Single-walled Carbon Nanotubes Loading Research Articles

Machine learning algorithms to optimize the properties of bio-based poly(butylene succinate-co- butylene adipate) nanocomposites with carbon nanotubes

Poly[(butylene succinate)-co-adipate] (PBSA)-based materials are gathering much attention in the packaging industry, agriculture, and other fields owed to their biocompatibility and biodegradability. Nonetheless, poor thermal and mechanical properties of biodegradable polymers, such as PBSA, have hampered their wide-spread use. Herein, a simple, cost-effective and scalable solution to improve the mechanical properties of PBSA is reported by using functionalized single-walled carbon nanotubes (SWCNTs). Different SWCNT loadings have been incorporated in the PBSA matrix via simple solution casting, and the ultrasonication conditions have been optimized to attain a homogenous SWCNT dispersion. The nanocomposites have been characterized in detail by scanning electron microscopy (SEM), Infrared spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), tensile and impact strength tests. Unprecedented increments in stiffness were found at low nanotube loadings, ascribed to the outstanding reinforcing capability of the SWCNTs combined with their superior modulus and strong interfacial adhesion with the matrix via H-bonding, polar and CH-π interactions. Further, four machine learning (ML) algorithms, Polynomial Regression (PR), Support Vector Machines for Regression (SVR), Gradient Boosting (GB) and Artificial Neural Network (ANN), were applied to predict their mechanical properties. The algorithm´s performance was assessed using analytical parameters such as the coefficient of determination (R2), the mean square error (MSE) and the mean absolute error (MAE). The developed models exhibited strong performance, achieving R2 values ranging from 0.69 to 0.99 across the evaluated properties. The results corroborate that even when the same prediction model is used, its performance varies depending on the physical property to be predicted. Thus, SVR, GB, PR, and ANN were found to be the most effective for estimating the Young’s modulus, tensile strength, elongation at break and impact strength, respectively. This research holds great potential for advancing the field of modelling the mechanical properties of polymeric nanocomposites and their practical applications in various industries such as food, pharmaceutical and biomedicine. The development of accurate models for predicting nanocomposite properties would cheapen, simplify and systematize their design and production processes, resulting in improved final products and more efficient development procedures.

Investigation of the effect of load weight on the discharge capacity of lithium–O2 batteries using carbon-paper–based electrodes

We prepared carbon electrodes with nearly uniform thickness and varying loading weights using carbon paper (CP) as a support material and current collector for single-walled carbon nanotubes (SWCNTs). These electrodes were used as the positive electrode in a lithium–O2 battery, tested at a lower voltage limit of 2.4 V with a fixed current of 0.26 mA/cm2 (0.5 mA). Results demonstrated that the discharge gravimetric capacity (capacity normalized per weight of SWCNTs) did not change significantly for loading weights ≥0.42 mg/cm2. However, for loading weights <0.42 mg/cm2, the discharge gravimetric capacity exhibited an inverse correlation with weight. Analysis of the prepared electrodes revealed that at very low SWCNT loading weights, the sheets of SWCNTs became extremely thin, leading to occasional tears. Nonetheless, these structural changes had no significant impact on the specific surface area or contact resistance. Further analysis of the post-test electrodes using scanning electron microscopy and X-ray diffraction, along with considerations of the carbon paper's surface area as a percentage of the total electrode surface, led to the conclusion that at low loading weights, CP actively contributes to the discharge process and serves as a deposition site for Li2O2. Consequently, when the weight of the active material falls below a certain threshold, there is a risk of misperception, potentially leading to an overestimation of the discharge capacity.

Single-walled carbon nanotube interlayer modified gas diffusion layers to boost the cell performance of self-humidifying proton exchange membrane fuel cells

A tradeoff between the low humidity and the high performance remains a key challenge for the proton exchange membrane fuel cell (PEMFC). In this work, a novel self-humidifying gas diffusion layer (GDL) with a single-walled carbon nanotube (SWCNT) nonwoven layer between the gas diffusion substrate and the hydrophobic microporous layer is controllably prepared to elevate the cell performance under dry conditions. The membrane electrode assembly (MEA) with 0.25 mg cm−2 SWCNT loading exhibits a current density of 0.69 A cm−2 at 0.6 V, which is 392.8% higher than that of the counterpart without the SWCNT interlayer at the same relative humidity. Moreover, the SWCNT interlayer with rational pore structure and proper wettability dramatically improves the water retention capacity of MEA, thus enhancing the low-humidity performance of MEA. The structure design of GDL provides an effective strategy for self-humidifying PEMFC control optimization.

Structural Integrity Assessment of Aligned and Non-aligned Single Walled Carbon Nanotubes in Epoxy Resin

Carbon nanotubes have gained popularity due its unique electrical and thermal properties and high strength, widely finding it application in medical and electrical field. In the presented study the single walled carbon nanotubes (SWCNT) are assumed to be aligned using a DC electric field, taking into account transportation phenomena like the rotation of tube and its polarization to form chain like structure. Authors have examined and compared the structural properties under tensile loading of aligned and non-aligned single walled carbon nanotubes SWCNT in epoxy matrix using finite element analysis. COMSOL Multiphysics has been used to model the specimens and investigate its properties. The result lays out trends and relation between various parameters and the strength of the epoxy based SWCNT composite. The study draws out result on how changes in parameters of epoxy based SWCNT composite changes its physical properties.

Binder-free, pre-consolidated single-walled carbon nanotubes for manufacturing thermoset nanocomposites

In this work, we propose a pre-consolidated form of single-walled carbon nanotubes (SWCNT) – SWCNT briquettes – as a binder-free, robust, and safe material for manufacturing electrically and thermally conductive thermoset nanocomposites with universal applicability to all polymer matrices. We prove that the briquettes provide similar performance in nanocomposites compared to reference samples: a pristine powder, a commercial masterbatch and an aerogel based on the same type of SWCNTs. Using comprehensive sets of methods, we observe no significant differences in electrical (∼10−7-1 S/cm depending on SWCNT loading) and thermal (0.210–0.304 W/mK) conductivities for all sample types across a wide range of SWCNT concentrations. Moreover, the percolation thresholds of nanocomposites for SWCNT briquettes were ultra-low and close to that of pre-dispersed masterbatches (0.001–0.003 wt%). Pre-consolidated SWCNT powder is shown to provide the same final functional properties, while being free from common nanotube drawbacks such as the higher price of masterbatch manufacturing or aerosolization and low dispersibility during handling for the SWCNT powder/aerogel. The briquettes not only offer a safe solution for large scale fabrication, cutting away the need for personal and facility level safety measures, but do so at no significant cost increase, can be used with any polymer matrix and associated industrial processing route without any loss of final properties. This makes them universally attractive for all composite industrial production as well as small scale low capital laboratories.

Flexible film and thermoelectric device of single-walled carbon nanotube@conductive metal-organic framework composite

Conducting metal-organic frameworks (MOFs) hold a great potential for many electronic applications because of their unique chemical and physical properties. Thermoelectric (TE) conversation based on conductive MOFs is the cutting-edge frontiers and remains great challenges, such as low electrical conductivity, rigidity, and difficulty to process. Here, a free-standing flexible film of the composite, where covalent bond grafting exists between single-walled carbon nanotubes (SWCNTs) and porous MOF (SWCNT@Ni-1,2,5,6,9,10-triphenylenehexathiol (THT)), is prepared by a convenient vacuum filtration method. The as-fabricated SWCNT@Ni-THT composite films exhibit good flexibility and p-type TE characteristics. An optimized power factor and a maximum figure of merit are ∼98.1 μW m-1/K2 and ∼0.037, respectively, for the composite film with 4 wt% SWCNT loading at 300 K. Furthermore, a flexible TE device connected by four rectangular films in series can generate an open-circuit voltage (VOC) of ∼10.02 μV and the maximum power (Pmax) of ∼1.59 μW at a temperature difference of 60 K. This work provides a novel way to prepare high-performance flexible films of MOF-based TE composites and demonstrates their potential applications in wearable electronics.

Exploring the influence of ionic liquid and temperature on the dielectric properties and microwave absorption of SWCNT based PVDF/PANI blend nanocomposites

This study reveals the electromagnetic shielding effectiveness (EMISE) and dielectric relaxation phenomena of single walled carbon nanotube (SWCNT) based poly (vinylidene fluoride) (PVDF)/poly aniline (PANI) blend nanocomposites. An imidazolium base salt which is a liquid at room temperature is introduced in the polymer blend for improved dispersion of SWCNT phase. The extent of dispersion of SWCNT phase at the interface and the improved dispersion in the ionic liquid (IL) incorporated systems are investigated with High resolution transmission electron microscopy (HRTEM). The qualitative morphology and interaction between the different phases are correlated the obtained dielectric and EMISE outcomes. Analysis of various properties of the fabricated nanocomposite systems like, AC conductivity (σac), impedance (real and imaginary part), dielectric permittivity (ε′) have been done in the frequency range of 1–106 Hz of the applied external electric field. Introduction of IL to the composite systems affects the dielectric properties which is also analysed and the observed significant high value of ε′ is a result of effortless polarization at the interface of SWCNT and PANI phase. Microwave absorption efficiency of the SWCNT incorporated composite systems are explored in X-band range of frequencies (8–12 GHz) and high absorbance with low transmittance as well as low reflectance of microwave is noticed for the developed PVDF/PANI/SWCNT nanocomposites. The absorbance is predominantly increased with increasing the SWCNT loading level.

Microwave Attenuation Studies of Polypyrrole-SWCNT Nanocomposite Films for Improved EMI Shielding

In the process of finding stable, lightweight, broadband, cost-effective and improved electromagnetic interference (EMI) shielding material, electromagnetic wave attenuation properties of polypyrrole (PPy)—single-walled carbon nanotube (SWCNT) nanocomposite hybrid films were investigated in X-band region (8.2–12.4 GHz) and reported in the present work. The incorporation of SWCNT as a nanofiller in polymer matrix exhibits enhanced EMI shielding performance as compared to pure polymer films. The substantial values of dielectric loss with good impedance matching contribute to improvement in EMI shielding performance. It is found that with an increase of SWCNT loading in polymer matrix from 0 wt% to 5 wt%, nanocomposite films display a gradual increase in AC conductivity and total shielding effectiveness. The maximum total shielding effectiveness of 32.10 dB and minimum reflection loss of −45.54 dB with a wide bandwidth of 3.1 GHz, were obtained for 5 wt% CNT loading. The present results revealed that the prepared nanocomposite films are appropriate materials for lightweight, broadband EMI shields for radar and stealth applications.

Superior EMI shielding effectiveness with enhanced electrical conductivity at low percolation threshold of flexible novel ethylene methyl acrylate/single‐walled carbon nanotube nanocomposites

AbstractThe rising trend of electromagnetic pollution has motivated us to develop a novel electromagnetic interference shielding (EMI) material by adopting a facile, industry viable, and cost‐effective solution mixing strategy. Single‐walled carbon nanotubes (SWCNT) as conductive fillers is employed in a lightweight, highly flexible ethylene methyl acrylate (EMA) polymer to fabricate the superior electrically conductive and efficient EMI shielding material at a relatively lower percolation threshold limit compared to other carbonaceous fillers has been justified by their morphological characterization. The electrical conductive network formation is attained at just 1.96 wt% of SWCNT loading resulting in more than 20 dB of EMI shielding effectiveness (EMI SE) dominated by absorption mechanism to fulfill the industrial requirement along with excellent mechanical properties improvement, and the highest SE is 45 dB at 15 wt% of reinforcement facilitating their potential use in both industry and academia.

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

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

Influence of ionic liquid on the dielectric relaxation behavior of SWCNT reinforced poly(vinyl alcohol) based nanocomposites

Polymer nanocomposites based on single-walled carbon nanotubes (SWCNT) and poly(vinyl alcohol) have been successfully prepared using a solvent casting approach. The dispersion pattern of SWCNT in the PVA matrix has been analyzed by a high-resolution transmission electron microscope (HRTEM). The mechanical and thermal stability of the films were assessed. The effect of SWCNT loading and imidazolium-based ionic liquid on the dielectric relaxation behavior of the PVA-based nanocomposites has been explored in the frequency range of 1 to 106 Hz at room temperature. The dielectric properties such as dielectric permittivity (εʹ), real and imaginary impedance (Zʹ and Zʹʹ), AC conductivity (σac) as well as Nyquist plot of the fabricated nanocomposites were explored in the presence and absence of ionic liquid (IL). The dielectric permittivity and AC conductivity increased with an increase in SWCNT loading and presence of IL due to the enhanced interfacial polarization of the SWCNT at the interface and proper dispersion of SWCNT throughout the polymer matrix. The decrease in impedance (Zʹ and Zʹʹ) with the increase in SWCNT loading is due to the enhanced proximity between the conductive channels. The reduction in semicircular area under the Nyquist plot in presence of IL and increasing SWCNT loading indicated the capacitive nature of fabricated nanocomposites and a decrease in bulk resistivity.

Single-Walled Carbon Nanotube-Enhanced Bagasse-Epoxy Hybrid Composites under Varied Low Tensile Strain Rates

The production demand of high-performance polymer composites utilizing natural and renewable resources, especially agricultural waste fibres, is rapidly growing. However, these polymers’ mechanical properties are strain rate-dependent due to their viscoelastic nature. Particularly, for natural fibre-reinforced polymer composites (NFPCs), the involvement of fillers has caused rather complex failure mechanisms under different strain rates. Moreover, unevenly and micro-sized bagasse-reinforced polymer composites often cause the formation of micro-cracks and voids in composites. Consequently, the rates of crack initiation and propagation of these composites become extremely sensitive. This, in turn, causes low and unpredictable tensile performance at higher tensile crosshead speeds, even within the low strain rate range. In this study, single-walled carbon nanotubes (SWCNTs) were applied to enhance the bagasse-epoxy composites’ strength. The effects of the weightage in the SWCNT loadings on the composites’ tensile properties were subsequently investigated under low strain rates of 0.0005 s−1, 0.005 s−1 and 0.05 s−1. The composites’ failure shifted to a higher distribution (65.7% improvement, from 37.23 to 61.68 MPa, across strain rates) due to the addition of 0.05% SWCNTs, as indicated in a Weibull distribution plot. The high aspect ratio and strong interface adhesion of SWCNTs in and toward the epoxy matrix contributed significantly to the composites’ strengths. However, a further increase in SWCNT content in the tested composites caused early embrittlement due to agglomeration. The toughness and characteristic strength improved significantly as the strain rate increased. A scanning electron microscopic (SEM) analysis revealed that the SWCNTs’ high aspect ratios and large surface areas improved the interface bonding between the filler and matrix. However, higher SWCNT loadings (0.15% and 0.25%) caused a reverse effect in the same properties of these composites under the same strain rate variations, due to agglomeration. Finally, an empirical relationship was developed to describe the strain rate effect of tensile properties containing 0.05% SWCNT-reinforced bagasse-epoxy composites.

Carbon nanotubes integrated into polyamide membranes by support pre-infiltration improve the desalination performance

Carbon nanotubes (CNTs) are promising for realizing ultrafast membranes with implications to molecular separations and beyond. However, it is a big challenge to harness the potential of CNTs for designing scalable yet high-performance membranes. Here we systematically explore the role of loading and vacuum-assisted alignment of CNTs for improving the desalination performance of polyamide (PA) based thin-film composites. To rule out the dispersion instability issues, we focused on carboxylated single-walled CNTs (SWCNTs) commercially available in the market. After applying a pre-treatment for cleaning, we deposited SWCNTs on porous polysulfone supports by vacuum filtration and coated a PA layer on top via interfacial polymerization. Morphological assessments supported by polarized Raman microspectroscopy allowed the quantification of SWCNT alignment. At an optimum SWCNT loading, which we found critical for alignment, the water permeability of resulting membranes significantly improved without compromising NaCl selectivity. Also, we achieved an improved boric acid selectivity, arguably owing to the hydrophobic nature of nanotube channels. Moreover, nanotubes promoted resistance against chlorine degradation and improved mechanical strength. Vacuum deposition is instrumental for infiltrating SWCNTs into the support layer, but a mat layer forms between the support and PA layers when SWCNT loading exceeds the limit that the support pores can accommodate. Given that we use ordinary SWCNTs and a scalable methodology (vacuum-assisted infiltration), the developed membranes are promising for practical applications.

N-Type Flexible Films and a Thermoelectric Generator of Single-Walled Carbon Nanotube-Grafted Tin Selenide Nanocrystal Composites.

Despite the significant progress in thermoelectric composites in recent years, the enhancement of thermoelectric performance is mainly based on weak interfacial interactions, although strong interactions (such as covalent-bonding grafting) are expected to display a more significant effect. In this study, the thermoelectric composites are prepared using a covalent-bond grafting method between tin selenide (SnSe) and single-walled carbon nanotubes (SWCNTs) via a simple solvothermal process. The as-prepared highly flexible composite film shows an n-type thermoelectric characteristic. An optimized power factor of 58.86 μW m-1 K-2 at room temperature has been realized for the composite film with 16 wt % SWCNT loading. Finally, a flexible thermoelectric generator (TEG) consisting of three couples of p/n films is assembled, which can generate an open-circuit voltage of 15.55 μV and a maximum output power of 1.38 μW at a temperature gradient of 60 K. The results open a new avenue for the fabrication of n-type flexible films and TEG based on covalent-bonding-grafted composites and will benefit the design strategy of high-performance thermoelectric composites and flexible TEGs.

Size Discrimination of Carbohydrates via Conductive Carbon Nanotube@Metal Organic Framework Composites.

Traditional chemical sensing methodologies have typically relied on the specific chemistry of the analyte for detection. Modifications to the local environment surrounding the sensor represent an alternative pathway to impart selective differentiation. Here, we present the hybridization of a 2-D metal organic framework (Cu3(HHTP)2) with single-walled carbon nanotubes (SWCNTs) as a methodology for size discrimination of carbohydrates. Synthesis and the resulting conductive performance are modulated by both mass loading of SWCNTs and their relative oxidation. Liquid gated field-effect transistor (FET) devices demonstrate improved on/off characteristics and differentiation of carbohydrates based on molecular size. Glucose molecule detection is limited to the single micromolar concentration range. Molecular Dynamics (MD) calculations on model systems revealed decreases in ion diffusivity in the presence of different sugars as well as packing differences based on the size of a given carbohydrate molecule. The proposed sensing mechanism is a reduction in gate capacitance initiated by the filling of the pores with carbohydrate molecules. Restricting diffusion around a sensor in combination with FET measurements represents a new type of sensing mechanism for chemically similar analytes.

Incorporation of single-walled carbon nanotubes in ultrafiltration support structure for the removal of steroid hormone micropollutants

Ultrafiltration (UF) is an established water treatment solution that operates at relatively low pressures, but cannot remove pollutants with sub-nanometre sizes such as steroid hormones. To tackle this challenge while maintaining a fast flow of water through the membrane, UF can be coupled with a nanoparticle layer that removes micropollutants via adsorption. In this study, a mechanical method of incorporating single-walled carbon nanotubes (SWCNTs) in the UF structure is demonstrated. Such an SWCNT–UF composite with a SWCNT loading of 2 g/m2 offered the high UF-range permeability, and partial removal (50–75%) of hormones from a 100 ng/L feed solution at neutral pH. A full breakthrough was not achieved in the three-hour experiments. The diffusion of hormones to the highly accessible SWCNT surface area was a limiting factor. Nevertheless, adsorption kinetics were very fast, and adsorption was independent of residence time in the range of 0.08–7.1 s. Since dynamic adsorption is kinetic-dependent, water quality parameters such as pH could affect the adsorptive interactions. For example, adsorption was poor at pH 11–12. Although more work is needed to accomplish the drinking water guideline of 1 ng/L with such a composite, the adsorbent–membrane concept is promising, because the adsorption efficiency can be further enhanced by increasing the particle loading and/or choosing adsorbents with higher surface areas.

Enhancing Thermoelectric Performance of Polyaniline/Single-Walled Carbon Nanotube Composites via Dimethyl Sulfoxide-Mediated Electropolymerization.

The fabrication of flexible high-performance organic/inorganic thermoelectric (TE) composite films has been a hot spot for researchers in recent years. In this work, dynamic 3-phase interfacial electropolymerization of aniline, together with physical mixing with single-walled carbon nanotubes (SWCNTs), was adopted to prepare polyaniline/SWCNT (PANI/SWCNT) TE composites. The dimethyl sulfoxide (DMSO) added into the electrochemical polymerization system affords strong capability in improving the TE performance of composite films. Moreover, varying loadings of SWCNTs can also conveniently tune the TE performance of composites. Hence, the resultant composites afford the highest power factor (PF) of 236.4 ± 5.9 μW m-1 K-2 at room temperature. This work demonstrates that the introduction of DMSO into the electrolyte and the electrochemical polymerization are highly effective in fabricating high-performance PANI/SWCNT TE composites.

Studies of electrical, thermal, and mechanical properties of single-walled carbon nanotube and polyaniline of nanoporous nanocomposites

Hydrogel of single-walled carbon nanotubes and polyaniline has been used for thermopower engineering applications due to desirable thermal, electrical, and mechanical properties as well as tunable degradability. In this article, we fabricated nanoporous composite scaffolds from hydrogel of single-walled carbon nanotubes and polyaniline polymer using a standard in situ polymerization process. Our solution-based fabrication method prevented single-walled carbon nanotube aggregation which resulted in enhancing thermal, electrical, and mechanical properties with keeping optimum flexibility in the porous composite scaffold. We compared the mechanical, electrical, and thermal properties of nanoporous composites with different single-walled carbon nanotube loadings. The porous composite scaffold with a 25 wt% showed higher electrical conductivity, ultimate tensile strength, and tensile modulus. Lastly, our solution fabrication method prevents aggregation single-walled carbon nanotube and could help to build the thermoelectrical materials for flexible electronic applications.

Influence of CNT loading and environmental stressors on leaching of polymer-associated chemicals from epoxy and polycarbonate nanocomposites

Environmental context Carbon nanotubes are added to polymers such as polycarbonate and epoxy to form nanocomposites with enhanced material properties. Environmental factors including temperature, UV light exposure and pH have the potential to degrade these composites and increase the release of toxic polymer-associated chemicals. This study investigates how carbon nanotube loading decreases the release of known endocrine-disrupting compounds, bisphenol A and 4-tert-butylphenol, from polymer nanocomposites under simulated weathering environments. Abstract Nanoparticles such as carbon nanotubes are increasingly added to polymer matrices to improve tensile strength and electrical and thermal conductivity, and to reduce gas permeability. During use and after disposal, these plastic nanocomposites (PNCs) are degraded into microplastics by physical and chemical processes including mechanical abrasion, UV light exposure, hydrolysis and oxidation. Such polymers have the potential to enter aquatic environments and release potentially hazardous polymer-associated chemicals and transformation products. This work identifies and quantifies polymer-associated chemicals leached from polymers and nanocomposites during simulated environmental exposure. Epoxy and polycarbonate PNCs containing single-walled carbon nanotube (SWCNT) loadings ranging from 0 to 1 wt-% were exposed to water for 5 days, and the release of the chemicals bisphenol A (BPA) and 4-tert-butylphenol (TBP) was measured. The role of UV exposure, pH, temperature and natural organic matter in regulating chemical release was also investigated. Temperature, pH and UV light were found to be the most significant factors influencing release of TBP and BPA from PNCs. Additionally, increasing carbon nanotube loading in both polycarbonate and epoxy composites was found to decrease the release of these phenolic chemicals. A 0.3 % higher SWCNT loading decreased the release of BPA 45 ± 18 %, and a 1 % SWCNT loading decreased chemical release from epoxy by 48 ± 26 % for BPA and 58 ± 8 % for TBP. This information provides important data that can be used to help assess the risks posed by SWCNT polymer nanocomposites in aqueous environments, particularly as they age and are transformed.

Single-walled carbon nanotube filled thermoplastic polyurethane nanocomposites: Influence of ionic liquid on dielectric properties

Electrically conductive nanocomposites based on thermoplastic polyurethane (TPU) and single walled carbon nanotube (SWCNT) have been successfully prepared by solution casting technique. Prior to mixing, SWCNT is first dispersed in DMF and ionic liquid 1-Allyl-3-methyl imidazolium chloride (AMIC). The SWCNT phase is uniformly dispersed in the ionic liquid (IL) containing systems as observed in HRTEM and FESEM photomicrographs. The dielectric properties like dielectric permittivity (ε'), AC conductivity (σac), real and imaginary parts of impedance (Z' and Z'') of TPU/SWCNT nanocomposites have been analysed in the frequency range of 1–106 Hz. A comparison study of the dielectric properties of the systems with and without IL are thoroughly investigated. Increasing trend of ε' with increasing the SWCNT loading is mostly due to the increase in polarizable dipoles and adequate interfacial polarization of the charge carriers in the field direction. Frequent hopping and tunnelling mechanism with increasing the SWCNT loading is mainly responsible for the hike in σac. The increase in close proximity between the conductive channels with increase in conductive SWCNT loading and incorporation of IL reflects from the decrease in Zʹ and Z ʹʹ of the systems. The semi-circular nature of the Nyquist plot informs about the dielectric and capacitive characteristics of the developed nanocomposites and the decrease in area under the Nyquist plot significantly explains about the decrease in bulk resistivity.