Addition Of Multi-walled Carbon Nanotubes Research Articles

Structural, optical, morphological and mechanical studies of polyethylene oxide/sodium alginate blend containing multi-walled carbon nanotubes

Multi-walled carbon nanotubes were added to mixture of polyethylene oxide (PEO)/sodium alginate (SA) (70/30 wt.%) films via the casting way. X-ray diffraction exhibited the amorphous behavior of the polymer samples, also showed a decrease in the crystalline ratio after the addition of Multi-walled carbon nanotubes (MWCNTs). Fourier Transform Infrared (FTIR) spectroscopy exhibited changes in intensity of some peaks after embedding of MWCNTs, these changes were related to the interaction between PEO/SA blend and MWCNTs. The optical properties of samples were investigated by ultraviolet and visible (UV/vis) spectroscopy and showed decrease in optical energy gap as the concentration of MWCNTs increased. Scanning electron microscopy (SEM) exhibited a homogeneous growth mechanism which denotes the partial compatibility between the nanocomposite components. The mechanical behavior measurements of the prepared samples showed improvement of the modulus of elasticity and tensile strength after adding MWCNTs. This may be due to interaction and adhesion between MWCNTs and polymeric samples. Present results confirm the advantage of selecting MWCNTs as a nanofiller to improve the optical and mechanical properties of polymeric films.

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.

Study on the viscoelastic behaviour of the modified asphalt containing multi-walled carbon nanotubes (MWCNTs) and crumb rubber (CR)

Asphalt binder plays an important role on the performance of asphalt mixture, especially for the high-temperature performance. The purpose of this research is to investigate the viscoelastic behaviours of the modified asphalt containing multi-walled carbon nanotubes and crumb rubber. By adding multi-walled carbon nanotubes and crumb rubber to the base asphalt, the multi-walled carbon nanotubes modified asphalt, crumb rubber modified asphalt and multi-walled carbon nanotubes and crumb rubber composite-modified asphalt were prepared. The high-temperature viscosity and rheological property indices were obtained through the viscosity test and small amplitude oscillatory measurement. Besides, multiple stress creep recovery test and stress relaxation test were utilized to explore creep recovery behaviours and stress relaxation characteristics of the asphalt samples. Based on the time-temperature superposition principle, the master curves of complex shear modulus and phase angle were generated. Han curves of the asphalt samples were established based on superposition principle of Blotzmann. Furthermore, the Burgers model was used to model the creep-recovery data. The relaxation functions of Maxwell model and Burgers model were applied to fit stress relaxation curves of the asphalt samples. Results indicate that, the addition of multi-walled carbon nanotubes and crumb rubber caused an increase in high-temperature viscosity, and reduce the temperature susceptibility of base binder. In addition, the permanent deformation resistance, creep-recovery behaviours and stress relaxation characteristics of asphalt were enhanced remarkably by the two modifiers modification. Lastly, the composite-modified asphalt exhibited better viscoelastic behaviours than asphalt modified with either crumb rubber or multi-walled carbon nanotubes alone.

Enhancing the Heat Storage Performance of a Na2HPO4·12H2O System via Introducing Multiwalled Carbon Nanotubes.

The hydrated salt disodium hydrogen phosphate dodecahydrate (DHPD, Na2HPO4·12H2O) has a suitable phase transition temperature and high latent heat of phase transition. Still there are problems such as supercooling, phase separation, and low thermal conductivity. In this paper, DHPD, sodium carboxymethyl cellulose (CMC), aluminum oxide (Al2O3), and poly(vinylpyrrolidone) (PVP) are used to configure DHPD-CAP to suppress supercooling and phase separation successfully. Multiwalled carbon nanotubes (MWCNTs) are used to stabilize DHPD-CAP phase-change materials and improve the thermal conductivity of pure DHPD. Further studies show only a physical interaction between MWCNTs and DHPD, and no new phases are generated. The addition of MWCNTs can also promote the nucleation of the DHPD-CAP composite, and the corresponding latent heat of phase change shows a trend of increasing and then decreasing with the increase of MWCNT content. Compared with DHPD after one cycle, the latent heat of DHPD-CAP/MWCNT4 increases by 36.19%. With the addition of MWCNTs, the thermal stability of the composites is improved compared to pure DHPD. The DHPD-CAP/MWCNT4 composite has good stability after many cycles.

Polymer Blends and Polymer Nanocomposites for Photovoltaic (PV) Cells and an Investigation of the Material Deposition Techniques in PV Cell Fabrication

Polymer photovoltaics (PV) offer the advantage of low-cost, mass-produced, flexible PV films, but they generally suffer from a low-power conversion efficiency (PCE) compared to silicon. This paper studies ITO/PEDOT:PSS/bulk heterojunction/Al PV cells, where two different bulk heterojunction blends are researched: P3HT/PC61BM and PCDTBT/PC70BM. The addition of multiwall carbon nanotubes (CNT) is explored as a conductive network to accelerate the electron transport and extraction to the outer aluminium current collector while reducing the chance of charge recombinations. Several layer deposition techniques are investigated: spin coating and casting, as well as techniques that would induce transverse orientation of polymer grains, including inkjet printing, electrophoresis and the application of a transverse AC field during annealing. Transverse orientation techniques produced architectures that would facilitate charge transport without recombinations, but it is recommended to avoid such techniques for the deposition of conductive PEDOT:PSS and CNT layers as they create a high surface roughness that leads to short circuiting. The best performing PV cell is the ITO/PEDOT:PSS/PCDTBT/PC70BM/CNT/Al structure with a PCE of 11%.

Carbon Nanotubes Blended Nematic Liquid Crystal for Display and Electro-Optical Applications

In this paper, we investigate a commercial nematic liquid crystal (LC) mixture namely E7 dispersed with small concentrations of multi-walled carbon nanotubes (MWCNTs). The dielectric and electro-optical characterizations have been carried out in the homogeneously and vertically aligned LC cells. The electro-optical response of LC molecules has been enhanced by 60% after the addition of MWCNTs, which is attributed to the reduced rotational viscosity in the composites. MWCNTs act like barricades for ionic impurities by reducing them up to ∼34.3% within the dispersion limit of 0.05 wt%. The nematic–isotropic phase transition temperature (TNI) of the E7 LC has also been shifted towards the higher temperature, resulting in a more ordered nematic phase. The enhanced birefringence and orientational order parameter in the LC-MWCNTs are attributed to π-π electron stacking between the LC molecules and the MWCNTs. The outlined merits of the LC-MWCNTs composites evince their suitability for ultrafast nematic-based electro-optical devices.

Thermophysical and tribological behaviors of multiwalled carbon nanotubes used as nanolubricant additives

This study investigates the thermophysical and tribological characteristics of engine oil (SAE 10W-40) using multiwalled carbon nanotubes (MWCNTs) as nanolubricant additives. The MWCNT additives based nanolubricant were formulated using an ultrasonic probe. The tribological performances of MWCNTs nanolubricant were evaluated by a reciprocating platform that simulated the piston ring and cylinder liner interface under various circumstances (i.e., contact loads and sliding velocity). The thermophysical performances of MWCNTs nanolubricant were evaluated using ultraviolet-visible spectrometry, Brookfield viscometers, a thermal conductivity meter, and thermogravimetric analysis. Furthermore, the wear mechanisms of the frictional surfaces were supported by field emission scanning electron microscopy and energy dispersive spectrometer. Critically, the flow characteristics of MWCNTs nanolubricant samples displayed non-Newtonian (shear-thinning) behavior, but the behavior of SAE 10W-40 oil was similar to Newtonian fluids. The friction coefficient decreased by 4%–34% and 26%–32% at different loads and speeds. Moreover, the specific wear rate of the ring and liner surfaces decreased by 29% and 40%, respectively, at 240 N load and 0.33 m s−1 velocity after a sliding distance of 22.57 km. These results suggest that MWCNT additives based nanolubricant effectively lubricated the mechanical applications.

Attapulgite and multiwalled carbon nanotubes co-integrated hierarchical porous polyacrylonitrile membrane as a multifunctional interlayer for lithium-sulfur batteries with enhanced performance

• ATTP and MWCNTs co-integrated porous PAN membrane was first fabricated. • The membrane was investigated as a multifunctional interlayer for Li-S batteries. • A synergistic effect of ATTP and MWCNTs effectively suppress the shuttle effect. • The cell with such interlayer demonstrates superior cycling stability . As a kind of natural porous nanorods, attapulgites (ATTP) are widely used in many fields because of their high specific surface area, high porosity and strong adsorption ability. In this work, ATTP and multiwalled carbon nanotubes (MWCNTs) co-integrated polyacrylonitrile (PAN) hierarchical porous membrane (ATTP/CNTs@PAN) has been fabricated and investigated as a multifunctional interlayer for lithium-sulfur batteries. Due to a synergistic effect of ATTP and the carboxylated MWCNTs, the porous interlayer is able to effectively suppress the shuttle effect by trapping and confining the dissolved polysulfides. Meanwhile, the addition of MWCNTs improves the conductivity of the composite membrane, which is beneficial for the reutilization of the active species. Therefore, the cells with the interlayer demonstrates superior electrochemical performance, delivering a high initial discharge capacity of 1283 mAh g −1 at 0.2 C, and retaining 785 mAh g −1 after 300 cycles with a Coulombic efficiency exceeding 99%. Meaningfully, this porous composite membrane is low-cost and very effective for high performance Li-S batteries.

Development of Multiwalled Carbon Nanotube-Reinforced Biodegradable Polylactic Acid/Polybutylene Succinate Blend Membrane.

Currently, gas separation (GS) membranes are produced from petrochemical-based polymers, but their lifespan is severely impacting the environment. Therefore, there has recently been growing interest in developing ecofriendly biodegradable polymer-based GS membranes. This study developed a polylactic acid (PLA)/polybutylene succinate (PBS) blend composite membrane for GS using the dry/wet phase inversion technique. The influence of the multiwalled carbon nanotube (MWCNT) concentration in the PLA/PBS blend was studied by investigating tensile properties, porosity, percentage crystallinity, contact angle, and gas permeance.The obtained results demonstrate that the addition of MWCNT enhances the tensile strength, porosity, and percentage crystallinity, whereas it decreases the contact angle. The pure gas permeation was investigated at pressures of 2–4 bar at 25 °C. The gas permeation study revealed that the PLA/PBS blend with 0.5% wt. MWCNT enhanced the gas permeance and selectivity at 4 bar. The gas permeance acquired at 25 °C and 4 bar for PLA/PBS reinforced with MWCNT was highest in hydrogen followed by carbon dioxide, argon, and nitrogen. Additionally, a study of the membrane morphology illustrated the uniform dispersion of MWCNT in the PLA/PBS blend. The investigation concluded that membranes containing MWCNT are capable of separating gases at the molecular level, thereby reducing energy consumption.

Cam Fiber Sandviç Kompozitlerin Düşük Hızlı Darbe Mukavemetinin Nano Parçacık Takviyeli Yapıştırıcı Kullanılarak Artırılması

The use of sandwich composite structures in the aerospace industry is increasing. Improving the impact and other mechanical properties of sandwich composite panels (SCP) is important for aviation safety. In the manufacture of SCPs, bonding with the lower and upper surfaces of the honeycomb structure is provided by bonding connections. By improving the mechanical properties of the adhesives used in SCP, the mechanical rigidity of the whole structure will be improved. In this study, sandwich composite panels were produced using glass fiber reinforced composite, three different adhesives (pure polyurethane, 0.1% and 0.2% multi-walled carbon nanotube reinforced polyurethane) and an aluminum honeycomb with a cell diameter of 8.86 mm. Low-velocity impact tests were applied to the manufactured sandwich composites at the initial energy level of 50 J. After impact tests, load-time, load-deflection and energy-time graphs were obtained, and the effect of multi-walled carbon nanotube (MWCNT) contribution was evaluated. Also, the effect of the MWCNT addition on impact properties was determined by making a damage analysis. It was observed that the carbon nanotube addition to the polyurethane adhesive increased the maximum contact force by 3%, improving the low-speed impact properties of SCPs.

In-situ synthesis of aluminum matrix nanocomposites by selective laser melting of carbon nanotubes modified Al-Mg-Sc-Zr alloys

Aluminum matrix nanocomposites were manufactured by selective laser melting (SLM) of 0.5 wt% multi-walled carbon nanotubes (MWCNTs) modified Al-Mg-Sc-Zr alloys. The influence of MWCNT addition on the manufacturing quality, the phase formation and the mechanical properties of the Al-Mg-Sc-Zr alloys was investigated. It is found that primary Al3(Sc,Zr) particles precipitated and were uniformly dispersed in both equiaxed and columnar regions of the SLM-fabricated MWCNTs/Al-Mg-Sc-Zr nanocomposites. New Al4C3 phase was generated either on the open tip or in the defected and amorphous carbon layer of the MWCNTs, covering their overall surface. The unreacted MWCNTs completely transferred to Al4C3 upon heat treatment, forming a stable {003} Al4C3/{200}Al interface. The heat-treated MWCNTs/Al-Mg-Sc-Zr nanocomposites exhibit high microhardness of 169.0 ± 0.7 HV0.2, tensile strength of 544.2 ± 6.8 MPa, yield strength of 505.1 ± 6.3 MPa and elastic modulus of 97.8 ± 0.7 GPa, increasing by 6.3%, 4.5%, 5.0% and 5.6%, respectively, compared with the unmodified Al-Mg-Sc-Zr alloys. The improved performance was ascribed to the collective effects of precipitation strengthening of secondary Al3(Sc,Zr) nanoparticles, in-situ synthesis of Al4C3 as well as favorable interfacial bonding for effective load transfer. This study can provide reference values for laser additive manufacturing of MWCNTs modified other metallic alloys to enhance their comprehensive properties.

Optimization of the Rheological Properties and Tribological Performance of SAE 5w-30 Base Oil with Added MWCNTs

The augmentation of lubricant oil properties is key to protecting engines, bearings, and machine parts from damage due to friction and wear and minimizing energy lost in countering friction. The tribological and rheological properties of the lubricants are of utmost importance to prevent wear under unembellished conditions. The marginal addition of particulate and filamentous nanofillers enhances these properties, making the lubricant oil stable under severe operating conditions. This research explores the improvement in SAE 5w-30 base oil performance after the addition of multiwalled carbon nanotubes (MWCNTs) in six marginal compositions, namely, Base, 0.02, 0.04, 0.06, 0.08, and 0.10 weight percentage. The effect of the addition of MWCNTs on flash and pour points, thermal conductivity, kinematic viscosity, friction coefficients, and wear are investigated and reported. X-ray diffraction and transmission electron microscopy are used to characterize the MWCNTs. The purity, crystallinity, size, shape, and orientation of the MWCNTs are confirmed by XRD and TEM characterization. Pour points and flash points increase by adding MWCNTs but inconsistency is observed after the 0.06 wt.% composition. The thermal conductivity and kinematic viscosity increase significantly and consistently. The friction coefficient and wear scar diameter reduce to 0.06 wt.% MWCNTs and then the trend is reversed due to agglomeration and inhomogeneity. A composition of 0.06 wt.% is identified as the optimum considering all the investigated properties. This composition ensures the stability of the tribo-film and hydrodynamic lubrication.

Experimental investigations and optimization of MWCNTs-mixed WEDM process parameters of nitinol shape memory alloy

Excellent characteristics of multi-walled carbon nanotubes (MWCNTs), such as higher toughness and stiffness, enlarged strength, and high thermal conductivity, make them an attractive choice to improve surface characteristics and machining performance. In the current study, MWCNTs mixed with dielectric fluid in the wire electrical discharge machining (WEDM) process was used to enhance the machining performance of Nitinol shape memory alloy (SMA). Significance of WEDM machining variables such as current, pulse-on time (Ton), pulse-off time (Toff), and variation in powder concentration of MWCNTs are studied on material removal rate (MRR) and surface roughness (SR). The addition of MWCNTs substantially improves the machining performance by increasing MRR and simultaneously reducing the SR. Improvement in the MRR of 75.42% and SR of 19.15% is achieved with the use of MWCNTs at 1 g/L in comparison to the conventional WEDM process. An advanced parameterless TLBO algorithm is used for simultaneous optimization of multiple responses. An advanced parameterless TLBO algorithm is used to find the optimal solution of multiple responses. Single objective optimization result has yielded maximum MRR of 0.5262 g/min at a current of 5 A, Ton 110 μs, Toff 1 μs and MWCNTs amount of 1 g/L while minimum SR of 1.27 μm at a current of 1 A, Ton 1 μs, Toff 24 μs and MWCNTs amount of 1 g/L. MOTLBO algorithm is used for simultaneous optimization of MRR and SR. Lastly, the surface integrity of machined surfaces using a field emission scanning electron microscope (FESEM) is also studied to evaluate the effect of MWCNTs on recast layer thickness (RLT) and other surface defects. The incorporation of MWCNTs has shown a substantial reduction in RLT and other surface defects such as reduction in globules of debris, melted material deposition, micro-crack-free, and micro-pores-free surfaces.

Study of the influence of nanoparticles on the behavior of composite materials

The objective of this work is to study the influence of additives of multi-walled carbon nanotubes (MWCNT) and silica nano-powder (SiO2) on the mechanical behavior of epoxy resin. Different volume fractions of MWCNT and SiO2were added. Mechanical characterization by tensile, three-point bending and Charpy tests were carried out. The experimental results show an increase in the mechanical performance of the mixtures (MWCNT ​+ ​epoxy), (SiO2 ​+ ​epoxy) up to 2% of additive. Beyond this value, a degradation of performance was observed. The addition of MWCNT gives better results when compared to the addition of SiO2. KIC-KCV correlations were made using empirical formulas to estimate the critical stress intensity factor KIC from the impact energy of the Charpy test.Unfortunately, this estimation does not provided a promising results, but other optimization methods were used to fit these empirical models to the behavior of our nanocomposites for which a good estimate was obtained after fitting these empirical models for SiO2.

Effect of multi-walled carbon nanotubes (MWCNT) addition on the flame spread rate over a Jet A pool

Flame spread over liquids is of high importance because of its relation to fire hazards in liquid fuel spillages. Aviation fuels mixed with nanoparticles are rising as promising higher performance fuels for high-end applications. Fire safety characterization of aviation fuels mixed with nanoparticles is paramount to the successful implementation of these new fuels in the aerospace/aviation industry. In this paper, measurements of the flame spread rate on top of a fuel pool of Jet A mixed with carbon nanoparticles are reported. Multi-Walled Carbon Nanotubes (MWCNT) with a nominal diameter of 30–50 nm were added in concentrations varied between 2 g/L and 6 g/L. Jet A temperature was varied between 30oC to 100oC, and a Nd:YAG laser was used to ignite the fuel-air mixture established over the liquid fuel pool. Flame spread rate was observed to decrease with increased nanoparticle concentration for all temperatures. Reductions in the flame spread rate up to 50% were observed which are relevant for fire safety of liquids fuels.

Impact of gamma radiation and multi-walled carbon nanotubes on the mechanical and acoustical properties of reinforced sisal fiber/polyester resin composites

In this work, the effect of exposure to 5 kGy of Gamma radiation and the addition of Multi-walled carbon nanotubes (MWCNT) in different concentration 0, 0.2, 0.4 and 0.6 wt% to sisal fiber/unsaturated polyester resin (SF-UP) composites (40/60) on the mechanical and acoustical properties was investigated. An enhancement in the mechanical properties was achieved by addition MWCNT up to 0.4%, and then decreased at 0.6%. Also, irradiation of the composite manifested an enhancement in the mechanical properties more than unirradiated ones. The tensile strength and flexural strength of irradiated SF-UP composite which contains 0.4% MWCNT were higher than unirradiated SF-UP composite which contains 0% MWCNT by 73.2 and 91.9%, respectively. The addition of MWCNT and exposure to 5 kGy of gamma radiation increased both the storage modulus and the Tg while the damping factor (tan δ) decreased. Increasing the MWCNT % enhanced the sound absorption at the higher frequencies (0.6% MWCNT (unirradiated)∼0.9 within 5000–6300 Hz), while the irradiation shifted the highest absorption toward lower frequencies (0.6% MWCNT (irradiated)∼0.63 within 2500–3150 Hz). The produced composite displayed appreciable mechanical and acoustical properties which makes it as a new partner for many advanced industrial applications.

When nanoparticle and microbes meet: The effect of multi-walled carbon nanotubes on microbial community and nutrient cycling in hyperaccumulator system

Carbon nanotubes can potentially stimulate phytoremediation of heavy metal contaminated soil by promoting plant biomass and root growth. Yet, the regulating mechanism of carbon nanotubes on the rhizosphere microenvironment and their potential ecological risks remain poorly characterized. The purpose of this study was to systematically evaluate the effects of multi-walled carbon nanotubes (MCNT) on the diversity and structure of rhizosphere soil bacterial and fungal communities, as well as soil enzyme activities and nutrients, in Solanum nigrum L. (S. nigrum)-soil system. Here, S. nigrum were cultivated in heavy metal(loid)s contaminated soils applied with MCNT (100, 500, and 1000 mg kg-1 by concentration, none MCNT addition as control) for 60 days. Our results demonstrated more significant urease, sucrase, and acid phosphatase activities in MCNT than in control soils, which benefit to promoting plant growth. Also, there were significant reductions in available nitrogen and available potassium contents with the treatment of MCNT, while the organic carbon and available phosphorus were not affected by MCNT application. Notably, the alpha diversity of bacterial and fungal communities in the MCNT treatments did not significantly vary relative to control. However, the soil microbial taxonomic compositions were changed under the application of MCNT. Compared to the control, MCNT application increased the relative abundances of the Micrococcaceae family, Solirubrobacteraceae family, and Conexibacter genus, which were positively correlated with plant growth. In addition, the non-metric multidimensional scaling (NMDS) analysis revealed that the community structure of bacterial and fungal communities did not significantly change among all the treatments, and bacterial community structure was significantly correlated with soil organic carbon. At the same time, sucrase activity had the highest relation to fungal community structure. This study highlighted soil microbes have strong resistance and adaptation ability to carbon nanotubes with existence of plants, and revealed linkage between the rhizosphere microenvironment and plant growth, which well improved our understanding of carbon nanotubes in heavy metal phytoremediation.

Effect of MWCNT addition on the optical band gap of PVA/CS transient biocomposites

In recent years, as a result of increasing environmental concerns, biodegradable materials have gained great attention. With the rapid development of electronic technology, the importance of innovation and development of low-cost, sustainable, transient bioelectronics materials is increasing. In this research, the preparation of Poly(Vinyl Alcohol) (PVA), Chitosan (CS), and Multi-Walled Carbon nanotube (MWCNT) biocomposite films have been described. The solution mixing, ultrasonic mixing, and spin coating techniques were used to prepare the PVA/CS/MWCNT biocomposite thin films. UV–Vis absorption spectroscopy and two-point probe resistivity measurement techniques were used to study the optical and electrical properties of the biocomposite thin films. Optical band gap energies ( Eg) of PVA/CS/MWCNT biocomposites were obtained using the Tauc and Absorbance Spectrum Fitting (ASF) methods. Results obtained with both methods were found to be exactly the same. Experimental results have shown that with increasing MWCNT concentration, electrical conductivity (σ) increases from 1.75x10−16 S to 2.94x10−3 S, and Eg decreases significantly. At the same time, the fundamental optical parameters such as band tail (Urbach) energy ( Eu), refractive index ( n), absorption ( α), and extinction ( k) coefficient of the PVA/CS/MWCNT biocomposites were investigated in the UV-VIS range. The improvement observed in the optical and electrical properties of PVA/CS/MWCNT biocomposite films shows that these composites could be used as bioelectronics materials.

Healing Efficiency of CNTs-Modified-UF Microcapsules That Provide Higher Electrical Conductivity and EMI Shielding Properties.

In this study, the effect of the addition of multi-walled carbon nanotubes (MWCNTs), at three percentages, into the urea-formaldehyde (UF) shell-wall of microcapsules on the healing efficiency is reported. The modified shell-wall created a conductive network in semi-conductive epoxies, which led to an improvement of the electromagnetic interference shielding effectiveness (EMI SE); utilizing the excellent electrical properties of the CNTs. The microcapsule’s mean diameter and shell wall were examined via scanning electron microscopy (SEM). Thermal stability was evaluated via thermogravimetric analysis (TGA). The healing efficiency was assessed in terms of fracture toughness, while the electrical properties were measured using impedance spectroscopy. The measurements of the EMI SE were carried out in the frequency range of 7–9 GHz. The derived results indicated that the incorporation of the CNTs resulted in a decrease in the mean size of the microcapsules, while the thermal stability remained unchanged. In particular, the introduction of 0.5% w/v CNTs did not affect the healing efficiency, while it increased the initial mechanical properties of the epoxy after the incorporation of the self-healing system by 27%. At the same time, it led to the formation of a conductive network, providing electrical conductivity to the epoxies. The experimental results showed that the SE increased on average 5 dB or more after introducing conductive microcapsules.

Effects of carbon nanomaterials hybridization of Poly(3,4-ethylenedioxythiophene): poly (styrene sulfonate) on thermoelectric performance

The influence of multiple dimensional carbon nanomaterials, such as graphene quantum dots (GQD), multi-walled carbon nanotubes (MWCNT), and graphene sheets (GNS) of the thermoelectric properties in poly(3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT: PSS)-based hybrids have been investigated. PEDOT: PSS matrix was successfully used to prepare PEDOT: PSS/GQDs (PGQD), PEDOT: PSS/MWCNT (PCNT) and PEDOT: PSS/GNS (PGNS) composite films. According to structural characteristics, strong π–π interactions existed between carbon materials and PEDOT: PSS, and PEDOT: PSS layers with organized and arranged morphology were easier templated by GNS than GQD or MWCNT. It was found that besides energy filtering effect, hole-phonon interaction occurred with further addition of GNS and GQDs in PGNS and PGQD composite films. The optimal power factor (PF) of approximately 580 and 103 μW m−1 K−2 at 363 K were acquired in PGNS composite films at 5 wt% GNS and PGQD films with 1 wt% GQD filling, respectively. Unlike PGNS and PGQD films, electrical conductivity of PCNT reduced upon the addition of MWCNT, while the Seebeck coefficient decreased firstly, and then increased and reached to the highest value at 10 wt% MWCNT. The optimal PF of 381.8 μW m−1 K−2 at 363 K was obtained with weight fraction of 0.1 wt% in PCNT films.