Multi-walled Carbon Nanotubes Particles Research Articles

Incorporating multi-walled carbon nanotubes in rubberized concrete: impact on physical, mechanical, and fire resistance properties

In the current study, multi-walled carbon nanotubes (MWCNTs) were added to the crumb rubber concrete (CRC) to enhance its physical, mechanical, and fire-resistance properties. A comprehensive investigation into thirteen distinct concrete mixes incorporating rubber aggregate (RA) at levels of 5, 10, and 15%, combined with varying percentages (0, 0.1, 0.2, and 0.3%) of MWCNTs particles, evaluated workability, density, compressive strength, split tensile strength, and flexural strength of MWCNT-mixed CRC at ambient and elevated temperatures (200, 400, and 600 °C). The study demonstrated that MWCNTs, used as a partial substitute for cement in CRC, significantly improved concrete properties, enhancing density, flexural strength, split tensile strength, and compressive strength. Notably, adding 0.2% MWCNTs to CRC resulted in remarkable increases: 0.96% in density, 21.91% in 28-day compressive strength, 10.19% in split tensile strength, and 15% in flexural strength. The workability of CRC decreased with the inclusion of MWCNTs. Furthermore, results indicated that MWCNTs bolstered the residual compressive, tensile, and flexural strengths of rubberized concrete at elevated temperatures, with substantial improvements particularly evident at 200 °C. The present work was focused on the analysis of feasibility of MWCNT mixed CRC toward sustainable construction practices by comparing its physical, mechanical, and fire resistance properties with conventional concrete.

Incorporating multi-walled carbon nanotubes in rubberized concrete: impact on physical, mechanical, and fire resistance properties

In the current study, multi-walled carbon nanotubes (MWCNTs) were added to the crumb rubber concrete (CRC) to enhance its physical, mechanical, and fire-resistance properties. A comprehensive investigation into thirteen distinct concrete mixes incorporating rubber aggregate (RA) at levels of 5, 10, and 15%, combined with varying percentages (0, 0.1, 0.2, and 0.3%) of MWCNTs particles, evaluated workability, density, compressive strength, split tensile strength, and flexural strength of MWCNT-mixed CRC at ambient and elevated temperatures (200, 400, and 600 °C). The study demonstrated that MWCNTs, used as a partial substitute for cement in CRC, significantly improved concrete properties, enhancing density, flexural strength, split tensile strength, and compressive strength. Notably, adding 0.2% MWCNTs to CRC resulted in remarkable increases: 0.96% in density, 21.91% in 28-day compressive strength, 10.19% in split tensile strength, and 15% in flexural strength. The workability of CRC decreased with the inclusion of MWCNTs. Furthermore, results indicated that MWCNTs bolstered the residual compressive, tensile, and flexural strengths of rubberized concrete at elevated temperatures, with substantial improvements particularly evident at 200 °C. The present work was focused on the analysis of feasibility of MWCNT mixed CRC toward sustainable construction practices by comparing its physical, mechanical, and fire resistance properties with conventional concrete.

Magnetohydrodynamic Casson SWCNT-MWCNT/EG hybrid nanofluid flow over a stretching cylinder with Cattaneo-Christov double diffusion model

The present problem examines the flow features of a two-dimensional time-independent Casson hybrid nanofluid on a stretching cylinder with dual stratification and MHD effects. Heat and mass transfer effects are analyzed by utilizing the Cattaneo-Christov double diffusion scheme with entropy generation. Further, the energy losses due to viscous and Joulian dissipation are also considered in the problem. Due to the high thermal conductivity nature of the carbon nanotubes, which plays a crucial role in cooling systems, material sciences, electrical components and treatment of cancer cells, single and multi-walled carbon nanotube particles (SWCNT, MWCNT) are considered in the hybrid nanofluid. The carbon nanotubes are mixed with base fluid ethylene glycol (EG) to form the required hybrid nanofluid. Suitable transformations are adopted for transforming the non-linear PDEs to non-linear ODEs of the mathematical model. Then, the system of ODEs are resolved by utilizing bvp4c numerical approach in MATLAB software. The impact of the various flow pertinent parameters on the flow model are disclosed through graphs and tables and then explained elaborately. The important findings of the study reveal a reduction in the absolute value of coefficient of surface friction with the Casson and velocity slip parameters. The entropy generation rate (NG ) is diminished due to slip parameters, whereas the opposite effect is observed due to the SWCNT nanoparticle volume fraction. The thermal and mass relaxation parameters induce a significant amplification in the rates of heat and mass transport, respectively. Furthermore, it is observed that the heat and mass transfer rates of EG-based SWCNT – MWCNT hybrid nanofluid perform better than those of EG-based SWCNT nanofluid. The outcomes of the investigation exhibit an excellent agreement with the previously published results. The present analysis has applications in cancer therapy, microelectronics cooling, industrial heat generators, nuclear reactor maintenance, electrolytic condensers, and many more.

Effects of electroless nickel -coating on tribological and corrosion behaviour of TMT steel rebar with multi-walled carbon-nanotube and titanium dioxide nanoparticles

This study incorporated Multi-walled carbon nanotube particles (MWCNTs) and Titanium Dioxide Nanoparticles (TiO2) into a metal matrix composite in Ni–P coated substrate using an Electroless technique. This study significantly improves the tribological properties, enhances corrosion resistance, increases durability and extends the service life of coated rebar. Coated rebar helps make infrastructure more sustainable by extending the life of buildings and lowering their material consumption, trash output, and ecological footprint. The tribological behaviour of steel rebar has been studied by using a variety of characterization techniques, like X-ray diffraction, Atomic Force Microscopy, Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (EDX) including the corrosion test and the hardness test. The topographical roughness of the bare specimen, Ni–P coated specimen, CNT coated specimen and TiO2 coated specimen are 67.4 nm, 112 nm, 201 nm, and 162 nm respectively. The microhardness of the bare substrate, Ni–P coated, CNT doped coated, and TiO2 dopped coated specimens was done using Vicker's Hardness tester and the mean values were 455 HV, 580 HV, 810 HV, and 680 HV respectively. Resistance to corrosion of TMT steel rebar of Fe500 was examined using the polarisation method and Electrochemical-Impedance-Spectroscope (EIS) method. These techniques were examined in 3.5 wt% aqueous medium of NaCl and analysed the Ecorr (corrosion potential) and Icorr (Corrosion current density) of the bare substrate, Ni–P coated, Ni–P/CNT and Ni–P/TiO2 substrate. The corrosion inhabitation efficiency of the Ni–P-CNT doped was 22.5% more than the Bare substrate, and the TiO2 doped coated specimen was 10.63% more than the bare substrate. Resistance to corrosion of the CNT-coated substrate is better than Ni–P/TiO2 and Ni–P-coated specimens.

Comparative Study of Carbon Nanotubes and Lignosulfonate as Polyvinyl Acetate (PVAc) Wood Adhesive-Reinforcing Agents

This study aimed to reinforce a polyvinyl acetate-D3 (PVAc-D3) adhesive to improve its mechanical and thermal properties. The goal was to reach a polyvinyl acetate-D4 (PVAc-D4) adhesive performance that could make PVAc-D3 more attractive and add value to wood products. PVAc-D3 was modified by adding 0.05% and 0.5% (wt.) of multi-walled carbon nanotube particles (MWCNTs) as well as 0.5% and 2.5% (wt.) of lignosulfonate (LIGNO) particles. Adhesive blends were compared to neat PVAc-D3 and PVAc-D4, evaluating their physical–chemical properties. Also, they were analyzed using Fourier transform infrared spectroscopy (FT-IR) and mechanical dynamic analysis (DMA) with a storage module (E′). The blends were used to fabricate laminated wood pieces, pressed at 60 and 120 min (min), to be tested at shear strength under dry, elevated temperature and vacuum-pressure conditions. Delamination and adhesive penetration were determined by microscopy. Incorporating fillers into PVAc resulted in a decrease in viscosity. FT-IR evidenced that the PVAc-D4 adhesive had a bigger cross-linked degree than the other adhesive samples. The DMA showed that LIGNO and MWCNT fillers help increase E′ at the bond line, reaching a higher stiffness level than neat PVAc-D3. In dry conditions, specimens glued with D3-LIGNO 0.5% at 120 min reached shear strengths that were 100%, 28%, and 3% higher than the standard requirement, PVAc-D4, and neat PVAc-D3, respectively. Also, those glued with D3-MWNTC 0.05% reached shear strengths that were 91%, 21%, and 3% higher than the standard requirement, D4, and neat D3, respectively. Only PVAc-D4 reached the standard requirement for elevated temperature and vacuum-pressure conditions. Delamination of ≤5% (standard requirement) was achieved by wood specimens glued with neat PVAc-D3, D3-MWNTC 0.5%, D3-LIGNO 0.5%, and PVAc D4 adhesive samples. In this study, it was found specific ranges of average penetration (AP) to ensure a glue line good quality. To conclude, LIGNO and MWCNT particles improved the PVAc-D3 adhesive’s performance in dry conditions, but they were not very relevant to the D3 adhesive’s behavior. At high temperatures, the LIGNO filler worked very well as a thermic stabilizer compared to the MWCNT filler. The solubility of the reinforcing agent can affect an adhesive’s blend quality and its cohesion properties. An adequate penetration depth procures a good quality bond between an adhesive and substrate with less possibilities of delamination. An extensive pressing time may cause a weak interphase and poor mechanical properties in an adhesive bond in the presence of humidity.

Study of the Effect of Multi-Walled Carbon Nanotubes on the Mechanical Properties of Poly(Vinyl Alcohol)/Polyaniline Blend Film

In this research, poly(vinyl alcohol)/polyaniline blend films were fabricated using solution casting technique with different weight ratios of PANI (2, 4, 6, 8, and 10) wt.%. The results showed that the best ratio of the polymer blend was (92% PVA/8% PANI), based on the electrical conductivity of direct current. The results showed that 8 wt.% PANI possessed the highest conductivity. Then, the composite films were prepared by adding multi-walled carbon nanotubes (MWCNT) to the optimum ratio of the polymer blend as a base material and at different weight ratios (0, 1, 3, 5, 7 wt.%). A tension device was used to examine and characterize the prepared samples. It was found that the addition of MWCNT to PVA/PANI caused an obvious decrease in elongation while there was an increase in tension strength and “Young’s modulus”. Optical microscopy results showed a good picture of the distribution of MWCNT particles for composites up to 1 wt.% MWCNT. But, some aggregations can be observed in films with 3, 5, and 7 wt.% MWCNT content.

Role of multi-walled carbon nanotube particles on the wear behaviour of vacuum hot pressed Mg-AZ91 composite

The demerit of Mg-AZ91 alloy is poor wear resistance. In order to increase the wear resistance and decrease the CoF, MWCNT is reinforced in various wt% (0.5, 1, & 1.5) into Mg-AZ91 by a vacuum hot press technique. The OM image of the specimens shows the strong metallurgical bonding between matrix material, uniform dispersion of MWCNT for 0.5 and 1 wt% composites and agglomeration of MWCNT for 1.5 wt% composite. XRD analysis confirms MWCNT presence and peak shift towards a higher angle in the composites. MWCNT reinforced 1 wt% composite has exhibited the highest hardness values of 97.90 HV0.3, good wear resistance (wear rate = 3.28 × 10-5 g/m) due to the strengthening by grain size reduction and a low CoF value of 0.32 due to the self-lubrication effect of MWCNT. SEM investigation confirms that surface fatigue is the dominant wear mechanism in all specimens.

Experimental investigation of the mechanical behaviour of jute/glass fiber composite infused with MWCNT

Composite materials have attracted significant attention due to their superior properties, and this has led to extensive research in the field. To enhance their performance and reduce costs, hybridization of natural and synthetic fibers has become increasingly popular. The current study investigates the mechanical behaviour of jute and glass hybrid composites reinforced with multiwalled carbon nanotube (MWCNT) particles. The composites were manufactured with varying reinforcement fractions (0.5%, 0.75%, 1%, and 2%), and their tensile and flexural strength were evaluated. Additionally, the study examined the influence of hybridization between jute and glass fibers with different fiber stacking sequences, fiber orientations (0°, 30°, 45°, 60°, 90°), and various nano filler percentages. The results indicate a significant improvement in the mechanical performance of composites with increasing reinforcement weight fraction. Specifically, the tensile strength improved by 25% and flexural strength improved by 30% with a reinforcement weight fraction of up to 1 wt%, after which decreasing values were observed due to the agglomeration of nano particles in the matrix. These findings contribute to an understanding of the mechanical behaviour of jute and glass hybrid composites reinforced with MWCNT particles and provide insights for the development of advanced composite materials.

Pore size variation of nano-porous material fixer on the engine bowl and its combined effects on hybrid nano-fuelled CI engine characteristics

Environmental research is currently one of the most significant and pertinent fields of studies. Due to CI engines'unique nature, theyare widely used in densely populated cities for a variety of purposes. However, due to their impropercombustion for various acceptable reasonsat the engine cylinder, they considerably pollute the environment. This study prepared hybrid nano fuel from waste cooking oil by adding Al2O3 (aluminum oxide) and MWCNT (multi-wall carbon nanotubes) particles and adding ZnO (zinc oxide) nanoporous material fixture in the combustion chamber as an attachment for enhancing combustion efficiency to meet the aim of mitigating the CI engine emissions significantly. The research was evaluated in a 5.2 kW CI engine, and the ZnO nano-porous material is fixed to the combustor. Four distinct pores per inch (PPI) nanoporous materials of pore counts such as 60, 45, 30, and 15 PPI were considered to test the fuels such as diesel and hybrid nanofuel. The hybrid nano-fuel was created from the WCO biodiesel by mixing nanoparticles of MWCNT and Al2O3 nanoparticles in the ultrasonicator. The experiments were carried out at different engine loads from no load to full load with a 25% step-up. The performance of the results was compared with conventional diesel fuel with and without ZnO nano-porous material fixtures and ZnO nano-porous material fixtures with different PPI. The result exhibited that the nanoparticles-added biodiesel fuel in 15 PPI has produced less NOx emission, CO emission, and heat release rate by 55.2%, 7%, 26.5%, and 22.67%, respectively, and this combination also exhibited an improvement of 2.62% in the brake thermal efficiency. Finally, the present work proves that better engine characteristics are generally obtained as the pore size of nanoporous materials in the engine bowl gets smaller, and the hybrid nanoparticles usage in the biodiesel fuel ensures more efficient engine combustion, performance, and emission characteristics.

Immobilization of recombinant l-asparaginase from Geobacillus kaustophilus on magnetic MWCNT-nickel composites

In this study, L-asparaginase from thermophilic Geobacillus kaustophilus was heterologously expressed in Escherichia coli and purified by 6.14-fold using Ni-NTA column. The purified GkASNase was immobilized covalently on newly developed magnetic nickel/nickel oxide multi-walled carbon nanotubes particles modified with 3-aminopropyltriethoxysilane or (3-glycidoxypropyl) trimethoxysilane. The results of biochemical characterizations of free and immobilized L-asparaginase samples showed that the optimum pH was 8.5 for all the L-asparaginase samples. However, the optimum temperature was found to be 55 °C for the free enzyme, while the immobilized L-asparaginase samples had an optimum temperature at 60 °C. The thermal inactivation experiments showed that the thermal stability of immobilized L-asparaginase preparations increased at least 40 folds at 60 °C compared to the free enzyme. The both immobilized L-asparaginase preparations remained at least 90 % of their initial activities after 10 reuses. The acrylamide formation was reduced 100 % by the both immobilized L-asparaginase preparations in 60 min, whereas the corresponding value was 98 % for the free enzyme. The results showed that the covalent immobilization of L-asparaginase on modified nickel/nickel oxide multi-walled carbon nanotubes resulted in the obtention of ease of separable, thermally stable, reusable and more effective L-asparaginase preparations in the mitigation of acrylamide compared to free counterpart.

Combination of enhanced strength-ductility trade-off and stress relaxation resistance of MWCNTs reinforced Sn–5Sb-0.3Cu matrix composite

In this study, the strength-ductility trade-off and stress relaxation (SR) behavior of Sn–5Sb-0.3Cu (SSC503) alloy reinforced with (0, 0.05and 0.1 wt%) multi-walled carbon nanotubes (MWCNT) have been investigated under different pre-strains and initial stress levels. The results show that the pre-deformation can extend the duration of initial SR stage and significantly promote the stress reduction rate. The SSC503–0.05MWCNT composite alloy exhibits the optimum increase in SR resistance, yield strength (σy), ductility, and creep threshold stresses with the values of 75.8%, 17.3%, 77.9% and 10.6%, respectively. The scanning transmission electron microscopy (STEM) images and electron probe microanalyzer (EPMA) revealed that the distribution of MWCNT in SSC503 alloy was concentration dependent. 0.05MWCNT concentration induced a dendritic/cellular transition of β-Sn grains and restrained the growth of β-Sn, Cu6Sn5, SnSb, Sn3Sb2 and Cu2Sb IMC compositions, whereas 0.1MWCNT led to the partial agglomeration of MWCNT into β-Sn grain surfaces. MWCNTs are adsorbed at the surface-active atoms of Sb metalloid to form Sb-coated MWCNTs (Sb/C) in situ, which act as a bridge between MWCNT and Cu6Sn5 particles. The modified composites represent a vital technological progress for utilization in high temperature solder applications.

Experimental and 3D-Deform Finite Element Analysis on Tool Wear during Turning of Al-Si-Mg Alloy

Aluminum alloys are becoming increasingly significant in the manufacturing industry due to their light weight and durable properties. Widely applied in aerospace and construction, precision machining is required to ensure the best possible surface quality. The surface quality of a machined component is directly affected by the tool wear incurred during machining. This research investigated the effect of process parameters and machining conditions on tool wear. The critical process parameters selected were cutting speed, feed rate, and depth of cut. Multi-walled carbon nanotube particles were dispersed in a base fluid of mineral oil to create a new lubricant applied during machining. Pure mineral oil was also used as a lubricant to reduce friction. Machining experiments were carried out with the two lubricants, and the tool wear incurred was measured and compared using a Dinolite microscope. All experiments were carried out with high-speed steel (HSS) cutting tools. Taguchi’s L9 orthogonal array was employed as a methodology to design the experiments. A finite-element 3D simulation was also carried out using DEFORM-3D to provide a scientific explanation of the turning process. Results showed a significant reduction in tool wear when machining with multi-walled carbon nanotubes (MWCNTs), with an average reduction of 14.8% compared to mineral oil. The depth of cut was also the most influential process parameter in terms of tool wear.

Optimization of Electrode Material Composition from Activated Carbon, MWCNT & Graphene to Enhance Performance of Supercapacitor

The supercapacitor has gotten a lot of attention as a high-performance energy storage device because of its high power density, good energy density, long life cycle, and extensive application in various electronic applications. To effectively assess its performance, the electrode material composition was optimized with a blend of activated carbon (AC), multiwall carbon nanotube (MWCNT), and graphene (GR). The synergistic effect of AC, CNT, and GR supports the usage of AC/MWCNT/GR as a viable supercapacitor electrode. Furthermore, the surrounding MWCNT enhances AC and GR electronic conductivity, while AC efficiently suppresses GR re-stacking sheets and aggregates MWCNT particles. For supercapacitor electrodes, the optimal composite mixtures of AC, MWCNT, and GR were 71.7%, 20%, and 8.3% wt, respectively. Meanwhile, an outstanding capacitance value of 33.5 F g-1 in 6 M KOH electrolyte was obtained at 2 mV s-1.

Microwave Absorption Properties of Multi-Walled Carbon Nanotubes/Carbonyl Iron Particles/Polyurethane Foams.

In order to improve the microwave absorption performance of absorbing materials, the composite foam absorbing materials with different multi-walled carbon nanotube (MWCNT) contents were prepared using polyurethane foam as the substrate and MWCNTs and flaked carbonyl iron powder as absorbers. The electromagnetic properties of the materials were characterized and analyzed. Then, CST electromagnetic simulation software was used to simulate the electromagnetic shielding effect of absorbing materials on mechatronics products under a strong electromagnetic irradiation environment, and, finally, it was verified by irradiation experiment. The results show that the materials have good microwave absorption properties, in which the composites containing 1.5 wt.% MWCNTs exhibit good microwave absorption properties. The minimum reflectivity reaches −29 dB when the thickness is 3 mm and −15.6 dB when the thickness is 1.5 mm, with a bandwidth of 5.7 GHz for reflectivity less than −10 dB. The good microwave absorption performance of the material is due to the synergistic effect of MWCNTs particles and good impedance matching. The simulation and experimental results show that the mechatronics product with absorbing materials can protect against strong electromagnetic interference and ensure the normal operation of the mechatronics product circuits.

Effect of Nanosilica and Multiwalled Carbon Nanotubes on the Mechanical and Impact Performance of Unidirectional Kevlar/Epoxy Based Composites

The introduction of numerous nanoparticles into nanotechnology in recent years has opened the door for the incorporation of nanoparticles into polymeric-based composite materials for mechanical improvement. Composite materials are becoming a promising substitute material in the fabrication of numerous components due to their high weight-to-strength ratio and mechanical characteristics such as tensile Strength, flexural Strength, interlaminar shear strength, and impact strength. This research aims to determine the effect of a combined mixture of silica and multiwalled carbon nanotube particles (MWCNT) on the mechanical and impact properties of unidirectional Kevlar (UD)/epoxy composites for use in defence and aerospace applications. The addition of these Nanofillers results in high-performance reinforcement and the formation of hybrid composites with improved properties due to their use. The addition of specific nanomaterials can further enhance these characteristics, dependent on the concentration at which they are introduced into the solution. The most challenging aspects of incorporating nanomaterials into matrix materials are ensuring uniform mixing of the nanomaterials with the matrix material and increasing the viscosity of the matrix material when the nanomaterials are introduced into the matrix. Using different weight percentages, it is possible to determine the optimal ratio of nanofiller for predicting the enhanced mechanical properties of nano-composites. Preparation of the composite with different weight percentages (1 percent and 3 percent) of Nano SiO2 particles mixed with 0.25 percent MWCNT and 6 layers of the UD Kevlar fibre was accomplished using an ultrasonic vibration-assisted hand layup process. Tensile tests, Charpy impact tests, and interlaminar shear strength tests evaluated the material's mechanical properties. Experimental results revealed that tensile strength and impact strength increased by up to 80 percent and 50 percent, respectively, compared to the neat specimens. The ILSS test demonstrates a 271 percent improvement in shear strength at 3 percent and 0.25 MWCNT. The overall results determined that the combination of 3 percent SiO2 and 0.25 percent MWCNT provided the most enhanced mechanical properties while also being the most optimized. This study's findings indicate that applying a nano-silica and MWCNT mixture of Nanofillers to Kevlar fabrics is a promising method for improving a Kevlar-based hybrid composite's mechanical and impact energy absorption laminate.

The Effect of Multi-Walled Carbon Nanotubes Additives on the Tribological Properties of Austempered AISI 4340 Steel

Due to a combination of optimal properties such as great strength, high hardness, good process ability, and good mechanical properties, AISI 4340 steel is widely used in many critical industrial applications such as nuclear, military, defense, and aerospace. It is also widely used in hydraulic forged machine tools, forged automotive crankshaft systems, shafts and gears, because of their improved characteristics, and its good tribological properties. The purpose regarding this work is to check the tribological characteristics of austempered AISI 4340 steel while dry and lubricated with machinery oil of SAE 30 grade as base oil. As received, AISI 4340 steel samples have been austempered to four definitely austenitic phase temperatures (850℃, 900℃, 1000℃, and 1050℃) for 90 minutes before being immersed in a mixture of potassium nitrite and sodium nitrite at 400℃ for 45 minutes. Friction and wear tests were then performed on austempered samples. Multi-walled carbon nanotube particles were blended at weight concentrations of 0.055, 0.1, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, and 0.45 with typical machinery oil of 30 grade as base lubricant oil. A pin on the disc wear configuration was used in the experimental investigation. The use of Multi-Walled Carbon Nanotube (MWCNTs) additives in the base oil resulted in a decrease in both friction coefficients and wear rates values when compared to typical base oil lubricant. The results also showed a reduction in both friction coefficients and wear rates as the sample's austempering temperatures were raised. Sliding surfaces were also photo micro graphed, and when the volume concentrations of Multi-Walled Carbon Nanotube particles in the normal base oil lubricant were increased, smoother surfaces with less damage were shown.

A comparative study on thermophysical properties of functionalized and non-functionalized Multi-Walled Carbon Nano Tubes (MWCNTs) enhanced salt hydrate phase change material

Thermal energy storage (TES) system is one of the best options for harvesting, storing, and saving energy for long-term or short-term use of a modern energy production system. The nano-enhanced phase change materials (NePCM) are a new type of phase change materials (PCM) formed by suspended nano-sized particles in base PCM to improve the thermophysical properties of the base PCM. The major challenge in nanoparticle dispersion in PCM, especially for solar energy applications, is its poor thermal conductivity and light transmission capability. Present research aims to address the thermal conductivity and light transmission capability issues by dispersing pristine multi-walled carbon nanotube (MWCNT) and functionalized multi-walled carbon nanotube (FMWCNT) particles in various weight concentrations (0.1, 0.3, 0.7, and 1.0%) into the salt hydrate PCM. A two-step technique was implemented to develop the NePCM for various weight percentage of MWCNT and FMWCNT. The Fourier transform infrared (FTIR) spectrum shows the MWCNT and FMWCNT nano-sized particles physically mixed well in salt hydrate PCM and without disturbing the chemical properties. The thermal conductivity of developed composites at 0.7 wt% MWCNT/S50 (S50M-0.7) and 0.7 wt% FMWCNT/S50 (S50F-0.7) are 0.78 W/mK, and 0.92 W/mK, respectively. The Differential Scanning Calorimetry (DSC) results revealed that the maximum improvement in latent heat by 14.66% and 31.17% for 0.1 wt% MWCNT/S50 (S50M-0.1) and 0.3 wt% FMWCNT/S50 (S50F-0.3) respectively. Light transmittance of S50M-0.7 and S50F-0.7 reduced to 92% and 93.49% than pure salt hydrate PCM. It exhibits the reduction in transmittance, greater improvement in solar spectrum absorption, and excellent photothermal conversion. • Study on Functionalized and non-Functionalized MWCNT enhanced PCM. • Comparative thermal performance of MWCNT and FMWCNT enhanced salt hydrate PCM. • A remarkable enhancement in thermal conductivity by 100% for S50F-0.7 • A substantial reduction in light transmittance by 93.49% for S50F-0.7 than base PCM.

Interactions between multi-walled carbon nanotubes and plankton as detected by Raman spectroscopy

Raman spectroscopy has been commonly used in materials science to detect chemicals. Based on inelastic scattering of light after incident photons interact with a molecule, it has high potential for non-destructive detection of specific contaminants in living biological specimens. The increasing use of carbon nanotubes (CNTs) increases its chance to enter the aquatic habitats through direct discharge, surface runoff and atmospheric deposition, but their potential environmental impacts remain poorly known. We tested the use of Raman spectroscopy to investigate the interactions between multi-walled CNTs (MWCNTs) and aquatic plankton in vivo. For phytoplankton cells (Scenedesmus obliquus) that were exposed to MWCNTs, Raman spectroscopy was able to distinguish between background biological material and MWCNTs that adhere to the cells (G-band peak at 1590 cm−1 and D-band peak at 1350 cm−1 in the Raman spectra that were unique to MWCNTs). Harmful effects of MWCNT exposure manifested as lower photosynthetic efficiency and/or lower specific growth rate in the phytoplankton. MWCNT particles also adhered to the body surface of zooplankton, especially the carapace. Both Ceriodaphnia sp. and Daphnia sp. ingested MWCNTs directly, which was verified by the signature G-band and D-band Raman peaks in the zooplankton gut region. MWCNTs remained in the gut overnight after the zooplankton had been returned to clean water, showing that the zooplankton retained MWCNTs inside their body for an extended time, thereby increasing the chance to disperse and transfer the contaminants throughout the aquatic food web. Our results demonstrate that Raman spectroscopy is a promising method for non-destructive investigation of the uptake and dynamic fate of CNTs and other contaminants in aquatic organisms.

Investigating on the influence of multi‐walled carbon nanotube and graphene nanoplatelet additives on residual strength of bonded joints subjected to partial fatigue loading

AbstractAdhesively bonded joints in engineering structures, especially automotive body structures, inevitably experience long or limited fatigue loading conditions. In this article, the shear strength of steel bonded lap joints reinforced by multi‐walled carbon nanotube (MWCNT) and graphene nanoplatelet (GNP) were evaluated after being subjected to limited fatigue loading cycles. For this purpose, three specimen groups of neat, MWCNT, and GNP‐reinforced joints (with 0.2, 0.5, 1.0, and 2.0 wt% contents) were prepared. After performing the static lap shear tests, fatigue testing of each specimen group was conducted under a maximum fatigue load of 50% of its average static failure load until complete separation of the substrates. Accordingly, limited fatigue loadings were applied to each specimen group for 30%, 50%, and 70% of its total fatigue life, and subsequently, a second‐round static testing was performed to evaluate the residual strength of the joints. The results revealed that the maximum static shear strength improvements of MWCNT and GNP‐reinforced joints were associated with incorporating 1.0 and 0.5 wt% particle contents. Moreover, for 0.2 and 0.5 wt% contents, the static strength of the joints reinforced by GNPs was 3.4% and 3.9% greater than that of MWCNTs reinforced joints. On the contrary, for 1.0 and 2.0 wt% filler contents, specimens including MWCNTs had 9.1% and 18.6% higher strength than GNP‐reinforced ones. The highest fatigue life enhancements of 34.1% and 31% were obtained by adding 1.0 and 0.5 wt.% of MWCNT and GNP particles to the adhesive, respectively. It was concluded that, for 0.2 and 0.5 wt% contents, nanoparticle type did not have a noticeable effect on the residual strength of the joints after being subjected to fatigue loading for 30% of its total life. The specimens subjected to 50% and 70% of their total fatigue life indicated a minimum loss in the shear strength for the joints reinforced by dispersing 1.0 wt% of MWCNTs.

Numerical study of MWCNT enhanced PCM melting through a heated undulated wall in the latent heat storage unit

The use of phase change materials (PCMs) is an efficient passive technique for thermal energy management. However, its low thermal conductivity presents significant technological challenges. Several methods have thus been employed to improve the thermal performance of a latent heat thermal energy storage (LHTES) unit. Here, the melting and heat transfer characteristics for the multi-walled carbon nanotube (MWCNT) enhanced PCM (n-octadecane) inside a square duct with a vertical undulated wall has been examined. Extensive results on streamlines, temperature contours, rate of melting and energy storage, and the Nusselt number have been presented to delineate the influence of various pertinent parameters as: amplitude of undulations (0 ≤ α ≤ 0.002 m), wavelength of undulations (0.0025 ≤ λ ≤ 0.02 m) and volume fraction of MWCNT particles (0 ≤ ϕ ≤ 0.06). In addition, the results from two different heat flux conditions, namely, uniform and sinusoidal heat flux have also been compared. Overall, the complete melting time reduces drastically with an increase in the value of the amplitude to wavelength ratio (α/λ). This functional dependence has been presented in form of a simple predictive correlation. Also, an increase in the volume fraction of MWCNT particles in the PCM enhances the rate of melting. However, this enhancement is more significant for high values of α/λ.