Search Results (58)

The influence of multiwall carbon nanotube (MWCNT) reinforcements on electrochemical corrosion investigations at varying NaCl concentrations (0.4 M, 0.6 M, 0.8 M, 1 M) of Mg-Zn-Ce nanocomposites is studied in this work. The Mg-Zn-Ce/MWCNT nanocomposites were developed by using an ultrasonication-assisted hybrid stir–squeeze (UHSS) casting method with different MWCNT concentrations (0, 0.4, 0.8, 1.2 wt.%) in a Mg-Zn-Ce magnesium alloy matrix. The microstructural characterizations shown using X-ray diffraction revealed the presence of secondary phases (MgZn₂, Mg₁₂Ce), T-phase (Mg₇Zn₃RE), α-Mg, and MWCNT peaks. Optical microscopy results showed grain refinement in the case of nanocomposites. Transmission electron microscope studies revealed well-dispersed MWCNT, indicating the good selection of processing parameters. The uniform dispersion of MWCNTs was achieved due to a hybrid stirring mechanism along with transient cavitation, ultrasonic streaming, and squeeze effect. The higher E_corr value of −1.39 V, lower I_corr value (5.81 µA/cm²), and lower corrosion rate of 0.1 mm/Yr (↑77%) were obtained by 0.8% nanocomposite at 0.4 M NaCl concentration, when compared to the monolithic alloy. The Mg(OH)₂ passive film formation on 0.8 wt.% nanocomposite was denser, attributed to the refined grains. At higher NaCl concentration, the one-dimensional morphological advantage of MWCNT helped to act as a barrier for further Mg exposure to excessive Cl⁻ attack, which reduced the formation of MgCl₂. Therefore, the UHSS-casted Mg-Zn-Ce/MWCNT nanocomposites present a good potential as sacrificial anodes for use in a wide range of industrial applications. Full article

Nanocomposite laminates containing carbon fibers, epoxy, and multiwalled carbon nanotubes were fabricated using a vacuum bag process. Ecofriendly ionic liquid (5 wt%)-treated multiwalled carbon nanotubes (pristine and nickel-coated) were added to the epoxy independently, in amounts ranging from 1 wt% to 3 wt%, in order to tailor the mechanical, electrical, and thermal performance of manufactured carbon fiber epoxy composite laminates. These nanocomposite laminates were later characterized through flexural testing, dynamic mechanical analysis, impedance spectroscopy, thermal conductivity tests, and FTIR spectroscopy to evaluate their suitability for battery pack applications. The findings showed that both types of multiwalled carbon nanotubes exhibited multifaceted effects on the properties of bulk hybrid carbon fiber epoxy nanocomposite laminates. For instance, the flexural strength of the composites containing 3.0 wt% of ionic liquid-treated pristine multiwalled carbon nanotubes reached 802.8 MPa, the flexural modulus was 88.21 GPa, and the storage modulus was 18.2 GPa, while the loss modulus peaked at 1.76 GPa. The thermal conductivity of the composites ranged from 0.38869 W/(m · K) to 0.69772 W/(m · K), and the electrical resistance decreased significantly with the addition of MWCNTs, reaching a minimum of 29.89 Ω for CFRPIP-1.5 wt%. The structural performance of hybrid nanocomposites containing ionic liquid-treated pristine multiwalled carbon nanotubes was higher than that of the hybrid nanocomposite of ionic liquid-treated Ni-coated multiwalled carbon nanotubes, although the latter was found to possess better functional performance. Full article

Hybrid nanocomposites incorporating multiple fillers are gaining significant attention due to their ability to enhance material performance, offering superior properties compared to traditional monophase systems. This study investigates hybrid epoxy-based nanocomposites reinforced with multi-walled carbon nanotubes (MWCNTs) and graphene nanosheets (GNs), introduced at two different weight concentrations of the mixed filler, i.e., 0.1 wt% and 0.5 wt% which are, respectively, below and above the Electrical Percolation Threshold (EPT) for the two binary polymer composites that solely include one of the two nanofillers, with varying MWCNTs:GNs ratios. Mechanical properties, such as contact depth, hardness, and reduced modulus, were experimentally assessed via nanoindentation, while morphological analysis supported the mechanical results. A Design of Experiments (DoE) approach was utilized to evaluate the influence of filler concentrations on the composite’s mechanical performance, and Response Surface Methodology (RSM) was applied to derive a mathematical model correlating the filler ratios with key mechanical properties. The best and worst-performing formulations, based on hardness and contact depth results, were further investigated through detailed numerical simulations using a multiphysics software. After validation considering experimental data, the simulations provided additional insights into the mechanical behavior of the hybrid composites. This work aims to contribute to the knowledge base on hybrid composites and promote the use of computational modeling techniques for optimizing the design and mechanical performance of advanced materials. Full article

In this work, the synergistic effect of graphene nanosheets (GNs), as well as multiwalled carbon nanotubes (MWCNTs), as reinforcing agents of polydimethylsiloxane (PDMS) was investigated, in order to explore the possibilities of designing composite materials, tailored for use in the field of coatings, which might be, in fact, a very interesting application. It was shown that the addition of GNs and MWCNTs in PDMS matrices significantly improves the thermal stability of the obtained nanocomposites, especially those reinforced exclusively with GNs. The tensile tests indicated that strength increased for all the examined composites. It was also observed that the Young’s moduli had an increasing trend, with the exception of the composites containing only GNs, while those reinforced solely with MWCNTs exhibited the best performance. The O₂ permeability measurements revealed that the highest reduction in the permeability was observed in GN-MWCNT/PDMS composite membranes, in comparison to those reinforced only with graphene or carbon nanotubes. Dielectric relaxation spectroscopy showed that all the examined composites, and especially those of MWCNTs, possess electrical conductivity, apart from the samples reinforced exclusively with graphene. The electromagnetic shielding effectiveness was also improved at higher filler loadings, which is more evident in composites reinforced with MWCNTs. It was concluded that the improved properties of the above studied hybrid composites make them suitable for protective coating applications. Full article

The production of cost-effective novel materials for PV solar cells with long-term stability, high energy conversion efficiency, enhanced photon absorption, and easy electron transport has stimulated great interest in the research community over the last decades. In the presented work, Cu/Cu₂S-MWCNTs nanocomposites were produced and analyzed in the framework of potential applications for PV solar cells. Firstly, the surface of the produced one-dimensional Cu was covered by Cu₂S nanoflake. XRD data prove the formation of both Cu and Cu₂S structures. The length and diameter of the one-dimensional Cu wire were 5–15 µm and 80–200 nm, respectively. The thickness of the Cu₂S nanoflake layer on the surface of the Cu was up to 100 nm. In addition, the Cu/Cu₂S system was enriched with MWCNTs. MWCNs with a diameter of 50 nm interact by forming a conductive network around the Cu/Cu₂S system and facilitate quick electron transport. Raman spectra also prove good interfacial coupling between the Cu/Cu₂S system and MWCNTs, which is crucial for charge separation and electron transfer in PV solar cells. Furthermore, UV studies show that Cu/Cu₂S-MWCNTs nanocomposites have a wide absorption band. Thus, MWCNTs, Cu, and Cu₂S exhibit an intense absorption spectrum at 260 nm, 590 nm, and 972 nm, respectively. With a broad absorption band spanning the visible–infrared spectrum, the Cu/Cu₂S-MWCNTs combination can significantly boost PV solar cells’ power conversion efficiency. Furthermore, UV research demonstrates that the plasmonic character of the material is altered fundamentally when CuS covers the Cu surface. Additionally, MWCN-Cu/Cu2S nanocomposite exhibits hybrid plasmonic phenomena. The bandgap of Cu/Cu₂S NWs was found to be approximately 1.3 eV. Regarding electron transfer and electromagnetic radiation absorption, the collective oscillations in plasmonic metal-p-type semiconductor–conductor MWCNT contacts can thus greatly increase energy conversion efficiency. The Cu/Cu₂S-MWCNTs nanocomposite is therefore a promising new material for PV solar cell application. Full article

Dye-sensitized solar cells (DSSCs) have attracted renewed research interest as a potential low-cost substitute for conventional silicon photovoltaics. This work aims to improve the photovoltaic performance of the DSSCs by incorporating multi-walled carbon nanotubes (MWCNTs) into the BaTiO₃ photoelectrode. The pure BaTiO₃ and BaTiO₃/MWCNT nanocomposites were sensitized with N719 dye and fabricated into solar cell devices for testing. The structural characterization confirmed the successful formation of the nanocomposite with an optimal dispersion at 6% of MWCNT incorporation, beyond which agglomeration effects manifested. The optical analysis verified the modulation of defect states and bandgap engineering induced by the MWCNT network. The morphological studies revealed irregular nanoparticle clusters with embedded nanotubes. Solar cell testing under AM1.5G-simulated sunlight demonstrated a peak power conversion efficiency of 4.044% for 6% of MWCNT doping, constituting a 6-fold increment versus pure BaTiO₃ (0.693%). It originated from the simultaneous enhancements in the open-circuit voltage and short-circuit current enabled by the favorable band structure alterations and percolation-assisted charge transport. However, further increasing MWCNT content deteriorated the device metrics, owing to emerging limitations like trapping. The rational integration of multi-walled carbon nanotubes with lead-free ferroelectric metal oxides can contribute to the development of emerging organic-inorganic hybrid solar platforms. Full article

In recent years, conductive polymer nanocomposites have gained significant attention due to their promising thermoresistive and Joule heating properties across a range of versatile applications, such as heating elements, smart materials, and thermistors. This paper presents an investigation of semi-crystalline polyvinylidene fluoride (PVDF) nanocomposites with 6 wt.% carbon-based nanofillers, namely graphene nanoplatelets (GNPs), multi-walled carbon nanotubes (MWCNTs), and a combination of GNPs and MWCNTs (hybrid). The influence of the mono- and hybrid fillers on the crystalline structure was analyzed by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). It was found that the nanocomposites had increased amorphous fraction compared to the neat PVDF. Furthermore, nanocomposites enhanced the β phase of the PVDF by up to 12% mainly due to the presence of MWCNTs. The resistive properties of the nanocompositions were weakly affected by the temperature in the analyzed temperature range of 25–100 °C; nevertheless, the hybrid filler composites were proven to be more sensitive than the monofiller ones. The Joule heating effect was observed when 8 and 10 V were applied, and the compositions reached a self-regulating effect at around 100–150 s. In general, the inclusion in PVDF of nanofillers such as GNPs and MWCNTs, and especially their hybrid combinations, may be successfully used for tuning the self-regulated Joule heating properties of the nanocomposites. Full article

The potential of electrically conductive graphene nanoplatelets (GNPs)/epoxy, multi-walled carbon nanotubes (MWNCTs)/epoxy and hybrid GNPs-MWCNTs/epoxy nanocomposites as adhesives for out-of-autoclave (OoA) and in-the-field CFRP repair via Joule heat curing was investigated. Scanning electron microscopy revealed a good dispersion of the nanoparticles in the matrix in all the nanocomposite adhesives above their percolation thresholds, which led to a homogeneous distribution of the heat generated during Joule CFRP repair. The joints bonded with neat epoxy and the nanocomposites showed similar lap shear strengths, with the addition of nanoparticles enhancing the fatigue performance of the adhesively bonded joints relative to when neat epoxy was used as an adhesive and oven-cured. The interfacial and cohesive failure mechanisms were found to coexist in all the cases, with an increasing dominance of the cohesive when nanofillers were embedded into the adhesive. No effect of the specific type of nanofiller incorporated into the epoxy as the conductive component was observed on the mechanical performance of the bonded joints, with the adhesives containing MWCNTs showing similar results to those filled with GNPs at considerably lower loadings due to their lower percolation thresholds. The independence of the properties regardless of the curing method highlights the promise of these Joule-cured adhesives for industrial applications. Full article

A combined computational and experimental study of 3D-printed scaffolds made from hybrid nanocomposite materials for potential applications in bone tissue engineering is presented. Polycaprolactone (PCL) and polylactic acid (PLA), enhanced with chitosan (CS) and multiwalled carbon nanotubes (MWCNTs), were investigated in respect of their mechanical characteristics and responses in fluidic environments. A novel scaffold geometry was designed, considering the requirements of cellular proliferation and mechanical properties. Specimens with the same dimensions and porosity of 45% were studied to fully describe and understand the yielding behavior. Mechanical testing indicated higher apparent moduli in the PLA-based scaffolds, while compressive strength decreased with CS/MWCNTs reinforcement due to nanoscale challenges in 3D printing. Mechanical modeling revealed lower stresses in the PLA scaffolds, attributed to the molecular mass of the filler. Despite modeling challenges, adjustments improved simulation accuracy, aligning well with experimental values. Material and reinforcement choices significantly influenced responses to mechanical loads, emphasizing optimal structural robustness. Computational fluid dynamics emphasized the significance of scaffold permeability and wall shear stress in influencing bone tissue growth. For an inlet velocity of 0.1 mm/s, the permeability value was estimated at 4.41 × 10⁻⁹ m², which is in the acceptable range close to human natural bone permeability. The average wall shear stress (WSS) value that indicates the mechanical stimuli produced by cells was calculated to be 2.48 mPa, which is within the range of the reported literature values for promoting a higher proliferation rate and improving osteogenic differentiation. Overall, a holistic approach was utilized to achieve a delicate balance between structural robustness and optimal fluidic conditions, in order to enhance the overall performance of scaffolds in tissue engineering applications. Full article

This work is devoted to the development of epoxy-encapsulated zinc oxide-multiwalled carbon nanotubes (ZnO–MWCNT) hybrid nanostructured composites and the investigation of their thermoelectric performance in relation to the content of MWCNTs in the composite. For the preparation of nanocomposites, self-assembling Zn nanostructured networks were coated with a layer of dispersed MWCNTs and subjected to thermal oxidation. The resulting ZnO–MWCNT hybrid nanostructured networks were encapsulated in commercially available epoxy adhesive. It was found that encapsulation of ZnO–MWCNT hybrid networks in epoxy adhesive resulted in a simultaneous decrease in their electrical resistance by a factor of 20–60 and an increase in the Seebeck coefficient by a factor of 3–15, depending on the MWCNT content. As a result, the thermoelectric power factor of the epoxy-encapsulated ZnO–MWCNTs hybrid networks exceeded that of non-encapsulated networks by more than 3–4 orders of magnitude. This effect was attributed to the ZnO–epoxy interface’s unique properties and to the MWCNTs’ contribution. The processes underlying such a significant improvement of the properties of ZnO–MWCNT hybrid nanostructured networks after encapsulation in epoxy adhesive are discussed. In addition, a two-leg thermoelectric generator composed of epoxy-encapsulated ZnO–MWCNT hybrid nanocomposite as n-type leg and polydimethylsiloxane-encapsulated CuO–MWCNT hybrid nanocomposite as p-type leg characterized at room temperatures showed better performance at temperature difference 30 °C compared with the similar devices, thus proving the potential of the developed nanocomposites for applications in domestic waste heat conversion devices. Full article

The development of thermally conductive rubber nanocomposites for heat management poses a formidable challenge in numerous applications, notably within the realm of tire technology. Notably, rubber materials are characterized by their inherently low thermal conductivity. Consequently, it becomes imperative to incorporate diverse conductive fillers to mitigate the propensity for heat build-up. Multi-walled carbon nanotubes (MWCNTs), as reinforcement agents within the tire tread compounds, have gained considerable attention owing to their extraordinary attributes. The attainment of high-performance rubber nanocomposites hinges significantly on the uniform distribution of MWCNT. This study presents the influence of MWCNTs on the performance of carbon black (CB)-reinforced natural rubber (NR)/styrene butadiene rubber (SBR) tire compounds prepared via high shear melt mixing. Morphological analysis showed a good distribution of MWCNTs in the NR/SBR/CB compound. The vulcanization parameters, such as the maximum and minimum torque, cross-linking density, hardness, abrasion resistance, tensile strength, and Young modulus, exhibited a progressive improvement with the addition of MWCNT. Remarkably, adding MWCNT into CB improved the heat conductivity of the NR/SBR/CB compounds, hence decreasing the heat build-up. A percolation mode was also proposed for the hybrid carbon fillers based on the data obtained. Full article

A notable application of polymeric nanocomposites is the design of water vapor permeable (WVP) membranes. “Breathable” membranes can be created by the incorporation of micro/nanofillers, such as CaCO₃, that interrupt the continuity of the polymeric phase and when subjected to additional uniaxial or biaxial stretching this process leads to the formation of micro/nanoporous structures. Among the candidate nanofillers, carbon nanotubes (CNTs) have demonstrated excellent intrinsic WVP properties. In this study, chemically modified MWCNTs with oligo olefin-type groups (MWCNT-g-PP) are incorporated by melt processes into a PP matrix; a β-nucleating agent (β-ΝA) is also added. The crystallization behavior of the nanocomposite films is evaluated by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The WVP performance of the films is assessed via the “wet” cup method. The nanohybrid systems, incorporating both MWCNT-g-PP and β-NA, exhibit enhanced WVP compared to films containing only MWCNT-g-PP or β-NA. This improvement can be attributed to the significant increase in the growth of α-type crystals taking place at the edges of the CNTs. This increased crystal growth exerts a form of stress on the metastable β-phase, thereby expanding the initial microporosity. In parallel, the coexistence of the inherently water vapor-permeable CNTs, further enhances the water vapor permeability reaching a specific water vapor transmission rate (Sp.WVTR) of 5500 μm.g/m².day in the hybrid composite compared to 1000 μm.g/m².day in neat PP. Notably, the functionalized MWCNT-g-PP used as nanofiller in the preparation of the “breathable” PP films demonstrated no noteworthy cytotoxicity levels within the low concentration range used, an important factor in terms of sustainability. Full article

Bisphenol A (BPA), an endocrine-disrupting compound with estrogenic behavior, is of great concern within the scientific community due to its high production levels and increasing concentration in various surface aquifers. While several materials exhibit excellent capacity for the photocatalytic degradation of BPA, their powdered nature and poor chemical stability render them unsuitable for practical application in large-scale water decontamination. In this study, a new class of nanocomposite membranes based on sulfonated polyethersulfone (sPES) and multiwalled carbon nanotubes decorated with TiO₂ nanoparticles (MWCNTs-TiO₂) were investigated as efficient and scalable photocatalysts for the photodegradation of BPA in aqueous solutions. The MWCNTs-TiO₂ hybrid material was prepared through a facile and inexpensive hydrothermal method and extensively characterized by XRD, Raman, FTIR, BET, and TGA. Meanwhile, nanocomposite membranes at different filler loadings were prepared by a simple casting procedure. Swelling tests and PFG NMR analyses provided insights into the impact of filler introduction on membrane hydrophilicity and water molecular dynamics, whereas the effectiveness of the various photocatalysts in BPA removal was monitored using HPLC. Among the different MWCNTs-TiO₂ content nanocomposites, the one at 10 wt% loading (sP-MT₁₀) showed the best photoactivity. Under UV irradiation at 254 nm and 365 nm for 240 min, photocatalytic oxidation of 5 mg/L bisphenol A by sP-MT₁₀ resulted in 91% and 82% degradation, respectively. Both the effect of BPA concentration and the membrane regenerability were evaluated, revealing that the sP-MT₁₀ maintained its maximum BPA removal capability over more than 10 cycles. Our findings indicate that sP-MT nanocomposite membranes are versatile, scalable, efficient, and highly reusable photocatalysts for the degradation of BPA, as well as potentially for other endocrine disruptors. Full article

This study used a hybrid combination of kenaf and hemp fibers and the multi-walled carbon nanotube (MWCNT) reinforcements in the matrix phase to synthesize the composites. A kenaf/hemp fiber blend with MWCNTs in epoxy was used for the specific concentration. The procedure used three composite materials chosen from pilot trials. The ratio of MWCNT filler particles was altered up to the agglomeration limit based on initial trials. Two specimens (2 and 3) were supplemented with MWCNTs in a concentration range of 0.5 wt. % to 1 wt. %, with the fiber concentration being maintained in equilibrium with the epoxy resin, all of the materials were tested under the same conditions. The hybrid nanocomposite was characterized for its morphological and mechanical properties; the tensile properties were higher for 1% MWCNTs concentration (specimen 2), while the flexural properties were higher for 0.5% MWCNTs, with values of 43.24 MPa and 55.63 MPa, correspondingly. Once the MWCNT concentration was increased to 1 wt. %, the maximum impact strength was achieved (specimen 3). In the limits of the Shore-D scale, the kenaf fiber and hemp fiber matrix composite (specimen 1) gained a hardness index of 84. Scanning electron microscopy was carried out to analyze the morphological features of the fractured samples and to assess the adhesion between the fiber, matrix, and surface. Among the various fillers tested, the kenaf fiber/hemp/MWCNT composite (specimen 3) demonstrated superior binding and reduced the incidence of fiber pull-out, breakage, and voids. In addition to the comparative analysis, the addition of 0.5 wt. % MWCNTs resulted in better mechanical properties compared to the other two combinations. Full article

Novel ternary hybrid polyphenoxazine (PPOA)-derived nanocomposites involving Co-Fe particles and single-walled (SWCNTs) or multi-walled (MWCNTs) carbon nanotubes were prepared and investigated. An efficient one-pot method employing infrared (IR) heating enabled the formation of Co-Fe/CNT/PPOA nanocomposites. During this, the dehydrogenation of phenoxazine (POA) units led to the simultaneous reduction of metals by released hydrogen, yielding bimetallic Co-Fe particles with a size range from the nanoscale (5–30 nm) to the microscale (400–1400 nm). The synthesized Co-Fe/CNT/PPOA nanomaterials exhibited impressive thermal stability, demonstrating a half-weight loss at 640 °C and 563 °C in air for Co-Fe/SWCNT/PPOA and Co-Fe/MWCNT/PPOA, respectively. Although a slightly broader range of saturation magnetization values was obtained using MWCNTs, it was found that the type of carbon nanotube, whether an SWCNT (22.14–41.82 emu/g) or an MWCNT (20.93–44.33 emu/g), did not considerably affect the magnetic characteristics of the resulting nanomaterial. By contrast, saturation magnetization escalated with an increasing concentration of both cobalt and iron. These nanocomposites demonstrated a weak dependence of electrical conductivity on frequency. It is shown that the conductivity value for hybrid nanocomposites is higher compared to single-polymer materials and becomes higher with increasing CNT content. Full article