Study of low weight % Filler on Dielectric Properties of MWNT-Epoxy Nanocomposites (original) (raw)
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Study of low weight percentage filler on dielectric properties of MWCNT-epoxy nanocomposites
An attempt is made to study the effect of low weight percentage multiwall carbon nanotube (MWCNT) powder on dielectric properties of MWCNT reinforced epoxy composites. For that MWCNT (of different low weight percentage) reinforced epoxy composite was prepared by dispersing the MWCNT in resin. Samples were prepared by solution casting process and characterized for their dielectric properties such as dielectric constant (" 0), dielectric dissipation factor (tan) and AC conductivity (ac). The main objective is the investigation of the dielectric properties of the prepared samples at the low weight percentage of the filler at different temperatures and frequencies. From the two mechanisms of electrical conduction, first the leakage current obtained by the formation of a percolation network in the matrix and the other by tunneling of electrons formed among conductors nearby (tunneling current); here we are getting conduction by the second mechanism. Generally, leakage current makes more contribution to conductivity than tunneling current. Dielectric dissipation factor at 250 Hz frequency is greater than all other frequencies and starts increasing from 60 C. The peak height of the transition temperature decreases with increasing frequency. This study shows that the addition of a low weight percentage of MWCNT can modify considerably the electrical behavior of epoxy nanocomposites without chemical functionalization of filler.
Study of low weight percentage filler on dielectric properties of MCWNT-epoxy nanocomposites
Journal of Advanced Dielectrics, 2016
An attempt is made to study the effect of low weight percentage multiwall carbon nanotube (MWCNT) powder on dielectric properties of MWCNT reinforced epoxy composites. For that MWCNT (of different low weight percentage) reinforced epoxy composite was prepared by dispersing the MWCNT in resin. Samples were prepared by solution casting process and characterized for their dielectric properties such as dielectric constant ([Formula: see text]), dielectric dissipation factor (tan [Formula: see text]) and AC conductivity ([Formula: see text]). The main objective is the investigation of the dielectric properties of the prepared samples at the low weight percentage of the filler at different temperatures and frequencies. From the two mechanisms of electrical conduction, first the leakage current obtained by the formation of a percolation network in the matrix and the other by tunneling of electrons formed among conductors nearby (tunneling current); here we are getting conduction by the sec...
Composite Structures, 2015
In this study, the authors attempted to enhance the flexural and dielectric properties of epoxy resin using advanced carbon nanotube-alumina (CNT-Al 2 O 3) hybrid filler system that was chemically synthesised via chemical vapor deposition (CVD). The hybrid CNT-Al 2 O 3 filled epoxy composite was compared to the physically mixed CNT-Al 2 O 3 filled epoxy composites. The assessment showed that the CNT-Al 2 O 3 hybrid filler produced more homogeneous dispersion in the epoxy matrix with higher flexural and dielectric properties as compared to the physically mixed CNT-Al 2 O 3 filler. The flexural strength, flexural modulus and dielectric constant of CNT-Al 2 O 3 hybrid epoxy composites improved significantly up to 30%, 35% and 20%, respectively, compared to the neat epoxy.
Composites Science and Technology
A study of the ac electrical transport properties of a diglycidyl ether of bisphenol A-based epoxy resin (DGEBA) polymerized with a diethylene triamine (DETA) and reinforced with single wall carbon nanotubes (SWNTs) is presented. The main objective is the investigation of the particular electrical behavior of the conductive filler in the composite and the development of new nanocomposite materials based on epoxy resins with controlled structural and electrical properties. The structural and electrical characterization of the SWNT-DGEBA/DETA hybrid system, performed by differential scanning calorimetry, Raman and ac impedance spectroscopy show interesting effects, including the particular interaction between the polymer and nanotubes, the tendency of the nanotube structure to increase the rate of reaction and substantial effects of the nanotube bundle conformation, dependent on matrix intercalation, on the dielectric behavior of the composite. #
Dielectric behavior of epoxy matrix/single-walled carbon nanotube composites
Composites Science and Technology, 2004
A study of the ac electrical transport properties of a diglycidyl ether of bisphenol A-based epoxy resin (DGEBA) polymerized with a diethylene triamine (DETA) and reinforced with single wall carbon nanotubes (SWNTs) is presented. The main objective is the investigation of the particular electrical behavior of the conductive filler in the composite and the development of new nanocomposite materials based on epoxy resins with controlled structural and electrical properties. The structural and electrical characterization of the SWNT–DGEBA/DETA hybrid system, performed by differential scanning calorimetry, Raman and ac impedance spectroscopy show interesting effects, including the particular interaction between the polymer and nanotubes, the tendency of the nanotube structure to increase the rate of reaction and substantial effects of the nanotube bundle conformation, dependent on matrix intercalation, on the dielectric behavior of the composite.
Polymer Engineering and Science, 2020
This study investigated the correlation between the electrical conductivity and the micro and nanomorphology of multiwalled carbon nanotubes (MWCNTs)/ epoxy nanocomposites with and without the inorganic fillers montmorillonite (MMT), sepiolite and calcium carbonate (CaCO 3). The nanocomposites were prepared by dispersing the MWCNT and fillers through ultrasonication directly in the resin or solvent. For nanocomposites without fillers, the compositions prepared with solvent demonstrated higher electrical conductivities, which correlate with a microscale morphology formed by networks of highly interconnected MWCNT agglomerates. The addition of MMT induced a deleterious effect on the electrical conductivity of the nanocomposites since this filler hinders the formation of MWCNT agglomerate networks. The effect of sepiolite on electrical conductivity is also negative, but in this case, nonmorphological effects are likely of greater importance. The addition of CaCO 3 improved the electrical conductivity of the binary nanocomposites under specific conditions. For this filler, a synergic effect was achieved for the composition prepared with solvent, which resulted in an approximately sixfold increase in electrical conductivity relative to the nanocomposite without filler.
Dielectric Spectroscopy and Tunability of Multi-Walled Carbon Nanotube/Epoxy Resin Composites
The dielectric response of oxidized multi-walled carbon nanotube / epoxy resin composites, is investigated with respect to filler content concentration, over a wide temperature and frequency range. Specimens, below the percolation threshold, exhibit similar behaviour to that of the neat epoxy. Two relaxation modes are observed in the low temperature region, attributed to the re-arrangement of small parts of the polymer chain (γ-mode) and the reorientation of polar side groups (β-mode) respectively, where in the high temperature region the evolution of the α-mode is present. Direct current (DC) conduction follows the Vogel -Tamann -Fulcher equation as expected. The dielectric response of specimens, above the percolation threshold, follows the "Random Free Energy Barrier Model". DC conductivity exhibits Arrhenius temperature dependence with two distinct regions. The activation energies of both regions were evaluated. The contact resistance between two adjacent carbon nanotubes was also calculated. The effective dielectric constant as well as the capacitance of the specimens, above the percolation threshold, can be modulated by means of an applied DC bias voltage.
Structural characterization and electrical properties of carbon nanotubes/epoxy polymer composites
Journal of Applied Polymer Science, 2016
The purpose of this study is to identify the relationship between the electrical and structural characteristics of multiwalled carbon nanotubes dispersed into the polymer matrix of a resin. In a first step, the composites were characterized by small-angle neutron scattering, which provide information about the bulk dispersion of nanotubes in the matrix and form three-dimensional networks with a surface fractal behavior. In the second step, a dielectric and electrical study was carried out in the frequency range between 1 Hz and 10 MHz at room temperature. We have found that the electric and dielectric behavior of these composites can be described by Jonscher's universal dielectric response. We show that the critical exponents describing the concentration dependence of the conductivity and the dielectric constant, obtained in the vicinity of the percolation threshold, are in good agreement with the theoretical values.
Electrical and mechanical properties of carbon nanotube‐epoxy nanocomposites
Journal of Applied Polymer …, 2010
In this work, electrical conductivity and thermo-mechanical properties have been measured for carbon nanotube reinforced epoxy matrix composites. These nanocomposites consisted of two types of nanofillers, single walled carbon nanotubes (SW-CNT) and electrical grade carbon nanotubes (XD-CNT). The influence of the type of nanotubes and their corresponding loading weight fraction on the microstructure and the resulting electrical and mechanical properties of the nanocomposites have been investigated. The electrical conductivity of the nanocomposites showed a significantly high, about seven orders of magnitude, improvement at very low loading weight fractions of nanotubes in both types of nanocomposites. The percolation threshold in nanocomposites with SW-CNT fillers was found to be around 0.015 wt % and that with XD-CNT fillers around 0.0225 wt %. Transmission optical microscopy of the nanocomposites revealed some differences in the microstructure of the two types of nanocomposites which can be related to the variation in the percolation thresholds of these nanocomposites. The mechanical properties (storage modulus and loss modulus) and the glass transition temperature have not been compromised with the addition of fillers compared with significant enhancement of electrical properties. The main significance of these results is that XD-CNTs can be used as a cost effective nanofiller for electrical applications of epoxy based nanocomposites at a fraction of SW-CNT cost.
Journal of Polymer Science Part B: Polymer Physics, 2012
The electrical properties and dispersion of vaporgrown carbon nanofibers (VGCNF) and multiwalled carbon nanotubes (MWCNT)-epoxy resin composites are studied and compared. A blender was used to disperse the nanofillers within the matrix, producing samples with concentrations of 0.1, 0.5, and 1.0 wt % for both nanofillers, besides the neat sample. The dispersion of the nanofillers was qualitatively analyzed using scanning electron microscopy, transmission optical microscopy, and grayscale analysis. The electrical conductivity and the dielectric constant were evaluated. The percolation threshold of MWCNT epoxy composites is lower than 0.1 wt % while for VGCNF lies between 0.1 and 0.5 wt %. The difference on the dispersion ability of the two nanofillers is due to their intrinsic characteristics. Celzard's theory is suitable to calculate the percolation threshold bounds for the VGCNF composites but not for the MWCNT composites, indicating that intrinsic characteristics of the nanofillers beyond the aspect ratio are determinant for the MWCNT composites electrical conductivity.