Amount Of Carbon Nanotubes Research Articles

Simulation-based analysis of impact of CNT dispersion on hydration of cement paste

Dispersion of carbon nanotubes (CNTs) is one of the key factors determining the mechanical properties of cement composites. This study analyzed impact of CNT dispersion on hydration of cement paste. An image analysis method based on optical microscopy images was proposed to quantitatively consider the CNT dispersion. To quantify CNT dispersion, this paper proposed PCNT, which is the percentage of a 1 μm2 space containing CNTs within entire water volume. To investigate CNT dispersion effect, the same amount of CNT was classified into six steps (S1, S5, S15, S30, S50, and S100) according to PCNT. The relationship between CNT dispersion and the hydration, porosity, and compressive strength of the cement paste was analyzed using a CEMHYD3D considered CNT effect. The optimal CNT dispersion for 0.1 wt% CNT reinforcement in a cement paste with water-to-cement ratio of 0.3 was found to be 15 % PCNT. The improvement in CNT dispersion resulted in acceleration of hydration of cement paste, improvement in compressive strength, and densified microstructure.

Prediction Models for the Hybrid Effect of Nano Materials on Radiation Shielding Properties of Concrete Exposed to Elevated Temperatures

In modern construction, nanomaterials can be added to concrete to improve its radiation shielding properties. A prediction model for the gamma-ray radiation shielding properties, such as linear attenuation coefficient (LAC) of nanomaterial-based concrete remains necessary. This study aims to develop prediction models for LAC of nano modified concrete (NMC) using nano alumina (NA) and carbon nano tubes (CNTs) subjected to high temperatures. These models are based on linear regression and three machine learning algorithms: M5 Prime (M5P), random forest (RF), and extreme gradient boosting (XGBoost). To build the models, results of 117 concrete cubic specimens (100mm size) was utilized as a dataset with varying amounts of NA and CNTs. Relevant variables including temperature, exposure time, and NA and CNTs dosages were considered. To further validate the predicted results, various statistical metrics and K-fold cross-validation were employed to compare and validate the models' output. The results showed that the XGBoost model outperformed other models, with the highest R2 of 0.9975 and the lowest error of 0.4365%. In addition, the impact of each parameter on LAC of NMC was assessed using Shapley Additive Explanations (SHAP) analysis. Sensitivity and SHAP analyses reveal that CNTs has the highest influence on the radiation shielding properties of NMC. In comparison with the previously developed ANN model, the XGBoost and ANN models showed approximately the same prediction power for predicting LAC of NMC.

In situ foam 3D printed microcellular multifunctional nanocomposites of thermoplastic polyurethane and carbon nanotube

Electrically conductive and mechanically robust thermoplastic polyurethane (TPU)/carbon nanotube (CNT) foams were achieved using a novel in situ foam 3D printing (F-3DP) process. Thermally expandable microspheres (TEMs), as blowing agent, were incorporated into the TPU/CNT filaments and fed to the F-3DP process. Foams with uniform morphologies and repeatable properties were achieved in a wide density range by solely regulating the nozzle temperature and its correlated flow rate. Overall, the degree of foaming increased substantially with an increase in the temperature, providing a density range of 0.96 to 0.17 g/cm3. It was interestingly found that a small amount of CNT (1 wt%) increased the expansion ratio. A further increase of CNT (to 3 and 5 wt%), however, caused a reduction in the expansion ratio. These opposing trends were attributed to the competing effects of CNT on the melt's thermal conductivity and viscosity. Both CNT content and nozzle temperature exhibited significant impacts on the tensile properties and electrical conductivity. This resulted in foams with diverse Young's modulus and strain at break in the range of 3.9–29.5 MPa and 260 to 52 %, respectively. More importantly, the electrical conductivity increased up to several orders of magnitude, as the foam expansion was increased due to temperature rise. This interesting finding was thoroughly discussed in terms of the enhanced inter-bead adhesion, vanishing inter-bead gaps, and realignment of CNTs around the growing TEMs. The results demonstrate a great potential of F-3DP to produce functional foams with controllable density and performance in a wide range.

3D printable carbon nanotubes-based composites with reconfigurable shapes and properties

In this work, we developed an efficient approach to fabricating composites of carbon nanotubes (CNT) with shape reconfiguration ability and Joule heating behavior by incorporating the direct ink writing (DIW) technique. Our 3D printable ink consisted of a high concentration of CNT stabilized by polyvinylpyrrolidone (PVP) in an aqueous polyvinyl alcohol (PVA) solution. The rheology of the ink was tuned by the amounts of CNT and PVP. The printed objects underwent the freeze-thaw process to form weak hydrogels induced by the crystallization of PVA. Subsequently, the hydrogels were immersed in a deep eutectic solvent (DES) bath consisting of choline chloride and glycerol. This process replaced the water in the hydrogels with DES and led to mechanically tough DES/CNT gels. We utilized the high stretchability of DES/CNT gel to achieve complex geometries that would be challenging to accomplish solely with DIW. After reshaping the DES/CNT gels, the target shape was fixed by further solvent exchange with ethanol and drying. The final CNT composites showed a high electric conductivity of up to 33.94 S/m and exhibited remarkable Joule heating performance using a low applied voltage (5 V). Additionally, we successfully achieved a spatial variation of mechanical stiffness, electrical conductivity, and Joule heating across the printed objects by a selective solvent removal process. In short, this work expands the scope of possible shapes and properties of CNT-based composites.

Improving Signal Transmission Quality of Wind Turbine Pitch Slip Ring With Copper Matrix Composites

Abstract To improve the signal transmission quality, copper matrix composites added with different contents of carbon nanotubes (CNTs) and molybdenum disulfide (MoS2) were prepared. The electrical and tribological properties of composites were studied. A new parameter, the correlation dimension of electrical noise, was proposed to quantitatively characterize the stability of signal transmission. Copper matrix composites added with reasonable amount of CNTs and MoS2 can effectively reduce the values and fluctuations of friction coefficient and improve the wear resistance, efficiency, and stability of the signal transmission. Tribo-films are generated on the surface of composites. The contents of CNTs and MoS2 affect the stability of tribo-film and further affect the signal transmission quality. 0.5 wt% CNTs and 15 wt% MoS2 can make good synergistic effects on improving the signal transmission quality of composites. The results provide good guidance to improve the signal transmission quality of wind pitch slip rings.

Impact of surfactants on SWCNT dispersion in N-methylmorpholine N-Oxide for cellulose dissolution

A well dispersed slurry of single-walled carbon nanotube (SWCNT) and 60 % hydrated N-methylmorpholine N-oxide (NMMO) solution was prepared by probe sonicator. The proper dispersion of carbon nanotube (CNT) has been verified by optical microscope by varying the sonication time. Further, the slurry was concentrated to 76 % (for cellulose dissolution) and during this process some agglomeration of CNTs has been observed. The dispersion of CNT aggregation was checked by addition of surfactants like sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS) (with 2 % (w/w) with respect to CNT) to the surface of CNT. SDBS is giving better dispersion as compared to SDS when the slurry is heated to obtain 76 % NMMO as checked by optical microscope and UV–Vis spectrophotometer to get quantitative amount of dispersed CNT. 88 % dispersion has been obtained in case of SDBS-assisted CNT after heating followed by centrifugation of the concentrated solution. Similarly, 78 % dispersion has been observed in case of SDS-assisted CNT and 46 % dispersion in case of CNT without any surfactant. The stronger dispersion ability of SDBS could improve its use for SWCNT separation in NMMO solution which can be used further for cellulose dissolution to prepare lyocell fiber.

CARBON NANOSTRUCTURES OBTAINING FROM POLYMER MATERIALS

As part of the expansion of raw material base used in the development of technological and productive methods for the synthesis of carbon nanostructures (CNS) and solving the problem of environmentally friendly and economical polymer recycling, the results of investigation of microwave (MW) catalytic pyrolysis of macromolecular compounds from the range of polystyrene, polypropylene, polyethylene terephthalate, polyvinyl alcohol are presented. The information about existing approaches to solving these problems is briefly considered, and the prospects for MW processing of polymers are shown. The process was carried out by microwave treatment of a mixture of polymer raw materials acting as a carbon donor and substances-precursors of metal catalysts – cobalt and nickel compounds, their mixtures, as well as metal iron and nickel. Graphite and carbon fiber were used as temperature regulator. Experiments have demonstrated that effective conversion of the studied compounds occurs only in the presence of MW energy absorbers-converters, regardless of the nature of metal catalyst precursor. According to electron microscopy data, the resulting materials are a mixture of carbon nanostructures of disordered morphology with the predominant content of carbon nanotubes (CNTs) in the reaction products for experiments with polystyrene, polypropylene and polyethylene terephthalate. The use of polypropylene and polyvinyl alcohol leads to the production of carbon nanostructures containing only a small amount of CNTs. X-ray phase analysis data confirm the formation of multi-walled carbon nanotubes as the main structural component of the obtained carbon nanomaterials. It has been suggested that transformation pathways of the investigated hydrocarbons are similar, despite the difference in pyrolysis temperatures, which may be related to the simultaneous processes of polymer cracking, carbonization of decomposition products and CNS synthesis due to the rapid growth of reaction mass temperature during microwave treatment. The efficiency of different precursors of catalytic systems based on transition metals in the processes examined is substantiated. It has been shown that the high carbon content in feedstock promotes the formation of carbon nanostructures, but is not decisive for carbon nanotubes obtaining. For citation: Zaritovskii A.N., Kotenko E.N., Grishchuk S.V. Carbon nanostructures obtaining from polymer materials. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 5. P. 99-106. DOI: 10.6060/ivkkt.20246705.6957.

On the roles of strain gradient tensors in quasi‐3D nonlinear dynamics of microplate‐type piezoelectric systems of energy harvesting under triangular mechanical actuation

AbstractThe small‐scale‐dependent nonlinear dynamical attributes of microplate‐type laminated piezoelectric systems of harvesting energy subjected to a triangular mechanical actuation are explored in the current exploration. The core of harvesting systems is supposed to be made of nanocomposites reinforced by randomly oriented carbon nanotubes (CNTs) having various degrees of agglomeration coated by piezoelectric layers. In this regard, the microplate‐type systems of harvesting energy are modeled via a quasi‐3D plate theory combined with the modified strain gradient elasticity in the presence of various microsize‐dependent strain gradient tensors. Thereafter, the solution of the developed coupled electromechanical size‐dependent nonlinear problem is obtained numerically by utilizing the meshless collocation approach employing incorporation of the polynomial and radial basis functions to remove any feasible singularity for the associated moment matrices. It comes to the conclusion that by elevating the quantity of CNTs disclosed within the clusters, the significance of the microsize dependency in the achieved voltage enhances from 22.06% to 22.73% toward the simply supported bridge‐type context, and from 33.00% to 33.92% toward the clamped bridge‐type context.Highlights Development of a microstructural‐dependent quasi‐3D shear flexible energy harvester model. Incorporating the roles of various strain gradient tensors in the nonlinear dynamics of microharvesters. Size‐dependent time‐histories of achieved voltage from triangular mechanical‐loaded microharvesters. Influence of the CNT reinforcement clustering on the nonlinear dynamic performance.

In-Situ Flame-Synthesized Carbon Nanomaterials via an Impinging Swirl Flow with an N-Butanol Pool

ABSTRACT This study aims to investigate the impact of flow rotation and oxygen concentration on the synthesis of carbon nanomaterials using n-butanol diffusion flames in a rotating stagnation flow with a liquid pool and a catalytic Ni substrate. With increasing angular velocity (ω), the diffusion flame shifts slightly toward the upper oxidizer nozzle, experiences a lower strain rate, and becomes stronger with a higher maximum flame temperature at a fixed oxygen concentration (ΩO). Meanwhile, the soot layer thickens and gradually turns yellowish. Field Emission Scanning Electron Microscopy (FESEM) analyses confirm that carbon nanotubes (CNTs) can only be fabricated at ω = 2 or 3 rps when ΩO = 21%, highlighting the critical role of flow rotation. Interestingly, the optimal positions for CNT synthesis consistently occur at the same sampling position (1.5 mm below the upper edge of the blue flame) for all values of oxygen concentration (ΩO). The corresponding temperature ranges for ΩO = 19%, 18%, and 17% are approximately 950°C, 820–920°C, and 800–850°C, respectively, which align with existing literature. High-resolution transmission electron microscopy (HRTEM) images reveal both typical straight tubular and bamboo-like CNT structures. Raman spectra indicate superior graphitization at high angular velocities (ω). Notably, at ω = 0 rps, the intensity ratio of the D- and G-bands is greater than 1 (ID/IG >1); however, as ω increases, the opposite holds (ID/IG <1), with its value gradually decreasing. This suggests that the swirl effect enhances graphite layer crystallization. Importantly, the strain rate controlled by flow rotation significantly influences CNT fabrication, considering both residence time and carbon source. The key finding of this study is that swirl flow enhances both the quality and quantity of CNTs synthesized via n-butanol diffusion flames.

Carbon nanotubes enhancement of tribological and nanomechanical properties of PVDF-BN nanocomposites

There have been continuous efforts to further promote various properties of polymeric materials to meet various industrial demands, especially in the area of thermal, electrical, mechanical and wear properties. This study developed polyvinylidene fluoride (PVDF)-boron nitride (BN) nanocomposites and significantly enhanced their wear and nanomechanical properties by incorporating very low content of carbon nanotubes (CNT). The nanocomposites were developed via simple technique of solution mixing and hot compression. Scanning electron microscope showed that the nanocomposites achieved uniform microstructure with no significant agglomeration of the nanoparticles in the PVDF matrix. The wear rate of PVDF-10wt%BN-0.1wt%CNT was reduced from 5.68 × 10–4 and 5 × 10–3 mm3/Nm for pure PVDF to 1.6 × 10–6 and 8 × 10–6 mm3/Nm at applied loads of 10 N and 20 N, respectively. Also, an increase in hardness and elastic modulus of 225% and 219% for PVDF-10wt%BN-0.1wt%CNT was obtained relative to the pure PVDF at 100-mN applied load. While the nanocomposite showed about 75% and 103% increments compared to PVDF-10wt%BN at 100 mN. This study revealed that the addition of small amount of CNT could further improve the wear and mechanical properties of PVDF-BN as well as any other polymer-ceramic binary systems various advanced engineering applications.

NO2 gas response and recovery properties of ambipolar CNT-FETs with various CNT/CNT junctions

Gas sensors based on ambipolar carbon nanotube (CNT) field-effect transistors with various amounts of CNTs were fabricated by dielectrophoretic assembly. The nitrogen dioxide (NO2) gas response and recovery properties of the transistors were measured to investigate the effect of CNT amount on gas response. For the device with a small amount of CNTs, responses from the CNT bulk and CNT/electrode contacts were observed. For devices with a large amount of CNTs, in which a network-like structure of CNTs was observed near the electrodes, an increased current in both electron and hole conduction regions was observed compared with that for the device with a small amount of CNTs. The increased current in the electron conduction region rapidly decreased during recovery. This response is consistent with that of CNT/CNT X-type contacts, which have a high resistance before NO2 adsorption. Equivalent circuits of CNT channels with CNT/CNT contacts were developed, allowing the transistor behavior to be qualitatively discussed. Evaluation of time constants revealed that CNT/electrode contacts and CNT/CNT X-type contacts exhibited high NO2 adsorption and desorption rates, respectively.

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

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

Effect of Positively Charged Lipids (DOTAP) on the Insertion of Carbon Nanotubes into Liposomes and the Separation Performance of Thin-Film Nanocomposite Membranes

A liposome vesicle is an ideal carrier for carbon nanotubes (CNTs) serving as the water channel that allows for the fast transport of water molecules, thus enhancing membrane permeability. However, a low quantity of CNTs inserted into the liposome vesicle is an important factor that limits the further improvement of the membrane flux. In the present study, a positively charged lipid, (2,3-dioleoyloxy-propyl)-trimethylammonium-chloride (DOTAP), was introduced to 1,2-dioleoyl-sn-glycero-3-phosphoethanolamineon (DOPE) liposome vesicles to tailor the vesicle charge so as to evaluate the effect of positively charged DOTAP on the insertion of CNTs into liposomes and the separation performance of thin-film nanocomposite (TFN) membranes. The results show that the addition of DOTAP increased the quantity of CNTs inserted into the liposome vesicles, as the shrinkage rate (k) and permeability (Pf) of the liposome vesicles presented an obvious increase with the increased content of DOTAP in the liposome vesicles. Moreover, it contributed to a 252.3% higher water flux for TFN membranes containing DOPE/DOTAP2:1-CNT liposomes (the mass ratio between DOPE and DOTAP was 2:1) than thin-film composite (TFC) membranes. More importantly, it presented a 106.7% higher water flux for TFN membranes containing DOPE/DOTAP4:1-CNT liposomes (the mass ratio between DOPE and DOTAP was 4:1), which originated from the greater number of water channels that the CNTs provided in the liposome vesicles. Overall, positively charged DOTAP effectively tailored the vesicle charge, which provided a better carrier for the insertion of a greater quantity of CNTs and contributed to the higher permeability of the TFN membranes.

Production of supertough and semiconductive PLA-based polymer blend nanocomposites by kinetic microstructural control

Polymer nanocomposites with superior multi-functional properties can be fabricated by tuning their morphology. In this work, a supertough and semiconductive polylactide (PLA)-based polymer blend nanocomposite (PBNANO) was produced for the first time via melt blending with a core-shell rubber (CSR) and carbon nanotubes (CNT). Reference binary blends (PLA/CSR and PLA/CNT) revealed that, when added separately, 20 wt% of CSR and 0.25 wt% of CNT were the suitable quantities to achieve a supertough and a semiconductive PLA-based material, respectively. Based on the obtained results, PLA/CSR/CNT PBNANOs with 20 wt% of CSR and CNT amounts between 0.15 and 0.50 wt% were prepared in one extrusion step. Although supertoughness was achieved in all the cases, the PBNANOs were insulating due to the selective localization of the CNT in the poly(methyl methacrylate) (PMMA) shell of the CSR and the good dispersion of the CSR nanoparticles. However, a supertough and semiconductive PLA-based PBNANO was obtained by a two-step melt compounding. Using this processing sequence, a worse dispersion of the CSR was obtained, allowing contact between some CSR nanoparticles. The differences in PBNANOs morphology prepared in one or two extrusion steps were determined by TEM and corroborated by rheological measurements. In the case of the two extrusion steps PBNANO, the CNT were located in both the PLA matrix and in the shell of the CSR. This morphological change enabled the PBNANO to be conductive, as the CNT percolation was achieved in this case while still remaining supertough.

Engineered nano-architecture for enhanced energy storage capabilities of MoS2/CNT-heterostructures: A potential supercapacitor electrode

Hydrothermal synthesis was utilized to achieve the direct growth of molybdenum disulphide (MoS2) nanoflakes on carbon nanotubes (CNT). Through this method, MoS2/CNT heterostructures with engineered microstructure have been obtained by suitably optimizing the synthesis conditions. Raman, X-ray photoelectron spectroscopy, and electron microscopy have been utilized to characterize the heterostructure. The present study investigated the influence of varying amounts of CNT and MoS2 within the heterostructure on its electrochemical properties. The optimization of the heterostructure morphology has resulted in enhanced electrochemical performance, with a high specific capacitance of ∼436 F/g at 1 A/g, along with good rate capability. The charge storage mechanism was explained by using Dunn's power law. Further, the MoS2/CNT heterostructure was employed to fabricate a solid-state symmetric supercapacitor. The device exhibited a specific capacitance of ∼164 F/g at 1 A/g, along with good cyclic stability, retaining 96 % of its capacitance after 1000 cycles. Additionally, the device demonstrated high energy and power density values of ∼27 Wh/Kg and 603 W/Kg, respectively. The present study indicates that the MoS2/CNT heterostructure holds great promise as an electrode material for high-performance solid-state supercapacitor devices.

Biodegradable Electrospun Conduit with Aligned Fibers Based on Poly(lactic-co-glycolic Acid) (PLGA)/Carbon Nanotubes and Choline Bitartrate Ionic Liquid.

Functionally active aligned fibers are a promising approach to enhance neuro adhesion and guide the extension of neurons for peripheral nerve regeneration. Therefore, the present study developed poly(lactic-co-glycolic acid) (PLGA)-aligned electrospun mats and investigated the synergic effect with carbon nanotubes (CNTs) and Choline Bitartrate ionic liquid (Bio-IL) on PLGA fibers. Morphology, thermal, and mechanical performances were determined as well as the hydrolytic degradation and the cytotoxicity. Results revealed that electrospun mats are composed of highly aligned fibers, and CNTs were aligned and homogeneously distributed into the fibers. Bio-IL changed thermal transition behavior, reduced glass transition temperature (Tg), and favored crystal phase formation. The mechanical properties increased in the presence of CNTs and slightly decreased in the presence of the Bio-IL. The results demonstrated a decrease in the degradation rate in the presence of CNTs, whereas the use of Bio-IL led to an increase in the degradation rate. Cytotoxicity results showed that all the electrospun mats display metabolic activity above 70%, which demonstrates that they are biocompatible. Moreover, superior biocompatibility was observed for the electrospun containing Bio-IL combined with higher amounts of CNTs, showing a high potential to be used in nerve tissue engineering.

Preparation of Transparent Conductive Films Using Carbon Nanotubes

Carbon nanotubes (CNTs), since the discovery by Iijima, have attracted tremendous interests in scientific research mainly due to their exceptional structure and physical properties. The high aspect ratio, light weight, extraordinary stiffness, and strength make CNTs a potentially very functional material to be used in polymer nanocomposites application. Carbon nanotubes are single or multilayered coaxial tubes of six-membered ring networks composed of carbon. It is an allotrope of carbon and is sometimes classified as a type of fullerene. Carbon nanotubes are expected to be applied to materials that normally do not conduct heat or electricity, such as resin, rubber, ink, and paint. In addition, it is expected to be applied to the electronics field because of its conductivity and thermal conductivity even in small quantities and high strength when made into long lengths. One of the problems of CNTs is the tendency of CNTs to aggregate with each other due to intermolecular interactions. In the aggregated state, CNTs cannot exhibit their inherently useful characteristics, and therefore, a technology to disperse CNTs at the nano-level is required. Currently, two major methods are being considered for dispersing CNTs: The first is dispersion by chemical modification. By introducing carboxylic acid into strong acid treated CNTs and introducing hydrophilic or hydrophobic substituents here, solubilization in water or organic solvents is possible. However, there is a problem that this destroys the structure of CNTs and thus greatly impairs their original properties.The other method is to physically disperse CNTs. This is a very simple method that uses ultrasonic irradiation to loosen bundled CNTs, but the dispersion is only temporary, and re-agglomeration occurs quickly. Problems have also been reported, such as excessive ultrasonic irradiation destroying the structure of the CNTs. We have succeeded in producing CNTs nano dispersion gels by adding an aromatic compound to agglomerated CNTs and applying agitation and ultrasonic irradiation. The following describes the process of preparing CNTs dispersion gels. After agglomerated CNTs are temporarily dispersed by ultrasonic irradiation, an aromatic compound (dispersant) is added and mixed and agitated. The dispersed CNTs and the aromatic compound are combined by π-π interaction, and the aromatic compound is adsorbed on the CNTs surface. When CNTs molecules adsorbed with aromatic compounds approach each other, the aromatic compounds on the surface form π-π interactions. At this point, the CNTs are in a gel-like state. Since this dispersion gel does not chemically modify the CNTs, it can be prepared without destroying the structure of the CNTs. The CNTs gel proved to be free from aggregation even after the dispersant component was removed, and the network structure was maintained. In addition, this dispersion gel shows high electrical conductivity because the CNTs are dispersed three-dimensionally and the CNTs form three-dimensional conductive paths in the gel.Next, we introduce the preparation of CNT composite resin. CNT composite resin is prepared by adding binder resin to the carbon nanotube dispersion gel prepared earlier, mixing, and stirring, and ultrasonic irradiation. A transparent conductive film is created by forming the prepared CNT composite resin on a glass slide. In recent years, transparent conductive films have been in high demand due to the development of electronics products, and the use of CNTs as the main material is expected to significantly reduce the cost of development, as they are less expensive than Metallic materials such as indium tin oxide and can be stably supplied. The challenge of this research is that the amount of black CNTs added, which imparts conductivity, significantly affects the transparency of the transparent conductive film. Therefore, it is necessary to select aromatic compounds and resin materials that achieve both high conductivity and transparency with low amounts of added CNTs from a molecular chemistry perspective. In our previous research, we focused on the chemical bonding between resin materials and CNTs for the first time and attempted to improve electrical conductivity by using hydrogen bonding for CNTs. In addition, by combining polycarbonate, which exhibits high transparency and impact resistance, with CNT dispersion gel, we attempted to fabricate a transparent conductive film with high durability. As a result, we succeeded in developing a transparent conductive film material with performance applicable to touch panels.In this study, CNTs dispersion gels prepared with aromatic compounds were evaluated using absorbance measurements and Raman spectroscopy. The Raman spectra measurements allowed us to quantitatively evaluate the interaction between SWCNTs and aromatic compounds. The possibility of charge-transfer complex formation was also suggested by the results of absorbance measurements. Figure 1

Rheological Properties of Carbon Nanotube Infused Cementitious Composites with Various Amounts of CNT

The addition of carbon nanotubes (CNTs), which are hydrophobic materials, significantly influences the rheology of cementitious materials but requires important mix modifications in order to provide proper flowability for further use. This paper investigates the influence of various dosages of carbon nanotubes (0.05 wt.%, 0.1 wt.%, 0.2 wt.%, 0.5 wt.%, and 1 wt.%) on the flowability, rheological parameters, air content, and volume density of cement mortars. The results show an increase in the yield stress parameter with an increment in CNT dosage up to the threshold of 0.5 wt.% for mixes with an increased amount of cement. For standard proportions, it was on a stable level for all mixes except for 0.2 wt.%. The plastic viscosity parameter also increased with the CNT dosage; mixes with standard proportions of components were not higher than the reference, and mixes with an increased amount of cement were lower than the reference for dosages up to 0.5 wt.% of CNT. The addition of a superplasticizer and modifications of the ratio of the components were employed to achieve proper flowability and measure the rheological parameters. The presented results show that regardless of the negative influence of carbon nanotubes on the properties of fresh mortar, it is possible to achieve a stable flow and workability using simple modifications of the composition.

Styrene–butadiene rubber‐based nanocomposites toughened by carbon nanotubes for wide and linear electromechanical sensing applications

AbstractThe contribution from specific interactions between rubber and filler sometimes plays a crucial role in the mechanical reinforcement and electromechanical sensitivities of rubber composites. This research explores the physical, mechanical, and electromechanical properties of styrene‐butadiene rubber (SBR) composites reinforced with carbon nanotubes (CNTs). Mechanical, thermodynamic, and scanning electron microscopy studies reveal that CNTs primarily enhance the mechanical properties through physical interactions with the rubber. Notably, π‐stacking interactions between the aromatic π‐electrons in SBR and the delocalized π‐electrons in CNTs contribute to significant improvements in mechanical strength. For instance, adding 4 phr (per hundred grams of rubber) of CNTs results in an impressive 871% increase in fracture toughness compared to unfilled rubber. These composites also exhibit remarkable stress and strain improvements even with small amounts of CNTs, making them suitable for robust strain sensing applications. Specifically, the composite containing 3 phr of CNTs demonstrates superior strain sensitivity (2.87 &lt; GF &lt; 48.62), a wide detection range (0% &lt; Δε &lt; 187%), and excellent linearity (0.927 &lt; R2 &lt; 0.995). Lower CNT content enhances sensitivities but reduces overall linearity, while higher CNT content improves linearity but decreases sensitivity. Moreover, these composites perform exceptionally well under compressive forces, even at a 0.5 N applied force. Given their excellent response to mechanical forces and strain, these composites hold promise for applications like electronic skin, strain sensors, and energy‐harvesting devices.Highlights Carbon nanotubes (CNTs) were used as reinforcing fillers in SBR composites. CNTs significantly improve physical, mechanical, and electrical properties. Primarily, π‐stacking may be involved in enhancing these properties. The composites exhibit strong strain and force‐sensing capabilities. These composites could be valuable for wearable electronics in the future.

Characterization of thermal resistance and mechanical strength recovery of carbon nanotubes incorporated Portland cement composites subjected to heating and rehydration: Visualization of pore structural evolutions via synchrotron 3D X-ray nanoimaging

Carbon nanotubes (CNTs) enhance the thermal resistance and post-fire mechanical recovery of cementitious composites; however, the underlying mechanism has not been fully elucidated. This study aimed to reveal the effect of the incorporation of CNTs on the physicochemical properties of cementitious composites subjected to heating and rehydration. We assessed the variations in compressive and tensile strengths, volume, bulk density, surface morphology, and hydration products of Portland cement composites based on the amount of CNTs incorporated, heating temperature (200, 400, 600, and 800 °C), and re-curing conditions (under 25 °C/65 %RH and in water). Synchrotron three-dimensional X-ray nanoimaging was performed to visualize the internal nano- and micro-sized pore structure evolutions of the composites due to heating and rehydration. The CNT-incorporated samples exhibited improved thermal resistance and noticeable mechanical strength recovery by water re-curing, even after heating temperatures higher than the CNTs decomposition temperature (>600 °C). The CNTs improved the stability of the volume and density changes of the paste matrix and did not affect the formation of additional hydrates during the heating process. X-ray nanoimaging results revealed that cement hydrate formation on the dispersed CNTs resulted in a fastened and interconnected structure with dense pores (<2.5 μm3 and rod-like shape); these pores resist thermal deterioration and are advantageous for strength recovery by rehydration.