 MPa for 1wt. % of MWCNTs content. The thermal conductivity of BaTiO3/epoxy nanocomposites improved with increase of BT content. At 3wt. % and 5wt. % of BaTiO3 the thermal conductivity of nanocomposites decreased. The increase of MWCNTs concentration from 0.2 wt. % to 1 wt. % resulted in a thermal conductivity enhancement.

Influence of Multiwalled Carbon Nanotubes on the Rheological Behavior and Physical Properties of Kenaf Fiber-Reinforced Polypropylene Composites.

The incorporation of kenaf fiber fillers into a polymer matrix has been pronounced in the past few decades. In this study, the effect of multiwalled carbon nanotubes (MWCNTs) with a short kenaf fiber (20 mesh) with polypropylene (PP) added was investigated. The melt blending process was performed using an internal mixer to produce polymer composites with different filler contents, while the suitability of this melt composite for the injection molding process was evaluated. Thermogravimetric analysis (TGA) was carried out to investigate the thermal stability of the raw materials. Rheological analyses were conducted by varying the temperature, load factor, and filler content. The results demonstrate a non-Newtonian pseudoplastic behavior in all samples with changed kenaf fillers (10 to 40 wt %) and MWCNT contents (1 to 4 wt %), which confirm the suitability of the feedstock for the injection molding process. The addition of MWCNTs had an immense effect on the viscosity and an enormous reduction in the feedstock flow behavior. The main contribution of this work is the comprehensive observation of the rheological characteristics of newly produced short PP/kenaf composites that were altered after MWCNT additions. This study also presented an adverse effect on the composites containing MWCNTs, indicating a hydrophilic property with improved water absorption stability and the low flammability effect of PP/kenaf/MWCNT composites. This PP/kenaf/MWCNT green composite produced through the injection molding technique has great potential to be used as car components in the automotive industry.

Influence of multi-walled carbon nanotubes on the hydration products of ordinary Portland cement paste

We elucidate the mechanisms by which multi-walled carbon nanotubes (MWCNTs) influence the microstructure, fracture behavior, and hydration of cement paste. We disperse MWCNTs using a multi-step approach that involves high-energy pre-dispersion using ultrasonic energy followed by low-energy dispersion using un-hydrated cement particles. In turn, the low-energy dispersion step involves high-shear mixing and mechanical stirring. High-resolution environmental scanning electron microscopy of cement+0.2 wt% MWCNT, cement+0.5 wt% MWNCT, and of cement+1 wt% MWCNT show that MWCNTs bridge air voids, thereby refining the pore size and strengthening the C-S-H matrix. The fracture toughness increased by 9.38% with the addition of 0.2 wt% multi-walled carbon nanotubes, and by 14.06% with the addition of 0.5 wt% multi-walled carbon nanotubes and ligament bridging was the dominant toughening mechanism. Moreover, for all reinforcement levels, MWCNTs induced a conversion of low-density C-S-H into high-density C-S-H along with a drastic drop in the capillary porosity: adding 0.1–0.5 wt% MWCNT resulted in a 200% increase in the volume fraction of high-density C-S-H. Thus, our experiments show that MWCNT enhances the mechanical properties and transport properties by: (i) promoting high-density C-S-H formation, (ii) promoting calcium hydroxide formation, (iii) filling microscopic air voids, (iv) reducing the capillary porosity, (v) increasing the fraction of small gel pores (1.2–2 nm in size), and (vi) by bridging microcracks.

Influence of MWCNTs and nano-Fe3O4 on the properties and structure of MWCNTs/ Fe3O4/PLA composite film with electromagnetic interference shielding function

A large number of electronic devices could generate a lot of electromagnetic waves, which could interfere with other equipment and harm the human body. Therefore, an electromagnetic interference shielding (EMI) material is urgently needed to protect the human body and the electronic equipment. In this paper, the multi-wall carbon nanotubes (MWCNTs) and the nano-Fe3O4 were added into the polylactic acid (PLA) matrix to form the composite film with electromagnetic interference shielding performance. And the structure and properties of MWCNTs/Fe3O4/PLA composite films, such as the morphology, chemical structure, crystallization, mechanical property, conductive property, magnetic property and electromagnetic interference shielding property, were researched. The result shows that too much Fe3O4 could lead to agglomeration, and the coupling agent KH570 had grafted and modified the surface of MWCNTs. The MWCNTs and nano-Fe3O4 could increase the crystallinity of PLA matrix. With the increase of MWCNTs, the maximum tensile stress of composite films gradually increased, and the maximum tensile strain decreased, and the resistance value showed a significant downward trend. The Fe3O4 could improve the magnetic properties of composite film. The MWCNTs and Fe3O4 could improve the electromagnetic interference shielding efficiency (EMI SE). The MWCNTs played a more significant role than the Fe3O4 in the process of EMI, and the EMI SE of the composite film with 3:1 ratios of MWCNTs/Fe3O4 could rise to 22 dB.