Uniform Dispersion and Exfoliation of Multi-Walled Carbon Nanotubes in CNT-MgB2 Superconductor Composites Using Surfactants

We developed a novel yet commercially viable strategy of synthesizing superior high-TC superconducting composites by dispersing fully exfoliated carbon nanotubes (CNTs) uniformly throughout the grain of CNT-MgB2 composites. First, we optimized the amount of the surfactant required to produce a highly stable and homogeneous colloidal suspension of CNTs. This amount was found to be 1/8th of the amount of CNTs. Second, we prepared a homogeneous CNT-B mixture by adding amorphous nano-boron (B) to the colloidal CNT suspension. Next, two different MgB2 synthesis routes were explored. In one case, we mixed an appropriate amount of Mg in the CNT-B mixture and carried out sintering. In the second case, the CNT-B mixture was heat treated at 500 °C, prior to mixing with Mg and sintering to form CNT-MgB2. Both kinds of samples were rigorously characterized to obtain an insight into their properties. The direct synthesis route shows a clear exfoliation and uniform dispersion of CNTs with a critical current density (JC) of 104 A/cm2 at 3.5 T and 20 K, which is useful for the application in magnetic resonance imaging MRI magnet operating with a cryogen free cooler. Our JC(H) result is 10 times higher than that of the pure sample. By contrast, the performance of the sample subjected to heat processing before sintering was severely compromised given the formation of MgO. Despite its simplicity, the direct synthesis route can be used for the cost-effective fabrication of CNT–MgB2 superconducting composites.

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Two-step synthesis of polyurethane/multi-walled carbon nanotubes polymer composite to achieve high percentage particle reinforcement for mechanical applications

Journal of Composite Materials ◽

10.1177/0021998321999451 ◽

2021 ◽

pp. 002199832199945

Author(s):

Dinesh Kumar ◽

Suneev Anil Bansal ◽

Navin Kumar ◽

Prashant Jindal

Keyword(s):

Carbon Nanotubes ◽

Synthesis Method ◽

Step Method ◽

Molding Method ◽

Uniform Dispersion ◽

Noticeable Improvement ◽

Multi Walled Carbon Nanotubes ◽

Mixing Method ◽

Compressive Testing ◽

Walled Carbon Nanotubes

The present work has been aimed to synthesize Polyurethane (PU)/Multi-Walled Carbon Nanotubes (MWCNTs) composite using a two-step method to enhance mechanical properties. In the first step, films (0.2 mm thickness) have been synthesized using a solution mixing method to disperse MWCNTs in the PU matrix. In the second step, thin films of uniformly dispersed MWCNTs in the PU matrix have been compression molded to synthesize PU/MWCNTs composite required for real mechanical applications. The two-step method has the advantages of solution mixing as well as compression molding method. The results of quasi-static nanoindentation tests indicated that in comparison to pure PU, elastic modulus and hardness have been enhanced by 124% and 53% respectively for 10 wt% PU/MWCNTs composite. Fracture resistance of PU/MWCNTs composites, with 7 wt% of MWCNTs, has been enhanced by 52% as compared to pure PU. To understand bulk behavior, nanoindentation results have been cross-verified with compression testing. Results of compressive testing shown that the modulus of composite material has been significantly improved under the influence of the increasing composition of MWCNTs. A noticeable improvement of 52% has been observed in compressive modulus of 10 wt% composite in equivalence to pure PU. The overall improvement in mechanical behavior has been attributed to the uniform dispersion of MWCNTs in the PU matrix by the two-step synthesis method.

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Fabrication and Characterization of Polylactic Acid Electrospun Scaffolds Modified with Multi-Walled Carbon Nanotubes and Hydroxyapatite Nanoparticles

Biomimetics ◽

10.3390/biomimetics5030043 ◽

2020 ◽

Vol 5 (3) ◽

pp. 43

Author(s):

Athanasios Kotrotsos ◽

Prokopis Yiallouros ◽

Vassilis Kostopoulos

Keyword(s):

Mechanical Properties ◽

Carbon Nanotubes ◽

Polylactic Acid ◽

Physical And Mechanical Properties ◽

Polymeric Materials ◽

Cost Effective ◽

Electrospinning Process ◽

Wide Range ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes

The solution electrospinning process (SEP) is a cost-effective technique in which a wide range of polymeric materials can be electrospun. Electrospun materials can also be easily modified during the solution preparation process (prior SEP). Based on this, the aim of the current work is the fabrication and nanomodification of scaffolds using SEP, and the investigation of their porosity and physical and mechanical properties. In this study, polylactic acid (PLA) was selected for scaffold fabrication, and further modified with multi-walled carbon nanotubes (MWCNTs) and hydroxyapatite (HAP) nanoparticles. After fabrication, porosity calculation and physical and mechanical characterization for all scaffold types were conducted. More precisely, the morphology of the fibers (in terms of fiber diameter), the surface properties (in terms of contact angle) and the mechanical properties under the tensile mode of the fabricated scaffolds have been investigated and further compared against pristine PLA scaffolds (without nanofillers). Finally, the scaffold with the optimal properties was proposed as the candidate material for potential future cell culturing.

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Cost-Effective Potentiometric Platforms Modified with Multi-Walled Carbon Nanotubes (MWCNTs) and Based on Imprinted Receptors for Fluvoxamine Assessment

Polymers ◽

10.3390/polym12030673 ◽

2020 ◽

Vol 12 (3) ◽

pp. 673

Author(s):

Heba M. Hashem ◽

Saad S. M. Hassan ◽

Ayman H. Kamel ◽

Abd El-Galil E. Amr ◽

E. M. AbdelBary

Keyword(s):

Carbon Nanotubes ◽

Electrochemical Impedance ◽

Biological Fluids ◽

Pharmaceutical Preparations ◽

Cost Effective ◽

Hplc Method ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes ◽

Screen Printed

A simple, efficient and reliable analytical method was developed and used for the determination of the fluvoxamine drug (FLV) in pharmaceutical preparations and biological fluids. The method is based on the cost-effective screen-printed platform for the potential transduction of the drug. Host-tailored molecular imprinting polymer (MIP) was integrated with the potentiometric platform as a recognition receptor, in which FLV, acrylamide (AAm), ethylene glycol dimethacrylate (EGDMA) and acetonitrile were used as a template, functional monomer, cross-linker, and solvent, respectively. MIP particles were dispersed in plasticized poly (vinyl chloride) (PVC) and the membrane was drop-casted on carbon screen-printed electrode. The MIP, in addition to non-imprinted polymers (NIP), was characterized and the binding experiment revealed high affinity and adsorption capacity of MIP towards FLV. The proposed sensor displayed near-Nernstian cationic slope of 55.0 ± 0.8 mV/decade (r2 = 0.999) with a low detection limit of 4.8 × 10−6 mol/L over a wide pH range (3.0–8.5). The electrochemical features of the proposed sensors including electrochemical impedance spectroscopy (EIS) and chronopotentiometry measurements (CP) in the presence of multi-walled carbon nanotubes (MWCNTs) as a solid contact transducer were also investigated. The applications of the proposed sensor for the determination of FLV in different dosage forms with recovery values (98.8%–101.9%) and (97.4%–101.1%), respectively compared with the reference HPLC method with acceptedFandt-student tests values at the 95% confidence level.

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Dispersion of Multi-Walled Carbon Nanotubes in Portland Cement Concrete Using Ultra-Sonication and Polycarboxylic Based Superplasticizer

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.802.112 ◽

2015 ◽

Vol 802 ◽

pp. 112-117 ◽

Cited By ~ 1

Author(s):

Ali Yousefi ◽

Norazura Muhamad Bunnori ◽

Mehrnoush Khavarian ◽

Taksiah A. Majid

Keyword(s):

Mechanical Properties ◽

Carbon Nanotubes ◽

Portland Cement ◽

Cement Matrix ◽

Portland Cement Concrete ◽

Cement Concrete ◽

Uniform Dispersion ◽

Multi Walled Carbon Nanotubes ◽

Sonication Technique ◽

Walled Carbon Nanotubes

The potential properties of carbon nanotube-cement based materials strongly depend on the dispersion of carbon nanotubes (CNTs) within the cement matrix and the bonding between CNTs and the hydrated cement. The homogeneous dispersion of CNTs in the cement matrix yet is one of the main challenges due to strong van der Waals forces between nanotubes. In this study, a polycarboxylic ether based superplasticizer and ultra-sonication technique was used for dispersion of multi-walled carbon nanotubes (MWCNTs). Portland cement concrete specimens with different concentrations of MWCNTs (0.04 and 0.1 % by the weight of cement), with and without the presence of superplasticizer were investigated. Compressive strength test results revealed a significant improvement in mechanical properties of sample containing 0.1 % MWCNTs and 0.2 % superplasticizer. Moreover, field emission scanning electron microscopy (FESEM) images of fractured surfaces of hardened specimens showed a good dispersion of MWCNTs within the cement matrix. This method was developed to facilitate the uniform dispersion of MWCNTs in the cementitious concrete for better reinforcement in nanoscale and mechanical properties enhancement by transfer of load between the nanotubes and matrix.

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Load Sensing Capability of Cementitious Matrixes—Nanomodified Cement Versus Carbon Nanotube Dispersion

Proceedings ◽

10.3390/proceedings2019034019 ◽

2019 ◽

Vol 34 (1) ◽

pp. 19

Author(s):

Buasiri ◽

Habermehl-Cwirzen ◽

Krzeminski ◽

Cwirzen

Keyword(s):

Carbon Nanotubes ◽

Electrical Properties ◽

Carbon Nanomaterials ◽

Compressive Load ◽

Weight Changes ◽

Load Sensing ◽

Carbon Nanotube Dispersion ◽

Uniform Dispersion ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes

A cement-based matrix incorporating conductive materials such as carbon nanotubes and carbon nanofibers can have self-sensing capability. Both nanomaterials are characterized by excellent physical, mechanical and electrical properties. A disadvantage is that due to their hydrophobic nature it is very difficult to ensure uniform dispersion throughout the cementitious matrix. To overcome this problem a new nanomodified cement containing in-situ attached CNFs was developed leading to a very homogenous and conductive binder matrix. This study aimed to compare the piezoresistive responses of two types of matrixes, one based on the nanomodified cement and the second containing multi-walled carbon nanotubes. Several mortars were prepared containing either MWCNTs or the nanomodified cement, which partially replaced the untreated cement. The effective amount of the carbon nanomaterials was the same for both types of mixes and ranged from 0 wt.% to 0.271 wt.%, calculated by the all binder weight. Changes in the electrical properties were determined while applying compressive load. The results showed that the binders based on the nanomodified cement have significantly better load sensing capabilities and are suitable for applications in monitoring systems.

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Simulation and experimental investigation of multi-walled carbon nanotubes/aluminum composite fabrication using friction stir processing

Proceedings of the Institution of Mechanical Engineers Part E Journal of Process Mechanical Engineering ◽

10.1177/09544089211034029 ◽

2021 ◽

pp. 095440892110340

Author(s):

Mostafa Akbari ◽

Parviz Asadi

Keyword(s):

Carbon Nanotubes ◽

Wear Resistance ◽

Friction Stir Processing ◽

Particle Distribution ◽

Base Alloy ◽

Stir Zone ◽

Friction Stir ◽

Uniform Dispersion ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes

Multi-walled carbon nanotube/aluminum composites are fabricated on Al–Si cast alloy employing friction stir processing. First, the microstructure of the stir zone, as well as the effect of process parameters on the size of silicon particles, is investigated. Then, the process is numerically simulated using a thermo-mechanically coupled three-dimensional finite element method model. Material flow, as the primary reason for the dispersion of reinforcing particles, is considered in the numerical model, and proper conditions to obtain a uniform dispersion of multi-walled carbon nanotubes are determined. Scanning electron microscope analysis is carried out to consider the particle distribution in the texture of the stir zone. The results show that the particle distribution improves significantly by changing the tool rotation direction between the friction stir processing passes. The hardness test is accomplished on the cross-section of the friction stir processed specimens, and finally, the wear test is performed to compare the wear resistance of the composites with the base alloy. The results show that the wear resistance and hardness of the produced composites are considerably enhanced compared to the base alloy.

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Fabrication of β-cyclodextrin modified mesostructured silica coated multi-walled carbon nanotubes composites and application for paraben removal

Water Science & Technology ◽

10.2166/wst.2018.257 ◽

2018 ◽

Vol 78 (5) ◽

pp. 1001-1009 ◽

Cited By ~ 1

Author(s):

Chuyuan Ding ◽

Jun He ◽

Mengxia Xu ◽

Chengjun Wang

Keyword(s):

Carbon Nanotubes ◽

Removal Efficiency ◽

Cost Effective ◽

X Ray Diffraction ◽

Solution Ph ◽

Mesostructured Silica ◽

Multi Walled Carbon Nanotubes ◽

High Regeneration ◽

The Stability ◽

Walled Carbon Nanotubes

Abstract In this work, the novel β-cyclodextrin modified mesostructured silica coated multi-walled carbon nanotubes (MWCNTs) composites were synthesized and applied for the removal of parabens in aqueous solution. The prepared MWCNTs/SiO2/β-CD composites were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and thermogravimetric analysis. The effects of the amount of adsorbent, pH and elution solvents on the removal efficiency of parabens from water solutions were investigated. Under the optimized conditions, over 95% removal efficiency was achieved by using 40 mg of MWCNTs/SiO2/β-CD adsorbents to absorb the parabens from 60 mL of 0.5 μg/mL parabens solutions. The solution pH in the range from 5 to 9 has no influence on the removal efficiency and the parabens sorption capacity of the prepared adsorbents were around 0.75 μg/mg. Furthermore, the stability and reusability studies demonstrated that the prepared MWCNTs/SiO2/β-CD composites are cost-effective adsorbents for the removal of parabens from water with high regeneration efficiency. The composites fabricated in this study could become an attractive candidate for water purification.

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Cr as a key factor for direct synthesis of multi-walled carbon nanotubes on industrial alloys

Chemical Engineering Journal ◽

10.1016/j.cej.2013.12.073 ◽

2014 ◽

Vol 242 ◽

pp. 278-284 ◽

Cited By ~ 15

Author(s):

Noriaki Sano ◽

Suguru Yamamoto ◽

Hajime Tamon

Keyword(s):

Carbon Nanotubes ◽

Direct Synthesis ◽

Key Factor ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes

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Electrophoretic Deposition of Carbon Nanotubes on Metallic Surfaces

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.314.141 ◽

2006 ◽

Vol 314 ◽

pp. 141-146 ◽

Cited By ~ 22

Author(s):

B.J.C. Thomas ◽

M.S.P. Shaffer ◽

Sarah Freeman ◽

M. Koopman ◽

Krish K. Chawla ◽

...

Keyword(s):

Carbon Nanotubes ◽

Electrophoretic Deposition ◽

Cost Effective ◽

Heat Extraction ◽

Metallic Surfaces ◽

Tissue Engineering Scaffolds ◽

Homogeneous Microstructure ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes ◽

Steel Substrates

A method based on electrophoretic deposition has been developed to produce uniform deposits of multi-walled carbon nanotubes on stainless steel substrates. Aqueous suspensions were used under constant voltage conditions in the range of 5 to 50 V, with deposition times ranging from 0.5 to 10 minutes. The thickness of the coatings was controlled by variation of voltage and deposition time during EPD. Coatings of up to 100μm thickness were achieved, which exhibit homogeneous microstructure. The EPD technique is fast, cost-effective, and it can be applied to complex shapes. Possible applications of CNT coatings are in heat extraction devices or porous nanostructured coatings for tissue engineering scaffolds.

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