Search Results (2,274)

The integration of carbon nanomaterials with organic compounds offers a promising strategy for developing next-generation electrode materials with superior properties. A novel type of carbon paste electrode was fabricated by modifying a graphite matrix with functionalized multiwalled carbon nanotubes and juglone as a redox mediator, and then it was deposited by manual packing into a PEEK body (JUG-MWCNT/CPE). The surface morphology and structural parameters of the composite materials were meticulously characterized using scanning electron microscopy (SEM), nitrogen adsorption–desorption isotherms, and spectroscopic techniques, while their electrochemical properties were rigorously evaluated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). This study demonstrates that the synergistic interaction between the conductive nanotube network and the electroactive juglone significantly reduces the oxidation overpotential and enhances the peak current response of melatonin. Under optimized DPV parameters, the developed sensor presents outstanding analytical performance, featuring a wide linear response range from 0.002 to 0.16 mg L⁻¹, a low detection limit of 0.49 µg L⁻¹, excellent long-term signal stability for up to 30 days, and valid applicability for real-sample monitoring in commercial tablets and dietary supplements. Full article

Cement slurry is a staple grouting agent, yet its properties can weaken when exposed to heat. Studying grouting materials for use in high-temperature tunnels is therefore a matter of considerable importance. To enhance the applicability of cement-based slurry in high-temperature tunnels, multi-walled carbon nanotubes (MWCNTs), polycarboxylate ether superplasticizer (PCE), and hydroxypropyl methylcellulose (HPMC) were added to improve their performance at elevated temperatures. Various experimental methods were employed to investigate the properties of the modified slurry at different temperatures, including flowability, setting time, compressive strength, and dynamic water retention ratio. Additionally, X-ray diffraction (XRD), thermogravimetric analysis (TG), and scanning electron microscopy (SEM) were used to study the effects of temperature on hardened slurry. Experimental results indicate that the optimal MWCNTs content is 0.32%. At this content, the compressive strength of the hardened slurry after 28 days of curing at 80 °C increases by approximately 20%, reaching 26.4 MPa. PCE improves the fluidity of the slurry, while HPMC enhances its water dynamic water retention ratio. The optimal proportion was found to be 0.3% PCE and 0.2% HPMC. At this ratio, the fluidity of the slurry increased by about 8%, reaching approximately 17.7 cm; the dynamic water retention ratios of 0.8 m/s and 1.0 m/s improved by approximately 22% and 38%, respectively, achieving 35.8% and 18.1%. Furthermore, multi-walled carbon nanotubes significantly enhance the compressive strength of the hardened slurry primarily by suppressing the formation of ettringite during the later stages of hydration, as well as by providing nucleation sites, encapsulating hydration products, and bridging hydration product clusters within the microstructure. This investigation lays a theoretical groundwork for formulating and choosing grouting materials suited to high-temperature tunnel environments. Full article

In polymer selective laser sintering (SLS), powder acts as a support material during additive manufacturing, generating significant amounts of un-sintered powder exposed to prolonged thermal cycles. Although partial reuse with virgin powder is common practice, material degradation eventually renders the powder unsuitable for further SLS processing. This study investigates a sustainable approach for valorising SLS waste powder through its conversion into filament feedstock for fused filament fabrication (FFF). Polyamide 12 filaments containing 0, 2, 3, and 4 wt.% multi-walled carbon nanotubes (MWCNTs) were produced by twin-screw extrusion to tailor the electrical conductivity of the polymer matrix. The filaments were processed by FFF to manufacture specimens for thermal, mechanical, and electrical characterization. Differential scanning calorimetry revealed the influence of reprocessing on the thermal behaviour of the reused material and resulting filaments, while thermogravimetric analysis demonstrated improved thermal stability with increasing MWCNT content. Tensile testing showed increased Young’s modulus (up to 9.4%), despite an initial drop, and tensile stress at break (up to 56.3%) with increasing nanofiller concentration. In addition, distinct electrostatic-discharge (ESD) protection ranges were achieved depending on the MWCNT loading. The results demonstrate the potential of reused SLS powder as a sustainable feedstock for functional AM materials suitable for ESD-sensitive applications. Full article

Composite materials based on humic acids and multi-walled carbon nanotubes were synthesized using ultrasonic-enhanced co-precipitation. The effect of ultrasonic treatment duration on the structure and adsorption properties of the composite materials with respect to phenol was studied. The structural and functional characteristics of the materials were investigated using elemental analysis, FTIR spectroscopy, SEM, TGA/DTA, and determination of the content of oxygen-containing functional groups. It was found that the Σ(COOH+OH) values for the studied composites are in the range of 3.00–4.45 mmol/g. The highest value of this indicator was observed for the HA:MWCNTs-20 (US = 30 min) composite. The results of physicochemical studies show that the ultrasonic treatment duration has a significant effect on the morphological, functional, and thermal characteristics of the composites. Adsorption properties were studied in the phenol concentration range of 0.5–15 mg/dm³. It was shown that the HA:MWCNTs-20 (US = 30 min) composite exhibited the highest adsorption capacity for phenol among the studied samples. Analysis of adsorption isotherms revealed that the experimental data were most satisfactorily described by the Langmuir model (r = 0.996–0.999), while the kinetic data were best described by the pseudo-second-order model. These results demonstrate the potential of HA:MWCNTs composites as sorption materials for extracting phenol from aqueous solutions. Full article

Aiming to develop high-performance flexible electrode materials for dielectric elastomer actuation systems applied to micro-crawling robots, this study proposes multi-dimensional filler composite electrode materials with a methyl vinyl silicone rubber matrix. Three types of conductive fillers—namely, zero-dimensional super-conductive carbon black, one-dimensional single-walled carbon nanotubes, and two-dimensional flaky micron-sized silver powder—were employed to construct a hierarchical multi-dimensional conductive network within the silicone rubber matrix via a three-stage fabrication strategy. The electrical conductivity and conductive stability of the as-prepared composite electrode materials were systematically investigated, where the intrinsic mechanisms and evolutionary laws of material electrical performance variations were analyzed. Furthermore, the effects of fillers with different dimensional morphologies on the comprehensive properties of the composites at each fabrication stage were explored, and the optimal filler dosage for each component was determined. Microstructural observations of the staged conductive network formation further verified the rationality of the stage-based functional design model. The optimized composite electrode delivers an initial electrical conductivity of 1.5 × 10⁴ S/m, with only a 14.9% conductivity attenuation under 50% tensile strain, demonstrating excellent electromechanical stability. Moreover, a prototype micro-crawling robot was fabricated using the optimized composite electrode, achieving a maximum linear crawling speed of 8 mm/s. These experimental results validate the feasibility and superiority of the proposed multi-dimensional filler composite strategy. This work provides a novel technical approach for the design and development of high-performance flexible electrode materials for flexible electronic and micro-robotic actuation applications. Full article

Hybrid conductive materials have attracted increasing attention due to their combined electrical conductivity, mechanical flexibility, and sustainability. In this work, new hybrid materials based on polyaniline (PANI)-wrapped multi-walled carbon nanotubes (MWCNTs) and microfibrous cellulosic substrates were developed and assessed for photocatalytic degradation of a model dye pollutant. First, in situ oxidative polymerization of aniline in formic acid (FA) was conducted in the presence of MWCNTs to afford stable dispersions of carboxylated polyaniline-wrapped carbon nanotubes (c-PANI/MWCNTs). Next, the dispersions were used for affordable impregnation of microfibrous cellulosic filter paper. The influence of the initiator type—potassium peroxodisulfate (KPS) and hydrogen peroxide—on polymer–nanotube interactions, stabilization and surface deposition was emphasized. The structural, surface, morphological and thermal properties of the obtained dispersions and cellulose nanocomposites were systematically investigated using Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and thermal gravimetric analysis. The results revealed strong interfacial interactions between c-PANI and the pristine MWCNTs, resulting in improved dispersion stability and effective and even surface deposition of the conductive c-PANI/MWCNT hybrids into the cellulose fiber mesh. The photocatalytic degradation of 5 ppm methylene blue (MB) dye in the presence of the developed nanocomposite materials under UV-A illumination was studied. The results showed that the c-PANI@MWCNT-impregnated cellulose substrates exhibited enhanced photocatalytic ability (up to 83% degree of degradation of MB dye) in comparison with the pure c-PANI. Full article

Polyethylene (PE) fibers are promising reinforcements for engineered cementitious composites (ECC); however, their highly hydrophobic nature and inherent chemical inertness limit their reinforcing effectiveness. This study investigated the use of different types of multi-walled carbon nanotubes (MWCNTs) to modify PE fibers under varying immersion times. Microstructural characterizations were conducted to investigate the effects of MWCNTs type and immersion time on the surface properties of PE fibers, while mechanical testing was undertaken to evaluate the mechanical performance of the resulting fiber-reinforced cementitious composites. MWCNTs were found to form a uniform coating on the surface of the reinforced PE fibers, resulting in a reduction in water contact angle from 164.2° to 118.4° and an increase in oxygen contents by 242.27%. With increasing immersion time, the single-fiber pull-out strength improved by up to 40.48%, with an optimal modification duration of 8 h. The MWCNTs modified PE fibers were found to increase the 28-day uniaxial tensile strength and three-point bending strength of the cementitious composites by up to 16.17% and 6.96%, respectively, while exhibiting negligible effects on compressive strength. This study implies that MWCNTs can effectively enhance surface wettability and mitigate surface inertness of PE fibers, thereby enhancing the overall performance of ECC. Full article

Enhancing the mechanical performance of aluminium-based materials remains a critical challenge for their application in demanding environments. In this context, aluminium-based hybrid nanocomposites reinforced with multi-walled carbon nanotubes (MWCNTs) and nano-sized silicon carbide (nSiC) have been developed to overcome inherent limitations of pure aluminium, such as relatively low hardness, limited compressive strength and poor wear resistance. The composites were fabricated via powder metallurgy by incorporating a fixed 1 wt.% MWCNT content along with varying nSiC additions in the range of 0–4 wt.%, enabling a systematic evaluation of the effect of hybrid reinforcement on the overall material properties. Compared to pure aluminium, the composites exhibited significant improvements in mechanical and tribological properties, with the Al–1 wt.% MWCNT–4 wt.% nSiC composition showing the highest enhancement, achieving increases of ~149% in hardness and ~45% in compressive strength. Microstructural analysis revealed strong matrix–reinforcement bonding, notable grain refinement, and a largely uniform reinforcement distribution, with minor agglomeration at higher nSiC content. The hybrid nanocomposites also demonstrated superior wear resistance, while fractography indicated a transition from ductile fracture in pure aluminium to a mixed intergranular–transgranular mode, promoting effective load transfer and improved performance. Full article

This study aims to develop sustainable conductive nanocomposites based on poly(lactic acid) (PLA)/poly(ε-caprolactone) (PCL) blends reinforced with multi-walled carbon nanotubes (MWCNT) and graphene nanoplatelets (G), focusing on their multifunctional performance. The novelty lies in the production of hybrid nanocomposites based on PLA/PCL blends with MWCNT/G using conventional industrial processing techniques, enabling the development of eco-friendly nanocomposites with tailored electrical, mechanical, and electromagnetic properties. The nanocomposites were prepared by twin-screw extrusion followed by injection molding. Rheological, scanning electron microscopy (SEM), mechanical, thermal, thermomechanical, electrical conductivity, and electromagnetic shielding properties were systematically evaluated. From a rheological perspective, the PLA/PCL/MWCNT and PLA/PCL/MWCNT/G nanocomposites exhibited a plateau at low frequencies, associated with the formation of a percolated network. This was confirmed by the significant increase in electrical conductivity and electromagnetic shielding response. The morphology observed by SEM showed a refinement of the PCL phase in the PLA matrix with the incorporation of MWCNT. The PLA/PCL/MWCNT/G (4/2 parts per hundred resin, phr) nanocomposite showed a 309% increase in impact strength compared to neat PLA, while maintaining the heat deflection temperature (HDT). The elastic modulus exceeded 2300 MPa and accelerated the crystallization process by more than 15 °C compared to PLA, which makes it important to reduce injection molding time. Additionally, it exhibited the highest electrical conductivity level, around 6.79 × 10⁻⁵ S/cm, which resulted in improved electromagnetic shielding performance in the 8.2–18 GHz range, highlighting the synergistic effect between 1D and 2D fillers. The developed PLA/PCL/MWCNT and PLA/PCL/MWCNT/G nanocomposites demonstrate potential for antistatic applications, combining sustainability with multifunctional performance and industrial scalability. Full article

The use of hydrolytic enzymes is one of the most promising methods for combating bacterial biofilms. However, the use of native enzymes is limited by the rapid loss of activity under unfavorable conditions. Immobilization of enzymes on carbon nanoparticles enhances their stability, allows for biocatalyst reuse, and creates a synergistic effect due to the intrinsic antimicrobial properties of the nanomaterials. The aim of this investigation was to create and comparatively analyze conjugates of acid and alkaline proteases with carboxylated multiwalled carbon nanotubes (MWCNTs-COOH) and to assess their effect on the formation and destruction of E. coli VKM B-3858D biofilms. The immobilization efficiency and kinetics of enzyme adsorption on the support were quantified by determining the protein concentration using the Bradford assay. The morphology and dispersion of the resulting conjugates were analyzed using atomic force microscopy (AFM). Protease activity was determined by a modified Anson method using the Folin–Ciocalteu reagent. Biofilm biomass was determined using crystal violet staining. The binding efficiency of the acid protease to MWCNTs-COOH was shown to reach 93%, which is significantly higher than that of the alkaline protease. The highest degree of immobilization was observed at a protein concentration of 117–338 μg/mL (10–20 mg/mL of the enzyme preparations). The interaction of the acid protease with the carbon nanoparticles increased dispersion, reducing the size of aggregates from ~1 μm to ~68 nm. As a result, acid protease conjugates with MWCNTs-COOH significantly reduced the biofilm biomass compared to both the enzyme-free control and the native enzyme. Alkaline protease, unlike the acid protease, destroys mature biofilms, and immobilization on MWCNTs-COOH enhances this ability. Native alkaline protease and acid protease conjugates with MWCNTs-COOH are effective in combating the biofilm formation of Gram-negative bacteria, while alkaline protease conjugates are suitable for disrupting mature biofilms. Full article

Carbon nanotubes (CNT) are among the strongest candidates for electromagnetic interference (EMI) shielding materials because of their excellent performance. However, when assembled into macroscale materials, their conductivity is usually limited to 10⁴ S/m, restricting further application as shielding materials. Here, we prepared a carbon nanotube composite film (Au/Cl-CNT) with high conductivity and excellent EMI properties. Characterizations confirm that Au exists in the form of uniform Au plates and particles anchored on the CNT surface, while Cl is doped into the CNT framework as halogen dopants. The optimized Au/Cl-CNT film delivers an ultra-high electrical conductivity of 3.39 × 10⁵ S/m, which is approximately 23 times higher than that of the pristine CNT film. The excellent electrical properties of the Au/Cl-CNT films endow them with excellent EMI shielding effectiveness (SE). Au/Cl-CNT films with a thickness of ~10.5 μm achieve an EMI SE of up to 67 dB across both the X-band and Ku-band. The superior EMI SE mainly results from the combined effect of various mechanisms, namely reflection inside and outside the material, as well as absorption inside the material. This work clarifies the synergistic enhancement mechanism of Au and Cl on CNT conductivity and EMI shielding, offering new insights into halogen-modified shielding materials. Full article

The performance and durability of asphalt pavements are strongly influenced by the rheological properties of asphalt binders, particularly under severe climatic and traffic conditions. This study investigates the synergistic effects of incorporating multi-walled carbon nanotubes (CNTs) at dosages ranging from 0.25% to 1% into AC 40-50 asphalt binders modified with 4% Styrene–Butadiene–Styrene (SBS). A comprehensive experimental program involving physical, rheological, and chemical characterization tests was conducted, including penetration, softening point, viscosity, storage stability, a Dynamic Shear Rheometer (DSR), Multiple Stress Creep Recovery (MSCR), Linear Amplitude Sweep (LAS), Fourier Transform Infrared Spectroscopy (FTIR), and Glover-Rowe (G-R) analysis. Statistical inference using one-way ANOVA was also conducted to evaluate the significance of differences among the binder formulations investigated. The results showed a continuous increase in binder stiffness with increasing CNT content, as indicated by decreasing penetration values, higher softening points, and increased viscosity. Incorporating 1% CNT reduced the softening-point difference from 3.1 °C to 1.6 °C in SBS-modified binders, indicating improved storage stability. Rheological evaluations showed that 0.75% CNT increased the high-temperature performance grade from 82 °C to 88 °C and provided the best rutting resistance, as indicated by MSCR results. In contrast, the 0.5% CNT formulation exhibited superior fatigue resistance and the lowest Glover-Rowe index, indicating improved cracking resistance and durability. Overall, the findings demonstrate that CNTs can effectively enhance the performance of SBS-modified asphalt binders, with 0.75% CNT being optimal for hot-climate applications, while 0.5% CNT exhibited improved fatigue and cracking resistance under moderate-temperature conditions. Full article

To address the severe wear and galvanic corrosion of TC4/Mg three-dimensional interpenetrating composites caused by the potential difference and hardness disparity between the two phases, this work proposes a hybrid surface modification strategy combining plasma electrolytic oxidation (PEO) with a self-assembled monolayer (SAM) doped with multi-walled carbon nanotubes (MWCNTs). A PEO ceramic coating was first grown in situ on the composite surface, followed by sealing modification using MWCNTs-containing SAM. The microstructure, phase composition, tribological behavior and potentiodynamic polarization curves of the coatings were systematically evaluated. The results show that the PEO coating is mainly composed of Mg₂SiO₄, MgO, MgF₂ and TiO₂, exhibiting a typical porous structure. After the MWCNTs-doped SAM composite modification, the nano-fillers and the molecular layer synergistically seal the micropores and cracks, and the surface transforms into a continuous and dense layered morphology. Wear tests reveal that the composite coating reduces the friction coefficient to 0.195 and decreases the wear volume by 93.53% compared with the bare composite. The “micro-roller bearing” effect and debris adsorption of MWCNTs significantly improve the wear resistance, and the dominant wear mechanism changes from abrasive wear to three-body wear. Electrochemical measurements show that the corrosion current density of the composite coating decreases from 2 × 10⁻⁴ A·cm⁻² (bare composite) to 1.401 × 10⁻⁹ A·cm⁻², i.e., a reduction by five orders of magnitude, with a protection efficiency of 99.99%. This is attributed to the physical barrier effect of the PEO coating and the synergistic sealing of defects, as well as the blocking of electron transfer by MWCNTs/SAM. The multi-level protection system of “PEO + MWCNTs + SAM” constructed in this work achieves a synergistic improvement in both wear resistance and corrosion resistance of the TC4/Mg two-phase interpenetrating composite, and holds promise for further investigation as an osseointegration implant material. Full article

The present study investigated the effect of a 3D-printed nanocomposite scaffold on bone healing in vivo. The scaffolds used were made from the bioresorbable thermoplastic polycaprolactone polymer, blended with Multi-Walled Carbon Nanotubes functionalized with chitosan, and manufactured with a rectilinear infill pattern and interconnected pores of 500 μm in size. The study included three groups of 10 Wistar rats, in which a 2 mm bone defect was created in the middle of the right femur. In the scaffold/peptide group, the gap was filled with the scaffold loaded with a peptide corresponding to human pleiotrophin amino acids 48-56 (PTN_48-56), and the fracture was stabilized with a 12 mm K-wire as an intramedullary nail. In the scaffold group, the scaffold did not contain the peptide, and in the control group, the bone defect was stabilized without the use of a scaffold. Radiological examination revealed that bone healing was achieved on average in 6.6 weeks in the scaffold/peptide group, 7.2 weeks in the scaffold group, and 8.1 weeks in the control group. Histopathological examination performed 2 weeks postoperatively showed that angiogenesis in the scaffold/peptide group was 1.5 times higher than in the scaffold group and 2.5 times higher than in the control group. In conclusion, our osteo-inductive 3D-printed scaffold covered with PTN_48-56 is a promising option for accelerating bone defect healing. Full article

The rapid advancement of microelectronic packaging has created a critical need for lead-free solder joints with enhanced mechanical and thermal reliability. This study introduces a novel approach to improve Sn-3.0Ag-0.5Cu (SAC 305) solder joints by incorporating Sn-decorated multiwalled carbon nanotubes (MWCNTs). To address the poor wettability and agglomeration of carbon nanotubes in molten solder, MWCNTs were functionalized and uniformly coated with ~70 nm Sn nanoparticles via electroless plating. Soldering was conducted using intense pulsed light (IPL), a rapid, energy-efficient heat source, and was compared with conventional reflow soldering. The study systematically investigated the influence of MWCNT content (0, 0.05, 0.1, and 0.2 wt.%) and IPL soldering conditions with pulse numbers: 27–36 for shear tests, and 30–42 for drop impact tests. IPL processing produced thinner Cu₆Sn₅ IMC layers than reflow soldering due to its shorter duration. The composite solder with 0.1 wt.% Sn-decorated MWCNTs achieved the highest density, superior thermal dissipation in LED packages, and maximum shear strength and drop impact resistance. These results demonstrate that optimizing Sn-MWCNT content, especially at 0.1 wt.%, and precisely controlling IPL energy can yield highly reliable, mechanically robust, and thermally efficient lead-free solder joints for advanced electronic packaging. Full article