Inclusion Of Multi-walled Carbon Nanotubes Research Articles

Efficient electromagnetic interference shielding performance of poly(amide imide)/MWCNT‐based nanocomposites

AbstractThe establishment of conducting network in a polymer matrix is essential for the improvement in electrical conductivity and electromagnetic interference (EMI) shielding performance. Here, we report the fabrication of nanocomposites comprising polyamideimide and multiwalled carbon nanotubes (MWCNTs) (from 0.5 to 5.0 wt%). The effect of MWCNTs on electrical conductivity, morphology, and EMI shielding behavior has been examined. The morphology of nanocomposites was investigated by scanning electron microscope and x‐ray diffraction, which confirms the uniform dispersion of MWCNTs in the matrix. The electrical conductivity increases from 1.4 × 10−12 to 0.145 × 10−4 S/cm by the inclusion of MWCNTs. The composite PACNT‐5 exhibits a good EMI shielding efficiency of −17 dB in the X‐band region by employing only 5.0 wt% of MWCNTs. The incorporation of MWCNTs formed an interconnected conducting network, which boost the transferability of electrons or charge carriers. This work demonstrates a feasible, simple, and effective strategy for the fabrication of potential PAI/MWCNT composites for highly efficient EMI shielding materials.

Improved Performance of QDSSCs Can Be Achieved by Constructing a Transparent Anatase TiO2@MWCNT Photoanode Based on the Bionic Mountain Lotus.

In this research, the structural characteristics of the mountain holly leaf were emulated. It was observed that after the initially uneven surface of the petals is filled with infiltrated water, it exhibits a distinctive transparent beauty after rainfall. Furthermore, the presence of leaf veins enhances the structural strength of the petals and facilitates nutrient transport. Inspired by previous studies on double-layer spin-coated films, we further developed and designed the TA TiO2@MWCNT photocathode thin film. This innovative film incorporates multiwalled carbon nanotubes (MWCNT) into a previously established TA TiO2 photocathode thin film. The inclusion of MWCNT results in the formation of a three-dimensional highway structure, where MWCNT intertwines within the TA TiO2 film. Under the operational state of immersion in the electrolyte, it maintains a level of transparency similar to that of the TA TiO2 photoanode thin film. The high-temperature sintering process results in the oxidation and depletion of MWCNTs on the surface of the film, leaving behind uniformly dispersed concave defects, thereby greatly enhancing the specific surface area. The findings demonstrate that the optoelectrode of high transparency and high specific surface area, TA TiO2@MWCNT, comprehensively enhances the performance of the solar cells. The transparent QDSSC surpasses its counterparts for the first time, achieving a power conversion efficiency (PCE) of 6.335%. This sets the stage for new materials and innovative approaches in the field of solar cells and other titanium dioxide film-related areas.

Effect of cellulose nanocrystals and carboxylated multiwalled carbon nanotubes on performance of polyethersulfone membrane for humic acid removal

Persistent declines in flux due to membrane fouling result in decreased treated water production, higher energy consumption, and a frequent need for chemical cleaning. Carbon nanotubes-based membranes have shown remarkable separation capabilities in water treatment processes while being relatively resistant to biofouling. Cellulose-based membranes, on the other hand, have demonstrated outstanding biocompatibility and versatile surface chemistry. In the current study, a hybrid polyethersulfone (PES) membrane was synthesized by integrating with single cellulose nanocrystals (CNC), single carboxylated multiwalled carbon nanotubes (MWCNT), and a mixture of CNC and MWCNT utilizing the phase inversion method. This combination of nanomaterials was aimed at eliciting synergistic effects to enhance the overall membrane performance. The evaluation of the hybrid membranes encompassed an analysis of membrane structure, morphology, porosity, hydrophilicity, water flux, humic acid (HA) rejection, and the flux recovery ratio (FRR). The experimental outcomes unveiled notable changes in the morphology of the polymeric membrane when CNC and MWCNT were introduced into the PES membrane structure. All hybrid membranes displayed heightened hydrophilicity compared to the original pristine PES membrane. The PES/CNC0.3/CNT0.03 membrane demonstrated exceptional performance, with a remarkable HA rejection rate and FRR of 93.05% and 92.09%, respectively. This outstanding performance can be attributed to the synergistic combination of two separation mechanisms: electrostatic repulsion and size exclusion. The inclusion of MWCNTs into the hybrid membranes significantly reduced humic acid-induced membrane fouling due to improve surface hydrophilicity and decreased membrane roughness.

Investigation on Thermophysical Properties of Multi-Walled Carbon Nanotubes Enhanced Salt Hydrate Phase Change Material

Thermal Energy Storage (TES) is a valuable tool for improving the energy efficiency of renewable energy conversion systems. One of the most effective methods for harnessing thermal energy from solar sources is through energy storage using phase change materials (PCMs). However, the thermal performance of PCMs is hindered by their low thermal conductivity. This research focuses on enhancing the thermal performance of salt hydrate PCM using multi-walled carbon nanotubes (MWCNTs) and surfactants. Through experimental investigations, a salt hydrate PCM with varying concentrations of MWCNTs (ranging from 0.1% to 0.9%) was prepared using a two-step technique and their thermophysical properties were thoroughly characterized. Various techniques such as field emission scanning electron microscope, thermal conductivity analyzer, ultraviolet-visible spectrum, thermogravimetric analyzer, and Fourier transform infrared spectroscopy were utilized to study the effect of surfactant on the nanocomposites and examine their morphology, thermal conductivity, optical properties, thermal stability, and chemical stability. The results indicated that the inclusion of MWCNTs with salt hydrate significantly improved the thermal conductivity by 68.09% at a concentration of 0.7 wt %, compared to pure salt hydrate. However, this enhancement in thermal performance was accompanied by a reduction in optical transmittance in the developed nanocomposite PCM. Additionally, the formulated nanocomposite demonstrated excellent thermal and chemical stability up to temperatures as high as 468 °C. As a result, this nanocomposite shows great promise as a potential candidate for solar TES applications, offering favourable characteristics for efficient energy storage from solar sources.

Composite aerogels of alginate/poly(acrylamide)/carbon nanotubes with enhanced performance for cationic dyes adsorption

This study presents the preparation and characterization of a composite aerogel with a double network of alginate (Alg) and poly(acrylamide) (PAM), filled with multi-walled carbon nanotubes (MWCNT). The double network structure was formed by mixing alginate and the PAM network and subsequently cross-linking the polysaccharide with Ca2+ ions. Characterization analyses demonstrated that the inclusion of MWCNT resulted in significant changes to the thermal, morphological, mechanical, and swelling properties of the composite compared to the pristine aerogel (Alg/PAM). Adsorption experiments demonstrated the effectiveness of Alg/PAM/MWCNT in removing cationic dyes (methylene blue, MB, and crystal violet, CV) from aqueous solutions. Notably, the aerogel containing MWCNT exhibited 1.5 times higher adsorption capacity for MB and CV compared to Alg/PAM under similar experimental conditions. Isothermal analyses revealed distinct adsorption behaviors for MB and CV on Alg/PAM/MWCNT, and competitive adsorption was observed when both dyes were present in the solution simultaneously. The composite aerogel also demonstrated excellent reusability, maintaining its performance for at least five cycles, indicating its potential for long-term application.

Effect of structural properties in the electrical impedance spectrum of multi-walled carbon nanotube/graphite/polyester ternary composites

The aim of this study is to establish a connection or correlation between the electrical and structural properties of ternary composites, which were prepared by adding multi-walled carbon nanotubes (MWCNT) and graphite (Gr) as conductive fillers to an insulating polyester matrix. The study utilized small-angle neutron scattering, infrared and Raman spectroscopy for structural characterization. Electrical measurements were conducted within a frequency range of 100 Hz to 1 MHz and a temperature range of 200–380 K. The alternating current (AC) conductivity showed a frequency dependence following Jonscher’s power law. The temperature dependence of the AC conductivity suggested that the electrical conduction within the material is a thermally activated process. The temperature-dependent behavior of the direct current (DC) conductivity suggests that below and above the critical temperature, there is a pronounced positive and negative temperature coefficient of resistivity, respectively. In comparison to MWCNT/polyester or Gr/polyester composites, the percolation threshold of the MWCNT/Gr/polyester composite is much lower. Additionally, applying the Arrhenius equation to analyze the temperature dependence of DC conductivity reveals that the inclusion of MWCNT and Gr in the polyester matrix results in a decrease in activation energy.

Fabrication of CNTs-reinforced poly(vinyl alcohol) nanocomposite film with tailored structural, surface chemical and optical properties

Purpose This study aims to fabricate multiwalled carbon nanotubes (MWCNTs)-mediated polyvinyl alcohol (PVA) composite films using the solution casting approach. Design/methodology/approach The prepared films were evaluated for diverse structural, surface, optical and electrical attributes using advanced analytical techniques, i.e. electron microscopy for surface morphology, Fourier transform infrared spectroscopy for tracing chemical functionalities, x-ray diffraction (XRD) for crystal patterns, water contact angle (WCA) analysis for surface wettability and UV visible spectroscopy for optical absorption parameters. The specimens were also investigated for certain rheological, mechanical and electrical properties, where applicable. Findings The surface morphology results expressed a better dispersion of MWCNTs in the resultant PVA-based nanocomposite film. The XRD analysis exhibited that the nanocomposite film was crystalline. The surface wettability analysis indicated that with the inclusion of MWCNTs, the WCA of the resultant nanocomposite film improved to 89.4° from 44° with the pristine PVA film. The MWCNTs (1.00%, w/w) incorporated PVA-based film exhibited a tensile strength of 54.0 MPa as compared to that of native PVA as 25.3 MPa film. There observed a decreased bandgap (from 5.25 to 5.14 eV) on incorporating the MWCNTs in the PVA-based nanocomposite film. Practical implications The MWCNTs’ inclusion in the PVA matrix could enhance the AC conductivity of the resultant nanocomposite film. The prepared nanocomposite film might be useful in designing certain optoelectronic devices. Originality/value The results demonstrated the successful MWCNTs mediation in the PVA-based composite films expressed good intercalation of the precursors; this resulted in decreased bandgap, usually, desirable for optoelectronic applications.

Design of Solid-contact Ion-selective Electrode with Multiwall-carbon Nanotubes for Assay of Sulfacetamide in Rabbit Aqueous Humour

Background: Inclusion of multiwall-carbon nanotubes (MWCNTs) as ion-to-electron transducers within the ionophore-doped PVC membrane has a great impact on the stability and robustness of the produced sensor performance compared to conventional liquid-based ISEs. Objective: Solid-contact ion selective electrodes (SC-ISEs) were fabricated and optimized for the assay of sulfacetamide sodium in both ophthalmic eye drops and in rabbit aqueous humor. Methods: 2-hydroxypropyl-β-cyclodextrin (2HP-β-CD) was selected as an ionophore to dope the ionselective membrane to enhance its selectivity towards sulfacetamide. The performance of multiwall-CNTs as ion-to-electron transducer was evaluated by comparing MWCNT-based SC-ISE with control sensor which does not include the MWCNTs. The electrochemical performance characteristics of the proposed sensors were assessed in accordance with the IUPAC recommendations. A green profile assessment of the proposed method was performed using Eco-Scale and AGREES metrics. Results: Inclusion of MWCNT into the sensing membrane improved the performance of the developed sensor. The linearity range was (2.5 x 10-4 M - 1.0 x 10-2 M) for both sensors and the LOD was estimated to be 5.6 x 10-5 M for GCE/ISM(CNT) and 1.5x 10-4 M for control sensor GCE/ISM. The results of green assessment for both the developed and the official method showed an excellent greenness of the proposed method. Conclusion: The proposed sensor can be applied successfully for the determination of sulfacetamide in eye drops and rabbit aqueous humour.

Piezoresistive response of carbon nanotube and carbon fiber/epoxy composites under cyclic loading

Maintaining the mechanical properties and long-term operational safety is considered the main challenge for composite materials under cyclic loading. This work presents mechanical performance of tri-component composites based on multiwall carbon nanotubes (MWCNTs), carbon fibres (CFs) and epoxy resin, and their electrical conductance property for applications like strain gauges. As a result of incorporation of MWCNTs into the epoxy resin in the composite’s morphology, their electrical, mechanical and piezoresistive performance can indicate the self-sensing of carbon fiber reinforced epoxy resin matrix (CF/Epoxy matrix) composites; and thus its influence has been systematically examined. The inclusion of multiwall carbon nanotubes increased the resin bonding to the surface of the CF’s leading to an increased electrical conductivity and mechanical performances. The piezoresistive performance was significantly influenced by the amount of MWCNTs added to the resin, where the Gauge Factor (GF) with respect to the MWCNTs concentration under cyclic tensile and cyclic bending were in the range of 0.6∼1.5 and 2.5∼5.5 respectively. Moreover, the piezoresistive behaviour of the composite samples showed reasonable sensitivity, stability, and reversibility under cyclic mechanical loading, and the samples withstood more than 500 cycles of load without detectable loss in performance. The exceptional mechanical, electrical and piezoresistive performance and easy manufacturing process of the tri-component composites make them attractive for applications such as self-monitoring structural components.

Energy transmission through carreau yasuda fluid influenced by ethylene glycol with activation energy and ternary hybrid nanocomposites by using a mathematical model

The current study aims to assess the augmentation of energy transmission in the presence of magnetic dipole through trihybrid Carreau Yasuda nanofluid flow across a vertical sheet. The rheological properties and thermal conductivity of the based fluids are improved by framing an accurate combination of nanoparticles (NPs). The trihybrid nanofluid (Thnf) has been synthesized by the addition of ternary nanocomposites (MWCNTs, Zn, Cu) to the ethylene glycol. The energy and velocity conveyance has been observed in the context of the Darcy Forchhemier effect, chemical reaction, heat source/sink, and activation energy. The trihybrid nanofluid flow across a vertical sheet has been accurately calculated for velocity, concentration, and thermal energy in the form of a system of nonlinear PDEs. The set of PDEs is reduced to dimensionless ODEs by using suitable similarity replacements. The obtained set of non-dimensional differential equations is numerically computed through the Matlab package bvp4c. It has been perceived that the energy curve enhances by the influence of heat generation factor and viscous dissipation. It is also noted that the magnetic dipole has a momentous contribution to raising the transmission of thermal energy of trihybrid nanofluid and declines the velocity curve. The inclusion of multi-wall carbon nanotubes (MWCNTs), zinc (Zn), and copper (Cu) nano particulates to the base fluid “ethylene glycol”, augments the energy and velocity outlines.

Nano filler incorporated epoxy based natural hybrid fiber confinement of concrete systems: Effect of fiber layers and nano filler addition

The utilization of environment friendly materials in the construction industry is essential for sustainable development. For the purpose of strengthening and retrofitting concrete structures, fiber reinforced polymer (FRP) composites have been predominantly used. In the area of structural strengthening, as an alternative to synthetic fiber reinforced composites, the application of natural fiber reinforced composites is of immense interest. This study discusses the mechanical properties of externally strengthened concrete cylinders using a natural hybrid fiber system with two layers of sisal fiber sheets followed by 1 to 3 layers of basalt fiber sheets. In addition, the effect of multi walled carbon nanotubes (MWCNT) incorporation in the epoxy matrix from 0.5 to 1.5 wt%, on the various properties are analyzed. The inclusion of MWCNT in the epoxy matrix improved the overall performance of the FRP significantly. The results show that there is substantial improvement in mechanical properties up to 1 wt% MWCNT content in composites, beyond which it is reduced due to agglomeration of nanofiller. The MWCNT incorporated epoxy based five layered hybrid sisal basalt FRP confined specimens showed an improvement of 114% and 427% in peak strength and strain values under axial compressive strength tests. Moreover, the axial compressive behavior, stress–strain response, energy absorption and ductility characteristics of the confined column specimens were evaluated. The major focus of the study is to assess the influence of basalt FRP layers on the ultimate load carrying capacity and performance of hybrid sisal basalt FRP (HSBFRP) confined specimens. Statistical analysis of variance (ANOVA) was carried out and revealed that the number of FRP layers and addition of MWCNT in epoxy significantly affect the overall performance. The addition of basalt fiber layers in hybrid sisal basalt FRP systems is found to improve the load carrying capacity and energy absorption characteristics of confined specimens. Therefore, HSBFRP confinement can be used in areas where moderate strength and greater ductility is commanded.

Carbon foam composites containing carbon nanotubes and graphene oxide as additives for enhanced mechanical, thermal, electrical and catalytic properties

Based on the versatile nature and applications of Carbon foam (CF), up to now many attempts were performed to improve the structure and properties of CF by incorporating various additives in the CF matrix. But these additives improved one property on the cost of another ones. Herein, we have synergistically incorporated multi-walled carbon nanotubes (MWCNTs) and graphene oxide (GO) with varying loadings as additives in the CF matrix via direct pyrolysis to achieve all the desired properties. Seven different types of CF composites including pure CF were prepared and their effect on the structure, mechanical, thermal, electrical and catalytic characteristics has been reported. The results revealed that after the inclusion of MWCNTs and GO contents, the microstructural performance of CF samples was amazingly improved. Additionally, it was observed that mechanical, thermal, electrical and catalytic behaviors of the CF samples were significantly enhances by the increase of nanohybrids. The compressive strength and Young's modulus reveals their optimum limits up to 19.3 and 57.4 MPa respectively on 2 wt.% MWCNTs-GO additive loadings. Similarly, the greatest thermal and electrical conductivities of 30.92 W/m. K and 27.4 × 103 S/m were showed by CF samples having 2 wt. % MWCNTs-GO loadings. Whereas, the decolorization activity of the CF and their nanocomposites were tested against methyl orange dye and it was observed that the sample with enhanced MWCNTs and GO have good decolorization activity and much sustainable than other samples. The 4% CF/MWCNTs-GO decolorized about 76% MO dye under exposure to UV light within 60 min. The decolorization of MO dye increases with increasing nanocomposite dosage and decreasing initial dye concentration.

Effect of Multi-Walled Carbon Nanotubes (MWCNTs) in Reducing the Corrosion Rate in Cr-MWCNTs Composite Coatings

Carbon steel was coated with Cr-multi-walled carbon nanotube (MWCNTs) coatings via electrodeposition. In this article, the impact of a combination of MWCNTs into the chromium coating on the morphology of the coating surface and corrosion characteristics was inspected. The MWCNTs seem to be evenly distributed across the chromium layer, according to scanning electron microscopy (SEM). Electrochemical measurements were used to conduct corrosion tests on samples of MWCNTs– chromium composite coated and pure chromium coated samples in aqueous NaCl (3.5 wt.%). The outcomes demonstrated a considerable increase in the resistance of corrosion due to the inclusion of MWCNTs during the chromium deposition procedure. In addition, the mechanism of anti-corrosion of the composite coating is also presented. Using an electrolyte bath containing various concentrations of dispersed MWCNTs (0.5, 1, and 1.5 g/L), crack-free and compact coating of Cr-MWCNT composite were electrodeposited on the substrates of the mild steel. The potentiodynamic polarization technique was used to examine the coatings corrosion performance subjected to a 3.5 weight percent of NaCl medium. When compared to chromium coating, the Cr-MWCNT composite coating showed the lowest corrosion rate (1.045x108 mpy) compared to chromium coating (4.891x108 mpy).

Mechanical properties of concrete containing recycle concrete aggregates and multi-walled carbon nanotubes under static and dynamic stresses

The growing demand for natural aggregates in the construction industry has motivated researchers to utilize recycled concrete aggregates (RCA) to preserve the natural resources and provide sustainable structure. However, the use of RCA in concrete applications has revealed defects in performance with low strength and rapid collapse under static and dynamic loads, respectively. Thus, the objective of present research is to improve these properties by using multi-walled carbon nanotubes (MWCNT). This study involves evaluating the fresh and hardened properties of recycled aggregate concrete (RAC) modified with different levels of MWCNT. The study involves RCA (i.e., 0 %, 25 %, 50 %, 75 % and 100 %) as replacement for natural aggregates, and MWCNT (i.e., 0.05 %, 0.1 % and 0.25 %) as weight of cement. The experimental testing consists of 240 specimens prepared from different mixtures. Workability is assessed using slump tests. Mechanical properties including static compressive strength and dynamic impact resistance are evaluated at 7 and 28 days. Experimental results show that incorporating MWCNT at all levels significantly reduces the slump values for all specimens. On the other hand, the compressive strength is increased by adding MWCNT to the concrete samples. The compressive strength of the RAC increased by as much as 70 % when modified with MWCNT. Furthermore, the inclusion of MWCNT is found to significantly increase the impact resistance of RAC specimens with percentage developments reaching approximately 11–508 % and 110–679 % at 7 and 28 days, respectively, at both first crack and failure stages. The dosage of 0.1 % MWCNT is shown to exhibit the highest percentage enhancement in impact resistance among the other nano levels. The failure patterns and cracks propagation are presented as well.

Tuning Optical and Electrical Properties of Ultra-Fast Prepared Nanoflower Mg:ZnO Films by MWCNTs Coating

Mg doped ZnO films were coated multi-walled carbon nanotubes (MWCNTs) via fast chemical bath onto ZnO seed layers. XRD analysis showed preferential orientation shift from high-energy (002) peak to low-energy (101) peak with MWCNTs coating. Average crystalline size of Mg doped ZnO samples are 15 nm. diameter and 50% percent reduction has been observed with MWCNTs coating. SEM images reveals the presence of high accumulative nanoflower forms on Mg:ZnO surfaces and homogenous net-shaped coating has been achieved by MWCNTs inclusion so active surface area may increase. No major difference of optical absorption edge is detected in both films however MWCNTs coating cause an increase direct band gap. Due to Burstein-Moss effect, Mg:ZnO and Mg:ZnO/MWCNTs films with using Tauc plot calculated band gap values are 3.04 eV and 3.34 eV, respectively. From FTIR spectra, no obvious change is not detected the functional groups of the samples. Electrical studies show that MWCNTs decrease the resistance and the resistance of films at room temperature were calculated 29.85 and 8.53 k for Mg:ZnO and Mg:ZnO/MWCNTs films , respectively.

Effect of Multi-Walled Carbon Nanotubes on Infill Material for Pipeline Composite Repair

The properties of the infill material are an important parameter in predicting the performance and behaviour of Fibre Reinforced Polymer (FRP) composite for effective design. This paper identifies the potential of Multi-walled Carbon Nanotubes (MWCNTs) as nanofiller in enhancing the performance of infill material. Two compositions of MWNTs at 0.1% and 0.5% of weight fractional were evaluated toward neat epoxy on tensile and lap shear test. By comparing MWCNTs-based modified epoxy grouts and neat epoxy grout, a significant increase in tensile strength was observed, especially with 0.5% of MWCNTs by almost 53.3%. While the inclusion of MWCNTs showed a comparable increment in shear strength in both 0.1% and 0.5% weight fractional by 13%. The image of morphologies showed that MWCNTs were well incorporated into the matrix, making the cross-section of the fracture rougher by sharing stress. This shows the potential of the MWCNTs in changing the properties of the modified epoxy grout, provided that the MWCNTs are appropriately dispersed throughout the resin matrix.

Enhanced Thermal Stability, Mechanical Properties and Structural Integrity of MWCNT Filled Bamboo/Kenaf Hybrid Polymer Nanocomposites.

Recently, there has been an inclination towards natural fibre reinforced polymer composites owing to their merits such as environmental friendliness, light weight and excellent strength. In the present study, six laminates were fabricated consisting of natural fibres such as Kenaf fibre (Hibiscus cannabinus L.) and Bamboo fibre, together with multi-walled carbon nanotubes (MWCNTs) as reinforcing fillers in the epoxy matrix. Mechanical testing revealed that hybridization of natural fibres was capable of yielding composites with enhanced tensile properties. Additionally, impact testing showed a maximum improvement of ≈80.6% with the inclusion of MWCNTs as nanofiller in the composites with very high energy absorption characteristics, which were attributed to the high specific energy absorption of carbon nanotubes. The viscoelastic behaviour of hybridised composites reinforced with MWCNTs also showed promising results with a significant improvement in the glass transition temperature (Tg) and 41% improvement in storage modulus. It is worth noting that treatment of the fibres in NaOH solution prior to composite fabrication was effective in improving the interfacial bonding with the epoxy matrix, which, in turn, resulted in improved mechanical properties.

Структура и электропроводность пленок поливинилового спирта с многостенными углеродными нанотрубками, отвержденных в магнитном поле

The results of the study of the effect of the permanent magnetic field of a neodymium magnet on the polymerization process and the electrophysical characteristics of polyvinyl alcohol (PVA) films with the inclusion of multi-walled carbon nanotubes (MWCNTs) are presented. When studying the morphology of films using a scanning electron microscope, it was found that nanocomposite films with a thickness of 30 microns, cured in the presence of a magnetic field with the direction of the magnetic induction vector perpendicular to the surface of the films, have a homogeneous structure, while a significant number of MWCNTs agglomerations are observed in control samples of films. Measurements of the conductivity of films in the direction of the MWCNTs orientation at direct and alternating current showed that the conductivity of films obtained in a magnetic field significantly (by almost two orders of magnitude) exceeds the conductivity of control samples. The obtained results are analyzed on the basis of known models of electrical conductivity of nanocomposites with oriented MWCNTs. The degree of orientation of the MWCNTs during the curing of films in a magnetic field is estimated, taking into account the increase in the viscosity of the nanocomposite during the curing process.

Fabrication, characterization and mechanical testing of carbon fiber sandwich composites with nanoparticle included polyurethane adhesives

In honeycomb core and composite face sheet sandwich panels, it is essential to understand the bonding characteristics of adhesive in relevance with its properties to observe synergistic effects of reinforcing nanoparticles such as multi-walled carbon nanotubes (MWCNTs). This study investigates the effects of MWCNT inclusion on polyurethane (PU) adhesive, which directly affects sandwich structures' structural and mechanical performance. MWCNTs are added to PU adhesive up to 0.2%, and their RAMAN spectroscopic analysis, Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analyses (TGA) and differential-scanning calorimetry analyses (DSC) are evaluated. Aluminum honeycomb carbon-fiber-reinforced composite (CFRC) sandwich panels are fabricated using an out-of-autoclave manufacturing process. Carbon-fiber prepreg is used for top/bottom face sheets. Mechanical strength of face/core bonding evaluated as a function of MWCNT addition and core cell sizes. Manufactured sandwich composite structures are investigated for flat-wise tensile strength and three-point bending strength. Results show that MWCNT reinforcement to PU adhesive and lower cell size increases bending and flat-wise tensile resistances.

Influence of the magnetic field on the formation and properties of polyvinyl alcohol - multi-walled carbon nanotube nanocomposites

The effect of a magnetic field on the polymerization process and the electrophysical characteristics of polyvinyl alcohol (PVA) films with the inclusion of multiwalled carbon nanotubes (MWCNTs) was studied. Using SEM micrographs, it was shown that the films obtained under the action of a magnetic field have a more homogeneous structure, while a significant number of MCNT agglomerations are present in the control samples. In the study of the conductivity at direct and alternating current, it was found that the films obtained in a magnetic field have a conductivity that significantly exceeds the conductivity of the control samples. It has been shown that the use of a magnetic field during polymerization has a noticeable effect on the properties and characteristics of nanocomposite films based on PVA and MWCNTs.