Electrical Properties Of Nanocomposites Research Articles

Experimental and simulation studies of hybrid MWCNT/montmorillonite reinforced FDM based PLA filaments with multifunctional properties enhancement

AbstractThe recent investigation in the development of novel multifunctional thermoplastic polymer‐based filaments has contributed to the extensive use of hybrid nanofiller combinations. Montmorillonite (MMT) and multiwalled carbon nanotubes (MWCNT) are nanofillers with exceptional properties and their combination tends to induce synergistic property enhancement on incorporation within the polymer matrix. In our current study, CNT‐MMT hybrid has been synthesized, while XRD, FTIR, Raman, and TEM confirmed its successful formation. Different wt% (0.5–2) of CNT‐MMT were reinforced into polylactic acid (PLA) matrix and their inclusive properties were analyzed in order to obtain percolation threshold concentration. The tensile strength analysis of PLA with 1% CNT‐MMT displayed 47.4% enhancement as compared to virgin PLA, while DMA analysis confirmed storage modulus enhancement. These results were also corroborated with simulation studies using ANSYS. However, with 2% addition of CNT‐MMT, the tensile strength reduced due to nanofiller agglomeration, which was also verified with SEM studies. The thermal and electrical properties of nanocomposites also augmented considerably due to CNT‐MMT reinforcement with electrical conductivity of PLA + 1% CNT‐MMT enhanced by 9 orders of magnitude. These multifunctional filaments tend to produce refined 3D printed structure using FDM and could be harnessed toward advanced 3D printing applications for commercial devices.Highlights Different wt% of CNT‐MMT were reinforced into polylactic acid (PLA) matrix and their inclusive properties were analyzed. The tensile strength analysis of PLA with 1% CNT‐MMT displayed 47.4% enhancement as compared to virgin PLA, simulation studies using ANSYS confirmed it. The thermal and electrical properties of nanocomposites also augmented considerably due to CNT‐MMT reinforcement. These multifunctional filaments tend to produce refined 3D printed structure using FDM. This could be harnessed toward advanced 3D printing applications for commercial devices.

Effect of zinc oxide nanoparticle size on the dielectric properties of polypropylene‐based nanocomposites

AbstractTo develop new environmentally friendly and recyclable high‐voltage cable insulation materials, the effects of the particle size of zinc oxide (ZnO) on the mechanical and electrical properties of nanocomposites were investigated based on a feasibility study of polypropylene (PP) as a high‐performance cable insulation material. The small particle size of ZnO can synergistically toughen PP with a polyolefin elastomer (POE), but the large particle size of ZnO leads to lower elongation at break. Adding ZnO nanoparticles can improve the bulk resistivity of the composites and suppress space charge injection. 0.5ZnO200 has the highest direct current and alternating current breakdown field strengths, 36.6% and 14.7% higher than PP/POE, respectively. This improvement may be due to the ability of 200 nm ZnO to introduce more deep traps. However, as the nanoparticle content rises and the particle size decreases, the agglomeration becomes more frequent, leading to the overlap of inter‐nano interfaces and reducing the modification effect of the nanoparticles. This study on the effect law of nano‐ZnO with different particle sizes on the microstructure, mechanical properties, and electrical properties of PP can provide a reference for developing new recyclable high‐voltage insulated cable materials.

Stretchable conductive nanocomposites and their applications in wearable devices

Recently, highly conductive polymer nanocomposites, particularly soft polymer nanocomposites, have received extensive attention as promising material candidates for wearable devices. Compared with the cases of the wearable devices based on conventional rigid electronic materials, the wearable devices based on polymer nanocomposites exhibit excellent conformal contacts with the skin due to the soft mechanical properties of these nanocomposites; therefore, soft polymeric nanocomposites can be applied to stretchable wirings, electrodes, and sensor units in various on-skin electronics. The types of polymers and nanofillers used for the synthesis of these nanocomposites are critical factors determining the properties of polymer nanocomposites. The overall physical properties of nanocomposites depend on the type of polymer used, whereas the electrical properties of nanocomposites are governed by the type of nanofiller employed. Herein, we review the latest studies on the polymer nanocomposites constructed using different polymers and nanofillers that are applied to wearable devices. We have classified the polymers into non-elastic polymers, hydrogels, chemically crosslinked elastomers, and physically crosslinked elastomers and the nanofillers into C, liquid metal, Ag, Au, and other emerging nanomaterials. Detailed characteristics, fabrication methods, applications, and limitations of these nanocomposites are reviewed. Finally, a brief outlook for future research is provided.

Correlation between multiple chemical modification strategies on graphene or graphite and physical/electrical properties

Chemical modifications of carbon based materials are often used to improve their dispersion in polymer matrix and increase the nanocomposite electrical properties. This work concerned the control of graphene and graphite physical and chemical structure thanks to different chemical modification (oxidation, copolymer functionalization and reduction). This article exposes a complete study of different chemical modifications impact on graphene and graphite microstructure, chemical structure, and its relative electrical property. A first oxidation step by Hummers or nitric acid method was necessary to further graft a copolymer of methyl methacrylate and hydroxyethyl methacrylate via a versatile “grafting onto” covalent functionalization. Hummers’ and nitric acid methods were considered as strong and soft oxidation treatments, respectively. Reduction steps were also performed using hydrazine or thermal treatments to recover high electrical conductivity. Chemical modifications of graphene and graphite were characterized by X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy and pyrolysis–gas chromatography–mass spectrometry. Moreover, a new method for the electrical measurement of the modified particles is presented in this work. This measurement requires adhesive tape and an electrical circuit with a diode using the four probes protocol, it allows the evaluation of the electrical conductivity of the graphene and graphite samples in powder state. Finally, the electrical resistances of the different graphene and graphite submitted to all the chemical treatments are reported.

Introduction of Rare-Earth Oxide Nanoparticles in CNT-Based Nanocomposites for Improved Detection of Underlying CNT Network.

Epoxy resins for adhesive and structural applications are widely employed by various industries. The introduction of high aspect ratio nanometric conductive fillers, i.e., carbon nanotubes, are well studied and are known to improve the electrical properties of the bulk material by orders of magnitude. This improved electrical conductivity has made carbon nanotube-based nanocomposites an attractive material for applications where their weight savings are at a premium. However, the analytical methods for validating carbon nanotube (CNT) nanofiller dispersion and for assuring that the properties they induce extend to the entire volume are destructive and inhibited by poor resolution between matrix and tube bundles. Herein, rare-earth oxide nanoparticles are synthesized on CNT walls for the purpose of increasing the contrast between their network and the surrounding matrix when studied by imaging techniques, alleviating these issues. The adherence of the synthesized nanoparticles to the CNT walls is documented via transmission electron microscopy. The crystalline phases generated during the various fabrication steps are determined using X-ray diffraction. Deep ultraviolet-induced fluorescence of the Eu:Y2O3-CNT nanostructures is verified. The impacts to nanocomposite electrical properties resulting from dopant introduction are characterized. The scanning electron microscopy imaging of CNT pulp and nanocomposites fabricated from untreated CNTs and Eu:Y2O3-CNTs are compared, resulting in improved contrast and detection of CNT bundles. The micro-CT scans of composites with similar results are presented for discussion.

An experimental study on multiwalled carbon nanotube nanocomposite piezoresistivity considering the filler agglomeration effects

AbstractPiezoresistive strain sensing of multiwalled carbon nanotube (CNT)‐reinforced polymer nanocomposites considering the effect of agglomeration is experimentally investigated. Thermoplastic polyurethane is used as composite matrix with melt mixing method for fabricating the nanocomposite. The electrical resistance of the nanocomposite specimens is measured by a designed electrical circuit in conductivity and piezoresistivity tests. The electrical resistance of the nanocomposite decreases by a nonlinear relation when CNT is added up to 1.5 wt% and has an inverse behavior after this weight fraction. Comparison between scanning electron microscope images of the nanocomposite specimen fracture surfaces shows that the CNT agglomeration is the reason for decreasing the nanocomposite electrical properties. Also, decrease of the mechanical properties of the nanocomposite in higher filler content than 1.5 wt%, confirms the agglomeration effects. In addition, it is illustrated that the CNT agglomeration decreases strain sensing in the nanocomposite. Moreover, different piezoresistive behaviors of the nanocomposite in low and large strains are explained, according to the piezoresistivity mechanisms. Change of the piezoresistivity mechanism type, causes a nonlinear growth of the nanocomposite electrical resistance, in large strain.

A Simulation for the Electrical Conductivity of Nanocomposites Filled with Carbon Black Based on the Three-dimensional Monte Carlo Method

In this work, the electrical conductivity of nanocomposites filled with carbon black is simulated by the three-dimensional Monte Carlo method. First, three-dimensional model of the nanocomposites and carbon black is constructed and the conductive mechanism is studied. Then the calculation method of electrical conductivity of nanocomposites filled with carbon black is proposed according to the equivalent resistance of large-scale pure resistor network. Then the proposed electrical conductivity calculation method is verified by comparing with the simulation and experimental results. This result shows that it is feasible to directly obtain the conductivity of nanocomposites using the proposed conductivity calculation method. This study helps to estimate the electrical properties of nanocomposites filled with carbon black. And it also can help for studying nanocomposites filled with carbon nanotubes or graphene and the synergistic effect of hybrid fillers-filled nanocomposites.

폴리도파민/환원 산화그래핀/게르마늄 복합체의 One-pot 합성 및 나노복합재료의 전기적 물성 향상

자연 모사 접착 및 코팅 특성을 발현시킬 수 있도록 폴리도파민을 이용하여 높은 전기전도성과 표면적을 갖는 환원된 그래핀 산화물 표면에 게르마늄 결정을 균일하게 형성시켜 폴리도파민/환원 산화그래핀/게르마늄 전도성 복합체를 합성하였다. 기존에 이러한 전도성 복합체를 합성하는데 필요한 고온, 고압, 소결 등 고비용의 가혹한 조건 대신 상온 및 상압의 온화한 조건에서 one-pot 공정으로 전도성 복합체를 합성하였다. 전도성 복합체는 폴리도파민이 코팅된 환원 산화그래핀 표면에 게르마늄 결정이 균일하게 고정되어 있는 형태학적 특성을 나타내었다. 폴리비닐알코올과 폴리도파민/환원 산화그래핀/게르마늄 복합체를 사용하여 제조된 나노복합재료는 전도성 복합체의 전기적 및 형태학적 특성에 기인하여 우수한 전기적 특성을 나타내었다.

Structure and electrical transport properties of carbon nanofibres/carbon nanotubes 3D hierarchical nanocomposites: Impact of the concentration of acetylacetonate catalyst

The aim of this study was an extensive analysis of the correlations linking the structure with the electrical properties of hierarchical nanocomposites – electrospun carbon nanofibres/carbon nanotubes (eCNF/CNT). Herein, we focus primarily on the determination and separation of the impact of iron (III) acetylacetonate (Fe(Acac)3) on the structure of core-eCNFs from the overall effect it exerts on the global ordering and electrical properties of nanocomposites. The structure of materials was evaluated using highly local microscopic and diffraction techniques as well as global spectroscopic methods. The charge transport properties were determined through analysis of the temperature-dependent conductivity via Mott's variable-range hopping model. The investigation revealed that increasing concentration of Fe(Acac)3 results in higher surface density of CNTs, which affects the electrical transport in nanocomposites positively (158% increase in σ298K; notable decline in T0). However, it was proved that high catalyst concentrations simultaneously cause amorphisation of core-eCNFs and increase the activation energy of hopping conduction in them. As a consequence of the above, we estimated the concentration of Fe(Acac)3 (~3.0%), ensuring the best electrical properties. Additionally, it was demonstrated that desorption of electrically active guest molecules causes notable changes in the electronic transport in nanocomposites.

A study of the appropriateness, geometry, size, and fillers boundary restraint on representative volume element in electrical simulation for carbon-based nanocomposites

In three-dimensional Monte Carlo simulation for carbon-based conductive nanocomposites, representative volume element (RVE) establishes a relationship between the microstructure and electrical properties of nanocomposites. Generating RVE is the first step in simulation, but the lack of systematic research on RVE results in low simulation accuracy and reliability. In this work, a study of the appropriateness, geometry, size, and fillers boundary restraint on RVE for conductive nanocomposites filled with single filler of CNTs, CB or GNPs is studied. The results show that it is reasonable to use RVE in the simulation. The cube is suggested as the standard shape of RVE and the size of RVE can determine by the Chi-square test results obtained from percolation threshold. It is also concluded that periodic and aperiodic boundary restraint are superior to truncated boundary restraint. This study can provide the theoretical and technique foundation for reasonably setting RVE parameters and accurately predicting the electrical properties for nanocomposites filled with different dimension fillers.

Effect of different surface treatment agents on the physical chemistry and electrical properties of polyethylene nano‐alumina nanocomposites

Generally, the electrical properties of nanocomposite are affected by the type, size, filling concentration and surface treatment process of the nanoparticle. In this study, nanocomposites of polyethylene (PE) with varying filling contents of nano-alumina particles were prepared by the melting blending method and three different kinds of coupling agents were applied for surface modification properties of the nanoparticles. Two of them were silane based and the other was titanate based. The effect of different coupling agents on the dielectric properties was studied. Fourier-transform infrared spectroscopy and thermo-gravimetric analysis were used to verify their compositions. Scanning electron microscope and polarised optical microscopy were used for morphology study. Dielectric permittivity, direct current (DC) volume resistivity and DC breakdown strength characterised their improved insulation performance with nano-alumina as filler. Thermal stimulated current results revealed that adding nano-alumina particles into low-density PE could provide more deep traps and increase DC resistivity.

Rapid Microwave Polymerization of Porous Nanocomposites with Piezoresistive Sensing Function.

In this paper, polydimethylsiloxane (PDMS) and multi-walled carbon nanotube (MWCNT) nanocomposites with piezoresistive sensing function were fabricated using microwave irradiation. The effects of precuring time on the mechanical and electrical properties of nanocomposites were investigated. The increased viscosity and possible nanofiller re-agglomeration during the precuring process caused decreased microwave absorption, resulting in extended curing times, and decreased porosity and electrical conductivity in the cured nanocomposites. The porosity generated during the microwave-curing process was investigated with a scanning electron microscope (SEM) and density measurements. Increased loadings of MWCNTs resulted in shortened curing times and an increased number of small well-dispersed closed-cell pores. The mechanical properties of the synthesized nanocomposites including stress–strain behaviors and Young’s Modulus were examined. Experimental results demonstrated that the synthesized nanocomposites with 2.5 wt. % MWCNTs achieved the highest piezoresistive sensitivity with an average gauge factor of 7.9 at 10% applied strain. The piezoresistive responses of these nanocomposites were characterized under compressive loads at various maximum strains, loading rates, and under viscoelastic stress relaxation conditions. The 2.5 wt. % nanocomposite was successfully used in an application as a skin-attachable compression sensor for human motion detection including squeezing a golf ball.

Physical and electrochemical investigations on hybrid materials synthesized by polyaniline with various amounts of ZnO nanoparticle

Hybrid-materials were prepared via chemical polymerization in presence of aniline with various amounts of ZnO. The structural, functional, optical, morphological and electrical properties of nanocomposites were investigated by XRD, FT-IR, UV–Visible, TGA, SEM and electrical conductivity. XRD and SEM analysis shows the formation of nanocomposite and confirms the amorphous and crystalline nature of material. FT-IR spectrum reveals the functional groups present in the samples and the electroactive and optical properties were affected. Results showed that our nanocomposites exhibited a direct optical energy gap that decreased from 3.12 to 2.76 eV with the increment of the amounts of ZnO in nanocomposite.

An investigation into mechanical properties of the nanocomposite with aligned CNT by means of electrical conductivity

In the present study, a novel modelling approach based on electrical properties was proposed to replicate the mechanical behaviour of aligned carbon nanotube/polymer nanocomposites. Firstly, an electrical analytical model with Monte-Carlo method involved was established and validated by accurately predicted electric conductivity. The microstructure of the nanocomposite was then determined according to the electric property. Subsequently, a large-scale representative volume element model based on the predicted distribution of the carbon nanotubes was built to replicate the mechanical response of the nanocomposite under tension, which can be validated by existing experiments. To consider the crystalline structure of the matrix, two cases on the nanocomposites with crystalline and amorphous polymer were investigated, locating their difference on the bonding condition of the interface between CNT and matrix. Results evidenced that the electrical properties of nanocomposites can be used to identify the internal microstructure of nanocomposite. Moreover, the effects of the loading direction, the interfacial strength and the weight fraction were studied by numerical models. The reinforcement effect of the carbon nanotubes was significant when loaded along the aligned direction, but the effect was limited in the other directions. The modulus and the strength of nanocomposite were improved by the increase of the weight fraction of CNTs, while the increase of interfacial strength improves the strength of nanocomposite along CNT-aligned direction significantly, but had negligible effect on its modulus.

Structure-property relationship in silicone rubber nanocomposites reinforced with carbon nanomaterials for sensors and actuators

A small amount of nanofillers can significantly improve the mechanical and electrical properties of nanocomposites, which have a wide range of applications such as sensing and actuation. In this work, rubber nanocomposites were prepared with 0-dimensional (0-D) carbon black (CB), 1-D carbon nanotube (CNT), 3-D graphitic nanofiller (GR), and room temperature vulcanizing (RTV) silicone rubber. The different structures of the CB, CNT, and GR nanofillers were characterized. In addition, the effects of the structures on the mechanical properties and electromechanical applications of the nanocomposites were experimentally demonstrated. At a filler loading of 6 phr, the elastic modulus was improved by 150, 350, and 130 % with the nanofillers of GR, CNT, and CB, respectively. We found that the CNT-based silicone rubber nanocomposite exhibited the highest tensile strength and the reinforcing effect compared to that of others. Based on the improved mechanical, electrical properties of RTV rubber by the nanofillers, the nanocomposites were successfully adopted for strain sensing and actuation applications. The CNT- and CB-based nanocomposites have been used as piezoresistive strain sensors with a gauge factor of 1.3 and 7.8, respectively. The stretchability of strain sensor is up to 80 and 100 % for CNT and CB nanocomposites, respectively, while both of them show high durability. In addition, the nanocomposites are used as an electrode for piezoelectric actuation, and the mechanical displacement was 2.5, 0.34 and 0.5 mm for CNT-, GR-, and CB-based nanocomposite, respectively, under identical actuation voltage of 12 kV. A series of experiments demonstrate the dependency of properties of nanocomposites on the structural characteristic of carbon nanofillers.

Temperature dependent electrical properties of thermoplastic polypropylene nanocomposites for HVDC cable insulation

Polypropylene has been regarded as a potential recyclable insulation material for HVDC cable, which is beneficial to improve the working temperature and transmission capacity of HVDC cables. However, the electrical properties of polymeric insulation materials exhibit apparent temperature dependent characteristics. Temperature influences the generation and migration of charge carriers, thereby affecting the electrical properties. This paper focuses on the electrical properties of polypropylene nanocomposites at different temperatures, including volume resistivity, space charge and DC breakdown strength. The temperature dependent electrical properties of polypropylene are regulated by adding MgO nanoparticles. Based on the characterization of microstructure and trap characteristics, the mechanism of regulating the charge carrier transport process and the electrical properties of the nanocomposites by introducing MgO nanoparticles is explained. The polypropylene nanocomposites show decreased electrical conduction, suppressed space charge accumulation and increased DC breakdown strength, which are desirable for recyclable HVDC cable insulation application. This work may pave a way for tailoring the high temperature electrical properties of polymeric insulation material.

Silane Modification of Carbon Nanotubes and Preparation of Silane Cross‐Linked LLDPE/MWCNT Nanocomposites

The objective of this study is to investigate the effects of carbon nanotube (CNT) content, surface modification, and silane cross‐linking on mechanical and electrical properties of linear low‐density polyethylene/multiwall CNT nanocomposites. CNTs were functionalized by vinyltriethoxysilane to incorporate the ─O─C2H5 functional groups and were melt‐blended with polyethylene. Silane‐grafted polyethylene was then moisture cross‐linked. Silanization of CNT was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), and EDX analysis. Hot‐set test results showed that silane cross‐linking of polyethylene and incorporation of modified CNTs into polyethylene led to an increase in cross‐linking density and the number of entanglements resulting in a decrease in elongation. It was found that the addition of pristine multiwall carbon nanotubes (MWCNTs) and functionalized MWCNTs does not affect silane cross‐linking density. Silane modification resulted in a stronger adhesion of the silane cross‐linked LLDPE to silanized MWCNTs according to scanning electron microscopy micrographs. Additionally, the electrical tests revealed that the silane modification of CNTs results in an improvement in electrical properties of nanocomposites, while silane cross‐linking will not have an effect on electrical properties. Rheological properties of MWCNT/LLDPE nanocomposites have been studied thoroughly and have been discussed in this study. Moreover, according to TGA test results, modification of the MWCNTs led to a better dispersion of them in the LLDPE matrix and consequently resulted in an improvement in thermal properties of the nanocomposites. Crystallinity and melting properties of the nanocomposites have been evaluated in detail using DSC analysis. J. VINYL ADDIT. TECHNOL., 26:113–126, 2020. © 2019 Society of Plastics Engineers

Fabrication of PVA/NiO/SiC Nanocomposites and Studying their Dielectric Properties For Antibacterial Applications

PREPARATION of PVA/NiO/SiC nanocomposites and studying their dielectric properties for antibacterial applications have been investigated. The A.C electrical properties of nanocomposites were studied in frequency ranging (100-5×106) Hz at room temperature. The experimental results showed that the dielectric constant and dielectric loss of (PVA-NiO-SiC) nanocomposites were decreased with an increasing the frequency of applied electric field. The A.C electrical conductivity increases with increasing of frequency. The dielectric constant, dielectric loss and A.C electrical conductivity of (PVA-NiO) nanocomposites were increased with increasing of SiC nanoparticles concentrations. The antibacterial applications for (PVA-NiO-SiC) nanocomposites tested against gram-positive (S. aureus) and gram-negative (E. coli). The results showed that the inhibition zone was increased with increase the concentrations of SiC nanoparticles.

Effect of Carbon Nanotube and Surfactant on Processing, Mechanical, Electrical and EMI-Shielding of Epoxy Composites

Dispersing nanoparticles in a polymer matrix is intrinsically challenging due to unfavorable entropic interactions between the matrix and the nanoparticle. In this research dispersion of nanoparticles in polymer matrix was studied and the effect of dispersion on properties was investigated. The properties of polymer composite depend on the type, size, shape, concentration of nanoparticles, and interactions of polymer-nanaoparticle. The lack of compatibility between inorganic particles and polymer matrix limits the applications of produced nanocomposite. Due to incompatibility, the dispersion of nanoparticles in polymer matrix is very difficult. The epoxy/MWCNT composite was fabricated by solution mixing process. The effect of MWCNT and Amine-Functionalized surfactant, on curing process, EMI-shielding, mechanical and electrical properties of nanocomposite were investigated. Dispersion of MWCNT in solution was investigated using UV-vis spectroscopy. Curing behavior of nanocomposites at different MWCNT loadings was investigated. EMI-shielding of nanocomposite at different concentrations of MWCNT was studied and the results showed that MWCNT and ferric oxide improve absorption loss, reflection loss and shielding effectiveness. Effect of MWCNT inclusion on thermal and mechanical properties of nanocomposites was investigated. Finally, the electrical conductivity was measured using a two-point conductivity test method.

Graphene Nanosheets Reinforced Epoxy Nanocomposites: Mechanical and Electrical Properties Evaluation

Utilizing the direct mixing and conducting ultra-sonication with two solvent free and solventborne methods, Graphene nanosheets (GNSs)/Epoxy nanocomposites were fabricated through the present research. Mechanical and electrical properties of nanocomposites with various contents of GNSs were investigated. Mechanical properties such as tensile and flexural modulus, tensile and flexural strength were taken into account and the electrical conductivity was monitored throughout the tests. A considerable improvement in tensile modulus (12%) of the nanocomposites was observed using 0.5 wt % of GNSs and flexural modulus was enhanced by 10% in the presence of GNSs with the same filler contents. Moreover, flexural strength and tensile strength of the nanocomposites were improved by 5 and 15% at 0.1 wt %, respectively. In addition, the results revealed that the non-solvent method had a better effect on improving the mechanical properties rather than the solvent-borne method. Furthermore, the electrical conductivity was enhanced by increasing in GNSs contents, while the percolation threshold was at 1 wt %.