Thermal and Electrical Properties of Carbon Nanotube Based Materials (original) (raw)
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Thermal and electrical properties of carbon nanotubes based polysulfone nanocomposites
Polymer Bulletin
Carbon nanotubes (CNTs)-reinforced polysulfone (PSU) nanocomposites were prepared through solution mixing of PSU and different weight percent of multi-walled carbon nanotubes (MWCNTs). Thermal properties of nanocomposites were characterized using thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA studies revealed an increase in thermal stability of the PSU/MWCNTs nanocomposites, which is due to the hindrance of the nanodispered carbon nanotubes to the thermal transfer in nanocomposites and also due to higher thermal stability of CNTs. Morphological properties of nanocomposites were characterized by high resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscope (FESEM). The influence of CNTs loading on electrical properties of PSU/MWCNTs nanocomposites was studied by the measurement of AC and DC resistivity. Dielectric study of nanocomposites was carried out at different frequencies (10 Hz–1 MHz) by using LCR meter. An increase in dielectric constant and dielectric loss was observed with increase in CNTs content, which is due to the interfacial polarization between conducting CNTs and PSU.
Super Heat-Resistant Conductive Nanocomposites Based on Polysulfone–Carbon Nanofillers
Polymer-Plastics Technology and Engineering, 2015
The present article describes the morphology, mechanical, thermal, electrical, and dielectric properties of polysulfone (PSU) nanocomposites filled with different concentrations of multiwalled carbon nanotubes (MWCNT) and carbon nanofibers (CNF) [Only one carbon material per each]. The tensile strength and tensile modulus of both MWCNT-and CNFfilled nanocomposites increased with the increase in filler loading up to 3 wt.%. The addition of 3 wt.% CNF led to increase in tensile strength and modulus by 22% and 46%, respectively. Similarly at the same loading of MWCNT, the tensile strength and tensile modulus increased by 16% and 44%, respectively. Thermogravimetric analysis indicated continuous upgrade in thermal stability compared to pure PSU matrix up to 3 wt.% nanofiller loading. Electrical conductivity of both nanocomposites obeyed a power law model of the percolation theory having very low percolation threshold of 0.0079 (0.9 wt.%) for PSU/CNF nanocomposite and 0.014 (1.5 wt.%) for PSU/MWCNT nanocomposite. Dielectric properties of nanocomposites were enhanced significantly with increasing MWCNT/CNF concentration, but decreased with increasing frequency. The dielectric
Journal of Physics: Conference Series, 2013
The dielectric, electric and thermal properties of carboxylic functionalized multiwalled carbon nanotubes (F-MWCNT) incorporated into the polydimethylsiloxane (PDMS) were evaluated to determine their potential in the field of electronic materials. Carboxylic functionalization of the pristine multi walled carbon tubes (Ps-MWCNT) was confirmed through Fourier transform infrared spectroscopy, X-ray diffraction patterns for both Ps-MWCNTs and F-MWCNTs elaborated that crystalline behavior did not change with carboxylic moieties. Thermogravimetric and differential thermal analyses were performed to elucidate the thermal stability with increasing weight % addition of F-MWCNTs in the polymer matrix. Crystallization/glass transition / melting temperatures were evaluated using differential scanning calorimeter and it was observed that glass transition and crystallization temperatures were diminished while temperatures of first and second melting transitions were progressed with increasing F-MWCNT concentration in the PDMS matrix. Scanning electron microscopy and energy dispersive x-ray spectroscopy were carried out to confirm the morphology, functionalization, and uniform dispersion of F-MWCNTs in the polymer matrix. Electrical resistivity at temperature range (100-300 o C), dielectric loss (tanδ) and dielectric parameters (ε / , ε //) were measured in the frequency range (1MHz-3GHz). The measured data simulate that the aforementioned properties were influenced by increasing filler contents in the polymer matrix because of the high polarization of conductive F-MWCNTs at the reinforcement/polymer interface.
2009
The influence of multi-walled carbon nabotubes(MWCNT) on electric/dielectric, thermal and mechanical properties of CNT -reinforced polymer nanocomposites is studied. The nanocomposites under study was polyamide-6 polymer matrix filled with MWCNTs (PA-6/MWCNT), and polypropylene polymer matrix filled with MWCNTs (PP/MWCNT). The investigation is focused on electrical and dielectric properties in relation to percolation : ac and dc conductivity above the percolation threshold p c and dielectric permittivity, ε΄, below p c . To that aim, broadband dielectric relaxation spectroscopy (DRS) was used. In addition, the effect of MWCNT on the thermal transitions and thermomechanical properties (storage modulus, loss tangent) of the nanocomposites was examined by dynamic mechanical analysis (DMTA) measurements.
Temperature dependence of the electrical properties of the carbon nanotube/polymer composites
Express Polymer Letters, 2009
In this paper, pristine and oxidized multi-walled carbon nanotube (MWCNT)/poly(vinylidene fluoride) (PVDF) composites were prepared and the temperature dependence of some electrical properties of these composites were studied. It is found that the transition temperature (Tt), from positive temperature coefficient (PTC) to negative temperature coefficient (NTC) effect, of the oxidized MWCNT/PVDF composites shifted to a higher temperature. The shift of the Tt of the oxidized MWCNT/PVDF composites can be attributed to the chemical functionalization of the MWCNTs. The dielectric constants of these composites are enhanced remarkably, which can be understood by the interfacial polarization effect. The largest dielectric constant of 3600 is obtained in the composite with about 8 vol% oxidized MWCNTs at 1 kHz. The dielectric constants of these composites increase firstly and then decrease with increasing temperature. However, when the temperature reaches a higher value, the dielectric constants increase again with increasing temperature. The 'wave' phenomenon of the temperature dependence of the dielectric constants can be understood by the temperature dependence of the interfacial polarization.
Thermal and Electrical Characterization of Polypropylene/Carbon Nanotubes Nanocomposites
TechConnect Briefs, 2007
The influence of multi-walled carbon nanotubes (MWCNT) on electric/dielectric and thermal properties of CNT-reinforced polypropylene (PP) nanocomposites is studied. The investigation is focused on electrical and dielectric properties in relation to percolation: ac and dc conductivity, σ ac and σ dc , respectively, above the percolation threshold p c and dielectric permittivity, ε′, below p c. To that aim, broadband dielectric relaxation spectroscopy (DRS) was used. In addition, the effect of MWCNT on the thermal transitions (glass transition, crystallization, melting) of the nanocomposites was examined by differential scanning calorimetry (DSC) measurements.
Design and development of thermally conductive hybrid nano‐composites in polysulfone matrix
Polymer Composites, 2018
A percolating network of hybrid fillers can provide significant synergic enhancement of thermal conductivity in polymer matrix composites. Especially, when platelets and fibers of high aspect ratios are mixed to form a percolating network, the percolation thresholds are small. However, the optimum ratio of platelets to fibers must be acquired for the maximum synergic enhancement. In this work, polysulfone (PSU) matrix‐hybrid fillers composite is designed with high thermal conductivity using a computational model. The calibration of computational model with several experimentally measured thermal conductivities of polymer matrix‐hybrid nanocomposites leads to the composition where maximum synergic effect/maximum thermal conductivity is expected. For the specific PSU–Graphene nano‐platelets (GNPs)/Carbon nano‐tubes (CNTs) hybrid composites synthesized in this study, the composition with maximum thermal conductivity as designed by the model is PSU/8.4% GNPs/1.6% CNTs. The samples produ...
Design, Development and Evaluation of Thermal Properties of Polysulphone–CNT/GNP Nanocomposites
2021
Polysulphone (PSU) composites with carbon nanotubes (PSU-CNT) and graphene nanoplatelets (PSU-GNP) were developed through the solution casting process, using various weight load percentages of 1, 3, 5, and 10 wt% of CNT and GNP nanofillers. The microstructural and thermal properties of the PSU-based composites were compared. The microstructural characterisation of both composites (PSU-CNTs and PSU-GNPs) showed a strong matrix–filler interfacial interaction and uniform dispersion of CNTs and GNPs in the PSU matrix. The analysis demonstrated that both the thermal conductivity and effusivity improved with the increase in the weight percentage (wt%) of CNTs and GNPs because of the percolation effect. The polysulphone-based composite containing 10 wt% CNTs showed a remarkably high thermal conductivity value of 1.13 (W/m·K), which is 163% times higher than pure PSU. While the glass transition temperature (Tg) was shifted to a higher temperature, the thermal expansion was reduced in all th...
Composites Science and Technology, 2012
Commercial Udel Ò poly(ether sulfone) (PSU) was filled with three different commercially available multiwalled carbon nanotubes (MWCNTs) by small scale melt mixing. The MWCNTs were as grown NC 7000 and two of its derivatives prepared by ball milling treatment. One of them was unmodified (NC 3150); the other was amino modified (NC 3152). The main difference beside the reactivity was the reduced aspect ratio of NC 3150 and NC 3152 caused by ball milling process. All PSU/MWCNT composites with similar filler content were prepared under fixed processing conditions and comparative analysis of their electrical and mechanical properties were performed and were correlated with their microstructure, characterized by optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). A non-uniform MWCNT dispersion was observed in all composites. The MWCNTs were present in form of agglomerates in the size of 10-60 lm whereas the deagglomerated part was homogeneously distributed in the PSU matrix. The differences in the agglomeration states correlate with the variations of properties between different PSU/MWCNT composites. The lowest electrical percolation threshold of 0.25-0.5 wt.% was observed for the shortened non-functionalized MWCNT composites and the highest for amine-modified MWCNT composites (ca. 1.5 wt.%). The tensile behavior of the three composites was only slightly altered with CNT loading as compared to the pure PSU. However, the elongation at break showed a reduction with MWCNT loading and the reduction was least for composite with best MWCNT dispersion.
Polymer Science, Series A, 2017
Multi-walled carbon nanotubes (MWCNTs)-Thermoplastic polyurethanes (TPU) composites were characterized by means of differential scanning calorimetry (DSC) and Dielectric Relaxation Spectroscopy (DRS). The DSC analysis shows the existence of two glass transition temperatures (T g) linked to the soft and hard segment of TPU. The T g associated with the soft segment decrease by increasing MWCNT content, while the T g associated with the hard segments is not affected significantly by the MWCNT content. DRS analysis was used to analyze how the MWCNT content affects the electrical properties of the composites. The results of DRS showed a correlation between MWCNT content and the electrical properties of the material. Thus, it was observed that rising temperature and MWCNT content, both increased the dielectric permittivity and the loss factor. Otherwise, the presence of MWCNT produces an enhancement of charge carriers trapping, increasing the electrical conductivity. The conductivity process was analyzed by means of several functions as (i) complex impedance (Z * ()), (ii) dielectric conductivity ( ' ()) and loss dielectric modulus (M " ()). From the study of the MWCNT content effect on the conductivity behavior, it follows that there is an increase of several orders of magnitude of the conductivity value. The electrical conductivity of the composite was found to exhibit an insulator to conductor transition at a MWCNT critical content, i.e. the percolation threshold, near 6% wt. The activation energy values, associated with the conductive process, obtained by the different procedures are in good agreement. The lower activation energy 1 MJS and MC acknowledge the financial support of the DGCYT through Grant MAT2015-63955-R 2 values observed for the high MWCNT contents can be rationalized if we consider that the mean distance between MWCNT decreases with increasing MWCNT content.