Multi-walled Carbon Nanotubes Support Research Articles

Thermo-electric Characterization of Hydroxyapatite/ Multi-walled Carbon Nanotube Reinforced Polyetheretherketone Polymer Composites

Thermo-electric Characterization of Hydroxyapatite/ Multi-walled Carbon Nanotube Reinforced Polyetheretherketone Polymer Composites

Characterization of thin-walled self-healing microcapsules reinforced with multi-walled carbon nanotubes

This study presents a novel approach to fabricating thinner shells and significantly enhancing the fracture strength of melamine-urea-formaldehyde (M-U-F) microcapsules reinforced with multi-walled carbon nanotubes (MWCNTs). Unlike previous studies that primarily focused on single-walled carbon nanotubes (SWCNTs) or MWCNTs in polyurea-formaldehyde (PUF) shells, this research advances microcapsule technology by exploring MWCNT reinforcement in M-U-F shells. We employed a dual experimental-numerical approach, combining the precision of micro-compression tests with the predictive capabilities of finite element analysis (FEA) to determine the elastic modulus of MWCNT-reinforced M-U-F microcapsules. This method offers new insights into the mechanical behavior of these microcapsules. Our findings indicate an 8.8% increase in fracture load and a 14.6% reduction in fracture displacement for MWCNT-reinforced microcapsules compared to conventional M-U-F microcapsules. Additionally, FEA confirmed the results of the micro-compression tests, showing that MWCNT-reinforced microcapsules had the best correlation with an elastic modulus of 4.00 GPa. Conventional M-U-F microcapsules corresponded to an elastic modulus of 2.25 GPa. These results provide a comprehensive understanding of how nano-reinforcement influences the structural properties of thin-walled microcapsules, with potential applications in composite damage repair and beyond.

Evaluation of Fracture Durability and Wear Resistance Properties for Orthopaedic Implant Application

Hydroxyapatite (HA) coated metallic substrates are commonly used for load-bearing orthopedic implants. In the present work Titanium grade 2 and Titanium grade 5 substrates were coated with hydroxyapatite and hydroxyapatite reinforced with 5% (by wt.) multiwalled carbon nanotubes (MCNT) separately using plasma spray coating. The wear behavior of these coated substrates was studied with the simulated body fluid (SBF) having a pH between 7.20 to 7.40. Fracture toughness and wear resistance of HA reinforced with 5 % (by wt.) MCNT composite coating was found to be higher as compared to pure HA coating. This improvement is by virtue of inherent mechanical properties and the crack bridging effect offered by MCNT. The addition of MCNT also helped in restricting crack propagation in the coatings. As evident from SEM images, abrasive and adhesive wear mechanism were observed which reduces greatly with reinforcement of MCNT.

Structural, Mechanical and Thermal Behaviour of MWCNT-PCS Hybrid Polymer Matrix Nanocomposites: An Extension Study of Graphene-Epoxy Polymer Matrix Nanocomposites

This study extends previous research on graphene-epoxy nanocomposites by investigating the thermal, mechanical, electrical, and chemical properties of multi-walled carbon nanotube (MWCNT)-reinforced polycarbosilane (PCS) hybrid polymer matrix nanocomposites. Building on the foundational work that demonstrated the enhanced performance of graphene-epoxy nanocomposites, this research explores the potential of MWCNTs as a superior reinforcing agent within the PCS matrix. The MWCNT-PCS nanocomposites were synthesized and characterized using a comprehensive suite of techniques, including X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, specific gravity analysis and surface resistance measurements. The results indicate that MWCNT-PCS nanocomposites exhibit improved thermal stability, higher degradation temperatures, and enhanced thermal conductivity, along with significant improvements in mechanical strength and lower surface resistance, indicating superior electrical conductivity. Additionally, the chemical interactions between MWCNTs and the PCS matrix were analyzed to assess the dispersion and bonding quality, contributing to the overall performance of the nanocomposites. These findings suggest that MWCNT-PCS nanocomposites are promising candidates for high-performance applications in aerospace, where thermal stability, mechanical strength, electrical conductivity and chemical stability are critical. This paper not only confirms the benefits of MWCNT reinforcement but also provides a direct comparison with graphene-epoxy nanocomposites, underscoring the advancements made in this ongoing research.

A new approach for determination of urinary 8-hydroxy-2′-deoxyguanosine in cancer patients using reinforced solid/liquid phase microextraction combined with HPLC-DAD

AbstractThe concentration level of urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG), an oxidative stress biomarker for various diseases especially cancer, has been attracted as a pathway suitable for diagnostic purposes. Determination of urinary 8-OHdG is challenging due to its low level within a complex matrix. In this study, a new approach of solid/liquid phase microextraction technique prior to high-performance liquid chromatography diode-array detection (HPLC-DAD) analysis was developed for the determination of trace levels of 8-OHdG in urine samples. The solid/liquid phase microextraction device was constructed by reinforcement of multi-walled carbon nanotubes into the pores of a short segment 2.5 cm of hollow fiber microtube with two ends heat sealed. Based on the optimized procedure, the selected analyte was extracted from an acidic sample solution (10 mL adjusted at pH = 5) into the five extraction devices. After the extraction period (30 min), the 8-OHdG was eluted from the extraction device using methanol (350 µL) under ultrasonication for 5 min. The analytical performance of the method in synthetic urine samples showed good linearity (R2 > 0.999) with the limits of detection of 0.85 ng mL−1, and extraction recovery > 92.36%. The developed microextraction technique exhibited a confident sensitivity, feasible operation, and simplicity in comparison with other published methods and was valid to determinate trace 8-OHdG in urine cancer patients' samples by using a cheap and commonly available HPLC-DAD instrument.

Optimized in vitro assessment of ZrO2–CaO/PMMA hybrid biocomposite with multi-walled carbon nanotube reinforcement for enhanced bone reconstruction

In this study, multi-walled carbon nanotubes (MWCNTs) are integrated into a poly (methyl methacrylate) (PMMA) and zirconium oxide (ZrO2) biocomposite, stabilized with calcium oxide (CaO). This research aims to pave the way for further optimization of the biocomposite for targeted applications in bone tissue engineering. The incorporation of MWCNTs is intended to enhance the mechanical properties and bioactivity of the composite, making it a suitable candidate for bone reconstruction. Comprehensive analyses were conducted using field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDS) to characterize the structural and chemical changes in the biocomposite during immersion in simulated body fluid (SBF). These analyses revealed a significant formation of a robust apatite layer on the composite surface after three days of immersion. Notably, the rate of apatite formation accelerated with the incorporation of MWCNTs, indicating an enhancement in the bioactivity of the composite. The study findings demonstrate that an MWCNT-reinforced PMMA/ZrO2–CaO composite exhibits excellent biocompatibility, as well as accelerated bioactivity. These properties are crucial for bone tissue engineering applications, where materials must integrate seamlessly with natural bone and support new bone formation. The results confirm the potential of this advanced biocomposite as a promising biomaterial for bone replacement procedures, offering improved performance over traditional materials.

Effect of multi-walled carbon nanotubes reinforcement on self-healing performance of natural rubber

Abstract This work is motivated by the desire to restore the quality of rubber-based product properties with the intention of prolonging the service life period, thus helping create a sustainable environment by proposing effective rubber waste management. This study experimentally investigated an intrinsically self-healing zinc thiolate grafted natural rubber (NRZT) compound filled with multi-walled carbon nanotubes (MWCNT) to assess its influence on mechanical properties and self-healing performance. The MWCNT loading varied to 0, 2, 4, 6, and 8 phr. The Equilibrium swelling test was used to quantify the amount of ionic and covalent crosslinks formed. Fourier Transform Infrared (FTIR) spectra were used to detect the presence of MWCNT in the compound. The mechanical properties computed by the tensile and tear strength tests showed that the incorporation of MWCNT increased both properties up to three and twofold, respectively. However, as expected, the elongation at break (Eb) value was reduced. The unfilled sample showed that it can heal up to ∼98 %, measured from the tensile strength. However, the healing efficiency obtained from tensile strength reduces to ∼88 % by incorporating 2 phr MWCNT. The Eb and its self-healing efficiency gradually decreased as the MWCNT amount increased. All samples showed outstanding properties under the tearing mode, where the healed samples produced higher tear strength (>100 % healing) than the initial value. Scanning Electron Microscopy (SEM) micrographs revealed a noticeable gap along the healed cut line with increased MWCNT numbers, possibly due to the lower reaction between polymerized zinc thiolate (PZTh) radicals with zinc thiolate (ZT) and rubber molecules. The work aims to investigate the influence of MWCNTs on the mechanical and healing performance of self-healing NR composites by comparing them to their unfilled sample.

Vibration assessment of dual core sandwich beam with a biomimetic lamellar honeycomb core and MWCNT reinforced facesheets

The usage of sandwich structures has been increasing in the field of defense, transportation, and aerospace applications due to the many advantages like, thickness to mass ratio, high bending stiffness, and strength. In this present work, the vibration assessment of the dual-core sandwich beam with biomimetic core and multiwalled carbon nanotube (MWCNT) reinforced composite face layers has been performed. The lamellar honeycomb (LHC) core is a biomimetic design developed here from the pistachio shell structure and manufactured by 3D printing process. The mechanical characteristics of biomimetic core are measured using an alternative dynamic technique and impulse excitation test was used to assess the material properties of MWCNT composite laminates. Using finite element software, a numerical model is created for a composite dual-core sandwich beam containing MWCNTs and a biomimetic core. The developed numerical model is validated with experimental and available literature results in terms of natural frequencies and it shows good agreements. Additionally, parametric studies are performed to investigate the natural frequencies of MWCNT composite dual-core sandwich beam with biomimetic cores for ply orientation angles, aspect ratio, and support conditions. The MWCNT reinforcement in the facesheets and LHC core enhances the structural performance and stiffness of the laminated composite dual-core sandwich beam. This research will provide the valuable insights to engineers and scientists for the construction of large capacity ships and race boat structures.

An investigation of the impact of functionalized MWCNT reinforcement on interlaminar strength of glass/epoxy composites: a comparative view

ABSTRACT In the present investigation, diverse functionalized states of multi-walled carbon nanotubes (MWCNT) were employed in fabricating glass/epoxy composites, with the MWCNT consistently incorporated at a 0.5 wt.% concentration. These functionalization states included pristine, hydroxyl, amine, and carboxylic conditions, systematically compared against neat glass/epoxy composites. The findings elucidated that all three functionalizations positively influenced the enhancement of interlaminar shear strength, mode-I interlaminar fracture toughness, and mode-II interlaminar fracture toughness properties. Notably, the amine-functionalized MWCNT exhibited superior performance relative to other formulations. The composite reinforced with amine MWCNT demonstrated significant improvements in ILSS, mode-I ILFT, and mode-II ILFT by 41.82%, 37.75%, and 40.93%, respectively. These enhancements are attributed to factors such as the presence of a more functional group, the quantity of individual MWCNT, and the introduction of additional damage mechanisms, including MWCNT pullout and bridging.

Effects of PVA fibers and multi-walled carbon nanotubes reinforcement on uniaxial compression fatigue properties of Engineered geopolymer composites

As a new type of green and environmentally friendly cementing material, engineered geopolymer composites (EGC) have broad application prospects. In this study, uniaxial compression fatigue tests were conducted to investigate the fatigue properties of geopolymer material. A total of 137 samples were tested to investigate the effects of carbon nanotubes content, polyvinyl alcohol (PVA) fibers volume content, and maximum stress level on the fatigue life and deformation of geopolymers. The results showed that the fatigue life of geopolymers obeys Weibull distribution, and PVA fibers and multi-walled carbon nanotubes (MWCNTs) achieved multiscale enhancement of the fatigue life by up to 16.34 times. The total strain accumulation, residual strain, and fatigue stiffness of the geopolymers under fatigue loading exhibited a three-stage evolution rule, with stability within the secondary creep branch. In the process of EGC production, the innovative adoption of optimized MWCNTs surface modification and dispersion strategies improved the uniformity of MWCNTs distribution in the matrix. Scanning electron microscopy (SEM) confirmed the hybridization of MWCNTs and PVA fibers at the microscopic level, which can achieve multi-scale enhancement of geopolymers. This study successfully optimized the content of MWCNTs and PVA fibers, further expanding the application range of composite materials.

Multi-walled carbon nanotube reinforcement in polypropylene nanocomposites: comprehensive analysis of thermal behavior, mechanical properties, and dispersion characteristics

Multi-walled carbon nanotube reinforcement in polypropylene nanocomposites: comprehensive analysis of thermal behavior, mechanical properties, and dispersion characteristics

Fabrication and Characterization of Electrically Conductive 3D Printable TPU/MWCNT Filaments for Strain Sensing in Large Deformation Conditions

AbstractThis study investigates the development of thermoplastic polyurethane (TPU) filaments incorporating multi‐walled carbon nanotubes (MWCNT) to enhance strain‐sensing capabilities. Various MWCNT reinforcement ratios are used to produce customized feedstock for fused filament fabrication (FFF) 3D printing. Mechanical properties and the piezoresistive response of samples printed with these multifunctional filaments are concurrently evaluated. Surface morphology and microstructural observations reveal that higher MWCNT weight percentages increase filament surface roughness and rigidity. The microstructural modifications directly influence the tensile strength and strain energy of the printed samples. The study identifies an apparent percolation threshold within the 10–12 wt.% MWCNT range, indicating the formation of a conductive network. At this threshold, higher gauge factors are achieved at lower strains. A newly introduced Electro‐Mechanical Sensitivity Ratio (ESR) parameter enables the classification of composite behaviors into two distinct zones, offering the ability to tailor self‐sensing structures with on‐demand properties. Finally, flexible structures with proven application in soft robotics and shape morphing are fabricated and tested at different loading conditions to demonstrate the potential applicability of the custom filaments produced. The results highlight a pronounced piezoresistive response and superior load‐bearing performance in the examined structures.

Experimental and numerical investigation on Multiwalled carbon nanotubes (MWCNTs) dispersed CFRP laminate subjected to spherical and conical impacts

ABSTRACT As lightweight and load-bearing efficiency needs have grown, conventional metal has steadily given way to carbon fibre-reinforced polymer (CFRP) laminates. Also, CFRP laminates are more prone to localised damage due to impact loads like tool drop, runway debris and hail stone. This paper, investigated the penetration and perforation behaviour of CFRP laminate reinforced with 0.2 and 0.5 wt% MWCNTs. The projectile impact experiment was conducted using spherical and conical projectiles and the impact resistance was evaluated. The results revealed that 0.5 wt% MWCNTs embedded in CFRP laminate provided better impact resistance to both projectiles. The ballistic limit velocity was enhanced by 14.2% and 17.9% for spherical and conical projectiles, respectively, in the case of 0.5 wt% MWCNTs. Furthermore, numerical simulations were performed using an orthotropic model with Chang-Chang composite failure criteria. The results from numerical findings were consistent. It was concluded that MWCNTs reinforcement improves the projectile impact resistance and energy absorption.

Kenaf Fiber and Hemp Fiber Multi-Walled Carbon Nanotube Filler-Reinforced Epoxy-Based Hybrid Composites for Biomedical Applications: Morphological and Mechanical Characterization

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.

Reinforcing potential of MWCNTs on mechanical and machining performance of hot-pressed ZTA-MgO ceramic cutting inserts

A new generation cutting insert was manufactured by multi-walled carbon nanotube (MWCNT) reinforcement (0–0.25 weight percentage (wt%)) into zirconia toughened alumina (ZTA)- magnesium oxide (MgO) ceramic matrix using a powder metallurgy route. The hot-press sintering technique was used to compact the uniformly mixed ZTA-MgO-MWCNT powders, sintered at 1500 °C followed by morphological, mechanical and functional characterizations. The relative densities of the samples were between 98 % and 99 %. The mechanical properties of the matrix were improved up to 0.15 wt% MWCNTs. The highest microhardness was ~2366 HV0.5 for 0.15 wt% due to grain refinement by synergistic pinning between spinel (MgAl2O4) and MWCNTs. Similarly, the highest indentation fracture toughness was ~7.33 MPa.m1/2 for 0.15 wt% MWCNT content due to micromechanical interlocking mechanism from a combined effect of MWCNT size variation and inter-particle distance between MWCNTs featuring proper crack bridging and crack deflection. To function as a cutting insert, the sintered samples up to 0.15 wt% was selected and shaped according to SNGN120408 cutting tool geometry. For minimum cutting force with high surface roughness, the optimized parameters were observed as a cutting speed of 300 m/min, feed rate of 0.12 mm/rev and 0.2 mm depth of cut using the design of experiment technique while machining AISI 4340 steels. Furthermore, regression models were developed to correlate the machinability with machining conditions. The comparative study suggested that the significant improvement of cutting force (~26.4 %), surface roughness (~55.3 %) and tool life (~29.4 %) was achieved for ZTA-MgO-0.15 wt% MWCNT ceramic tool with respect to ZTA-MgO inserts depending upon self-lubrication phenomenon alongside with the retention of proper tool geometry for a longer tool life ~44 min. The morphological and Raman spectra analysis of the worn region justifies the self-lubricating phenomenon at the interface by breaking and rolling of MWCNTs.

Multi-Walled Carbon-Nanotube-Reinforced PMMA Nanocomposites: An Experimental Study of Their Friction and Wear Properties.

This manuscript presents an experimental investigation of the friction and wear properties of poly (methyl methacrylate) (PMMA) nanocomposites reinforced with functionalized multi-walled carbon nanotubes (MWCNTs). The aim of this study is to evaluate the potential of MWCNTs as a reinforcement material for enhancing the tribological performance of PMMA. Three types of multi-walled carbon nanotubes, i.e., pristine, hydroxyl functionalized, and carboxyl functionalized, were utilized in this study. The nanocomposite samples were prepared by dispersing varying concentrations of MWCNTs (0.1 wt.%, 0.5 wt.%, and 1 wt.%) within the PMMA matrix via a 3D mixing approach, followed by injection molding/compression molding. The resulting nanocomposite films were characterized using scanning electron microscopy (SEM) to observe the dispersion of MWCNTs within the PMMA matrix. The friction and wear tests were conducted using a pin-on-disk tribometer under dry sliding conditions. The effects of functionalization and MWCNT content on the tribological behaviors of the nanocomposites were analyzed. The nanocomposites exhibited lower friction coefficients and reduced wear rates compared to pure PMMA. The lowest friction coefficient and wear rate were achieved at an optimum MWCNT loading of 0.5 wt.%. It was further revealed that the amount of MWCNT reinforcement, average load, and track diameter significantly affect the coefficient of friction (COF) and rate of wear. The COF and wear rate are best at a filler loading of 0.5 wt.%, a 20 Kg load, and 90 mm. The improved tribological performance of the MWCNT-reinforced PMMA nanocomposites can be attributed to the effective transfer of load between the MWCNTs and the PMMA matrix, as well as the reinforcement effect of the MWCNTs. The MWCNTs acted as reinforcing agents, enhancing the mechanical properties and wear resistance of the nanocomposites.

Extrinsic/intrinsic cohesive zone modelling and experiments on interface failure of multi-walled carbon nanotube reinforced adhesively bonded joints under mode II loading

The present work is primarily concerned with determining mode II cohesive zone parameters for eliminating the crack tip stress-field singularity for constant, linear, and parabolic extrinsic cohesive zone models (CZMs). A semi-analytical approach is used to estimate the stress intensity factor (SIF) associated with the cohesive zone ahead of the physical crack tip. Simultaneously, the obtained SIF is compared with the popular Interaction integral technique results considering the influence of crack face traction. The influence of the order of the traction-separation law (TSL) on the global load–displacement responses is numerically investigated using a crack propagation methodology based on the nullification of SIF. The effectiveness of the proposed approach has been demonstrated through a series of experiments involving the failure of epoxy-based adhesively bonded modified compact tension specimens (CTS) subjected to pure mode II loading. The adhesives are reinforced with different multi-walled carbon nanotubes (MWCNTs) reinforcement of 0.1 wt%, 0.2 wt%, and 0.3 wt%, and its effect on the global load vs displacement responses are recorded. Specific cohesive zone parameters are obtained for the experimental problem to model the failure behaviour for a broad spectrum of cases considered using extrinsic and intrinsic TSLs.

Analysis of the Multiwalled Carbon Nanotubes Reinforced Polymethyl Methacrylate Bone Cement’s Characteristics and In Vitro Bioactivity to Prolong Its Functionality in Orthopedic Application

Polymethyl methacrylate (PMMA) bone cement is being used to fill voids that are created due to vertebral compression fractures. It is also a grouting medium in orthopedic joint replacement surgeries as they possess fast primary fixation to the bone. Considering the cement properties and in vitro bioactivity of bone cement is essential for cemented hip and knee joint replacement surgeries. In this study, commercial Simplex P bone cement (SPBC) is modified with carboxyl- (-COOH-) functionalized multiwalled carbon nanotubes (MWCNTs) to overcome high polymerization temperature, volumetric shrinkage, surface wettability, and in vitro bioactivity. A geometric dilution method is used to incorporate MWCNTs with the PMMA powder, which is in unequal proportions. The PMMA/MWCNT nanocomposite with different concentrations of reinforcements, such as 0.1, 0.3, 0.5, and 0.7 weight percentages, is prepared for the investigation. It was observed that the MWCNTs had a beneficial impact on PMMA bone cement (PMMA-BC) by enhancing its setting time (2.94%↑) and surface wettability (23.58%↑). Also, diminished polymerization temperature (29%↓) and volumetric shrinkage (40.9%↓) are observed for an optimum concentration of 0.7 wt. %. The bioactivity of the cement surface is validated by the in vitro bioactivity observed in simulated body fluid (SBF) through the development of primary and secondary apatite. It is concluded that the synthesized PMMA/MWCNT nanocomposites are found to have enhanced cement properties compared to PMMA-BC.

High-strain-rate Response of GFRP Composites Impregnated with Multiwalled Carbon Nanotube Reinforced Shear Thickening Fluid

High-strain-rate Response of GFRP Composites Impregnated with Multiwalled Carbon Nanotube Reinforced Shear Thickening Fluid

EFFECT OF MULTI-WALLED CARBON NANOTUBES IN REINFORCED HYDROXYAPATITE COMPOSITE COATINGS FOR ORTHOPEDIC APPLICATIONS

Hydroxyapatite (HA)-coated metallic substrates are commonly used for load-bearing orthopedic implants. In this work, Titanium grade 2 and Titanium grade 5 substrates were coated with hydroxyapatite and hydroxyapatite reinforced with 5% (by wt.) multiwalled carbon nanotubes (MCNT) separately using plasma spray coating. The wear behavior of these coated substrates was studied with the simulated body fluid (SBF) having a pH between 7.20 and 7.40. Fracture toughness and wear resistance of HA reinforced with 5% (by wt.) MCNT composite coating was found to be higher as compared to pure HA coating. This improvement is by virtue of inherent mechanical properties and the crack bridging effect offered by MCNT. The addition of MCNT also helped in restricting crack propagation in the coatings. As evident from SEM images, abrasive and adhesive wear mechanisms were observed which reduce greatly with the reinforcement of MCNT.