Carbon Nanotubes In Matrix Research Articles

The role of graphene in Graphene-Filled carbon nanotube foam under compression and the corresponding microscopic deformation mechanism

Graphene-filling significantly improves the compressive properties of carbon nanotube (CNT) foam (CF). However, the role of graphene in the graphene-filled CNT foam (GFCF) and the corresponding microscopic deformation mechanism, are still unclear. Here, coarse-grained numerical models of pure CF and GFCF are constructed based on molecular dynamics, and the role of graphene in GFCF and corresponding microscopic deformation mechanisms under compression are investigated. It is found that the compressive modulus of GFCF (5.3 MPa) is much larger than that of pure CF (0.7 MPa). The filling of graphene inhibits the aggregation of CNTs, enhances the dispersion of CNTs, impedes the rearrangement of CNTs, and ultimately improves the compressive modulus of the whole material by improving the bending ability of CNTs. It is further found that the compressive modulus of GFCF can be increased to a maximum of 7.4 MPa as the number of graphene flakes increases to 300, but remains almost the same as the graphene thickness increases. The results in this paper deepen the understanding of the microscopic mechanisms of GFCF and provide scientific guidance for the application of CNT and graphene-based materials.

Concurrent topology optimization design for CNT orientation and CNTRC layout

In this study, the topology optimization (TO) design of carbon nanotube (CNT) orientation and material layout for carbon nanotube-reinforced composites (CNTRCs) is performed for the first time. The equivalent performance of CNTRCs is calculated by the extended easy-to-implement rule of mixtures. Then, by considering two independent angle variables, a 3-dimensional (3D) concurrent optimization model for CNT orientation and material layout is constructed. To decrease the possibility of falling into local optimal solutions, a discrete interval method is proposed to divide the search space into specific subintervals, and thus the original optimization problem is changed into material selection and subinterval angle optimization problems. In addition, different from conventional fiber-reinforced composites, CNTRCs employ nanoscale filler as reinforcement, which makes it more beneficial to achieve local material strengthening. Therefore, to decrease the possibility of local optimal solutions and achieve local structural strengthening, a concurrent TO model involving CNTRCs and isotropic materials under the volume constraint is proposed to achieve the optimal balance between structural stiffness and economy. Subsequently, the sensitivities of structural compliance with respect to design, selection, and angle variables are derived. Also, the effectiveness of the proposed method is verified by 2D and 3D examples.

Role of graded microstructure and electrolyte distribution in electrochemical capacitance of compressible three-dimensional carbon nanotubes-polymer foam based supercapacitor

Three-dimensional microstructure of carbon materials has a prime importance in supercapacitor for energy storage. Carbon nanotubes (CNT) provide microstructurally porous structure via entangled nodes that dynamically changes with the uniaxial compression. A unique graded CNT-polymer based three-dimensional compressible cellular foam is used as an electrode material for the solid-state supercapacitor. A direct correlation was established between the applied strain and resulting electrochemical capacitance when the foam electrode was soaked and unsoaked in the electrolyte. In a novel finding, unsoaked electrodes revealed in an extraordinary enhancement of ∼1216% in gravimetric capacitance measured at a uniaxial strain of 80% and to no surprise, the electrochemical capacitance of electrolyte-soaked electrodes remained nearly invariant from its uncompressed state. The response of electrochemical capacitance under compression is also observed varying with the mode of compression i.e. quasi-static versus pre-compressed state to a targeted strain. The role of graded microstructure during uniaxial compression was verified by using as-grown CNT mat for the electrodes of a supercapacitor. The results demonstrated a dominating contribution of dynamic variation in the density of nodes in the compressed CNT mat. The impact of macroscopic variation on the response of electrochemical capacitance of a compressed cellular CNT-polymer foam was further understood using the separators of varying pore sizes. Our results pave the way to engineer the three-dimensional compressible cellular structures for extraordinarily large energy storage capacity.

Long-Lasting Electret Melt-Blown Nonwoven Functional Filters Made of Organic/Inorganixc Macromolecular Micron Materials: Manufacturing Techniques and Property Evaluations.

Melt-blown nonwoven fabrics for filtration are usually manufactured using polypropylene, but after a certain time period the middle layer of the mask may have a reduced effect on adsorbing particles and may not be easily stored. Adding electret materials not only increases storage time, but also shows in this study that the addition of electret can improve filtration efficiency. Therefore, this experiment uses a melt-blown method to prepare a nonwoven layer, and adds MMT, CNT, and TiO2 electret materials to it for experiments. Polypropylene (PP) chip, montmorillonite (MMT) and titanium dioxide (TiO2) powders, and carbon nanotube (CNT) are blended and made into compound masterbatch pellets using a single-screw extruder. The resulting compound pellets thus contain different combinations of PP, MMT, TiO2, and CNT. Next, a hot pressor is used to make the compound chips into a high-poly film, which is then measured with differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). The optimal parameters are yielded and employed to form the PP/MMT/TiO2 nonwoven fabrics and PP/MMT/CNT nonwoven fabrics. The basis weight, thickness, diameter, pore size, fiber covering ratio, air permeability, and tensile property of different nonwoven fabrics are evaluated in order to have the optimal group of PP-based melt-blown nonwoven fabrics. According to the results of DSC and FTIR measurements, PP and MMT, CNT, and TiO2 are completely mixed, and the melting temperature (Tm), crystallization temperature (Tc) and endotherm area are changed accordingly. The difference in enthalpy of melting changes the crystallization of PP pellets, which in turn changes the fibers. Moreover, the Fourier transform infrared (FTIR) spectroscopy results substantiate that PP pellets are well blended with CNT and MMT, according to the comparisons of characteristic peaks. Finally, the scanning electron microscopy (SEM) observation suggests that with a spinning die temperature of 240 °C and a spinning die pressure lower than 0.01 MPa, the compound pellets can be successfully formed into melt-blown nonwoven fabrics with a 10-micrometer diameter. The proposed melt-blown nonwoven fabrics can be processed with electret to form long-lasting electret melt-blown nonwoven filters.

Shielding effectiveness study of CoZCF-MWCNT nanocomposite materials and its possible application as EM pollution reducer

In this article, Co0.40Zn0.40Cu0.20Fe2O4 (CoZCF) nanoparticles were synthesized using sol-gel method. The Field Emission Scanning Electron Microscopy (FESEM) micrographs delineate the proper encapsulation of the soft magnetic nanoparticles inside the matrix of multi-walled carbon nanotubes (MWCNTs) and ensuring proper fabrication of the CoZCF-MWCNT nanocomposites. The X-ray Diffraction (XRD) analysis and Raman spectroscopy confirms the presence of the multi-phase nature of CoZCF-MWCNT nanocomposites. The static magnetic development of the nanocomposites as a function of temperature and the shielding effectiveness behavior in X-band and Ku-band of microwave radiation have been studied herein. Different static magnetic quantities were extracted. The magnetic observation confirms the presence of ferrimagnetic state with magnetization of 48.4 and 44.8 emu g−1 respectively at room temperature (RT) in CoZCF-MWCNT nanocomposites. The variation of hysteresis loop area with the lowering of temperature depicts the transformation of CoZCF-MWCNT nanocomposites from superparamagnetic to ferromagnetic state. The shielding effectiveness study was conducted in the X- and Ku- bands of electromagnetic radiation and the observation shows a high value of total shielding effectiveness (SET) of ∼ −31.3 dB corresponding to 10.7 GHz. This is due to the high of attenuation of > 99.9% and wide bandwidth. This improved SET of CoZCF-MWCNT nanocomposites gives us completely new insights for the construction of microwave absorber/Radar Absorbing Materials (RAMs) that can contest against harmful electromagnetic pollution.

Carbon Nanotubes as an Alternative to Copper Wires in Electrical Machines: A Review

The surge in electric vehicles (EVs) and their electrical appliances requires highly efficient, lightweight electrical machines with better performance. However, conventional wire used for electrical machine windings have certain limits to the current requirements. Copper is a commonly used material in electrical windings, and due to its ohmic resistance, it causes 75% of total losses in electrical machines (copper losses). The high mass of the copper results in a bulky system size, and the winding temperature of copper is always maintained at less than 150 °C to preserve the thermal insulation of the electric machine of the windings. On the other hand, carbon nanotubes and carbon nanotube materials have superior electrical conductivity properties and mechanical properties. Carbon nanotubes ensure 100 MS/m of electrical conductivity, which is higher than the copper electrical conductivity of 59.6 MS/m. In the literature, various carbon nanotubes have been studied based on electrical conductivity, temperature co-efficient with resistivity, material thickness and strength, insulation, and efficiency of the materials. Here, we review the electrical and mechanical properties of carbon nanotubes, and carbon nanotube composite materials are reviewed with copper windings for electrical wires.

Stable and high-capacity SiO negative electrode held in reversibly deformable sponge-like matrix of carbon nanotubes

A lightweight, high-capacity negative electrode was developed by suspending carbon-coated silicon monoxide (SiO/C) particles in a sponge-like matrix of carbon nanotubes (CNTs) without using metal foils or polymeric binders. High initial delithiation capacities per electrode (SiO/C + CNT) of >1200 mA h gelectrode−1 and >1100 mA h cmelectrode−3 were achieved with an optimum SiO/C content of 85 mass%. The lithiation/delithiation cycle with capacity control at a 45% SiO utilization ratio achieved a high delithiation capacity of 584 mA h gelectrode−1 for 236 cycles. In addition, the flexible and electrically conductive CNT sponge matrix enabled reversible expansion/shrinkage of the entire electrode during lithiation/delithiation, as evidenced by scanning electron microscopy.

Urotropine-triggered multi-reactive sites in carbon nanotubes towards efficient electrochemical hydrogen peroxide synthesis

The production of hydrogen peroxide (H2O2) by electrochemical oxygen reduction is a clean and convenient route. Here, we develop a universal urotropine (hexamethylenetetramine) modified carbon-based catalyst strategy. Both experimental results and theoretical calculations proved that the introduction of urotropine not only provides the isolating O2 active sites to protect OOH* from being further split, but also excites carbon nanotube matrix to produce rich secondary O2 active sites. More importantly, the end-on type of adsorption of O2 on excited secondary reactive sites can be stabilized by the hydrogen bond effect, which greatly increases the productivity of H2O2. As a result, the urotropine (hexamethylenetetramine) modified commercial carbon nanotubes (denoted as H-CNTs) catalyst achieved 95% selectivity and 748 mmol·gcatalyst·h−1 yield of H2O2 at 0.7 V vs. RHE. Therefore, this work provides a highly potential urotropine modification strategy towards efficient electrochemical H2O2 synthesis.

Structural supercapacitor electrodes for energy storage by electroless deposition of MnO2 on carbon nanotube mats

Structural supercapacitors have great potential for the future of electric-powered vehicles and mobile robots, as they can serve a dual purpose of providing structural integrity and storing electric energy. However, a significant challenge in the development of these energy storage structures is the creation of electrodes that are mechanically strong and stiff. Herein, we report an electroless technique for depositing pseudocapacitive manganese dioxide (MnO2) uniformly throughout carbon nanotube (CNT) mats, resulting in multifunctional supercapacitor electrodes with simultaneously enhanced mechanical and electrochemical properties. The deposited MnO2 nanoporous material acts as a structural matrix supporting the CNTs, thus improving the strength and stiffness. Furthermore, the uniform distribution of MnO2 nanoparticles throughout the substrate reduces the through-thickness electrical resistance and achieves outstanding rate capability. With the optimum loading of MnO2 95 wt%, which gives the highest strength, the total capacitance of the electrode material increased by nine times compared to the baseline material, while the tensile strength and stiffness were improved by 110% and 430%, respectively. Employing these high-performance electrodes in supercapacitors results in improved device-level performance. Specifically, the optimum loading of MnO2 increased the device's energy density by around 100 times without compromising the power density. These new high-performance structural electrodes represent a promising technology that could accelerate the practical application of energy storage composite structures.

Sibutramine detection in weight-loss products using a sodium/phosphorus dual-doped carbon nanotubes modified electrode

A new electrode material of sodium and phosphorus dual-doped carbon nanotubes (Na/P-CNTs) was produced by a facile hydrothermal reaction. The Na/P-CNTs nanocomposite was used to modify an electrode for an electrochemical sensing system to determine sibutramine in weight-loss products. The nanocomposite was characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, and Fourier transform infra-red (FTIR) and Raman spectroscopy. Electrochemical properties of the nanocomposite were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrode modification improved electro-catalytic activity and electron transfer, which contributed to the effective oxidation of sibutramine. The analytical performances of the fabricated electrode were investigated by measuring sibutramine concentrations by adsorptive stripping voltammetry (AdASV). The electrode produced linear ranges from 0.025 to 20 μg mL−1 and 20 to 60 μg mL−1 and a detection limit of 0.010 μg mL−1, and exhibited good repeatability, reproducibility, anti-interference ability, and rapid analysis time (120 s) for sibutramine. The developed sensor was successfully applied to determine sibutramine in weight-loss products, achieving recoveries from 91 ± 3 % to 102 ± 1 %. This Na/P-CNT nanocomposite achieved performances comparable to standard methods and could be adapted to monitor other electroactive species and for other electrochemical applications.

ZIF-derived Co nanoparticles embedded into N-doped carbon nanotube composites for highly efficient electrochemical detection of nitrofurantoin in food

Designing efficient and sensitive methods for the detection of nitrofurantoin (NFT) residues is of great importance for food safety and environmental protection. Herein, a composite with cobalt nanoparticles encapsulated in nitrogen-doped carbon nanotube (N/Co@CNTs@CC-II) was synthesized by in-situ growth and sublimation-gas phase transformation strategy and used to establish an ultrasensitive electrochemical sensor for NFT determination. The N/Co@CNTs@CC-II sensor exhibits uniform N doping, fine hollow structure, and abundant active metal sites, which lays a solid foundation for the ultra-sensitive detection of NFT. Benefiting from these advantages, the N/Co@CNTs@CC-II exhibits excellent sensitivity (8.19 μA μM−1 cm−2) and low detection limit (18.41 nM) for NFT detection. The practical feasibility of N/Co@CNTs@CC-II was also demonstrated by the determination of NFT in milk and tap water samples. This study may open up new opportunities for the application of N-doped carbon nanotube materials encapsulating transition metals.

Investigation of laser micro-drilling machinability and performance optimization of polymer nanocomposites reinforced with different carbon allotropes

The comparative assessment of the laser micro-drilling machinability of polymer matrix nanocomposites dispersed with conducting fillers of different carbon allotropes (carbon nanotube (CNT), graphite, and carbon black (CB)) to produce minimum taper and heat-affected zone (HAZ) has been first time reported in this article. The required composite specimens are synthesized via ultrasonicator-assisted compression molding method and characterized for their thermal, electrical, and mechanical properties. The central composite design-based response surface methodology (CRSM) is implemented for the planification of experimentation using a pulsed Nd:YAG laser and subsequent higher-order regression modeling of the desired performance indicators. The contemporary accelerated particle swarm optimization (APSO) technique and metaheuristic whale optimization algorithm (WOA) have been utilized to define optimum controllable process parameters (pulse frequency, cutting speed, lamp current, and air pressure) and the assortment of optimum conditions are justified by performing confirmatory tests. CNT-reinforced composite material exhibits superior tensile, hardness, and thermal properties whereas graphite-based polymer composite show good electrical conductivity. The most minor taper and HAZ values are observed in the laser micro-drilling of epoxy-based CNT and CB materials, respectively. The two swarm-based algorithms predict more accurate results for the desired output responses than the statistical CRSM, with the least errors compared to the values attained by the WOA. Optimal taper (with CNT/epoxy composite at 30 m/s cutting speed, 22.6 amp lamp current, 3 kHz pulse frequency, and 1 kg/cm2 air pressure) and HAZ (with CB/epoxy composite at 30 m/s cutting speed, 22.97 amp lamp current, 3 kHz pulse frequency, and 5 kg/cm2 air pressure) values obtained in the confirmatory test showed 15% and 12% errors, respectively, as compared to the predicted data in WOA.

Switching the locus of oxygen reduction and evolution reactions between spinel active phase and carbon carrier upon heteroatoms doping

Multi-walled carbon nanotubes (MWCNTs) doped with nitrogen and sulfur atoms and with deposited manganese–cobalt spinel catalysts were studied to reveal the role of active centers in the oxygen reduction and evolution reactions (ORR and OER) in alkaline media. Commercial MWCNTs were oxidized by boiling in concentrated nitric acid and then double-doped with N and S heteroatoms using thiourea precursor. Manganese-cobalt spinels supported on the MWCNTs were synthesized by a microwave-assisted solvothermal route. The catalysts were comprehensively characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy (RS), and X-ray fluorescence spectroscopy. The deposited mixed spinel active phase consists of well-dispersed nanocrystals with sizes in the range of 5–8 nm. The electrocatalytic activities of the synthesized catalysts in ORR (the onset potential and the number of transferred electrons) and OER (the overpotential required to reach the 10 mA cm−2 current density) were examined in alkaline media by rotating ring-disc electrode (RRDE) and rotating disc electrode (RDE) techniques, respectively. It was found that N and S doped MWCNT catalysts exhibit high activity in ORR with Eonset = 0.890 ± 0.013 V, and a number of electrons exchanged n = 3.83 ± 0.03, which remained essentially the same, within experimental error, upon spinel deposition. The addition of the spinel phase does not improve the electrocatalytic properties. The advantage of the dispersed spinel active phase was observed in OER, the activity of these samples was comparable to that of the RuO2 benchmark catalyst. In the case of ORR, the observed reactivity was accounted for by the incorporation of nitrogen and sulfur to the MWCNTs, whereas for OER the locus of the active centers is moved towards the manganese-cobalt spinel nanocrystals dispersed on the carbon nanotubes matrix. Functionalization of the latter with N and S atoms is then catalytically redundant.

Manipulating active sites on carbon nanotube materials for highly efficient hydrogen storage

The active sites in porous carbon nanotube (CNT) would determine hydrogen storage performance of CNT. Here, we reported an effective, simple and controllable strategy to improve the hydrogen storage property of function group grafted CNT (fg-CNT). N-CNT-M (La2O3, Ni) would be obtained by the mixture of fg-N-CNT and metallic precursor at calcination of 600 °C. N-CNT-La2O3 has the highest H2 storage capacity of 7.4 wt%, displaying stable hydrogen adsorption/ desorption cycles for more than 20 times at 100 °C and 18 bar. fg-Ni-CNT-PLLA were formed by electrostatic interactions between CN bond of amide and carbonyl of l-polylactic acid (PLLA). fg- Ni-CNT-PLLA also has H2 storage capacity of 6.2 wt% at 100 °C and 18 bar. The experiment found that metal ions or PLLA might be dispersed uniformly in CNT by adjusting the ratio of grafted hydroxyl (OH) to acylamino (–CONH2). N-CNT-La2O3 has better hydrogen storage performance than fg-CNT-PLLA because the aggregation of CNT would be caused by the molecular movement of PLLA during hydrogenation and dehydrogenation. This work provides guidance for the development of efficient hydrogen storage materials.

Characterization of Conductive Carbon Nanotubes/Polymer Composites for Stretchable Sensors and Transducers.

The increasing interest in stretchable conductive composite materials, that can be versatile and suitable for wide-ranging application, has sparked a growing demand for studies of scalable fabrication techniques and specifically tailored geometries. Thanks to the combination of the conductivity and robustness of carbon nanotube (CNT) materials with the viscoelastic properties of polymer films, in particular their stretchability, "surface composites" made of a CNT on polymeric films are a promising way to obtain a low-cost, conductive, elastic, moldable, and patternable material. The use of polymers selected for specific applications, however, requires targeted studies to deeply understand the interface interactions between a CNT and the surface of such polymer films, and in particular the stability and durability of a CNT grafting onto the polymer itself. Here, we present an investigation of the interface properties for a selected group of polymer film substrates with different viscoelastic properties by means of a series of different and complementary experimental techniques. Specifically, we studied the interaction of a single-wall carbon nanotube (SWCNT) deposited on two couples of different polymeric substrates, each one chosen as representative of thermoplastic polymers (i.e., low-density polyethylene (LDPE) and polypropylene (PP)) and thermosetting elastomers (i.e., polyisoprene (PI) and polydimethylsiloxane (PDMS)), respectively. Our results demonstrate that the characteristics of the interface significantly differ for the two classes of polymers with a deeper penetration (up to about 100 μm) into the polymer bulk for the thermosetting substrates. Consequently, the resistance per unit length varies in different ranges, from 1-10 kΩ/cm for typical thermoplastic composite devices (30 μm thick and 2 mm wide) to 0.5-3 MΩ/cm for typical thermosetting elastomer devices (150 μm thick and 2 mm wide). For these reasons, the composites show the different mechanical and electrical responses, therefore suggesting different areas of application of the devices based on such materials.

Carbon-Coated Si Nanoparticles Anchored on Three-Dimensional Carbon Nanotube Matrix for High-Energy Stable Lithium-Ion Batteries

An easy and scalable synthetic route was proposed for synthesis of a high-energy stable anode material composed of carbon-coated Si nanoparticles (NPs, 80 nm) confined in a three-dimensional (3D) network-structured conductive carbon nanotube (CNT) matrix (Si/CNT@C). The Si/CNT@C composite was fabricated via in situ polymerization of resorcinol formaldehyde (RF) resin in the co-existence of Si NPs and CNTs, followed by carbonization at 700 °C. The RF resin-derived carbon shell (~10 nm) was wrapped on the Si NPs and CNTs surface, welding the Si NPs to the sidewall of the interconnected CNTs matrix to avoid Si NP agglomeration. The unique 3D architecture provides a highway for Li+ ion diffusion and electron transportation to allow the fast lithiation/delithiation of the Si NPs; buffers the volume fluctuation of Si NPs; and stabilizes solid–electrolyte interphase film. As expected, the obtained Si/CNT@C hybrid exhibited excellent lithium storage performances. An initial discharge capacity of 1925 mAh g−1 was achieved at 0.1 A g−1 and retained as 1106 mAh g−1 after 200 cycles at 0.1 A g−1. The reversible capacity was retained at 827 mAh g−1 when the current density was increased to 1 A g−1. The Si/CNT@C possessed a high Si content of 62.8 wt%, facilitating its commercial application. Accordingly, this work provides a promising exploration of Si-based anode materials for high-energy stable lithium-ion batteries.

Delay analysis of mixed CNT bundles as global interconnect for nanotechnology nodes

Abstract This paper presents modeling of high current capability of mixed carbon nanotube (CNT) bundle interconnects depending upon the type of constituent CNT materials and their orientations. With different arrangements, one category of novel mixed CNT bundles formed by the combination of multi-walled/multi-shell CNT and double-shell CNT bundles (MDCB) are proposed and compared with the mixed CNT bundles (MSCB) formed with multi-shell CNT and single-walled CNT bundles. A time-domain analysis is performed for these structures to analyse the effect of delay and power dissipation. It has also been observed that MDCB structures give better performance (≈ 30%) than MSCB structures in terms of power-delay product at the global length of interconnect for nano-regime technology nodes. Also, MDCB structure formed by placing multi-walled CNTs along the periphery and double-walled CNTs in the centre of structure yields the best result against all proposed mixed CNT bundled structures and can be employed for future interconnect applications.

EMI Shielding Effectiveness Study for Innovative Carbon Nanotube Materials in the 5G Frequency Region

It is crucial to extend the electromagnetic compatibility (EMC) studies to the new frequency regions where modern telecommunication systems operate, specifically those related to the fifth-generation (5G) technology standard for broadband cellular networks. Electric autonomous vehicles (EAVs) are systems that feature 5G technology on board and for which it is essential to ensure the proper management of EMC to prevent malfunctions. Given the considerable development of the EAV-related sector, new materials and solutions for EMI shielding with properties that reduce interference in the frequency regions of 5G technology are being investigated. Today, meatal-based solutions are the most common EMI shielding materials used to mitigate EMC problems. Nevertheless, with the appearance of EAVs, it is needed the design of novel materials that provide a significant balance in terms of shielding effectiveness (SE) and mechanical properties. Thereby, carbon nanotubes (CNTs) are an attractive alternative to conventional EMI shielding materials due to their characteristics. The lightweight condition, flexibility, cost-effectiveness, easy processing, and resistance to corrosion made this new type of material perfect to be used in the field of EAVs. This contribution focuses on describing and characterizing three nanocomposite materials manufactured by loading a polymer matrix with 5%, 7%, and 10% CNT concentrations, respectively. The SE measurement is carried out with a coaxial sample holder based on the standard ASTM D4935-18. This measurement setup makes it possible to determine the performance of the three materials under test up to 18 GHz, covering part of the operation frequencies of 5G systems.

PVK-grafted multiwalled carbon nanotube materials with enhanced mobility for electronic devices

Carbon nanotubes are unique due to their exceptional optical, electrical, thermal, and mechanical capabilities. This research included enhancing the electrical conductivity of a poly (9-vinyl carbazole) (PVK)-based organic semiconductor by combining it with a multi-walled carbon nanotube (MWCNT). The electrical conductivity was calculated utilizing composites of PVK-doped CNTs. In an organic medium, the composites were synthesized via in situ chemical polymerization. The immobility of PVK in the form of oxidation, high conductivity, and permitting electrochemical behavior of the materials for application in electronics was investigated. The study involved composites that alter electrical conductivity and different structure that shows stable dispersion in the PVK polymer of various molecular weights. It is an effective nanotube dispersion at low PVK concentration. X-ray powder diffraction (XRD), ultraviolet-visible spectroscopy, Thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) were used to validate the generation of composites from synthesized CNTs and composites. The morphological structures were examined using field emission scanning electron microscopy (FESEM). The electrical conductivity was evaluated, and the movement of charge between polymers and CNTs was discussed.

Carbon Hybrid Materials-Design, Manufacturing, and Applications.

Carbon nanotubes (CNTs) have extraordinary properties and are used for applications in various fields of engineering and research. Due to their unique combination of properties, such as good electrical and thermal conductivity and mechanical strength, there is an increasing demand to produce CNTs with enhanced and customized properties. CNTs are produced using different synthesis methods and have extraordinary properties individually at the nanotube scale. However, it is challenging to achieve these properties when CNTs are used to form macroscopic sheets, tapes, and yarns. To further improve the properties of macroscale forms of CNTs, various types of nanoparticles and microfibers can be integrated into the CNT materials. The nanoparticles and microfibers can be chosen to selectively enhance the properties of CNT materials at the macroscopic level. In this paper, we propose a technique to manufacture carbon hybrid materials (CHMs) by combining CNT non-woven fabric (in the form of sheets or tapes) with microfibers to form CNT-CF hybrid materials with new/improved properties. CHMs are formed by integrating or adding nanoparticles, microparticles, or fibers into the CNT sheet. The additive materials can be incorporated into the synthesis process from the inlet or the outlet of the reactor system. This paper focuses on CHMs produced using the gas phase pyrolysis method with microparticles/fibers integrated at the outlet of the reactor and continuous microfiber tapes integrated into the CNT sheet at the outlet using a tape feeding machine. After synthesis, characterizations such as microscopy and thermogravimetric analysis were used to study the morphology and composition of the CNTs, and examples for potential applications are discussed in this paper.