Multi-walled Carbon Nanotubes Loading Research Articles

Mechanical and physical characterizations of compatibilizer‐free recycled plastics blend composites modified with carbon nanotube and clay nanofiller

AbstractExcessive amount of disposable and reusable plastic wastes has increasingly gained a great environmental concern. This present article aims to investigate the individual effect of multiwalled carbon nanotubes (MWCNTs) and clay loadings at 0.5, 1.0, 2.0, 4.0, and 6.0 phr on the tensile, impact, density, and water absorption properties of polymer blend made from recycled high‐density polyethylene and recycled polyethylene terephthalate. Both nanocomposites were melt‐blended using a twin screw extruder before compression molding. For MWCNT nanocomposite, 4 phr showed the optimum tensile strength (14.5 MPa), Young's modulus (587.4 MPa), and strain at break (4.2%) as compared to other loadings. For clay nanocomposite system, the optimum tensile properties (13.9 MPa tensile strength, 525.7 MPa Young's modulus, and 4.7% strain) were achieved at 1 phr. The impact strength of the nanocomposites was reduced with both nanofillers' content. With the increment of MWCNT and clay loadings, the percentages of water uptake increased but the values were still considered low (<0.26% upon 35 days immersion) capacity. These research findings with the effect of nanofiller types and loadings were statistically significant as proven in ANOVA analysis. This study formalizes a chemical‐free environmental strategy to produce nanocomposite as a plastic‐replacement product.

Physico–mechanical properties of poly(ethylene‐co‐vinyl acetate)/acrylonitrile‐butadiene rubber/multi‐walled carbon nanotubes nanocomposites

AbstractThe influence of multi‐walled carbon nanotubes (MWCNTs) on thermal, mechanical and wetting properties as well as rheological behavior of poly(ethylene‐co‐vinyl acetate) (EVA)/acrylonitrile‐butadiene rubber nanocomposites were studied. The solid surface free energy (), work of adhesion (), interfacial free energy (), spreading coefficient () and Girifalco‐Good's interaction parameter () were calculated for the materials fabricated. The results showed that the contact angle and decreased; however, , , , and increased with the increase in MWCNTs content. The maximum tensile strength and toughness were obtained for the nanocomposite containing 1 wt% nanofillers. It was also found that both of the relaxation ratio (Rr) and relaxation rate index (n) decreased with increasing in the carbon nanotubes (CNTs) concentration. The results designated that the values of Rr and n for the nanocomposite containing 7 wt% MWCNTs were 19% and 60% smaller than those of the unfilled blend, respectively. The Casson plot analysis indicated that the yield stress of the molten materials incremented with the increase in MWCNTs loading according to a quadratic equation. The analysis of crystallization exotherms and melting endotherms revealed that CNTs triggered the crystallization process at slightly higher temperature, however, melting point slightly and the rate of nucleation noticeably reduced with the increase in the nanofillers content.

Study on the effect of tailoring the hard copolymer polyurethane on the thermal, mechanical and electrical properties of hard copolymer polyurethane/multi-walled carbon nanotubes nanocomposites

This study focusses on the effect of the addition of multi-walled carbon nanotubes (MWCNTs) on the morphology and thermal, rheological and electrical properties of hard copolymer polyurethane (HCPU) using 1,5 pentane-diols as a chain extender, containing 85% of hard segment blocks. Step-growth polymerisation was used to synthesise a HCPU polymer matrix, followed by melt compounding to prepare the nanocomposites. SEM investigation of the neat HCPU structure and its nanocomposites indicated the uniform dispersion of MWCNTs within the polymer matrix; further TEM morphology investigation showed some agglomeration regions, attributed to the high MWCNT content (2 wt%). An XRD test confirmed a homogeneous distribution of MWCNTs by observing the remaining location of the highest peaks of MWCNTs and amorphous peaks of the HCPU matrix. Analysis of the melt rheology test results showed an improvement in complex viscosity combined with an increase in the G’ and G” of nanocomposites from those of pure HCPU due to the presence of MWCNTs. Finally, electrical conductivity of nanocomposites demonstrated a significant improvement in its value at high loading of MWCNTs from that of pure HCPU matrix.

Buckling Behavior of SWCNTs and MWCNTs Resting on Elastic Foundations Using an Optimization Technique

This paper aims to investigate the buckling behavior of multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs) embedded in an elastic medium using the nonlocal cylindrical shell theory. The SWCNT is treated as a cylindrical shell and the MWCNT is considered as multiple SWCNTs nested inside one another; they interact with each other via van der Waals interactions. The interaction between the matrix and the outer wall is modeled as a foundation using Winkler, Pasternak, and Kerr models. An optimization technique is developed to estimate the nonlocal critical buckling load of SWCNT and MWCNT. Furthermore, analytical formulas are proposed to describe the buckling behavior of SWCNTs embedded in an elastic medium without taking into account the effect of the nonlocal parameter. In the proposed formulas, van der Waals interactions between adjacent tubes and the effect of terms involving tube radii differences are taken into account, although they are generally neglected in expressions published in the literature. The effects of the number of layers, the nonlocal parameter, and the elastic foundation parameters are investigated. Moreover, the effects of different parameters on the stability behavior of the carbon nanotubes are also discussed.

Flexible Temperature Sensor Utilizing MWCNT Doped PEG-PU Copolymer Nanocomposites.

In this study, polyethylene glycol (PEG) and polyurethane (PU)-based shape-stabilized copolymer nanocomposites were synthesized and utilized for developing low-cost and flexible temperature sensors. PU was utilized as a flexible structural material for loading a thermosensitive phase change PEG polymer by means of physical mixing and chemical crosslinking. Furthermore, the introduction of multi-walled carbon nanotubes (MWCNT) as a conductive filler in the PEG-PU copolymer resulted in a nanocomposite with thermoresistive properties. MWCNT loading concentrations from 2 wt.% to 10 wt.% were investigated, to attain the optimum conductivity of the nanocomposite. Additionally, the effect of MWCNT loading concentration on the thermosensitive behavior of the nanocomposite was analyzed in the temperature range 25 °C to 50 °C. The thermosensitive properties of the physically mixed and crosslinked polymeric nanocomposites were compared by spin coating the respective nanocomposites on screen printed interdigitated (IDT) electrodes, to fabricate the temperature sensor. The chemically crosslinked MWCNT-PEG-PU polymeric nanocomposite showed an improved thermosensitive behavior in the range 25 °C to 50 °C, compared to the physically mixed nanocomposite. The detailed structural, morphological, thermal, and phase transition properties of the nanocomposites were investigated using XRD, FTIR, and DSC analysis. XRD and FTIR were used to analyze the crystallinity and PEG-PU bonding of the copolymer nanocomposite, respectively; while the dual phase (solid–liquid) transition of PEG was analyzed using DSC. The proposed nanocomposite-based flexible temperature sensor demonstrated excellent sensitivity, reliability and shows promise for a wide range of bio-robotic and healthcare applications.

Effects of dispersed multiwalled carbon nanotubes on the micro-explosion and combustion characteristics of 2-methylfuran – diesel mixture droplets

Isolated droplet combustion experiments have been carried out on neat diesel, a 15 vol% 2-methylfuran – 85 vol% diesel mixture (MF15), and nanofuels made from MF15 base fuel with addition of multiwalled carbon nanotubes (MWCNTs) at 25 ppm, 50 ppm, and 100 ppm concentrations (referred to as MF15C25, MF15C50, and MF15C100). Compared to MF15, the nanofuels displayed increased micro-explosion intensity and reduced micro-explosion occurrences, both effects being more pronounced at higher MWCNTs loadings. This behavior is attributed to the higher surface tension and viscosity of the nanofuels compared to that of MF15. The ignition delay decreased from 2.33 s to 1.71 s, the combustion rate constant increased from 0.82 mm2 s−1 to 1.01 mm2 s−1, and the combustion period reduced from 5.31 s to 4.54 s when going from pure MF15 to MF15C50. The improved combustion characteristics can be related to the superior thermal conductivity and large specific surface area of the dispersed MWCNTs in the nanofuels. The combustion characteristics of the nanofuel deteriorate at the highest MWCNTs dosing investigated here, possibly due to nanoparticle agglomeration. Overall, the present results suggest that dosing of MWCNTs at optimum levels improves the thermal efficiency and reduces the NOx emissions upon combustion of MF-diesel blends.

Conductive Polymer Composites Fabricated by Disposable Face Masks and Multi-Walled Carbon Nanotubes: Crystalline Structure and Enhancement Effect

Influenced by recent COVID-19, wearing face masks to block the spread of the epidemic has become the simplest and most effective way. However, after the people wear masks, thousands of tons of medical waste by used disposable masks will be generated every day in the world, causing great pressure on the environment. Herein, conductive polymer composites are fabricated by simple melt blending of mask fragments (mask polypropylene, short for mPP) and multi-walled carbon nanotubes (MWNTs). MWNTs were used as modifiers for composites because of their high strength and high conductivity. The crystalline structure, mechanical, electrical and thermal enhancement effect of the composites were investigated. MWNTs with high thermal stability acted the role of promoting the crystallisation of mPP by expediting the crystalline nucleation, leading to the improvement of amount for crystalline nucleus. MWNTs fibers interpenetrate with each other in mPP matrix to form conducting network. With 2.0 wt% MWNTs loading, the tensile strength and electrical conductivity of the composites were increased by 809% and 7 orders of magnitude. MWNTs fibers interpenetrate with each other in mPP matrix to form conducting network. Thus, more conducting paths were constructed to transport carriers. The findings may open a way for high value utilization of the disposable masks.

Investigation of carbon nanotube reinforcement to polyurethane adhesive for improving impact performance of carbon fiber composite sandwich panels

In this study, the development of a polyurethane adhesive by using carbon nanotubes (CNT) to enhance the low-velocity impact behavior of aluminum honeycomb sandwich composite structures was investigated. The interaction of CNT and polyurethane for the impact behavior of sandwich composite panels is the main originality of this paper. The fabrication of carbon fiber reinforced composite (CFRC) sandwich structures was conducted using different polyurethane (PU) adhesives and different honeycomb cell sizes. CFRC sandwich structures were fabricated with multi-walled carbon nanotube (MWCNT) added and neat PU adhesives, 6.78 and 10.39 mm honeycomb cell sizes, and carbon fiber prepregs. Neat and nanotube added PU adhesives with MWCNT at reinforcement of 0.1% and 0.2% by weight percent were prepared. Sandwich composite panels were manufactured using the hot pressing method. Specimens of 100 × 100 mm were cut from the sandwich panels, and low-velocity impact tests were conducted at 100 J initial impact energy according to ASTM D7136 standard. After experiments, load-deflection curves, load-time, and energy-time histories were acquired. The absorbed energy values at maximum load were evaluated as a function of MWCNT content and honeycomb cell size. Specimens were sectioned from the impacted region and scanned using scanning electron and optical microscopes to analyze the damaged area. Specimens with MWCNT reinforced adhesives carried higher maximum loads compared to neat ones. CFRC sandwich structures with MWCNT added PU adhesives exhibited a 6% higher impact resistance at 100 J energy levels. Experimental results demonstrated that an increase in MWCNT loading and a decrease in PU adhesive cell size increased the maximum load values in CFRC sandwich panels. Among the nanotube added adhesives, 0.1 wt percent showed the best impact performance.

Optimization of thin polystyrene waste embedded multiwall carbon nanotubes (MWCNT) film for solid electrolyte of flexible dye-sensitized solar cell (DSSC)

The consumption of organic solvent in a conventional liquid-based electrolyte give rise to the solvent’s evaporation, hermetic sealing of the cell as well as lack of cell durability. In order to avoid fluidity and potential leakage, the composite polymer-based electrolyte has been investigated. Thus, the main objective of this study is to develop thin polystyrene waste embedded multiwall carbon nanotube (MWCNT) film with improving electrochemical properties as electrolyte host for flexible DSSC application. In this study, the MWCNT will be functionalized with carboxyl group using sulfonitric solution. Transmission electron microscope (TEM) were used to evaluate the morphology of MWCNT. Different weight percentage of the functionalized MWCNT were embedded into the polystyrene and their effect on the morphology, and uniformity of the thin polymer films were analysed using field emission electron microscope (FESEM). The electrochemical properties of the prepared polystyrene embedded MWCNT based polymer electrolyte were studied using electrochemical impedance spectroscopy (EIS). The finding shows that the optimum loading of MWCNTs in the thin polystyrene waste embedded MWCNTs film is 0.003 g. These composition exhibits the highest ionic conductivity and the lowest resistance. Further increase in the amount of MWCNTs results in reducing the ionic conductivity due to the percolation network of the MWCNT with the polystyrene.

Dynamic mechanical analysis, electrical properties and water sorption behaviour, of phenol formaldehyde nanocomposite reinforced with multiwalled carbon nanotubes

The goal of this research is to synthesise Phenol-formaldehyde nanocomposites containing pure multiwalled carbon nanotubes using an in-situ polymerisation process. The impact of filler loadings (MWCNT) with various weight percentages in the composite was explored in this research. The visco-elastic, electrical, morphological, and water sorption behaviour of the nanocomposites were investigated. The influence of MWCNT loading on the dynamic mechanical analysis, water uptake, electrical behaviour was examined. Using in-situ polymerisation, an effort was made to generate non agglomerated and homogenius dispersion of multiwalled carbon nanotubes (MWCNT) in the PF composite. The influence of MWCNT dispersion on the viscoelastic characteristics, electrical, morphological, and water sorption behaviour of PF-MWCNT nanocomposites has been thoroughly investigated. When compared to neat PF, lower filler loading (0.05 wt%, 0.08 wt percent) resulted in greater AC conductivity. According to DMA investigation of PF-MWCNT, 0.15 wt% has a greater storage modulus and 0.05 has a higher glass transition temperature. The addition of MWCNT has effectively reduced the water uptake of the entire nanocomposite.

Dynamic crystallization behavior of PA-12/PP-MWCNT nanocomposites: non-isothermal kinetics approach

Abstract The effect of multi-walled carbon nanotubes (MWCNT) loading on the crystallization behavior of matrix polyamide 12 (PA-12), in PA-12/polypropylene-MWCNT (PP-MWCNT)-based nanocomposites were analyzed for their non-isothermal crystallization behavior at various cooling rates of 2.5–20 °C/min in differential scanning calorimetry (DSC). Several kinetic models such as Jeziorny (modified-Avrami), Mo and Tobin models were employed to analyze the crystallization behavioral trend with respect to time and temperature of the nanocomposites. The crystallization rate increased half-time of crystallization with MWCNT content as estimated from the Jeziorny theory. The linear agreement between Jeziorny model and experimental relative crystallinity outperforms the Tobin analysis where the coefficient of linear regression was found to be considerably trailing behind and off the satisfactory mark. The Mo model accounts for the percentage crystallinity and thereby successfully explained the crystallization behavior of PA-12 where the kinetic parameters increased with crystallinity indicating higher cooling rate for higher crystallinity. The MWCNT induced crystallization (nucleation activity) values were close to zero irrespective of MWCNT loading which reiterates the enhanced crystallization (rate) of PA-12 in the nanocomposites. Estimations based on Friedman approach showed inter-relationship between activation energy and crystallinity where the later was found to be governed by major (matrix) PA-12 phase.

Enhancing shear strength and structural stiffness of composite joint with carbon nanotube reinforced adhesive through co-bonding technique

High-performance co-bonded joints are nowadays indispensable to join subcomponents of tails, wings and fuselage in aerospace assemblages. The current study examined the effect of incorporating multiwall carbon nanotube (MWCNTs) on mechanical and free vibrational behaviour, such as natural frequency and resultant damping factor of co-bonded single-lap composite joints. The experimental results indicated 0.25 wt.% MWCNT reinforcement into the epoxy adhesive considerably improved the joint strength of the co-bonded single-lap composite joints by 34.52%. However, the higher loading of MWCNTs reduced the shear strength of co-bonded single-lap composite joints due to agglomeration. Scanning electron microscopy (SEM) affirmed that lower wt.% MWCNT reinforcement improved the interfacial bonding, developed rougher surfaces, shear bands, and deviated crack growth path in the bond-line to an elongated path. Moreover, the comparison of failure surfaces of neat and CNT reinforced specimens confirmed that the effective presence of MWCNTs changed the failure mode failure of co-bonded lap joint from adhesive to cohesive failure mode. The experimental free vibrational analysis affirmed that 0.25 wt.% MWCNT reinforced co-bonded joint has the highest fundamental natural frequency. Results also depicted that higher wt.% MWCNT loading exhibited better damping owing to particle accumulation and higher interaction between adhesive and laminate.

Fabricating Solid State Fractional Capacitor in the Frequency Range of mHz to kHz

In this letter, we report a simple fabrication process for a wide bandwidth solid-state fractional capacitor (FC). The FC uses a composite of epoxy resin and a conductive gel (CG) as the dielectric in between the two parallel copper plates. The phase of the FCs is constant for a bandwidth of 10 mHz–100 Hz. The bandwidth has further been extended to the kHz range by adding multiwalled carbon nanotube (MWCNT) to the dielectric composite of epoxy resin and CG. We presume that the addition of MWCNT to the dielectric composite facilitates the occurrence of distributive time constant and results in increased bandwidth. The widest bandwidth is 10 mHz–73 kHz which is obtained when the CG and MWCNT loadings are 90% and 0.75%, respectively. We are able to vary the orders of the FC from 0.07 to 0.3 by varying the amounts of CG and MWNCT in the dielectric composite.

Effect of multi-walled carbon nanotube on thermal decomposition, mechanical and heat-induced shape memory properties of crosslinked poly(vinyl alcohol)

Shape memory polymers are attractive smart materials that have many promising applications in a wide variety of fields. Here the multi-walled carbon nanotube (MWCNT) was used to adjust the performance of crosslinked poly(vinyl alcohol) (PVA), which had acetal reaction with glutaraldehyde (GA). The thermal degradation, mechanical strength and shape recovery properties of PVA/MWCNT/GA membranes were investigated by thermogravimetry, differential scanning calorimetry, x-ray scattering, dynamic mechanical analysis, tensile test and thermal-stimulus shape memory recovery measurements. The MWCNT embedded in the crosslinked PVA matrix accelerated the breaking of C–O bonds. The mechanical strength and shape recovery properties of PVA/MWCNT/GA composites were tunable. As the MWCNT loading increase in crosslinked PVA matrix, the yield strength increased from 3.85 MPa to 10.21 MPa, breaking elongation decreased from 230% to 50%, the 100% shape recovery time decreased from 27 s to 16 s, respectively.

Basic Study of Extensional Flow Mixing for the Dispersion of Carbon Nanotubes in Polypropylene by Using Capillary Extrusion

Abstract This study evaluated the mixing effect of simple uniaxial extensional flow for the dispersion of multiwalled carbon nanotubes (MWCNTs) into polypropylene (PP) as a nonpolar matrix. An only converging flow allowed for a high strain rate and was suitable for the compounding process. The extensional flow was characterized from the entrance pressure drop (ΔP0) at the converging section. Thus, in this study, capillary extrusion was employed to generate uniaxial extensional flow. Based on the hypothesis that the dispersion of nanofillers depends on the magnitude of flow-induced stress, ΔP0, which related to extensional stress, was measured directly during capillary extrusion by using an orifice die. The influences of the mass flow rate and the hole diameter in the orifice die, which affected ΔP0, on the extrusion of PP nanocomposites with an MWCNT loading of 1.0 wt.% were studied. The extruded samples were collected, and the dispersion state was evaluated based on the melt viscoelastic properties, volume resistivity, and morphological observations by optical microscopy (OM) and transmission electron microscopy (TEM). The agglomeration area of the MWCNTs decreased with higher ΔP0 (higher mass flow rate and smaller hole diameter), which increased the uniformity of the dispersion. Moreover, the influence of the length-to-diameter (L/D) ratio of the hole in the capillary die on the dispersion state of the MWCNTs was investigated. A higher L/D ratio of the capillary die did not improve the dispersion state, although shear and extensional stresses were provided.

Experimental investigations of stability, density, thermal conductivity, and electrical conductivity of solar glycol-amine-functionalized graphene and MWCNT-based hybrid nanofluids.

This research article discusses properties such as density, thermal conductivity, and electrical conductivity of solar glycol with amine-functionalized graphene and multi-walled carbon nanotubes (MWCNTs). The hybrid nanofluid is prepared by dispersing the amine-functionalized graphene (AFG) and MWCNTs (50:50 in % by weight ratio) in pure solar glycol. The AFG and MWCNTs are dispersed in different volume concentrations of 0.05%, 0.1%, and 0.15% through the classical two-step homogenizing technique. Good colloidal stability nanofluid are prepared with Gum Arabic (non-covalent) as the surfactant. The stability of nanofluids is ensured through scanning electron microscopy, UV-Vis spectrometer, and zeta potential analyzer. The nanofluid thermal conductivity is measured with varying the nanomaterial loading from 0.05 to 0.15 vol% using a KD2 pro thermal analyzer. The thermal conductivity and electrical conductivity of nanofluid augmentations are considerably with an increasing volume concentration of AFG and MWCNT loading. The thermal conductivity of the AFG-MWCNT-based hybrid nanofluid is augmented by 8.59% for the maximum concentration of 0.15 vol% at 50 °C. The electrical conductivity of the solar glycol-based nanofluids is enhanced linearly with increased operating temperatures. The maximum electrical conductivity enhancement attained is ~28.85% at a nanoparticle loading of 0.15 vol% and 70 °C.

Effect of carbon nanotubes on aging properties of hydrogenated nitrile rubber in the dilute oxygen medium

To solve the key problem of accelerated aging for packer rubber cylinder under high temperature. The hydrogenated nitrile rubber (HNBR) composites reinforced by multi-walled carbon nanotubes (MWCNTs) were prepared. Effect of MWCNTs on the aging performance of HNBR/MWCNTs composites was studied with dilute oxygen as a medium at 180 °C. Fourier-infrared spectroscopy, differential scanning calorimetry, dynamic thermomechanical analysis and transmission electron microscope were used to investigate the aging behavior of HNBR/MWCNTs composites. The tensile strength of HNBR composites with 3, 6, and 9 phr MWCNTs loading increased by 35%, 37%, and 39% respectively. After 15 days at 180 °C, HNBR composites with 3 phr of MWCNTs had a tensile strength retention rate of 91% and an elongation retention rate of 57%, while the blank HNBR composites had a tensile strength retention ratio of 72% and elongation retention ratio of 52%. The result of DSC shows that the presence of MWCNTs can enhance T g of HNBR composite, the T g increase rate (2 °C) for HNBR/MWCNTs composites was lower than that (3.2 °C) for the blank in 15 days at 180 °C. MWCNTs exhibited better reinforcement and excellent anti-aging performance. The possible anti-aging mechanism has been proposed.

Thermo-Physics characterization of polypropylene/multi-walled carbon nanotube nanocomposites for rapid replication using hot embossing process

This study presents a comprehensive review of the thermophysical, rheological, and mechanical characteristics of nanocomposites reinforced with carbon nanotubes (CNTs). The high-loaded polypropylene (PP) nanocomposites with multi-walled carbon nanotube loadings ranging from 0.01 wt.% to 5 wt.% were elaborated via high-shear mixing using a twin-screw mixer. The structural and rheological properties of the neat polypropylene in the molten state and those of the elaborated composites were determined. The thermophysical properties of the nanocomposites were investigated via differential scanning calorimetry and thermogravimetric analysis. The mechanical properties were determined through quasi-static tensile testing at room temperature. The results clearly indicate that the incorporation of CNTs in a thermoplastic polymer matrix significantly improves the final thermophysical and mechanical properties of the nanocomposites, through excellent dispersion of CNTs in the thermoplastic matrix and an improvement in interfacial interaction. The produced nanocomposites were granulated and used in a hot embossing process to manufacture micro-structured components. These micro-shapes on the surface of a metal mould were successfully transferred to a CNTs/PP nanocomposite substrate.

Activation of peroxydisulfate by carbon nanotube for the degradation of 2,4-dichlorophenol: Contributions of surface-bound radicals and direct electron transfer

Carbon materials have been used to activate peroxydisulfate (PDS) for the degradation of organic pollutants. The mechanism involved, especially whether radicals are formed in these processes, is still under debate. In this research, multi-walled carbon nanotube (MWCNT) was employed to activate PDS for the removal of 2,4-dichlorophenol (2,4-DCP). The effects of solution pH, PDS concentration, 2,4-DCP concentration, and MWCNT loading on the degradation of 2,4-DCP were investigated. The mechanism was explored via radical scavenging experiments, electron paramagnetic resonance (EPR) and MWCNT surface characterization. The results showed that the rate of 2,4-DCP degradation increased with the increasing solution pH, PDS concentration and MWCNT loading. The presence of OH and SO4− signals in EPR studies, no inhibitory effect in radical scavenging experiments, and the chlorination of MWCNT observed by X-ray photoelectron spectroscopy (XPS) suggested that surface reactions involving both surface-bound radicals and direct electron transfer were responsible for 2,4-DCP degradation. Reusability tests showed that the surface sites responsible for surface-bound radical formation were poisoned after PDS activation, while those responsible for direct electron transfer remained active after five cycles. This research provided the first in-depth insights for the dual roles of MWCNT in the PDS activation process.

Structural Characterization, Global and Local Electrochemical Activity of Electroless Ni–P-Multiwalled Carbon Nanotube Composite Coatings on Pipeline Steel

In this work, composite Ni–P-multiwalled carbon nanotube films were produced by electroless deposition. The main goal was to investigate the influence of multiwalled carbon nanotube loading on the local electrochemical behavior of the composite films, as probed by scanning electrochemical microscopy (SECM). The coatings were also characterized with respect to their crystalline structure, surface, and cross-section morphologies. Adhesion strength was examined by scratch tests. The global electrochemical behavior was evaluated by potentiodynamic polarization. The local electrochemical activity was investigated by probing the Fe2+ oxidation in the surface generation/tip collection mode of the SECM. The results revealed that multiwalled carbon nanotubes increased the adhesion strength and reduced the electrochemical activity on the surface of the coated samples.