Dispersion Of Carbon Nanotubes Research Articles

Preparation and performance of biaxially stretched CNT-SBS/POE flexible strain sensor with a double percolation structure

Wearable flexible strain sensors have prospective application prospects in human motion monitoring, human-computer interaction, and information transmission. However, facilely manufacturing flexible strain sensors with a high sensitivity and extended sensing range remains challenging. Herein, a flexible strain sensor with a double percolation structure was prepared through simple melting mixing and biaxial stretching. To this end, carbon nanotubes (CNTs) filled styrene butadiene styrene (SBS) and polyolefin elastomer (POE) were employed as the conductive and insulating phases, respectively. The effects of biaxial stretching on sensor performance were systematically studied. During biaxial stretching, the as-obtained CNT-SBS/POE nanocomposites with double percolation structure exhibited better processing performance and stability than conventional CNT-SBS binary composites. Biaxial stretching results in better dispersion and planar orientation of CNTs in polymers, improving the sensing property of strain sensors. The optimized stretching ratio of double percolation structured composites was determined as 1.5, with 3 wt% CNT-SBS/POE sensor exhibiting high sensitivity (gauge factor = 7501.69) over a wide strain monitoring range (0–300% strain). Additionally, the flexible strain sensors could monitor physiological activities and information transmission with good reliability, thereby promising for human-machine interaction, wearable, and medical monitoring.

Microstructure and Mechanical Properties of Carbon Fiber Phenolic MatrixComposites containing Carbon Nanotubes and Silicon Carbide

A novel class of hybrid composites was prepared containing carbon fibers along with carbon nanotubes and silicon carbide particles in phenolic resin for improved mechanical performance. The loading of carbon fibers was ~60 wt% while carbon nanotubes and silicon carbide particles were reinforced in the fractions of 0.1 wt% and 5 wt%, respectively. Individually reinforced composites containing 0.1 wt% carbon nanotubes and 5 wt% silicon carbide particles were also manufactured for comparison with hybrid composites. Microstructural and mechanical property characterization was performed using electron microscopy and mechanical testing, respectively. Uniform dispersion of nanometer-scale carbon nanotubes and micrometer-scale silicon carbide particles was observed under microscopy. The pooled effect of carbon nanotubes and silicon carbide particles significantly increased the tensile, compressive, and flexural performance of composites while carbon nanotubes offered greater weight fraction value improvement than silicon carbide particles.

Review on Use of Nanomaterials in Concrete

Abstract: Various studies have highlighted the benefits of incorporating carbon nanotubes (CNTs) in concrete. They enhance compressive and flexural strength, prevent cracking, and improve durability. Different methods like sonication ensure uniform dispersion of CNTs in concrete. Additionally, research focuses on optimizing CNT concentrations to avoid adverse effects on properties like shrinkage and thermal conductivity. Overall, CNTs offer a promising solution to reinforce concrete and improve its mechanical properties effectively

Jute and Flax Fiber Composites Enhancement through Carbon Nanotube Filler

This investigation primarily focuses on enhancing the sustainable jute/flax/epoxy nanocomposite with the use of carbon nanotubes (CNTs) as filler. The flax and jute natural fibres were treated with sodium hydroxide solution. The compression moulding technique was preferred for better fabrication. The CNTs were thoroughly mixed with epoxy resin with the help of a ball milling-type mixture. The nanocomposite samples were prepared by varying the reinforcement and filler content. Jute fibre varied from 59 to 99 wt%, Flax Fiber varied from 0 to 40 wt% and the filler was maintained as constant of 1 wt%. The five types of laminated and fabricated composites were characterized in terms of tensile strength, flexural strength and modulus of elasticity. The SEM examinations were carried for the composite samples to analyse the fibre diameter (µm), CNT dispersion and interfacial adhesion. The results revealed that the sample fabricated with 69 jute fibre, 30 wt% flax fibre, and 1 wt% CNT filler outperformed with 60.1 MPa tensile strength, 79.3 MPa flexural strength, 8.1 GPa modulus of elasticity.

Influence of carbon nanotubes on printing quality and mechanical properties of 3D printed cementitious materials

This paper presents the impact of incorporating carbon nanotubes (CNTs) into the 3D printing of cementitious materials, along with the effective dispersion of CNTs. Compared to the control mix, adding CNTs with superplasticizer significantly enhanced the printing quality by reducing the error in height of two-layers from 38% to 30% and an 81% enhancement in the buildability. Moreover, rheology properties revealed shear-thinning behaviour with lower viscosity, resulting in improved flowability. The progressive increase in CNT concentrations up to 0.2% yielded a noteworthy improvement in the mechanical properties. At 28 days, the incorporation of 0.2% CNTs resulted in a significant increase in the flexural strength, compressive strength, and Young's modulus by 99%, 72%, and 43%, respectively, compared to the mix containing silica fume. Microstructural investigation of the CNT-cement matrix revealed nanoscale crack bridges formed by CNTs, reinforcing the cementitious material and improving its mechanical properties.

In-depth investigation of how carbon nanofiller dispersion affects microcellular foaming behavior in poly(butylene succinate) nanocomposites

This study explores the impact of carbon nanotubes (CNTs) dispersion on the microcellular foaming characteristics of poly(butylene succinate) (PBS) matrices. Two distinct dispersion methods, primary (PD) and secondary (SD), were employed to fabricate PBS/CNT nanocomposites, resulting in different filler dispersion states. The PD technique involves the conventional method of direct melt blending PBS with CNTs, while the SD technique adopts a more advanced strategy by integrating the Pickering emulsion template with melt blending, achieving finer CNTs distribution within the PBS matrix. The results reveal that the SD technique leads to significantly more uniform distribution of CNTs, which in turn enhances the melt strength and crystallization of the polymer matrix, thereby broadening the window for microcellular foaming. Notably, foams developed through the SD method exhibited a decrease in cell size to 10.4 μm and an increase in cell density to 1.8×1010 cells·cm‐3. Moreover, this uniform distribution of CNTs contributed to superior cell stability and an increase in compressive strength to 14.0 MPa. These findings highlight the pivotal role of nanofiller dispersion in determining foam properties and establish foundational knowledge for designing PBS foams with consistent and uniform cell structures. Such advancements are crucial for enhancing the applicability and performance of PBS-based materials across a spectrum of industries.

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.

A self-assembled carbon nanotube/silicon composite battery anode stabilized with chemically reduced graphene oxide sheets

This study presents a streamlined fabrication process for lithium-ion battery (LIB) electrodes, involving the dispersion of carbon nanotubes (CNT), silicon (Si), and graphene oxide (GO) in an aqueous solution, followed by vacuum filtration to produce self-standing composite electrodes. Two reduction routes are employed to form reduced graphene oxide (rGO). The chemically reduced CNT/Si/rGO-5 %-Chem anode exhibits superior mechanical resilience compared to thermally reduced counterparts, which suffer from reduced strength and structural integrity. Chemical reduction also enhances electrochemical performance, increasing the initial capacity of the non-reduced CNT/Si/GO-5 % composite anode from 1,461 to 2,342 mAh g−1, with improved long-term cycling performance. Electrochemical impedance spectroscopy shows lower pre-cycle charge transfer resistance (148 Ω) and superior solid electrolyte interphase (SEI) resistance (43 Ω) for chemically reduced anodes compared to thermally reduced ones. After cycling, the chemically reduced composite anode exhibits reduced electrolyte resistance and charge transfer resistance, indicating stable electrochemical reactions. The composite structure undergoes adaptive rearrangements during cycling, optimizing active material utilization. In summary, CNTs accommodate silicon swelling, while chemically reduced rGO promotes stable SEI formation, highlighting the benefits of chemical reduction in enhancing mechanical durability and electrochemical performance, making the self-standing CNT/Si/rGO composite film a promising LIB anode.

Development of cement nanocomposites reinforced by carbon nanotube dispersion using superplasticizers

Development of cement nanocomposites reinforced by carbon nanotube dispersion using superplasticizers

Conjugated Polymers with Self-Immolative Sidechain Linkers for Carbon Nanotube Dispersion.

Single-walled carbon nanotubes (SWNTs) are promising materials for generating high-performance electronic devices. However, these applications are greatly restricted by their lack of purity and solubility. Commercially available SWNTs are a mixture of semi-conducting (sc-) and metallic (m-) SWNTs and are insoluble in common solvents. Conjugated polymers can selectively disperse either sc- or m-SWNTs and increase their solubility; however, the conductivity of conjugated polymer-wrapped SWNTs is largely affected by the polymer side chains. Here, a poly(fluorene-co-phenylene) polymer that contains a self-immolative linker as part of its sidechains is reported. The self-immolative linker is stabilized with a tert-butyldimethylsilyl ether group that, upon treatment with tetra-n-butylammonium fluoride (TBAF), undergoes a 1,6-elimination reaction to release the sidechain. Sonication of this polymer with SWNTs in tetrahydrofuran (THF) results in concentrated dispersions that are used to prepare polymer-SWNT thin films. Treatment with TBAF caused side-chain cleavage into carbon dioxide and the corresponding diol, which can be easily removed by washing with solvent. This process is characterized by a combination of absorption and Raman spectroscopy, as well as four-point probe measurements. The conductance of the SWNT thin films increased ≈60-fold upon simple TBAF treatment, opening new possibilities for producing high-conductivity SWNT materials for numerous applications.

Influence of the addition of carbon nanotube on the physical behavior of a lateritic soil from the southwest Amazon

In this work we evaluate the physical-mechanical behavior of lateritic soil with addition of carbon nanotubes. The soil was collected in a commercial deposit located in Rio Branco – AC and later characterized through particle size tests, X-Ray Diffraction, X-Ray Dispersion Spectroscopy and Tropical Compressed Miniature essay. The dispersion of nanotubes in solution was carried out and the size of the nanoparticles was verified using Dynamic Light Spreading - DLS, Zeta Potential and PDI. Three percentages of additions (0.05%, 0.1% and 0.2%) of carbon nanotubes were evaluated and compared with the control group according to the parameters of Atterberg limits, real density, dry density maximum and optimum humidity. The results indicate that the soil has a clayey behavior with a medium texture, with the presence of clay mineral kaolinite in its composition and silicon and iron oxides. The dispersion of carbon nanotubes reached particles with an average hydrodynamic diameter of 68.9 nm and Zeta Potential of -24.87 mV and PDI of 0.231, characterizing a solution as moderately dispersed and kinetically stable. The results of the liquidity limit and plasticity tests showed a reduction of 10 and 13%, respectively, with the addition of carbon nanotubes, while for the parameters of plasticity index, real specific mass, maximum dry density and optimal moisture, they did not show significant variation. Carbon nanotubes interact with soils with lateritic behavior, and further studies are essential to better understand the mechanisms behind this interaction.

Functionalization of Carbon Nanotubes in Polystyrene and Properties of Their Composites: A Review.

The inherent π-π interfacial interaction between carbon nanotubes (CNTs) and polystyrene (PS) makes the CNT/PS composite a representative thermoplastic nanocomposite. However, the strong van der Waals force among CNTs poses challenges to achieving effective dispersion. This review provides an overview of various CNT functionalization methods for CNT/PS composites, encompassing covalent grafting with PS-related polymers and non-covalent modification. A focus in this section involves the pre-introduction surface modification of CNTs with PS or PS-related polymers, substantially enhancing both CNT dispersibility and interfacial compatibility within the PS matrix. Furthermore, a comprehensive summary of the mechanical, electrical, thermal, and electromagnetic shielding properties of CNT/PS nanocomposites is provided, offering an overall understanding of this material. The surface modification methods of CNTs reviewed in this paper can be extended to carbon material/aromatic polymer composites, assisting researchers in customizing the optimal surface modification methods for CNTs, maximizing their dispersibility, and fully unleashing the various properties of CNTs/polymer composites. Additionally, high-performance CNTs/PS composites prepared using appropriate CNT modification methods have potential applications in areas such as electronic devices, sensors, and energy storage and conversion.

Carbon nanotubes used to enhance the wear properties of AlSi10Mg/CNTs nanocomposites prepared through additive manufacturing

In this work, varying weight percentages of carbon nanotubes (CNTs) were reinforced in the AlSi10Mg alloy, and prepared nanocomposites through additive manufacturing. The distribution of CNTs in the metal matrix were achieved through functionalization and ball milling. The dispersion of CNTs were investigated through FESEM, TEM, and Raman spectroscopy. To study the wear properties, the prepared samples underwent wear tests at various loads and speeds. The wear properties, worn surfaces, and microhardness were thoroughly investigated. The results unveiled that the incorporation of CNTs led to a decrease in the wear rate and a reduction in the coefficient of friction. It was observed that CNTs functioned as a solid lubricant, resulting in a significant reduction in both the coefficient of friction and wear rate. The microstructures of the worn surfaces and wear channels became smaller and smoother after the addition of CNTs, and smaller-sized debris was produced.

Effect of the ratio of carbon nanotubes and carbon black on the properties of natural rubber

In this experiment, the effect of carbon nanotubes (CNTs) replacing some carbon black (CB) on the properties of natural rubber composites was investigated. 5 phr of CNTs were used to replace part of CB in the ratio of m(CNTs) : m(CB reduction) = 1 : X (X from 1 to 4.5). The properties of the vulcanized rubber such as vulcanization, thermal conductivity, tensile, heat generation and processing were investigated experimentally. The results showed that when the ratio of CNTs/CB(reduction) was 1:1, it could substantially improve the crosslink density of the sample and reduce the vulcanization time, while having better processing safety and having the best thermal conductivity. At this time, 5 phr of CNTs and 40 phr of CB were added to the sample, and the dispersion of CB and CNTs in the sample was studied by CB dispersion tester and rubber processing analyzer. The tensile property change regularity tested by rubber tensile tester matched with the experimental results of CB dispersion tester and rubber processing analyzer. When the ratio of CNTs/CB(reduction) was 1:1, it increased the heat generation of the sample significantly. When the ratio of CNTs/CB(reduction) was 1:3.5, all the properties of the sample were better than those of the 1# sample.

Strength-ductility synergy in a novel carbon nanotube-high entropy alloy co-reinforced aluminum matrix composite

Here we present a novel design strategy for the manufacturing carbon nanotube (CNT)-high entropy alloy (HEA) particles co-reinforced aluminum matrix composites (AMCs) with heterogeneous structures. This strategy involves in situ synthesis of CNTs@HEA hybrid reinforcement. The results demonstrate that the fabricated CNTs@HEA/Al composites have bimodal grain structure and nano-reinforced particle spatial distribution. The dispersion of CNTs within the Al matrix was achieved via the transport of micron-sized HEA particles. Simultaneously, the formation of Al4C3 and Cr7C3 occurred at the HEA/CNTs/Al interface, thereby augmenting the load-bearing capacity of CNTs. The enhanced strength of CNTs@HEA/Al composites is mainly attributed to the synergistic effect of load transfer, back stress strengthening, Orowan strengthening, grain refinements and stacking faults (SFs) strengthening. Moreover, the bimodal grains and SFs of the composite contribute sustained strain hardening, resulting in satisfactory tensile ductility.

Electrical property-selective noncovalent dispersion of carbon nanotubes by poly(perylene diimide-thiophene): a molecular dynamics study

ABSTRACT Thiophene polymers have been widely used to selectively disperse semiconducting single-walled carbon nanotubes (sc-SWNTs). Important questions concern the influence of the solvent on the adsorbability and adsorption-conformation of such polymers, along with the relation between the thiophene polymer structure and selectivity to SWNTs. These concerns about the behaviour of poly(perylene diimide (PDI)-thiophene) have been addressed in this study via molecular dynamics simulation. It is observed that the polymer does not adsorb to SWNTs in a solvent with strong polarity and shows an effective adsorbability in a solvent with moderate polarity or non-polarity. Its selectivity turns from metallic SWNTs to semi-conducting SWNTs in a solvent with a decreasing polarity. In addition, the rigid part in the polymer backbone (PDI) enlarges adsorbability significantly, and the flexible part (two thiophene units) adjusts its adsorption conformation onto SWNTs, which offers the selectivity. The study offers theoretical clues for designing the structure of thiophene polymers with respect to SWNTs-extraction.

The dielectric properties of silicone-multiwall carbon nanotubes nanocomposite in the frequency range from 0.5 to 20 GHz

Integrating carbon nanotubes (CNTs) into a polymer matrix can significantly modify its physical properties, providing that the challenges associated with CNT dispersion are successfully resolved. In this work, we investigate the enhancement of the dielectric properties of silicone when multiwall carbon nanotubes (MWCNTs) are introduced to its polymer matrix as a filler in the frequency range from 0.5 to 20 GHz. An optimized procedure is used to prepare nanocomposites with MWCNTs concentrations by weight of 0%, 0.5%, 1.0%, 1.5%, and 2.0%. The investigated dielectric properties for the prepared nanocomposites are the real dielectric constant ɛ′, the imaginary dielectric constant ɛ″, the loss tangent tan δ, and the AC conductivity σAC. The dispersion of the MWCNTs in the silicone matrix is confirmed using the Fourier-transform infrared (FTIR) spectroscopy and the scanning electron microscope. This study shows that the dielectric properties of the nanocomposite are enhanced as the MWCNT’s concentration is increased over the entire frequency range. For example, the enhancement in ɛ′ value was from 3.2 up to 21.6 at 0.5 GHz and from 2.5 to 10.6 at 20 GHz as the concentration increased from 0% to 2.0%. For the ɛ″ value, the enhancement was from less than 0.1 to 8.6 at 0.5 GHz and to 2.0 at 20 GHz, respectively. Based on the obtained tanδ values, the nanocomposites with MWCNTs of 0.5% and 1.0% can be classified as low-loss dielectrics, while the other nanocomposites with MWCNTs of 1.5% and 2.0% are classified as lossy dielectrics.

Oligofluorene main-chain length-dependence on one-pot extraction of chirality-selective semiconducting single-walled carbon nanotubes

Abstract Polyfluorene and their derivatives are noted for being fascinating dispersants for single-walled carbon nanotubes (SWCNTs) because they selectively solubilize semiconducting (sem-) SWCNTs. However, the selective extraction mechanism of this unique behavior has not yet been fully clarified. In this paper, we describe a unique SWCNT solubilization behavior using 12 fluorene oligomers with different main-chain lengths (FOn, n = 2∼30), in which n is the number of fluorene-repeating unit. Sonication of SWCNTs using these oligofluorenes in toluene was found to solubilize SWCNTs when the main-chain length was longer than n = 12. Raman spectra revealed that selective sem-SWCNT extraction occurred when using the FOn with n ≥ 18, while, when using FOn (n = 12, 15), both sem- and metallic (met-) SWCNTs were solubilized. The (n,m)chiralites of the extracted SWCNTs using the fluorene oligomers differed from those using a homopolymer, poly(9,9′-di-n-octylfluorene) (PFO); that is, PFO extracted (9,7)SWCNTs well, while only FO30 slightly dissolved the (9,7)tubes, and when using other FOn (n = 12∼27), no (9,7)tubes were solubilized. The present study demonstrated the importance of the main-chain length of the oligofluorenes on selected chirality extraction of sem-SWCNTs, which is useful for designing fluorene-based compounds with selective extraction of sem-SWCNTs with a specific (n,m) chirality.

Natural Convection Melting in a Rectangular Heat Storage Tank of Carbon Nanotube Dispersed Latent Heat Storage Material

Natural Convection Melting in a Rectangular Heat Storage Tank of Carbon Nanotube Dispersed Latent Heat Storage Material

Inkjet-Printed Multiwalled Carbon Nanotube Dispersion as Wireless Passive Strain Sensor.

In this study, a multiwalled carbon nanotube (MWCNT) dispersion is used as an ink for a single-nozzle inkjet printing system to produce a planar coil that can be used to determine strain wirelessly. The MWCNT dispersion is non-covalently functionalized by dispersing the CNTs in an anionic surfactant, namely sodium dodecyl sulfate (SDS). The fabrication parameters, such as sonication energy and centrifugation time, are optimized to obtain an aqueous suspension suitable for an inkjet printer. Planar coils with different design parameters are printed on a flexible polyethylene terephthalate (PET) polymer substrate. The design parameters include a different number of windings, inner diameter, outer diameter, and deposited layers. The electrical impedance spectroscopy (EIS) analysis is employed to characterize the printed planar coils, and an equivalent electrical circuit model is derived based on the results. Additionally, the radio frequency identification technique is utilized to wirelessly investigate the read-out mechanism of the printed planar MWCNT coils. The complex impedance of the inductively coupled sensor undergoes a shift under strain, allowing for the monitoring of changes in resonance frequency and bandwidth (i.e., amplitude). The proposed wireless strain sensor exhibits a remarkable gauge factor of 22.5, which is nearly 15 times higher than that of the wireless strain sensors based on conventional metallic strain gauges. The high gauge factor of the proposed sensor suggests its high potential in a wide range of applications, such as structural health monitoring, wearable devices, and soft robotics.