Multi-walled Carbon Nanotubes Content Research Articles

PH‐Tunable 3D Interconnected Network of Multiwalled Carbon Nanotubes /Polyacrylic Acid Hydrogel with Excellent Electromagnetic Radiation Shielding Capability

AbstractThe fabrication of durable and high anticorrosion hydrogel composite materials composed of multi‐walled carbon nanotubes (MCNTs) and crosslinked polyacrylic acid (PAA) for EMI shielding application is reported. The MCNTs contribute to the generation of 3D porous structures and enhance the mechanical properties of composite hydrogel. The 3D porous structure and high electrical conductivity inherited from ultrahigh electrically conductive MCNTs enable excellent EMI shielding properties with a total shielding efficiency EMI SE (SET) value of 32.8 dB (>99.9%) at only 3 wt% filler content of MCNTs. The MCNTs/PAA hydrogels also display superior EMI shielding performance under a strong acidic environment with SET > 99.99% while the 3D porous structure remained intact. The combination of electron–ion system in pH solution enriches the charge transfer and accumulation, enabling dipole orientation and polarization that are favorable for enhancing EMI attenuation. Moreover, the porous structure of MCNTs/PAA also contributes to partial trapping and dissipation of EM radiation energy via multiple scattering phenomena. This work thus paves the way toward applications of 3D hierarchical network materials for EMI shielding applications in both land and aqueous environments.

Construction of multi-functional silicone rubber/reduced graphene oxide/multi-walled carbon nanotube composites with segregated structure by surfactant-free Pickering emulsion method

Polymer composites with segregated structure (PC–S) have the advantages of low filler usage and excellent functionality. Emulsion blending combined with direct molding technology is the main method for the preparation of PC-S. However, due to the high fluidity of low-viscosity silicone rubber (SR), PC-S cannot be prepared by this technique. In addition, surfactants affect the heat resistance of the final SR composites (SRC). In order to solve the above problems, in this study, a Pickering emulsification combined with pre-crosslinking technology for SR was successfully developed by using graphene oxides (GO)/multi-walled carbon nanotubes (MWCNTs) hybrid fillers (GM) as emulsifiers, and SR/reduced GO (RGO)/MWCNTs composites with segregated structure (SSGM) were prepared. When RGO content is 4.5 wt%, MWCNTs content is 3.2 wt%, SSGM shows the highest electrical conductivity of 12.5 S/m, the highest electromagnetic interference shielding efficiency (EMI SE) of 41.4 dB, and an excellent flame retardant performance. The whole preparation process avoids the use of organic solvents and surfactants, which reduces the production cost of SSGM and the environmental pollution, and provides a feasible preparation route for the industrialized production of SSGM.

Energy harvesting by car-tire using piezoelectric polymer films blended with carbon-nanotubes

Energy harvesting through harnessing mobile cars is possible by combining mechanicals systems with advanced materials. Piezoelectric polymer blends with excellent mechanical properties facilitate energy harvesting using the car-tire as a source. Furthermore, by adding simplicity of preparation to the blends with multi-walled carbon nanotubes (MWCNT), an increase of energy conversion can lead to improved existing polyvinylidene fluoride/polymethylmethacrylate (PVDF/PMMA), films. This work focuses on investigating the best concentration of MWCNT to achieve car-tire energy harvesting as a sustainable and renewable energy option. The results show that 0.05 wt% of MWCNT is the best concentration among several values. A test set-up applying normal stress, simulating car-tire deformation indicated enhanced voltage generation. Compared to the energy consumption of combustion cars, the enriched films generate up to 4.3kWh. This energy is harvested over a car trip of 100 km. A higher nanotube concentration caused saturation of the blend film and poor output. The novel enriched polymer must be tested for resisting cyclic loads to encourage sustainable energy harvesting using car tires.

Effect of Hybrid Nanofillers on the Mechanical Characteristics of Polymethyl Methacrylate Denture Base Composite

The research study focused on enhancing the mechanical characteristics of polymethyl methacrylate (PMMA) denture bases. PMMA is commonly used in dentistry due to its easy fabrication, cost-effectiveness, and favourable physical properties. However, its limitations include low wear resistance, hardness, and mechanical strength, making it less suitable for long-term dental applications. To address these limitations, the study employed a combination of hybrid nano-fillers, specifically HNTs (halloysite nanotubes) and MWCNTs (multi-walled carbon nanotubes), at varying loading levels to improve the mechanical characteristics of the PMMA composite. These nano-fillers underwent treatment by using a coupling agent to enhance their compatibility with PMMA. Key findings of the research include that introducing HNTs/MWCNTs into the PMMA matrix led to a substantial increase in flexural strength, with a significant improvement of 109.1 MPa compared to unfilled PMMA. This indicates that the composite material became more resistant to bending or deformation. There was a substantial rise in flexural modulus values, suggesting improved stiffness in the nanocomposite compared to unfilled PMMA. In addition, the tensile strength of the PMMA composite increased by 64.4 MPa with the addition of the hybrid nano-fillers, indicating enhanced resistance to stretching or pulling forces. The study found that the improvement in flexural and tensile strength was dependent on the concentration of MWCNTs. Increasing the MWCNT concentration up to 0.75 wt.% led to improved mechanical properties, but further increases resulted in a reduction in PMMA properties. Although there was a modest improvement in Vickers hardness (approximately 18.93 kg/mm<sup>2</sup>), the addition of HNTs/MWCNTs as hybrid nano-fillers effectively enhanced the properties of the PMMA nanocomposite. The study concludes that incorporating hybrid nano-fillers into PMMA could contribute to the longevity and durability of dental composites, addressing some of the material's inherent limitations. The specific combination and concentration of nano-fillers played a crucial role in determining the mechanical properties of the resulting nanocomposite.

Influence of Twin Screw Extrusion Conditions on MWCNT Length and Dispersion and Resulting Electrical and Mechanical Properties of Polycarbonate Composites

The processing conditions were varied during the production of polycarbonate-based composites with the multiwalled carbon nanotubes (MWCNTs) Baytubes® C150 P (Bayer MaterialScience AG, Leverkusen, Germany), by melt mixing with an extruder on a laboratory scale. These included the screw design, rotation speed, throughput, feeding position and MWCNT content. Particular attention was paid to the shortening of the MWCNT length as a function of the conditions mentioned. It was found that there is a correlation between the applied specific mechanical energy (SME) during the melt mixing process and MWCNT dispersion, which was quantified by the agglomerate area ratio of the non-dispersed nanotubes based on optical microscopic analysis. The higher the SME value, the lower this ratio, which indicates better dispersion. Above an SME value of about 0.4 kWh/kg, no further improvement in dispersion was achieved. The MWCNT length, as measured by the quantitative analysis of TEM images of the MWCNTs dissolved from the composites, decreased with the SME value down to values of 44% of the original MWCNT length. At a constant loading of 3 wt.%, the tensile strength and tensile modulus were almost independent of the SME, while the elongation at break and notched impact strength showed an increasing trend. The variation in the feeding position showed that feeding the MWCNTs into a side feeder led to slightly better electrical and mechanical properties for both types of MWCNTs studied (Baytubes® C150 P and Nanocyl™ NC7000 (Nanocyl S.A., Sambreville, Belgium)). However, feeding into the hopper led to better CNT dispersion with Baytubes® C150 P, while this was the case with Nanocyl™ NC7000 when feeding into the side feeder. The screw profile had an influence on the dispersion, the MWCNT length and the electrical resistance, but only to a small extent. Distributive screws led to a greater shortening of the MWCNT length than dispersive screws. By varying the MWCNT content, it was shown that a greater MWCNT shortening occurred at higher loadings. Two-stage masterbatch dilution leads to stronger shortening than composite production with direct MWCNT incorporation.

Electrical and piezoresistive properties of ultra-high toughness cementitious composite incorporating multi-walled carbon nanotubes: Testing, analyzing, and phenomenological modeling

This study explores the electrical and piezoresistive properties of ultra-high toughness cementitious composites (UHTCC) enhanced with multi-walled carbon nanotubes (MWCNTs) ranging from 0 to 1 wt% of cementitious binders. The observed polarization behavior is found to be analogous to the charging process of a capacitor. The polarization process and resistivity drift over time in the piezoresistive response are explained using an existing equivalent electrical circuit model incorporating a capacitor. The average results of electrical conductivity initially decrease and subsequently increase with higher MWCNTs concentrations, a phenomenon attributed to increased porosity and reduced matrix conductivity. The percolation threshold is identified at a volume fraction of 0.00387. Notably, even in the absence of MWCNTs, UHTCC materials exhibit piezoresistive properties due to the presence of metal impurities and ionic compounds. The insufficient polarization process results in an increasing trend in fractional change in resistance (FCR). The highest FCR sensitivity to external load occurs within the percolation threshold. Additionally, three equations are proposed to calculate electrical conductivity, incorporating the effects of interfaces, porosity, and matrix conductivity reduction, which align well with the experimental findings. These insights contribute to a deeper understanding of the electrical properties of UHTCC-MWCNTs composites, enabling more precise conductivity measurements and improved sensor sensitivity.

Combined toxicity of multiwall carbon nanotubes and cadmium on rice (Oryza sativa L.) growth in soil

The comprehensive effects of nanoparticles and coexisting heavy metals on plant growth are still unclear, especially in soil medium. The single and combined effects of multiwall carbon nanotubes (MWCNTs) and cadmium (Cd) on rice (Oryza sativa L.) growth were examined in this study through a 4 months pot experiment in 2022. Rice plants were exposed to different concentrations of MWCNTs (100 and 500 mg kg−1) in the presence of 5.0 mg kg−1 Cd stress. At the tillering stage, the 500 mg kg−1 MWCNTs addition reduced plant height by 8.0% and increased soluble protein content in the leaves by 13.7%, demonstrating that a single MWCNTs had a slight negative impact on rice growth. When exposed to Cd stress, the inclusion of 500 mg kg−1 MWCNTs led to a 6.7%–9.0% decrease in bioavailable Cd level in soil, resulting in considerable reductions in Cd content in roots (23.4%–29.9%), shoots (24.5%–28.3%) and grains (28.3%–66.2%). Compared to the single Cd treatment, the O. sativa L. leaves treated with Cd and MWCNTs (500 mg kg−1) had considerably reduced levels of malondialdehyde (MDA), soluble protein, and activities of antioxidant enzymes (POD, CAT, and SOD). The findings of this study indicated that appropriate concentrations of MWCNTs application in soil could alleviate Cd-induced toxicity on rice growth.

Engineering bioactive MWCNT-reinforced hydroxyapatite coatings on Ti29Nb5Zr alloy by plasma electrolytic oxidation method: A comprehensive approach to dental implant surface optimization

Titanium-niobium-zirconium (TiNbZr) alloys represent a promising class of newly developed titanium-based biomaterials, engineered to exhibit superior properties for biomedical applications. This study investigates the influence of hydroxylated multi-walled carbon nanotubes (MWCNTs) on the surface properties of hydroxyapatite coatings prepared by the plasma electrolytic oxidation (PEO) method for implant applications. The optimal concentration of MWCNTs in the PEO coating was determined based on the superior surface, electrochemical, and biological properties obtained. The incorporation of MWCNTs led to an enhancement in surface roughness from Ra 0.06 ± 0.02 to Ra 0.618 ± 0.03 µm, improved wettability with a decrease in contact angle from 63.03° ± 1.1–28.29° ± 0.07, and a reduction in elastic modulus from 77.20 ± 2.26 GPa to 54.50 ± 2.22 GPa. Furthermore, electrochemical corrosion resistance analysis revealed an increase in inner passivation resistance up to 2.24 × 10 ×7 Ω.cm2 with the addition of MWCNTs. Antibacterial activity analysis demonstrated that the optimal concentration of MWCNTs resulted in a 3.1-fold and 2.7-fold reduction in E. coli and S. aureus bacteria, respectively, compared to uncoated samples. Cell viability against MC3T3-E1 cells showed a 25 % higher viability with MWCNTs than uncoated substrates.

Influence of the Dispersion of Carbon Nanotubes on the Electrical Conductivity, Adhesion Strength, and Corrosion Resistance of Waterborne Polyurethane Composites

Due to the presence of many flammable substances in the working environments of the petrochemical industry, anticorrosive conductive coatings need to be used on metal equipment to avoid safety accidents like fires. However, existing conductive solvent-based coatings are volatile when exposed to flammable and toxic organic solvents. Thus, in this work, a series of eco-friendly anticorrosive waterborne polyurethane (WPU) composites with multi-walled carbon nanotubes (MWCNTs) were prepared via a low-cost and practical process; the dispersion of MWCNTs was revealed when present in different amounts, and the mechanism behind the conduction of WPU composites was determined. We concluded that low amounts of MWCNTs were well dispersed, generating a conductive network, and the WPU composite was not entirely covered by the MWCNT particles, so the electrical conductivity in certain parts of the coating was good. When the content of MWCNTs was excessive, some stretched MWCNTs dispersed to the top of the composite and many MWCNTs agglomerated at the bottom. Additionally, when the content of MWCNTs was increased, the electrical conductivity, corrosion resistance, and adhesion strength of the WPU composite decreased. Our results could provide a theoretical foundation for the preparation of anticorrosive conductive waterborne composites for protecting equipment in the petrochemical industry.

Thermal, electrical, and mechanical performances of ultrahigh-performance cementitious composites with multiwalled carbon nanotubes

This study examines the influence of multiwalled carbon nanotubes (MWCNTs) on cementitious composites, specifically focusing on the fabrication of multifunctional cementitious composites known as ultrahigh-performance cementitious (UHPC) composites. Key properties such as compressive strength, thermal performance, and electrical resistance were examined with varying MWCNT contents, curing methods, curing duration, and supply voltage. The effects of the incorporation of MWCNTs on the hydration reactions of the cementitious composites were analyzed using field-emission scanning electron microscopy, thermogravimetric analysis, and X-ray diffraction. The study revealed that MWCNT UHPC composites can achieve a maximum ultrahigh strength of 120.8 MPa. Additionally, the incorporation of MWCNTs enabled the composites to reach a maximum surface temperature of 90.6 °C during heating. Furthermore, the power consumption of MWCNT UHPC composites was found to be predictable based on the curing type and the duration of curing. Notably, the hydration reactions in MWCNT UHPC composites remained unaffected by the MWCNT content. The findings emphasize the potential of multifunctional MWCNT UHPC composites by offering exceptional strength, heating capabilities, and electrical performance in construction materials.

Toxic effects of multi-walled carbon nanotubes and ZnO nanoparticle exposure on pathology and apoptosis on the liver of Cyprinus carpio

ZnO nanoparticles (ZnONPs) and carbon nanotubes (CNTs) are frequently used nanoparticles with unique features. Aquatic organisms are exposed to a combination of contaminants in natural water systems, so the combination effect of two or more nanomaterials has caused much concern. In this study, the toxicity to the liver of common carp was explored under four weeks of exposure to single ZnONPs or in combination with multi-walled CNTs (MWCNTs). The results demonstrated that ZnONPs induced pathological changes and apoptosis in the liver. In combination, decreased pathological changes were observed in the LSC-ZnONPs group (50 mg L-1 ZnONPs and 0.25 mg L-1 MWCNTs) at the microscopic level and ultrastructural level, and increased pathological changes in the HSC-ZnONPs group (50 mg L-1 ZnONPs and 2.5 mg L-1 MWCNTs). A 52% reduction in the percentage of TUNEL-positive nuclei in the LSC-ZnONPs group and a 33% increase in the HSC-ZnONPs group were observed compared to the ZnONPs group. The mRNA expression of apoptosis-related genes, including caspase3, BAX, and XBP1, were significantly up-regulated in the exposure groups, confirming the occurrence of apoptosis. Significantly decreased caspase 3 and BAX mRNA levels in the co-exposure groups were detected compared to the ZnONPs group. Nevertheless, the XBP1 mRNA level was significantly upregulated in the LSC-ZnONPs group, but downregulated in the HSC-ZnONPs group, indicating multiple signal pathways involved in the apoptosis. In conclusion, a low concentration of MWCNTs (0.25 mg L-1) decreased the toxic effect of ZnONPs on common carp, but a high concentration of MWCNTs (2.5 mg L-1) enhanced it. This study will contribute to developing future risk assessment and management strategies for nanomaterials.

Failure investigation of woven scarf-repaired laminates reinforced with nanoparticles: Experimental and numerical investigations

This study explores the efficacy of multi-walled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) as nano-reinforcement for the epoxy adhesive layer in scarf joints and 3D scarf-repaired laminates subjected to tensile loading. Experimental characterization of pure epoxy and nanocomposite mechanical properties was validated using the Mori–Tanaka method (incorporating agglomeration effects). A 3D finite element model considering material non-linearity and strain-based damage was employed to investigate joint failure behaviour, validated for 0.5 vol% MWCNT and GNP concentrations. A subsequent parametric study explored the influence of scarf angle, nanoparticle concentration, and patch configuration on 3D repaired specimens. The results suggest a 2.86° scarf angle with a [(+45/−45)]4s patch configuration reinforced with 1 vol% MWCNTs and 0.5 vol% GNPs exhibits the highest tensile strength improvement.

Influence of NR/MWCNT Blending on Rotor Metal Friction and Wear during Mixing Process.

Mixing involves blending raw rubber or masticated rubber with additives using a rubber mixer, which is the most critical process in rubber production. The internal mixer, as the most important mixing equipment, experiences rotor wear during prolonged operation, affecting the gap between the mixer rotor and the chamber wall. This wear reduces mixing effectiveness, weakens filler dispersion, and ultimately impacts rubber performance. In recent years, as research on multi-walled carbon nanotubes (MWCNTs) and nanomaterials has deepened, their broad application prospects have become increasingly apparent. The objective of the present study is to understand and quantify rotor wear in rubber blends during the mixing process as influenced by multi-walled carbon nanotubes. This study found that with the increase in MWCNT content, the proportion of abrasive wear rises, while the proportion of corrosive wear decreases, leading to reduced overall wear. Compared to rubber without MWCNTs, the Payne effect decreased by 6.78%, 9.57%, 13.03%, 20.48%, and 26.06% with the addition of 1 phr, 3 phr, 5 phr, 7 phr, and 9 phr of MWCNTs, respectively. The friction coefficients between the rubber and metal increased by 6.31%, 8.57%, 25.43%, 39.31%, and 47.61%, while the metal wear rate decreased by 9.08%, 10.73%, 13.41%, 17.46%, and 25%. Conversely, the friction coefficients were reduced by 19.39%, 22.42%, 33.94%, 66.06%, and 76.36%.

Collagen composite fibers with various functionalized carbon nanotubes fabricated via microfluidic spinning

AbstractCollagen (Col) composite fibers containing various functionalized multiwalled carbon nanotubes (MWNTs) were prepared via microfluidic spinning, and the influences of MWNT content and type on the performances of the composite fibers were investigated by transmission electron microscope, UV–vis, SEM, Fourier Transform Infrared Spectrometer, differential scanning calorimetry, X‐ray diffraction, and tensile testing. The Col composite fibers showed tightly packed bundle structures on surfaces originated from the high shear rates in the microfluidic channels, and MWNT facilitates the self‐assembly of Col molecules, leading to the ordered arrangement of Col fibrils along the fiber axis. When the loading of carboxylated MWNT (cMWNT) was 0.5 wt%, the tensile strength of Col/cMWNT achieved the maximum of 1.94 cN/dtex owing to the excellent hydrogen bond and electrostatic interactions between the carboxyl groups in cMWNT and amino groups in Col molecules, which is significantly higher than those composite fibers made from unfunctionalized and hydroxylated MWNT. Moreover, with the incorporation of MWNT the thermal stability and water resistance of Col fibers were improved due to the enhanced interfacial interactions between Col and MWNT. The fabrication method in this work enables the controlled formation of Col fibers and demonstrates huge potential for use in Col‐based biomaterials.Highlights Novel collagen (Col)/multiwalled carbon nanotube (MWNT) composite fibers were prepared via microfluidic spinning. The Col composite fibers showed tightly packed bundle surface structures. Col/carboxylated MWNT achieved the maximum tensile strength of 1.94 cN/dtex. MWNT enhanced thermal stability and water resistance of Col fibers.

Epsilon‐negative materials with lower percolation threshold derived from segregated structures

AbstractEpsilon‐negative materials (ENM) at radio frequency, usually designed based on percolation theory, recently drew much attention because of their potential applications in capacitors, transistors, and antennas. However, randomly distributed conductive functional materials cannot achieve directional long‐range electron transportation within the material, resulting in decreased utilization efficiency. The morphology design of the substrate material can change the distribution state and electron transfer pathway of conductive fillers. By controlling the size of the polystyrene (PS) and the content of multi‐walled carbon nanotubes (MWCNTs), PS/MWCNTs composites with random structures and segregated structures were designed, both of which exhibited negative permittivity with increasing MWCNTs content. Further investigation revealed that negative permittivity behavior is due to the establishment of the conductive network and the plasma oscillation of free electrons. Moreover, components with segregated structures have lower percolation thresholds, as directional electron transport is achieved and conductive fillers are efficiently utilized. This work provides a new method for guiding the electron transport pathway and effectively changing the distribution state of conductive fillers in ENM.Highlights Negative permittivity is achieved by plasma oscillation at radio frequency. The segregated structure leads to a decrease in the percolation threshold. Epsilon‐negative materials have good prospects in inductive components.

Elicitation with multi-walled carbon nanotubes improved growth and production of polyphenolic compounds in Melissa officinalis

Carbon nanotubes as novel plant elicitors are intensively studied in biotechnology due to their concentration-dependent effects on plant health. This emphasizes the importance of studying nanomaterials in the field of plant nanotoxicology and enables a better understanding of their advantages and disadvantages for plant health. Researchers examined how various concentrations of multi-walled carbon nanotubes (MWCNTs) affect growth and polyphenolic accumulation in the medicinal herb, Melissa officinalis. Two-month-old plant shoots were sprayed with various concentrations (0–250 mg L−1) of COOH- functionalized MWCNTs and harvested two and three weeks after elicitation. TEM images confirmed MWCNTs uptake into the mesophyll and the vessels of leaves. Low to moderate MWCNT concentrations (50–100 mg L−1) boosted growth indices and increased total amount of phenols, flavonoids, and phenolic acids, peaking three weeks after treatment with 100 mg L−1 MWCNTs, without destroying the cells and subcellular organelles. HPLC analysis showed this treatment yielded the highest content of rosmarinic acid, salvianolic acid B, apigenin, and kaempferol. However, 250 mg L−1 MWCNTs damaged cells without boosting metabolite production. We suggest that elicitation with low to moderate MWCNT concentrations can be a useful tool for laboratory-scale production of phenolic metabolites in M. officinalis.

Exploring the optical and electric features of PMMA/PVAc blended polymers doped with TBAI/MWCNTs fillers for different applications

The present study focuses on the production of poly (methyl methacrylate)/poly (vinyl acetate)/tetrabutylammonium iodide/multi-walled carbon nanotubes (PMMA/PVAc/TBAI/x wt %MWCNTs) blended polymers. These blends show great potential for use in advanced optical, energy storage and electronics applications. X-ray diffraction (XRD) and scanning electron microscopy techniques was used to explore the structure and morphology of PMMA/PVAc/TBAI with x wt% MWCNTs blended polymers. The optical transmittance lowered to a minimum value of 53–63 % within the specific wavelength range as the blend contained 0.55 wt % multi-walled carbon nanotubes (MWCNTs). The sample containing 0.11 wt% MWCNTs demonstrated the highest reflectance (R) values, whereas the sample with 0.55 wt% MWCNTs showed the lowest R values. As the concentration of MWCNTs increased, these values consistently decreased. The smallest direct (4.55 eV) and indirect (4.45 eV and 2.48 eV) optical band gap (Eg) values were achieved when wt% of MWCNTs were 0.44 % and 0.55 %, respectively. The doped blend with wt% of 0.11 exhibited the highest refractive index values. Blend with x = 0.55 wt % MWCNTs has the highest dielectric constant. The energy density (U) increased non-uniformly as the blend was infused with MWCNTs. Elevating the temperature enhances the values of U for all blends. All blends adhered to the correlated barrier hopping (CBH) model. The effects of MWCNTs doping amount and temperature on the impedance and electric modulus of the host blend were investigated. The dc conductivity of the doped samples was observed to be greater than that of the undoped blend, except for the blend with x = 0.44, where it diminished. The undoped blend displayed activation energy (Ea) values of 1.71 eV and 0.6 eV, depending on the temperature range. When the host blend is doped with MWCNTs, the Ea values either rise or fall depending on the quantity of MWCNTs. All samples have non-ohmic characteristics.

Electrical and structural investigations of PVA/CMC/PPy/MWCNTs blended polymer composites for energy storage applications

This work aims to form polyvinyl alcohol (PVA)/carboxymethyl cellulose (CMC)/0.1 wt% polypyrrole (PPy)/x wt.% multi-walled carbon nanotubes (MWCNTs) blended polymers using the casting technique to employ in energy storage applications. X-ray diffraction and scanning electron microscopy are used to investigate the structure and morphology of the formed blends. The maximum values of dielectric constant and energy density were obtained at x = 0.05. The dielectric constants are influenced by both the temperature and the concentration of MWCNTs, as well as the existence of PPy in the blended matrix. Blends with x = 0 and 0.2 displayed the small polaron mechanism, blends with x = 0.05 and 0.25 followed the CBH model, whereas the remaining samples demonstrated the OLP mechanism. Z′ reaches its maximum values at x = 0.2 and its lowest values at x = 0.05 in the low and intermediate frequency regions. In the higher frequency range doped blends have the lowest Z′ values as compared with the undoped blend. Samples with x = 0.05, 0.15, and 0.2 exhibit semiconductor properties, whereas the remaining samples display features associated with either insulators or partial conductors. The effect of MWCNTs doping amount and temperature on the ionic conductivity, electric modulus and relaxation time of different blends was studied. Also, the activation energy of every blend was determined using the Arrhenius relation.

Preparation and characterization of PVA/MWCNT nanocomposites: a composition dependence study of structural, optical and mechanical properties

This work investigates the properties of polyvinyl alcohol (PVA) nanocomposite films with varying multi-walled carbon nanotube (MWCNT) content, ranging from 2 to 8 wt.%. The films were prepared using a solution casting method and characterized using UV-visible spectroscopy, optical microscopy, X-ray diffraction, and tensile tests. The prepared PVA/MWCNT nanocomposite films exhibited optical band gap values ranging from 3.5 eV to 5.3 eV. XRD analysis confirmed the semi-crystalline nature of these nanocomposites. Mechanical properties, including hardness, yield strength, ultimate tensile strength, and Young’s modulus, were enhanced by increasing MWCNT content by up to 8%. Contact angle measurements showed an increase in hydrophobicity with increasing MWCNT content. Optical microscopy images revealed uniform dispersion of MWCNTs in the PVA matrix. These findings suggest potential applications of PVA-MWCNT nanocomposites in various fields, including photosensors, UV shielding, adjustable band gap devices, and flexible optoelectronic devices.

Exploring the optical and electrical features of PVA/CMC/PPy/MWCNTs blended polymers

The objective of this study is to create nanocomposite films using polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (CMC), polypyrrole (PPy) and Multi-walled carbon nanotubes (MWCNTs). These nanocomposites show potential for use in a range of optoelectronics devices. The structure and morphology of PVA/CMC/PPy/x wt % MWCNTs blends were explored using X-ray diffraction and scanning electron microscope techniques. In the visible range, the transmittance lowered from 78 to 87 % (PVA/CMC/PPy blend) to 3–5 % (x = 0.25 wt % MWCNTs). The transmittance in the UV range decreased significantly, approaching zero, for the blend containing 0.25 wt % MWCNTs. The material improves the absorption of UV–visible light and efficiently prevents the penetration of UV–visible light. When the concentration of MWCNTs reached 0.05 in the doped blend, the reflectance value improved considerably. The addition of MWCNTs to the PVA/CMC/PPy composite leads to a reduction in the optical bandgap values. The lowest direct and indirect band gaps are (4.98, 4.36) eV and (4.52, 3.19, 2.68, 1.18) eV, respectively, accomplished when the MWCNTs content was 0.2 wt %. A blend containing 0.15 wt % MWCNTs resulted in the highest values of refractive index and nonlinear optical parameters. In the visible light spectrum, the blend with 0.25 wt% MWCNTs had the best optical conductivity values. Doped blends can be used in optoelectronic or photocatalytic applications depended on the amount of MWCNTs doped. The current-voltage characteristics and logarithm of the current density and square root of the electric field strength of PVA/CMC/PPy/x wt % MWCNTs blended polymers at various temperatures were investigated.