Dispersion Of Carbon Nanotubes Research Articles

Optimization of the thermal performance of a lobed triplex-tube solar thermal storage system equipped with a phase change material

The thermal performance of a PCM-based triple-tube lobed heat exchanger storage system is here simulated and optimized, including performance improvements via lobed surfaces, Y-shaped fins, dispersed multi-walled carbon nanotubes, and metal foams, to be used in combination, or singly. Such computations are done with the finite volume method under different operating conditions. The reason behind this study is to look for solutions to improve the poor thermal performance of phase change materials (PCMs) as thermal energy storage materials, that limits their compactness and instantaneous heat stored/released. This is the first time that a throughout analysis of this aspect is presented. The result showed that higher modified Stefan number allow to improve melting time of a 50.88 %. The inclusion of lobes and fins resulted in a reduction of roughly 30.54 % in time needed for melting completion, compared to straight tubes. This reduction increases to 74.26 % when lobes are combined with both nanoparticles and metal foam, and to 73.60 % with just foam. The best solution also provides a 228.34 W mean heat rate. This study becomes an option to design tube-in-tube energy storage systems, where the best improvement is achieved by considering a lobed surface together with nano/PCM and foam, whereas the highest enhancement comes from using a metal foam.

Enhancement mechanisms of mechanical, electrical and thermal properties of carbon nanotube-copper composites: A review

Carbon nanotubes (CNTs), as potent reinforcements in composites, have demonstrated excellent strengthening effects when combined with copper in numerous recent studies. Challenges remain in the application of these composites and in fully leveraging the reinforcing capabilities of CNTs to achieve comprehensive performance enhancement. The performance of CNTs/Cu composites can be flexibly regulated owing to the unique structure and properties of CNTs. To achieve the fabrication of high-performance and diverse CNTs/Cu composites, a profound understanding of the reinforcement mechanisms of CNTs in the composites is essential, along with the consideration of key influencing factors on performance. This article provides a comprehensive overview of the reinforcement mechanisms of CNTs on the mechanical, electrical, and thermal properties of CNTs/Cu composites. Factors influencing the effectiveness of CNT reinforcement in composites are discussed, including the attributes and dispersion of CNTs, the architectures of composites, and the interface between CNTs and Cu. Furthermore, this study explores the role of CNTs in addressing the trade-off between high strength and high conductivity as well as between high strength and high ductility in the copper matrix.

Insights from dispersion in carbon nanotubes‐based poly(vinylidene fluoride‐co‐hexafluoropropylene) wearable sensors via solvent casting

AbstractFlexible sensors, made of PVDF‐HFP reinforced with carbon nanotubes (CNTs), are manufactured by solvent casting. More specifically, the effect of evaporation temperature and sonication time is explored. It is seen that two effects govern the dispersion of CNT: the sedimentation half‐time, and the breakage induced by the ultrasonication process. In this regard, it is found that 60°C is an optimum evaporation temperature to reach the highest value of electrical conductivity, since it offers a good balance between these effects, leading to the creation of a more efficient electrical network. This is also confirmed by the AC analysis, where these samples show the highest characteristic frequencies. The electromechanical results show a greater dependency on evaporation temperature for low sonication times, as the breakage induced by an ultrasonic process is not so pronounced and, therefore, the sedimentation effect plays a more dominant role. In addition, cycling tests show robust electromechanical response with cycling, and creep tests prove good electrical response of the sensors, less than 200 ms in some cases. Finally, proof of concept testing of wrist, shoulder, and neck monitoring highlights the potential of the proposed materials for sensing applications.Highlights PVDF‐HFP/CNT nanocomposite strain sensors via solvent casting are proposed. The effect of evaporation temperature and sonication time is studied. DC and AC conductivities were analyzed and modeled via an equivalent circuit. An outstanding Gauge Factor of 86.30 × 104 is achieved at 95% of strain level. Two proof‐of‐concepts of medium and large movements are successfully achieved.

Outstanding electromagnetic interference shielding of bamboo fiber/carbon nanotubes/polylactic acid composites with biodegradability and corrosion resistance

To cope with the increasing electromagnetic waves and environmental pollution, it is imperative for exploring environmentally friendly electromagnetic interference (EMI) shielding materials with prime shielding effectiveness (SE). In this study, a biodegradable bamboo fiber/carbon nanotubes/polylactic acid (BF/CNTs/PLA) composite with abundant pore structures were successfully produced by mixing, melting and hot-pressing approach by utilizing hydrophobically treated bamboo fiber (BF), carbon nanotubes (CNTs) with efficient electrical conductivity and biodegradable polylactic acid (PLA) with exceptional thermal stability. Specially, with the addition of 12 wt% CNTs, the BF/CNTs/PLA composite displayed excellent EMI SE of 47.7 dB at X-band due to the uniform dispersion of conductive CNTs in consecutive BF/PLA composite. In addition, the value of SEA/SET was 79.9 %, illustrating absorption was the primary shielding mechanism. what’s more, BF/CNTs/PLA presented superior thermal stability and EMI SE of 89.7 %, 84.5 %, and 81.3 % after immersion of BF/CNTs/PLA in HCl, NaCl, and NaOH solution, respectively, demonstrating its prime corrosion resistance. Therefore, BF/CNTs/PLA composites have enormous application potential in the field of high-temperature resistance, biodegradability, and biomass based electromagnetic shielding materials.

Biomass lignin as dispersion to substantially enhance carbon nanotubes thermoelectric converter for energy harvesting

Carbon nanotubes (CNTs) have attracted much attention as promising thermoelectric materials to harvest waste energy, however the agglomeration between nanotubes greatly limits their application. Despite various dispersants that have been devised to enhance the dispersion of CNTs, biomass lignin has been rarely employed to facilitate the dispersion of CNT for enhancing its TE properties. Herein, green lignin was incorporated with CNTs to synergistically improve the dispersion and TE properties of CNTs, in which π-π interactions between the aromatic ring structure of lignin and CNTs, as well as electrostatic charge brought by ionized groups of lignin promote the exfoliation of nanotubes and reduces CNTs entanglement. The well-dispersed structure of CNTs facilitates efficient charge transfer, and thereby enhances the thermoelectric properties. CNTs/lignin composite could reach a maximum power factor of 198.0 μW m−1K−2 at a lignin content of 11.8 wt%, which was then raised to 223.1 μW m−1K−2 with subsequent partial removal of lignin by alkali immersion treatment, higher than 98.6 μW m−1K−2 of pristine CNTs film. Furthermore, the flexible TE device with five pairs of CNTs/lignin and nickel wires generates a high power of 288 nW at ΔT = 30 K, demonstrating potential applications of lignin for sustainable energy harvesting.

From Nanoscale to Macroscale Characterization of Sulfur-Modified Oxidized Carbon Nanotubes in Styrene Butadiene Rubber Compounds.

The homogeneous dispersion of carbon nanotubes (CNTs) in a rubber matrix is a key factor limiting their amazing potential. CNTs tend to agglomerate into bundles due to van der Waals interactions. To overcome this limitation, CNTs have been surface-modified with oxygen-bearing groups and sulfur. Using atomic force microscopy (AFM) techniques, a deep nanoscale characterization of the morphology, the degree of dispersion of the CNTs in the styrene butadiene rubber (SBR) matrix, and the thickness of the interfacial layer was carried out in this study. In this context, the results from nanoscale characterization showed that the thermal oxidation-sulfur treatment leads to a composite with better dispersion in the matrix, as well as a thicker interfacial layer, indicating a stronger filler-rubber interaction. The second part of this work focused on the macroscale results, such as the Payne effect, vulcanization curves, and mechanical properties. The Payne effect, vulcanization curves, and mechanical properties confirmed the lower reinforcing effect observed in the case of the chemical oxidation treatment because, on the one hand, this composite showed the highest agglomeration of CNTs after the acid treatment. On the other hand, the presence of acid residues provoked the absorption of basic accelerators on the surface of the CNTs.

Enhancing Ablation Resistance of TaB2-Based Ultra-High Temperature Ceramics by Mixing Fine TaC Particles and Dispersed Multi-Walled Carbon Nanotubes.

Ultra-high temperature ceramics (UHTCs) have been widely applied in many fields. In order to enhance the comprehensive properties of TaB2-based UHTCs, the first collaborative use of fine TaC particles and dispersed multi-walled carbon nanotubes (MWCNTs) was employed via spark plasma sintering (SPS) at 1700 °C. The derived UHTCs exhibited an average grain size of 1.3 μm, a relative density of 98.6%, an elastic modulus of 386.3 GPa, and a nano hardness of 21.7 GPa, leading to a greatly improved oxidation resistance with a lower linear ablation rate at -3.3 × 10-2 μm/s, and a markedly reinforced ablation resistance with mass ablation rate of -1.3 × 10-3 mg/(s·cm2). The enhanced ablation resistance was attributable to the physical pinning effect, sealing effect and self-healing effect. Thus, this study provides a potential strategy for preparation of UHTCs with bettered ablation resistance and physical properties.

An effective utilization of raw fly ash obtained from thermal power plants using thermal spray technique to improve corrosion resistance for marine applications

Marine-grade steel structures in offshore environments often corrode due to the aggressive environmental conditions. Many ceramic materials can cater to this demand. However, as per economic and ecological concerns, fly ash (FA), an industrial waste, can be another strong contender to control corrosion. Therefore, the present study developed composite coatings of fly ash with additives ((50-48) wt.% Al2O3; 0–2 wt% carbon nanotube (CNT)) onto marine-grade steel using a plasma spray technique to improve its corrosion resistance. The microstructure of 1 wt% CNT-reinforced alumina-FA (1CAF) coating was denser than 2 wt% CNT-reinforced alumina-FA (2CAF) coating due to the uniform dispersion of CNT and, thereby, uniform remelting of coating at localized sites. Consequently, the microhardness and adhesion strength of the 1CAF coating were improved by ∼14.66 % and ∼15.96 %, respectively. Further, Rietveld's analysis of coatings showed that quartz, being the primary phase for corrosion control, was 19.23 ± 0.87 %, 16.33 ± 1.04 % and 14.60 ± 1.87 % for alumina-FA (AF), 1CAF, and 2CAF, respectively. The electrochemical impedance spectroscopy and the salt spray corrosion tests showed that 1CAF coating corrosion resistance was improved by ∼11.2 % compared to AF coating, even with a lower quartz phase (∼15.08 %) due to the densification of coating. This densification was due to the remelting by CNT to seal pores in the coating. Furthermore, for the same reason, an increase in coating resistance and charge transfer resistance of 1CAF coating by ∼80.9 % and ∼19.93 %, respectively, were seen in the equivalent circuit analysis, showing great promise in controlling interfacial corrosion. Further post-treatments like plasma or laser treatments can seal the coatings further to improve corrosion resistance. Therefore, such coatings are expected to withstand harsh, corrosive environments and are well-suited for marine applications.

Ultrasensitive electrospinning fibrous strain sensor with synergistic conductive network for human motion monitoring and human-computer interaction

With the rapid development of wearable electronic skin technology, flexible strain sensors have shown great application prospects in the fields of human motion and physiological signal detection, medical diagnostics, and human-computer interaction owing to their outstanding sensing performance. This paper reports a strain sensor with synergistic conductive network, consisting of stable carbon nanotube dispersion (CNT) layer and brittle MXene layer by dip-coating and electrostatic self-assembly method, and breathable three-dimensional (3D) flexible substrate of thermoplastic polyurethane (TPU) fibrous membrane prepared through electrospinning technology. The MXene/CNT@PDA-TPU (MC@p-TPU) flexible strain sensor had excellent air permeability, wide operating range (0–450 %), high sensitivity (Gauge Factor, GFmax = 8089.7), ultra-low detection limit (0.05 %), rapid response and recovery times (40 ms/60 ms), and excellent cycle stability and durability (10,000 cycles). Given its superior strain sensing capabilities, this sensor can be applied in physiological signals detection, human motion pattern recognition, and driving exoskeleton robots. In addition, MC@p-TPU fibrous membrane also exhibited excellent photothermal conversion performance and can be used as a wearable photo-heater, which has far-reaching application potential in the photothermal therapy of human joint diseases.

Understanding interfacial dynamics: Hydrostatic pressure-induced sono-dispersion of carbon nanotubes

Homogeneously dispersing carbon nanotubes (CNTs) is crucial for minimizing agglomeration issues commonly encountered in commercially available CNTs samples, thereby enhancing their unique mechanical, electrical, thermal, and optical properties. In this study, we propose an alternative hydrostatic pressure-driven dispersion approach to effectively disperse CNTs and assess the impact of hydrostatic pressure on CNTs dispersion in deionized water (DIW). Our results demonstrate that ultrasonic treatment under a hydrostatic pressure of 0.1 MPa enables the achievement of a high concentration of multi-walled carbon nanotubes (MWCNTs) at approximately 4.23 mg/ml, significantly surpassing concentrations reported in recent studies (∼1.9 mg/ml). Thin buckypaper generated from these solutions exhibit exceptional electrical conductivity (∼4938 S/m). Numerical modeling demonstrates that the shock wave induced by bubble implosion is significantly enhanced, reaching 80 MPa under hydrostatic pressure, markedly higher than atmospheric pressure in previous studies (∼1.6 MPa). This enhancement leads to a twofold improvement in dispersion efficiency. For the first time, we reveal the underlying mechanism of nanobubbles (NBs) in dispersion stability. Our experimental results show a significant increase in the generation of NBs resulting from ultrasonic bubble collapse under hydrostatic pressure. This phenomenon plays a crucial role in the long-term stabilization of dispersion, which we observed over several months. The presence of negatively charged hydroxyl groups on the interface of the NBs is identified as a key factor in this stabilization process. The hydrostatic pressure-driven dispersion approach presented is essential for the large-scale dispersion of CNTs and other nanomaterials.

Dispersion of Single-Walled Carbon Nanotubes by Aromatic Cyclic Schiff Bases via Non-Covalent Interactions.

One of the challenging issues that hinders the application of single-walled carbon nanotubes (SWCNTs) is the poor solubility and the inevitable formation of bundles. Efforts still need to be made towards solving the problem. Herein, we report a non-covalent strategy to disperse aggregated SWCNTs by aromatic cyclic Schiff bases assisted by ultrasonic techniques. The aromatic cyclic Schiff base (OMM) was synthesized via Schiff base reactions, and the molecular structure was determined by ATR-FT-IR, solid-state 13C-NMR, and HRMS. Although the yielded product showed poor solubility in aqueous solution and organic solvents, it could interact with and disperse the aggregated SWCNTs in dimethyl formamide (DMF) under the condition of ultrasound. UV-vis-NIR, FL, Raman spectra, AFM, and TEM, along with computer simulations, provide evidence for the interactions between OMM molecules and SWCNTs and the dispersion thereof. The semiconductive (7,5), (8,6), (12,1), and (9,7)-SWCNTs expressed a preference for dissolution. The capability of dispersion is contributed by π-π, C-H·π, and lone pair (lp)·π interactions between OMM and SWCNTs based on the simulated results. The present non-covalent strategy could provide inspiration for preparing organic cyclic compounds as dispersants for SWCNTs and then facilitate their further utilization.

Effect of immediate curing at elevated temperatures on the tensile and interfacial properties of carbon fiber-epoxy composites

Elevated temperature conditions known to improve curing from the onset and during the process of immediate curing are not available in the field, which can hinder the mechanical performance of these strengthening systems. In this study, mechanical testing and material characterization were conducted to identify the effects of subjecting nanomodified epoxy and fiber-reinforced nanomodified epoxy composites to room temperature (RT) (30 °C) and elevated temperature (110 °C) from the onset of curing. Static tensile testing and interfacial adhesion tests were conducted to evaluate the mechanical performance. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were performed to determine curing characteristics to inform on the immediate curing of nanomodified resins cured under the two temperature conditions. Scanning electron microscopy was performed to identify Carbon nanotube (CNT) dispersion characteristics. Overall, due to the incorporation of CNTs in epoxy, RT curing results in upto 62% increase in strain at failure. By supplying additional energy during immediate curing with elevated temperatures, a 51% increase in strength and 42% increase in Youngs Modulus can be observed in the nanomodified epoxy. In CFRP-epoxy composites, due to the incorporation of CNTs in the epoxy, RT curing results in upto 27% increase in strain at failure. By supplying additional energy during immediate curing with elevated temperatures, upto 133% increase in strain at failure is observed and upto 17% increase in strength is observed. CNTs incorporated in CFRP-epoxy composites demonstrated upto 50% increase in interfacial adhesion whereas supplying additional energy for their immediate curing with elevated temperatures, upto 130% increase in interfacial adhesion was observed. TGA and DSC results supported the mechanical observations and show a need for immediate curing when CNTs are used in epoxy matrices.

Thermomechanical bending of functionally graded carbon nanotubes reinforced composite plate by meshless method

AbstractFunctionally graded (FG) carbon nanotubes (CNTs) reinforced composite possessing continuously varied material properties have received extensive concern in the area of aviation, automotive, military, and spaceflight. The nonlinear bending of FG CNT composite is performed by developing a novel meshless model on the base of Smoothed Particle Hydrodynamics (SPH) method. The equivalent temperature relative material properties of composite is established in the light of the extended rule of mixture model. Different gradient dispersions of CNTs are taken into account and modeled. The governing equations are explored using the Mindlin theory and discretized though a symmetric SPH method with high prediction ability. The developed model is verified by analyzed several examples and compared to the solution obtained in literature. Influences of CNT dispersion, content, plate aspect ratio, boundary conditions and lamination angle on the bending response are elaborated. The present study provides an alternative potential method to solve the mechanical performances of FG CNT composites based on the meshless SPH formulation.Highlights Thermo‐mechanics of FG‐CNTRC is firstly solved by SPH method. The model is verified by solving the benchmarks in literature. Nonlinear bending behaviors of FG‐CNTRC are demonstrated. The minimum deflection take place in FG‐X type composite. For laminate plate, the smallest deformation occurs in 0° CNTRC.

Conjugated Polymers with Self‐Immolative Sidechain Linkers for Carbon Nanotube Dispersion (Small 28/2024)

Conjugated Polymers with Self‐Immolative Sidechain Linkers for Carbon Nanotube Dispersion (Small 28/2024)

Ultra-Mild Fabrication of Highly Concentrated SWCNT Dispersion Using Spontaneous Charging in Solvated Electron System.

The efficient dispersion of single-walled carbon nanotubes (SWCNTs) has been the subject of extensive research over the past decade. Despite these efforts, achieving individually dispersed SWCNTs at high concentrations remains challenging. In this study, we address the limitations associated with conventional methods, such as defect formation, excessive surfactant use, and the use of corrosive solvents. Our novel dispersion method utilizes the spontaneous charging of SWCNTs in a solvated electron system created by dissolving potassium in hexamethyl phosphoramide (HMPA). The resulting charged SWCNTs (c-SWCNTs) can be directly dispersed in the charging medium using only magnetic stirring, leading to defect-free c-SWCNT dispersions with high concentrations of up to 20 mg/mL. The successful dispersion of individual c-SWCNT strands is confirmed by their liquid-crystalline behavior. Importantly, the dispersion medium for c-SWCNTs exhibits no reactivity with metals, polymers, or other organic solvents. This versatility enables a wide range of applications, including electrically conductive free-standing films produced via conventional blade coating, wet-spun fibers, membrane electrodes, thermal composites, and core-shell hybrid microparticles.

Mechanical properties of carbon nanotube (CNT) reinforced polymers using electron‐deficient aromatics as additives

AbstractIn initial experiments the effects of aromatic model substances on carbon nanotube (CNT) dispersions in dimethylformamide (DMF) were investigated. Electron‐deficient aromatics interact strongly with CNTs, causing increased agglomeration and sedimentation. Conversely, electron‐donating aromatics stabilize CNT dispersions in DMF. Polymers with electron‐deficient aromatics, such as polydinitrostyrene (PDNS), exhibit a concentration‐dependent effect: low concentrations lead to stabilization of dispersions, while higher concentrations lead to sedimentation. This suggests that such polymers can enhance attraction between the matrix of CNT‐reinforced polymers as well as stabilize the dispersed CNTs. Polycarbonate, modified with polydinitrocarbonate (PDNC) and reinforced with CNTs showed improved mechanical properties. The addition of 6 wt.% CNTs and 6 wt.% PDNC resulted in a notable improvement with a 22% increase in tensile strength, a 29% increase in flexural strength, a 39% increase in Young's modulus and a 47% increase in flexural modulus. This enhancement resulted in an overall mechanical performance comparable to the high‐performance polymer polyetherimide. However, there must be noted, that the addition of PDNC increases the CNT particle size, which can negatively affect mechanical properties. The results highlight the additive's dual role in enhancing adhesive interactions while potentially increasing CNT agglomerate sizes.Highlights Interactions of CNTs dispersed in DMF and various aromatics were investigated. Polydinitrocarbonate (PDNC) was synthesized as a new additive for CNT‐composites. Polycarbonate/CNT‐composites were obtained using extrusion. Test specimens with CNT contents up to 6 wt.% were obtained. Mechanical properties of polycarbonate reached the level of polyetherimide.

Bonding performance of ethylene vinyl acetate reinforced carbon nanotube repair materials

Inorganic repair materials have significant advantages such as high durability, high strength, and good corrosion resistance. However, their low bonding strength and inadequate tensile performance are clear disadvantages, which often results in problems like cracking, delamination, and insufficient repairing strength. In the current study, a new repair material is developed, which enhances the interfacial bonding performance of carbon nanotubes (CNTs) repair materials by introducing ethylene vinyl acetate (EVA). The bonding strength of composite specimens was tested by splitting tensile test. Then the microstructure analysis of the repaired materials was conducted by X-ray computed tomography, backscattered electron imaging, and scanning electron microscopy. The phase composition of the repair material was further analyzed by Fourier transform infrared spectroscopy. Finally, the bonding mechanisms of EVA reinforced CNTs repair materials were discussed. The results indicate that the interaction between EVA and CNTs can enhance the bonding performance of repair materials. Additionally, the polymer film formed by EVA within the repair material can refine the pores, thereby reducing the porosity of the interfacial transition zone and that of repair materials. The electrostatic repulsion between EVA and CNTs contributes to the uniform dispersion of CNTs within repair materials.

Effect of Carbon Nanotubes on Chloride Diffusion, Strength, and Microstructure of Ultra-High Performance Concrete.

This study delved into the integration of carbon nanotubes (CNTs) in Ultra-High Performance Concrete (UHPC), exploring aspects such as mechanical properties, microstructure analysis, accelerated chloride penetration, and life service prediction. A dispersed CNT solution (0.025 to 0.075 wt%) was employed, along with a superplasticizer, to ensure high flowability in the UHPC slurry. In addition, the combination of high-strength functional artificial lightweight aggregate (ALA) and micro hollow spheres (MHS) was utilized as a replacement for fine aggregate to not only reduce the weight of the concrete but also to increase its mechanical performance. Experimental findings unveiled that an increased concentration of CNT in CNT1 (0.025%) and CNT2 (0.05%) blends led to a marginal improvement in compressive strength compared to the control mix. Conversely, the CNT3 (0.075%) mixture exhibited a reduction in compressive strength with a rising CNT content as an admixture. SEM analysis depicted that the heightened concentration of CNTs as an admixture induced the formation of nanoscale bridges within the concrete matrix. Ponding test results indicated that, for all samples, the effective chloride transport coefficient remained below the standard limitation of 1.00 × 10-12 m2/s, signifying acceptable performance in the ponding test for all samples. The life service prediction outcomes affirmed that, across various environmental scenarios, CNT1 and CNT2 mixtures consistently demonstrated superior performance compared to all other mixtures.

Research on optimizing ultrasonic frequencies for efficient single-walled carbon nanotube dispersion in water using a focused ultrasonic system

Single-walled carbon nanotubes (SWCNTs) can be applied in a wide range of fields owing to their excellent mechanical rigidity, electrical conductivity, and thermal conductivity. However, their application is limited because of their strong van der Waals forces and poor dispersion owing to their hydrophobic properties. To address this problem, ultrasonic dispersion technology has been used in the industry. However, very few studies have investigated the surface damage or effectiveness of the surfactants of SWCNTs with a focus on the frequencies of specific ultrasonic equipment. In this study, the dispersibility of SWCNTs at frequencies of 270, 400, and 700 kHz was investigated using a new focused ultrasonic instrument. The dispersion stability of the samples was analyzed according to each frequency, and the SWCNT surface was studied in detail using field-emission transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The adsorption of the polymeric surfactant to the SWCNT was most observed at 270 kHz, and the dispersion stability after processing at this frequency was better than that of the other samples. Therefore, the frequency of the ultrasonic intensity has a direct effect on the surface modification of SWCNTs.

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.