Distribution Of Multi-walled Carbon Nanotubes Research Articles

Multiscale modeling of polymers filled with MWCNTs: the effect of dispersion, waviness, interphase and agglomerations

PurposeThe purpose of this paper is the development of a multiscale model which simulates the effect of the dispersion, the waviness, the interphase geometry as well as the agglomerations of multi-walled carbon nanotubes (MWCNTs) on the Young’s modulus of a polymer filled with 0.4 Vol.% MWCNTs.Design/methodology/approachFor the determination of the homogenized elastic properties of the hybrid material representative unit cells (RUCs) have been used. The predicted homogenized elastic properties were used for the prediction of the Young’s modulus of the filled material by simulating a finite element (FE) model of a tensile specimen. Moreover, the model has been validated by comparing the predicted values of the numerical analysis with experimental tensile results.FindingsAs the MWCNT agglomerates increase, the results showed a remarkable decrease of the Young’s modulus regarding the polymer filled with aligned MWCNTs while only slight differences on the Young’s modulus have been found in the case of randomly oriented MWCNTs. This might be attributed to the low concentration of the MWCNTs (0.4 Vol.%) into the polymer. For low MWCNTs concentrations, the interphase seems to have negligible effect on the Young’s modulus. Furthermore, as the MWCNTs waviness increases, a remarkable decrease of the Young’s modulus of the polymer filled with aligned MWCNTs is observed. In the case that MWCNTs are randomly dispersed into the polymer, both numerical and experimental results have been found to be consistent regarding the Young’s modulus.Practical implicationsThe methodology used can be adopted by any system containing nanofillers.Originality/valueAlthough several studies on the effect of the MWCNTs distribution on the Young’s modulus have been conducted, limited results exist by using a more realistic RUC including a periodic geometry of more than 20 MWCNTs with random orientation and a more realistic waviness of MWCNTs with aspect ratio exceeding 150.

Fabrication of Thermoplastic Polyurethane/Polycaprolactone Multilayered Composites with Confined Distribution of MWCNTs for Achieving Tunable Thermo- and Electro-Responsive Shape-Memory Performances

Multilayered shape-memory composites composed of multiwalled carbon nanotube (MWCNT)-filled thermoplastic polyurethane (TPU) (denoted as cTPU) and polycaprolactone (PCL) were prepared through layer...

A systematic investigation of dispersion concentration and particle size distribution of multi-wall carbon nanotubes in aqueous solutions of various dispersants

Surfactant-assisted exfoliation of multi-walled carbon nanotubes (MWNTs) in aqueous solution have become a common procedure to generate high fraction of individualized nanotubes. Since well-controlled experimental methodologies and reliable comparative metrics are scarce, a systematic research was conducted in order to analyze the dispersibility and the dispersing mechanisms of MWNTs in aqueous solutions of various surfactants. The concentration of dispersed MWNTs was accurately measured for a wide range of surfactant concentration, using combined UV–vis spectroscopy and thermogravimetric analysis (TGA). The obtained dispersibility results indicated that the highest dispersion concentration and efficiency is achieved in the SDBS-assisted MWNTs dispersion. Furthermore, the nanotube morphology and surfactant properties can be evaluated and rationalized by analyzing the dispersed nanotube mass and the surfactant amount per nanotube surface area. The amount of dispersed MWNTs remaining after varying levels of sonication and centrifugation was investigated, and a controllable sonication-centrifugation method for the preparation of well-dispersed MWNTs was established. The experimental data of the concentration of MWNTs dispersions versus centrifugation speed (ω) are fitted reasonably well by a Boltzmann function. The SDBS-assisted MWNTs dispersion will be more susceptible to the high centrifugal speed,while PVP-assisted MWNTs dispersion will be sediment fast at the mild centrifugation. The distributions of diameter and length of MWNTs at maximum dispersibility show that the sizes for the MWNTs dispersed by SDBS are much more polydisperse. The results further suggest that preparation of controllable carbon nanotubes morphology and design of rational configuration of surfactants are the key factors for increasing the dispersion stability and maximum concentration of well-dispersed MWNT.

Effect of the gradient distribution of multiwalled carbon nanotubes on the bond strength and corrosion resistance of waterborne polyurethane conductive nanocomposites

To make the conductive anticorrosive coating containing low conductive filler content meet the requirements for antistatic applications, and improve the bond strength and anticorrosive ability of the coating, a series of eco-friendly waterborne polyurethane (WPU) graded conductive nanocomposites with low contents of multiwalled carbon nanotubes (MWCNTs) were prepared by two special multilayer coating processes on the basis of the gradient distribution of MWCNTs. Effects of the gradient distribution and the content of the MWCNT on the electrical conductivity, bond strength, and corrosion resistance of the nanocomposites were investigated. The graded conductive nanocomposites prepared by casting the upperlayer coating on the uncured underlayer coating can conduct electricity when the MWCNT content in the underlayer coating was only 0.4 wt%. The coating resistance of the obtained graded conductive nanocomposites exhibiting good properties of adhesion and anticorrosion met the requirements for antistatic. SEM tests showed that the high MWCNT content in the upperlayer coating could penetrate into the underlayer coating, leading to that the MWCNTs formed a gradient distribution of “low content–high content–low content–high content” in the whole coating. As the MWCNT content in the upperlayer coating increased, the dispersion of the MWCNTs in the whole coating became uniform.

Comparative Study of Multi-walled Carbon Nanotube Reinforced Natural Rubber Nanocomposite and Multiflex Dynamic Response – 2 Artificial Foot

The desire to restore the quality of life to amputees has been on the front burner in recent years. This study compares the functional properties of a home-grown nanocomposite (NC) and multiflex dynamic response-2 artificial foot (M.DR2). The inherent challenge of ensuring uniform distribution of multi-walled carbon nanotube (MWCNT) in host matrices was addressed by the use of sodium dodecylbenzene sulfonate (C18H29NaO3S). Carbon nanotubes (CNTs) were synthesised via catalytic chemical vapour deposition (CCVD) technique and the NC was produced using an electrically heated hydraulic press. While the initial decomposition temperature (Tonset) showed that the newly developed material with 260.01 °C is more thermally stable than M.DR2 artificial foot with the temperature of 238.17 °C, incorporation of MWCNTs into the unfilled NR matrix proved a significant change in Tonset. MWCNT loading was found to influence the moisture content of the reinforced matrix by about 7% with the NC being 35% more thermally stable than M. DR2 artificial foot. SEM/EDS micrographs indicated complete embedment of MWCNTs in NR matrix, thereby making it more suitable than M. DR2 foot which was inundated with cavities, thereby making it susceptible to early failure. While it took both materials 120 days to attain saturation point NR/MWCNT-3 is 93% more dimensionally stable that M. DR2 and also demonstrated better resistance to wear. The wear rate results revealed that M. DR2 wears faster than NR/MWCNT-3 by approximately 32%. It can, therefore, be concluded from the foregoing that the home-grown material is to be preferred to its foreign counterpart for anthropomorphic prosthetic foot application.

Simultaneously improving the thermal conductive and flame retardant performance for epoxy resins thermosets by constructing core‐shell‐brush structure and distributing of MWCNTs in brush intervals

Fire safety and thermal dissipation performance of epoxy resins thermosets were critical for its application in key fields such as electronic devices. The simultaneous improvement of flame retardant and thermal conductivity properties were still a challenge. Herein, ammonium polyphosphate (APP) was firstly encapsulated with 5‐wt% epoxy resins based on APP and then surface grafted with polyurethane polymer chain, and the resulting APP with core‐shell‐brush structure was constructed. Finally, the multiwalled carbon nanotube (MWCNT) was assembled in the intervals of polymer brush on APP surface, and the prepared filler was defined as MF‐APP. Its chemical structure and morphologies were characterized and confirmed. The wettability of MF‐APP was evaluated by water contact angles tests (WCA) and MF‐APP exhibited hydrophobic property with the WCA of 138°. When 9‐wt% MF‐APP was incorporated into EP thermosets, the thermal conductive value of EP/MF‐APP achieved 1.02 Wm−1 K−1, and the MWCNTs concentration was only 1.8 wt% in thermosets. Compared with the previous work, the prepared EP/MF‐APP thermosets exhibited outstanding thermal conductive efficiency because of the homogeneously distribution of MWCNTs. Moreover, the samples fulfilled UL‐94 V‐0 grade during vertical burning tests with the limiting oxygen index of 30.8%. As a result, the thermal conductivity and flame retardancy of EP thermosets were simultaneously enhanced with a relatively low addition amount of MF‐APP, which would bring more chance for wider application of EP thermosets in key fields.

Dry sliding wear behaviour of multi walled carbon nanotubes reinforced aluminium composites produced by powder metallurgy technique

The nanocomposites of Multi-Walled Carbon Nano Tubes (MWCNTs) having weight fractions of 0, 0.25, 0.5, 0.75 and 1.0 wt%, reinforced in 200 mesh size Aluminium (Al) particles, produced through Powder Metallurgy (PM) process. Uniform distribution of MWCNTs was achieved using ultrasonic blending and mechanical planetary ball milling. Dry sliding wear behavior of fabricated composites were studied in accordance with the ASTM G99-95a standard. Wear behavior were studied for various sliding distance, load, and disc rotation speeds. The results showed that, wear rate increased with increasing sliding distance and load because of an increased of temperature during an investigation. However, the wear rate decreased with an increased speed due to the formation of a stable tribolayer. Further Al 0.5 wt% of MWCNT nanocomposites were found to have better wear resistance characteristics compared to others. The resistance to wear enhanced because of bonding among matrix and MWCNTs and the formation of tribo layer was characterized using Scanning Electron Microscopy.

Adjusting Distribution of Multiwall Carbon Nanotubes in Poly(L-lactide)/Poly(oxymethylene) Blends via Constructing Stereocomplex Crystallites: Toward Conductive and Microwave Shielding Enhancement

Controlling distribution of conductive fillers is a key strategy to construct conductive networks with high efficiency and enhance the conductivity of conductive polymer composites (CPCs). In this work, the distribution of multiwall carbon nanotubes (MWCNTs) in a compatible poly(L-lactide) (PLLA)/poly(oxymethylene) (POM) blend was adjusted by constructing stereocomplex crystallites (SCs). Because of the nucleation effect of SCs, the total crystallinity of the polymer blends increased at the small content of poly(D-lactide) (PDLA). However, the total crystallinity decreased when adding large amount of PDLA due to the confinement effect of SCs. The distribution of MWCNTs could be tuned by the crystallinity of PLLA/POM blends due to the volume-exclusion effect. The electrical conductivity of PLLA/POM/MWCNT composites increased from 1.90 × 10–3 to 5.56 S/m by adding 2.5 wt % PDLA in PLLA phase. However, the electrical conductivity of the composites decreased at high content of PDLA in PLLA phase because the P...

Building homogeneous nanostructure in Ni(OH) 2 /MWCNTs composite by electrostatic attraction

A facile strategy for the preparation of composites with homogeneous distribution of multi-walled carbon nanotubes (MWCNTs) in Ni(OH)2 was proposed. The electrostatic attraction between positively charged Ni(OH)2 monolayer nanosheets and negatively charged MWCNTs was utilised to self-assemble the composites. The results of electrochemical measurement on the composite containing 30 wt% MWCNTs indicated that the homogeneous composition of MWCNTs in composite significantly reduced the electrical resistance and promoted the electrochemical utilisation of Ni(OH)2. As a result, the composite presented high electrochemical performance: having specific capacitance of 1568.8 F g−1 at low current density of 2.4 A g−1 and keeping a relatively high specific capacitance of 781.8 F g−1 at high current density of 81.7 A g−1. Based on the results in this works, it is hoped that the adopted strategy could provide a promising idea for the preparation of composites with homogeneous distribution of individual components.

Ultra‐Stretchable Porous Fiber‐Shaped Strain Sensor with Exponential Response in Full Sensing Range and Excellent Anti‐Interference Ability toward Buckling, Torsion, Temperature, and Humidity

AbstractAs a crucial element for wearable devices, high‐performance strain sensors have been spotlighted as an ideal strategy to develop machine‐human interfaces and healthcare systems. It still remains a huge challenge to construct flexible strain sensors with equational response in a broad range. Herein, highly stretchable multi‐walled carbon nanotubes (MWCNTs)–decorated thermoplastic polyurethane (TPU) fibers with a porous microstructure are produced through a scalable and facile strategy by wet‐spinning and ultra‐sonication. The fiber is composed of pure TPU fibers with MWCNTs decorated on the surface. The porous fiber is then assembled as a strain sensor. Interestingly, the effective MWCNTs distribution on the TPU fiber enables exponential sensing over the whole strain range. The sensor possesses a high gauge factor (GF, 102 at 300% strain), very large workable sensing range (300% strain), excellent durability (10 000 cycles), light weight (0.85 g cm−3), and fast response (200 ms). The as‐prepared strain sensor exhibits excellent insensitive properties toward buckling, torsion, temperature, and humidity stimuli. Based on the high sensing performance, the fiber‐shaped strain sensor detects human movements precisely by directly attaching to skin or embedding in garments, demonstrating huge potential in human–machine interfaces, health monitoring application, etc.

Reduced percolation threshold of multi-walled carbon nanotubes/polymer composites by filling aligned ferromagnetic particles

Conductive polymer composites, consisting of multi-walled carbon nanotubes and a small amount of carbonyl iron particles, are fabricated under an ordinary magnetic field, to form anisotropic microstructures. The alignment of carbonyl iron particles will change the structure of a multi-walled carbon nanotube network and consequently the electrical properties of conductive polymer composites. In this research, we focus on the effect of the anisotropic microstructures on the electrical properties of the composites, especially on the percolation threshold and electrical resistivity. Monte Carlo simulations for three-dimensional stick percolation systems are performed to predict the percolation threshold of the anisotropic conductive polymer composites in terms of orientation distribution of multi-walled carbon nanotubes. In addition, an eight-chain model is proposed to investigate the influence of the anisotropic distribution of multi-walled carbon nanotubes on the electrical resistivity of the composites. It is predicted that the percolation threshold could be reduced from 0.70 vol% for the isotropic composites to 0.49 vol% for the anisotropic composites. Meanwhile, the electrical resistivity of the anisotropic composites is about 10%–20% of that of the isotropic composites when the volume fraction of multi-walled carbon nanotubes is higher than the percolation threshold. The simulation results are compared with the experimental study results that show a very similar behavior although there are some deviations in the values.

Multiwalled Carbon Nanotube Reinforced Bio-Based Benzoxazine/Epoxy Composites with NIR-Laser Stimulated Shape Memory Effects.

Smart materials with light-actuated shape memory effects are developed from renewable resources in this work. Bio-based benzoxazine resin is prepared from vanillin, furfurylamine, and paraformaldehyde by utilizing the Mannich-like condensation. Vanillin-furfurylamine-containing benzoxazine resin (V-fa) is subsequently copolymerized with epoxidized castor oil (ECO). When the copolymer is reinforced with multiwalled carbon nanotubes (MWCNTs), the resulting composite exhibits shape memory effects. Molecular characteristics of V-fa resin, ECO, and V-fa/ECO copolymers are obtained from Fourier transform infrared (FT-IR) spectroscopy. Curing behavior of V-fa/ECO copolymers is investigated by differential scanning calorimetry. Dynamic mechanical properties of MWCNT reinforced V-fa/ECO composites are determined by dynamic mechanical analysis. Morphological details and distribution of MWCNTs within the copolymer matrix are characterized by transmission electron microscopy. Shape memory performances of MWCNT reinforced V-fa/ECO composites are studied by shape memory tests performed with a universal testing machine. After a significant deformation to a temporary shape, the composites can be recovered to the original shape by near-infrared (NIR) laser actuation. The shape recovery process can be stimulated at a specific site of the composite simply by focusing NIR laser to that site. The shape recovery time of the composites under NIR actuation is four times faster than the shape recovery process under conventional thermal activation. Furthermore, the composites possess good shape fixity and good shape recovery under NIR actuation.

Synergic effect of MWCNTs and SiC addition on microstructure and mechanical properties of closed-cell Al–SiC-MWCNTs HCFs

AlSi12Cu1Mg1–SiC-MWCNTs hybrid composite foam (HCFs) of varying relative densities (R.D.) were made through stir casting technique using CaH2 as a foaming agent. Varying wt.% of SiC and multi-wall carbon nanotubes (MWCNTs) were used as reinforcing as well as thickening agents. Uniform distribution of SiC and MWCNTs in the matrix was confirmed by FESEM images and Raman analysis. It was observed that the elastic modulus (E), plastic collapse stress (σpc), plateau stress (σpl), and energy absorption (Eab) of HCFs increase significantly when both (MWCNTs and SiC) were added together. But, when SiC and MWCNTs added individually, the extent of improvement in these properties is relatively low. However, densification strain varies marginally with the variation in reinforcement. Irrespective of reinforcement, the σpl, the E, and the Eab increased with increment in R.D. The different values also followed the existing relations, when the fraction of cell edge materials varied with R.D., the deformation mechanism was understood from photographs taken during deformation.

Optoelectrical and mechanical properties of multiwall carbon nanotube-integrated DNA thin films

Thin films made of deoxyribonucleic acid (DNA), dissolved in an aqueous solution, and cetyltrimethyl-ammonium-modified DNA (CDNA), dissolved in an organic solvent, utilising multiwall carbon nanotubes (MWCNTs) are not yet well-understood for use in optoelectronic device and sensor applications. In this study, we fabricate MWCNT-integrated DNA and CDNA thin films using the drop-casting method. We also characterise the optical properties (i.e. absorption spectra, Fourier-transform infrared spectra, Raman spectra, photoluminescence, and time-of-flight secondary ion mass spectrometry) to study spectral absorption, interaction, functional group, chirality, and compositional moiety and its distribution of MWCNTs in DNA and CDNA thin films. The electrical property for conductance and the mechanical characterisations of hardness, modulus and elasticity for stability are also discussed. Lastly, to show the feasibility of directional alignment of MWCNTs in DNA thin films, we perform an alignment experiment with MWCNTs in DNA via brushing and shearing methods, and we evaluate the results using polarised optical microscopy. Our simple methodology to align ingredients in DNA and CDNA thin films leveraging various optical, electrical and mechanical properties, provides great potential for the development of efficient devices and sensors.

Pulse-potential electrochemical fabrication of coaxial-nanostructured polypyrrole/multiwall carbon nanotubes networks on cotton fabrics as stable flexible supercapacitor electrodes with high areal capacitance

Flexible supercapacitors (FSCs) with a high areal capacitance are essential for future wearable energy-storage devices due to the limitation of available area on the surface of the human body (< 2 m2). To achieve the performance with high areal capacitance, the surface structure of electrodes should be designed carefully. In this paper, a hierarchical composite electrode based on coaxial-nanostructured polypyrrole (PPy) and multiwall carbon nanotube (MWCNT) was electrochemical co-deposited on the surface of the MWCNT-coated cotton fabric (MCF) by a facile pulse potential method. The pulse potential co-deposition conditions-lower potential (EL), the number of cycles (NC) and EL duration time (tL)-played crucial roles in the uniform distribution of MWCNT within PPy/MWCNT composites, thickness of PPy shell and porous morphology. The three-dimension porous networks of PPy/MWCNT/MCF electrodes not only enhanced the efficiency of faradaic redox reactions but also facilitated the accessibility of the electrolyte to electrode surface, accordingly presenting an ultrahigh areal specific capacitance of 5.05 F cm−2 (0.001 V s−1) and unexceptionable cycling stability of 129.20% specific capacitance retention (1000 cycles, 0.02 V s−1). This work provides a new route to develop FSCs electrodes and shows a promising application in wearable energy-storage technology.

Multi-layered stack consisting of PVDF nanocomposites with flow-induced oriented MWCNT structure can supress electromagnetic radiation

Polymeric nanocomposites have emerged as a potential material in the electronic world owing to its numerous advantages like ease of processing, design flexibility, light-weight, ease of embedding and integrating with the existing production line. Given the surge in electronic components, electromagnetic interference, which severely impairs the reliability of precise electronic devices, has emerged as a new challenge. Hence, technologically, viable design is the need of the day. However, the high concentration of fillers required to achieve the desired properties still remains a challenge with respect to the design of functional polymeric nanocomposites. In this context herein, we report as to how flow induced distribution of multi-walled carbon nanotubes (MWCNT) in poly-vinylidene (PVDF) matrix during mechanical rolling influence the texture, polymorphism and electromagnetic shielding properties. We demonstrate the flow induced orientation of MWCNT, polymorphism in PVDF and composites shielding performance by TEM, crystallographic texture and shielding effectiveness measurements, respectively. Further, mechanical and thermal properties of as pressed and mechanically rolled samples were investigated by DMA and DSC. TEM analysis revealed that MWCNT form small aggregate, however were aligned along the rolling direction. This observation is in sharp contrast to the random distribution for as pressed samples. Quantitatively, a strong texture was observed for rolled samples as compared to as pressed samples. Absorption of EM waves is the major shielding mechanism which is mechanistically discussed here through associated dielectric loss parameters. Interactions, alignment of MWCNTs, and polymorphism influence the shielding efficiency in these composites. In addition, stacking of such nanocomposite layers further enhances the overall shielding efficiency by absorption (up to 72%) due to the polarization, multiple internal reflections and interlayer charge storing capacity. A Bluetooth module was employed to successfully demonstrate the efficacy of this approach in supressing unwanted EM interference. This study comprehensively guides researchers as to how processing or flow-induced changes alter the distribution of MWCNTs in polymer composites and how this influences the overall shielding behaviour.

Microstructure and mechanical properties of ABOw and nickel-coated MWCNTs reinforced 2024Al hybrid composite fabricated by squeeze casting

Abstract Homogeneous distribution of multi-walled carbon nanotubes (MWCNTs) in aluminum matrix composites and optimization of the MWCNTs-aluminum interfacial strength are challenging for MWCNTs/Al metal-matrix composites (MMCs). Here, in order to improve the wettability and the interfacial bonding between MWCNTs and aluminum matrix alloy, a uniform nickel layer was created on MWCNTs by electroless plating. Hybrid preforms comprising of aluminum borate whisker (ABOw) and MWCNTs with/without nickel coating were prepared. It was found that the presence of ABOw and nickel coating ensured the homogeneous distribution of MWCNTs in composites. The presence of the nickel coating on MWCNTs also helps in decreasing the porosity of composite prepared by squeeze casting technique. Compared with ABOw/2024Al and ABOw + MWCNTs/2024Al composites, improvements in elongation and hardness were obtained in the ABOw + MWCNTs(Ni)/2024Al composite, which may be attributed to the reduced porosity, increased interfacial bonding strength and the crack deflection induced by dispersed MWCNTs. However, the addition of MWCNTs did not change the main fracture mechanism: ABOw break and ABOw-aluminum interfacial de-bonding dominated the fracture process in ABOw and MWCNTs(Ni) reinforced composites.

Optimization of Carbon Nanotube Dispersions in Water Using Response Surface Methodology.

The aim of this work was to demonstrate an optimization methodology to reliably obtain stable macrodispersions (i.e., for ≥24 h) of carbon nanotubes in water using sonication. Response surface methodology (RSM) was utilized to assess and optimize the sonication parameters for the process. The studied input parameters were (i) sonication time (duration), (ii) amplitude (of vibration), and (iii) pulse-on/off (duration) of the sonicator. The analyzed responses were mean diameter and size distribution of multiwalled carbon nanotube (MWNT) aggregates in water, which were measured by the dynamic light scattering technique. A semiempirical model was developed and statistically tested to estimate the magnitude of sonicator parameters required to obtain specified MWNT macrodispersions (i.e., aggregates’ mean diameter and distribution) in water. The results showed that MWNT aggregates of 2 ± 0.5 μm can be obtained by optimizing sonicator parameters to a sonication time of 89 s, amplitude of 144 μm, and pulse-on/off cycle of 44/30 s. These process settings for 100 mg/L MWNTs in a 30 mL aliquot of deionized water would consume 863 J/mL of sonication energy. Contrary to the popular belief, “sonication time” and/or “sonication energy input” were not found to be proportional to the degree of dispersion of MWNTs in water. This might be the reason for the frequent disparity and nonreproducibility of sonication results reported in scientific literature, especially for dispersing nanomaterials in a number of different systems. The amplitude of vibration was noted to be the most sensitive parameter affecting MWNT aggregates’ diameter and distribution in water. The characterization of MWNTs was performed using electron microscopy, surface area analyzer, thermogravimetric analyzer, and zeta potential analyzer. This study can be helpful in evaluating sonication dispersion of particulate matter in other incompressible fluids such as graphene dispersion in organic solvents.

High‐performance electromagnetic interference shielding material based on an effective mixing protocol

AbstractA facile and economic method is developed for the fabrication of new lightweight materials with high electromagnetic interference (EMI) shielding performance, good mechanical properties and low electrical percolation threshold through melt mixing. Electrical properties, DC conductivity, EMI shielding performance and mechanical properties of poly(trimethylene terephthalate) (PTT)/multiwalled carbon nanotube (MWCNT) nanocomposites with varying filler loading of MWCNTs were investigated. High‐resolution transmission electron microscopy was used to determine the distribution of MWCNTs in the PTT matrix. The newly developed nanocomposites show excellent dielectric and EMI shielding properties. Theoretical electrical percolation threshold was achieved at 0.21 wt% loading of MWCNTs, due to the high aspect ratio and the three‐dimensional network formation of MWCNTs. Experimental DC conductivity values were compared with those of theoretical models such as the Voet, Bueche and Scarisbrick models, which showed good agreement. The PTT/3% MWCNT composite showed an EMI shielding value of ∼38 dB (99.99% attenuation) with a sample thickness of 2 mm. Power balance was used to determine the actual contribution of reflection, absorption and transmission loss to the total EMI shielding value. The nanocomposites showed good tensile and impact properties and the composite with 2% MWCNTs exhibited an improvement in tensile strength of as much as 96%. © 2018 Society of Chemical Industry

Thermal Studies of Multiwalled Carbon Nanotube Reinforced with Silicone Elastomer Nanocomposites

This article studies the enhancement in the properties of silicon elastomer (SiR) reinforced by multiwalled carbon nanotube (MWCNT). Multiwalled carbon nanotube filled silicone rubber composites were prepared. The effects of loading levels of MWCNT on the thermal properties of silicone elastomer were investigated. SEM studies reveal the smooth distribution of MWCNT in silicon matrix. At higher concentration nanoparticles collapse together to form agglomerates. The high resolution transmission electron microscopy (HR-TEM) photographs shows excellent/homogeneous distribution of MWCNT in silicon matrix and agglomeration occurs at higher concentrations. Thermal properties of nanocomposites have been characterized using differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA). The transition temperature appears at below -25°C for MWCNT reinforced SiR nanocomposites. TGA thermogram, shows that temperature at 10%, 20%, 30%, and 50% weight loss for SiR nanocomposites is higher than as compared to unfilled SiR. The results indicate that the addition of MWCNT significantly enhanced the thermal stability of silicon elastomer.