scholarly journals Simulation of Percolation Threshold, Tunneling Distance, and Conductivity for Carbon Nanotube (CNT)-Reinforced Nanocomposites Assuming Effective CNT Concentration

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 114 ◽  
Author(s):  
Yasser Zare ◽  
Kyong Yop Rhee
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Percolation Threshold ◽  
Experimental Results ◽  
Filler Concentration ◽  
Experimental Measurements ◽  
Tunneling Conductivity ◽  
Tunneling Distance

This article suggests simple and new equations for the percolation threshold of nanoparticles, the tunneling distance between nanoparticles, and the tunneling conductivity of polymer carbon nanotubes (CNTs) nanocomposites (PCNT), assuming an effective filler concentration. The developed equations correlate the conductivity, tunneling distance, and percolation threshold to CNT waviness, interphase thickness, CNT dimensions, and CNT concentration. The developed model for conductivity is applied for some samples and the predictions are evaluated by experimental measurements. In addition, the impacts of various parameters on the mentioned terms are discussed to confirm the developed equations. Comparisons between the calculations and the experimental results demonstrate the validity of the developed model for tunneling conductivity. High levels of CNT concentration, CNT length, and interphase thickness, as well as the straightness and thinness of CNTs increase the nanocomposite conductivity. The developed formulations can substitute for the conventional equations for determining the conductivity and percolation threshold in CNT-reinforced nanocomposites.

scholarly journals Characterization of percolation behavior in conductor–dielectric 0-3 composites

2014 ◽  
Vol 04 (04) ◽  
pp. 1450035 ◽  
Author(s):  
Lin Zhang ◽  
Patrick Bass ◽  
Zhi-Min Dang ◽  
Z.-Y. Cheng
Keyword(s):  
Dielectric Constant ◽  
Percolation Threshold ◽  
Frequency Dependence ◽  
Experimental Results ◽  
Effective Dielectric Constant ◽  
Filler Concentration ◽  
Percolation Behavior ◽  
The Matrix ◽  
The Relationship

The equation ε eff ∝ (ϕc - ϕ)-s which shows the relationship between effective dielectric constant (εeff) and the filler concentration (φ), is widely used to determine the percolation behavior and obtain parameters, such as percolation threshold φc and the power constant s in conductor–dielectric composites (CDCs). Six different systems of CDCs were used to check the expression by fitting experimental results. It is found that the equation can fit the experimental results at any frequency. However, it is found that the fitting constants do not reflect the real percolation behavior of the composites. It is found that the dielectric constant is strongly dependent on the frequency, which is mainly due to the fact that the frequency dependence of the dielectric constant for the composites close to φc is almost independent of the matrix.

scholarly journals Segregated network polymer/carbon nanotubes composites

2004 ◽  
Vol 2 (2) ◽  
pp. 363-370 ◽  
Author(s):  
A. Mierczynska ◽  
J. Friedrich ◽  
H. Maneck ◽  
G. Boiteux ◽  
J. Jeszka
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Carbon Nanotube ◽  
Percolation Threshold ◽  
Network Formation ◽  
Processing Parameters ◽  
Low Grade ◽  
Single Walled Carbon ◽  
Conductive Composites ◽  
Grade Material

AbstractIn this work we present the preparation of conductive polyethylene/carbon nanotube composites based on the segregated network concept. Attention has been focused on the effect of decreasing the amount of filler necessary to achieve low resistivity. Using high- and low-grade single-walled carbon nanotube materials we obtained conductive composites with a low percolation threshold of 0.5 wt.% for high-grade nanotubes, about 1 wt% for commercial nanotubes and 1.5 wt% for low-grade material. The higher percolation threshold for low-grade material is related to low effectiveness of other carbon fractions in the network formation. The electrical conductivity was measured as a function of the single-walled carbon nanotubes content in the polymer matrix and as a function of temperature. It was also found that processing parameters significantly influenced the electrical conductivity of the composites. Raman spectroscopy was applied to study single wall nanotubes in the conductive composites.

An integrated XFEM modeling with experimental measurements for optimizing thermal conductivity in carbon nanotube reinforced polyethylene

2022 ◽  
Author(s):  
Serafeim Bakalakos ◽  
Ioannis Kalogeris ◽  
Vissarion Papadopoulos ◽  
Manolis Papadrakakis ◽  
Panagiotis Maroulas ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Effective Conductivity ◽  
Thermal Conductance ◽  
Integrated Approach ◽  
Parent Material ◽  
Experimental Measurements ◽  
Conductive Heat ◽  
Material Interfaces ◽  
Conductive Material

Abstract The present paper investigates the thermal properties of carbon nanotube reinforced polyethylene and specifically its potential as highly conductive material. To this end, an integrated approach is proposed combining both numerical and experimental procedures. First, in order to study conductive heat transfer in two-phase materials with imperfect interfaces, a detailed numerical model is developed based on the extended finite element method (XFEM), where material interfaces are modeled using the level set method. The thermal conductance at the interface of the carbon nanotubes and the polymer matrix is considered to be an unknown model parameter, the value of which is obtained by utilizing a series of experimental measurements of the composite material’s effective conductivity. The interfacial thermal conductance parameter value is inferred by calibrating the numerically predicted effective conductivity to the series of the corresponding experimental measurements. Once this parameter is estimated, the data-informed model is subsequently employed to provide reliable predictions of the effective conductivity of the composite for various weight fractions and configurations of carbon nanotubes in the parent material. Furthermore, microstructural morphologies that provide upper limits on the effective conductivity of the composite are identified via sensitivity analysis, demonstrating its potential as a highly conductive material.

Convenient and solventless preparation of pure carbon nanotube/polybenzoxazine nanocomposites with low percolation threshold and improved thermal and fire properties

2014 ◽  
Vol 2 (19) ◽  
pp. 6814-6822 ◽  
Author(s):  
Camilo Zúñiga ◽  
Leïla Bonnaud ◽  
Gerard Lligadas ◽  
Juan Carlos Ronda ◽  
Marina Galià ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Bisphenol A ◽  
Percolation Threshold ◽  
Multiwalled Carbon Nanotubes ◽  
Multiwalled Carbon ◽  
Pure Carbon ◽  
Fire Properties

This work contemplates the use of pristine multiwalled carbon nanotubes (MWNTs) as nanofillers in the preparation of bisphenol A-based polybenzoxazine and diphenolic acid derived polybenzoxazine.

Investigation of dielectric relaxation phenomena and AC electrical conductivity in graphite/carbon nanotubes/engine oil nanofluids

2020 ◽  
pp. 073168442095185
Author(s):  
S Barnoss ◽  
BMG Melo ◽  
M El Hasnaoui ◽  
MPF Graça ◽  
ME Achour ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Carbon Nanotube ◽  
Percolation Threshold ◽  
Complex Impedance ◽  
Engine Oil ◽  
Positive Temperature ◽  
Multiwalled Carbon ◽  
Remarkable Change ◽  
Ac Electrical Conductivity

In this paper, we report an investigation on electrical conduction mechanisms of nanofluids based on commercial engine oil loaded with graphite (Gt) and multiwalled carbon nanotubes, at different concentrations. The impedance spectroscopy technique was used to measure the resistance and capacity characterizing each sample in a frequency range 100 Hz–1 MHz and a temperature range 300–400 K. Two formalisms were used to analyze the data: (a) the electrical conductivity which has found to follow the Jonscher’s law with single and double exponents for carbon nanotube concentrations below and above the percolation threshold, respectively, and (b) the complex impedance that has permitted to identify the relaxation peaks according to the Cole–Cole model. Both the two formalisms showed that when the carbon nanotube concentration is higher than the percolation threshold, a positive temperature coefficient and a remarkable change in conductivity were observed, suggesting that the presence of the carbon nanotube greatly affect the electrical properties of the engine oil as a result of additional polarization effect induced by these nanoparticles. Furthermore, the analysis of the temperature dependence of dc conductivity and relaxation time using the Arrhenius equation indicated the addition of carbon nanotubes into engine oil increase the activation energies.

scholarly journals Mechanical and Self-Sensing Properties of Multiwalled Carbon Nanotube-Reinforced ECCs

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Chuanbo Liu ◽  
Guozhen Liu ◽  
Zhi Ge ◽  
Yanhua Guan ◽  
Zhiyong Cui ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Percolation Threshold ◽  
Tensile Strain ◽  
The Self ◽  
Fractional Change ◽  
Multiwalled Carbon ◽  
Mwcnt Content ◽  
Sensing Properties ◽  
Midspan Deflection

This paper investigates the effect of type and dosage of multiwalled carbon nanotubes (MWCNTs) on the mechanical and self-sensing properties of engineered cementitious composites (ECCs). Two types of MWCNTs (MWCNTa and MWCNTb) were employed. The tensile and flexural strengths of CNT-reinforced ECCs were improved compared with normal ECCs, while the ultimate tensile strain and midspan deflection were reduced. Compared with the dosage of MWCNTs, the type had less effect on these properties. The percolation threshold was around 0.3 wt.%. ECCs containing MWCNTs had good self-sensing ability under different loading conditions. When the midspan deflection increased from 0.1 to 0.6 mm, the fractional change in resistivity reached 9%. The dosage of MWCNTs had a significant effect on the self-sensing ability. As the MWCNT content increased, the amplitude of fractional change in resistivity decreased.

Impedance Spectroscopy and Dielectric Properties of Carbon Nanotube-Reinforced Epoxy Polymer Composites

2020 ◽  
Vol 13 (2) ◽  
pp. 113-121
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Impedance Spectroscopy ◽  
Grain Boundary ◽  
Polymer Composites ◽  
Equivalent Circuit ◽  
Epoxy Polymer ◽  
Equivalent Circuit Model ◽  
Circuit Model ◽  
Filler Concentration

Abstract: The aim of this work is to investigate the electric properties of carbon nanotube-reinforced epoxy polymer composites, using impedance spectroscopy, in the frequency range from 1 to 10 and over the temperature range from 25 to 105 . The dielectric response was analyzed using the complex permittivity and the electrical modulus formalisms, depending on temperature and filler concentration in the polymer matrix. Furthermore, an equivalent circuit model is proposed to describe the impedance response of carbon nanotubes/epoxy composites. The impedance studies disclosed the appearance of grain and grain-boundary effects, as confirmed by the Nyquist plot. Keywords: Carbon nanotubes, Composites, Impedance spectroscopy, Equivalent circuit model, Grain effect, Grain-boundary effect.

scholarly journals Study on carbon nanotube/shape memory polymer composites and their applications in wireless worm actuator

2021 ◽  
Vol 37 ◽  
pp. 636-650
Author(s):  
Wei-Hsuan Hsu ◽  
Chia-Wei Lin ◽  
Yi-Hung Chen ◽  
Shang-Ru Wu ◽  
Hung-Yin Tsai
Keyword(s):  
Carbon Nanotubes ◽  
Tensile Strength ◽  
Carbon Nanotube ◽  
Reaction Time ◽  
Shape Memory ◽  
Polymer Composites ◽  
Microwave Heating ◽  
Shape Recovery ◽  
Shape Memory Polymer ◽  
Experimental Results

Abstract In this study, the surface of the carbon nanotubes was modified by chemical functionalization. The carbon nanotubes were placed in a mixed acid solution with a nitric acid-to-sulfuric acid volume ratio of 1:3. The results of the functionalization of the carbon nanotubes were investigated by controlling the reaction time. From the experimental results, the functionalized carbon nanotubes with a reaction time of 12 hours show good dispersibility. In the study of the essential characteristics of composite materials, it was observed that the tensile strength decreased with increase of carbon nanotube content. Compared with the result of the tensile strength test, it can be found that with increasing carbon nanotube content, the microwave heating and shape recovery speed are greatly improved. The experimental results show that the shape memory polymer composite with 4 wt% carbon nanotubes has the fastest microwave heating rate, so it takes only 2 minutes to achieve complete shape recovery. Finally, this study used shape memory polymer composites doped with 4 wt% carbon nanotubes as the driving end, combined with an elastic structure made of polyimide (PI) film using origami techniques to form a worm actuator. In the test, the system could move a distance of 6 mm forward during a microwave time of 1 minute. In addition, this research also constructed a physical model of shape memory polymer and explored the simple movement mechanism of the system.

Smart properties of carbon nanotube-epoxy composites

2020 ◽  
Vol 234 (11) ◽  
pp. 1409-1416
Author(s):  
Changjin Tian ◽  
Youzhi Wang ◽  
Qilin Yang ◽  
Zhi Ge ◽  
Yefeng Du
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Percolation Threshold ◽  
Epoxy Resin ◽  
Smart Materials ◽  
Rate Of Change ◽  
Epoxy Composites ◽  
Effect Of Temperature ◽  
Architectural Structures ◽  
Sensitive Property

Intelligent smart materials can not only monitor the damage and degradation of architectural structures in real time but also the health structure. In recent years, carbon nanotubes materials have emerged to possess both excellent mechanical and electrical properties. Moreover, when carbon nanotubes are added to epoxy resin, intelligent composite materials with significant sensitivity are created. In this study, the stress–strain curves and anelasticity of carbon nanotube/epoxy resin composites with different carbon nanotube concentrations is analyzed. Through changing the level of carbon nanotubes using the two-pole method, the percolation threshold of carbon nanotube/epoxy composites was determined. Thereafter, the effect of temperature on the composites’ conductive properties was investigated. Moreover, using the stepwise cyclic loading method, the piezoresistivity of the carbon nanotube/epoxy composites was investigated. The test results show that the elastic limit, the yield point, and the elastic modulus range of the carbon nanotube/epoxy composites is approximately 45 MPa, 50 MPa, and 1–2 GPa, respectively. The anelasticity of the carbon nanotube/epoxy composites increases with the gradual increase of the stress level. The percolation threshold interval of carbon nanotube/epoxy composites ranges from 0.5 to 1.0 wt%. The rate of change of resistance for the different concentrations on carbon nanotube/epoxy specimens corresponds to the temperature. Notably, the carbon nanotube/epoxy composites have better discrimination and pressure sensitivity for different grades of load. When the carbon nanotube content is 0.5 wt%, the sensitivity of the carbon nanotube/epoxy composites pressure-sensitive property is the largest, which is in agreement with the threshold curve. The results of this investigation have implications for the application of carbon nanotube/epoxy composites in structural health monitoring.

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