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Elastic and engineering properties of nanoparticle enhanced composites and their constituents (matrix, reinforcement and interface)
are calculated. The nanocomposites considered in this study consist of a single-wall carbon nanotube (SWCNT) embedded in polyethylene
matrix. Molecular dynamics simulations are used to estimate the elastic properties o...
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Structural defects usually reduce the load carrying capacity of materials. Here, we show by
molecular dynamics simulations an anomalous vacancy-defect-induced enhancement of interwall
load transfer in annealed carbon nanotubes (CNTs). The large increase of load transfer mainly
stems from the hybrid sp2-sp3 interwall bonds at the vacancy edges, whic...
Citations
... Recent development in finite element based approaches have contributed to numerical studies on fracture toughness and crack propagation in a composite system [19][20][21][22][23]. However, to capture the detailed mechanical response at the nanoscale, molecular dynamics (MD) and multiscale simulations are now increasingly being adopted by numerous researchers [24][25][26][27][28][29][30]. MD simulations provide a molecular level understanding of the behavior of a nanocomposite system [31,32]. ...
Functionalization of nanofillers is known to have stiffening and strengthening effects on nanocomposites through improved interfacial bonding. However, the optimality in the interfacial bonding is generally not reported in the literature. This issue is addressed here through a series of reactive molecular dynamics simulations on carbon nanotube reinforced polymer nanocomposite. For various degrees of functionalization, uniaxial tension conditions are simulated to study the stress–strain behavior, crack propagation, and fracture toughness. The J-integral is used to quantify the fracture toughness. Through these simulations we demonstrate the existence of an optimal degree of functionalization for maximum enhancement in elastic property, tensile strength, ductility, and fracture toughness. The underlying mechanics behind this optimality is identified through careful studies on crack propagation mechanisms, including
crack arresting and formation of new crack surfaces. This optimality, which might also be expected in other material systems, will help in designing efficient nanocomposites
... Few MD works characterize and reveal the mechanics of rubber swelling behavior from an atomic perspective. MD was used by Al-Ostaz et al. [58] to examine CNT and the polymer interactions with the interface at the microscopic level. MD simulations have arisen as an alternate tool for studying atomic-scale material characteristics as well as providing intricacies of chemical interaction and microscopic information. ...
Rubber composites are used in many applications such as mats, shock absorbers for machinery, tires, gears, and tubes in the automobile sector, insulating transmission and elevator belts, tapes, gloves, and blankets in the industrial sector, adhesive and cementing elements in the construction sector. This paper reviews the experimental and molecular dynamics simulations of mechanical properties of carbon nanotube (CNT) reinforced rubber-based composites. Important mechanical properties of CNT with rubber nanocomposites have been described. This review will explain how CNTs can improve the mechanical properties of different rubber composites and will help the researchers working in this area. ARTICLE HISTORY
... Han and Elliott (2007) and Alian et al. (2015) estimated the elastic modulus of a CNT-reinforced polymer composite using MD simulation. Al-Ostaz et al. (2008), Zheng et al. (2017), as well as Dikshit and Engle (2018), studied the mechanical properties of nano-composites with different polymer substrates reinforced with CNTs using MD simulation. Al-Ostaz et al. (2008) found that SWCNT behaves as a linear elastic material. ...
... Al-Ostaz et al. (2008), Zheng et al. (2017), as well as Dikshit and Engle (2018), studied the mechanical properties of nano-composites with different polymer substrates reinforced with CNTs using MD simulation. Al-Ostaz et al. (2008) found that SWCNT behaves as a linear elastic material. Dikshit and Engle (2018) also found that CNT reinforced epoxy composite is five times stiffer than the pure epoxy matrix. ...
In the present study, the initiation and propagation of the damage in open-hole nano-composite laminates reinforced with carbon nanotube (CNT) and carbon fiber (CF) have been investigated using a multi-scale method. The fiber and matrix failure initiation is determined using Hashin-type 3D criteria, and the subsequent propagation is modeled using material-degradation law based on two methods. The computational models for the progressive damage modeling are implemented in the finite element (FE) code ABAQUS using user-defined field variable subroutine USDFLD. In order to estimate three-component nano-composite properties, first, the mechanical properties of CNT-reinforced polymeric nano-composite at a weight fraction of 0.5, 1, and 2% have been calculated using Molecular Dynamics (MD) method. Afterward, the CNT-reinforced polymeric nano-composite as an equivalent resin has been combined to a 45% volume fraction of CF, and the mechanical properties of the micro-scale three-component polymeric nano-composite have been calculated by applying periodic boundary conditions to the FE method. The required strength properties have also been calculated analytically using micromechanical equations. Subsequently, the damage and failure in nano-composite laminates containing a central hole subjected to uniaxial tension are simulated and analyzed. The results show the significant effect of CNT in increasing strength, improving the mechanical properties, and increasing damage resistance in three-component nano-composites. Numerical results also show that the damage model can accurately predict the behavior of progressive damage qualitatively and quantitatively.
... The value of the elastic modulus of the PE matrix was compared with that of the experiment under the same conditions to verify the reliability of the model. When the axial loading rate was 3 10 6 -Å·ps −1 , Young's modulus of pure PE was 1.25 Gpa at a temperature of 300 K, which was in good agreement with 1.22 Gpa reported by Alostaz et al [20]. The following steps were performed to calculate the elastic modulus of pure PE. ...
Carbon nanotube (CNT) filling in a polymer is an advanced approach to improve and manage the mechanical behaviors of polymer-matrix nanocomposites. However, some structural defects exist in CNTs, e.g., Stone–Wales (SW) defects on single-walled carbon nanotubes (SWCNT), which reduces the strength and changes the mechanical properties of CNT-reinforced nanocomposites. The influences of CNTs’ SW defects on the Young' modulus of the CNT-polyethylene (PE) composite and its interface were investigated. All studies were performed through molecular dynamics (MD) simulations with the consistent force field (PCFF) on the platform of a large-scale atomic/molecular massively parallel simulator (LAMMPS). In the MD model of the CNT-PE nanocomposite, CNTs contained SW defects. The elastic modulus of the nanocomposite was obtained from its stress-strain relation, and that of the CNT-PE interface varied with strain according to the interfacial interaction energy. The correctness and rationality of the work were verified by comparing the results from references, experiments, and the rule of mixtures (ROM). The results showed that SW defects of CNTs reduced the mechanical strength no matter for the interface and integral nanocomposite. Specifically, with increased SW defect concentration (defined as the ratio of atoms in the SW defect region to total atoms of a CNT), the interfacial strength significantly weakened, and the elastic modulus of the integral nanocomposite reduced on the macro level. These results are beneficial to understanding the mechanical properties of CNT-PE composites and the design of related products.
... Arash et al. [26] used MD to determine the mechanical properties of RVEs made of the short or the infinite CNTs embedded in the polymer matrix taking into account the interphase. Al-Ostaz et al. [27] applied MD to calculate the elastic properties of SWCNT-enhanced composites considering matrix, CNT, and interphase. They analyzed cases of aligned and randomly distributed SWCNTs. ...
Mechanical properties of carbon nanotube (CNT)-based nanocomposites are broadly discussed in the literature. The influence of CNT arrangements on the elastic properties of nanocomposites based on the finite-element method (FEM) and representative volume element (RVE) approach is presented here. This study is an application of RVE modeling in the characterization of elastic behavior of CNT polymer nanocomposites. Our main contribution is the analysis of the impact of a nanotube arrangement on the elastic properties of nanocomposite to comprehensively determine the material constants. While most of the articles are focused on one distribution, not all material constants are determined. Our FEM analysis is compared with micromechanical models and other results from the literature. The current work shows that nanotube arrangements lead to different results of elastic properties. The analytical micromechanical models are consistent with the numerical results only for axial Young’s modulus and Poisson’s ratio, whereas other elastic constants are lower than the numerical predictions. The results of these studies indicate that FEM can predict nanocomposite mechanical properties with good accuracy. This article is helpful and useful to comprehensively understand the influence of CNT arrangements on the elastic properties of nanocomposites.
... In addition, an elastic modulus of 1.63 GPa and a Poisson's ratio of 0.37 are estimated here for the pure PE at 300 K, which are rather lower than the corresponding computed values of 1.32 GPa and 0.32, respectively, found elsewhere [33]. In another MD formulation in which the COMPASS force field has been used instead [34], an elastic modulus of 1.22 GPa and a Poisson's ratio of 0.37 have Figure 6 depicts the numerically computed final densities for all the tested materials and temperatures. The density of the pure PE varies between 0.83-0.80 as the temperature increases from 300 to 400 K, a prediction that is in good agreement with other computational and experimental estimations [30,31]. ...
... The tensile curve is characterized by a stress-softening region after the yield for the pure PE at 300 K, which are rather lower than the corresponding computed values of 1.32 GPa and 0.32, respectively, found elsewhere [33]. In another MD formulation in which the COMPASS force field has been used instead [34], an elastic modulus of 1.22 GPa and a Poisson's ratio of 0.37 have been proposed for a temperature of 298 K. For all the tested temperatures, the computed shear stress-strain curves are almost linear for stains up to 10% while their slop decreases in a linear manner as the temperature increases. ...
In the present study, the thermomechanical effects of adding a newly proposed nanoparticle within a polymer matrix such as polyethylene are being investigated. The nanoparticle is formed by a typical single-walled carbon nanotube (SWCNT) and two equivalent giant carbon fullerenes that are attached with the nanotube edges through covalent bonds. In this way, a bone-shaped nanofiber is developed that may offer enhanced thermomechanical characteristics when used as a polymer filler, due to each unique shape and chemical nature. The investigation is based on molecular dynamics simulations of the tensile stress-strain response of polymer nanocomposites under a variety of temperatures. The thermomechanical behavior of the bone-shaped nanofiber-reinforced polyethylene is compared with that of an equivalent nanocomposite filled with ordinary capped single-walled carbon nanotubes, in order to reach some coherent fundamental conclusions. The study focuses on the evaluation of some basic, temperature-dependent properties of the nanocomposite reinforced with these innovative bone-shaped allotropes of carbon.
... Such height was considered to comply with the length of the selected NTH to ensure a periodic boundary condition. In literature, the considered monomer number ranges from 20 to 40, [23][24][25][26][27] thus, this work selected the PE chain with 20 monomers. i.e., -(CH 2 -CH 2 ) 20 -, to fill the empty space of the supercell. ...
Polymer nanocomposites with high thermal conductivity have been increasingly sought after in the electronic industry. Based on molecular dynamics simulations, this work assesses the thermal transport in polyethylene (PE) nanocomposites with the presence of a new one-dimensional nanofiller-a carbon nanothread (NTH). It is found that the axial thermal conductivity of PE nanocomposites increases linearly with the content of regularly aligned NTH fillers, while the aggregated pattern suppresses the enhancement effect. This phenomenon is explained by a stronger filler-filler interaction that reduces the intrinsic thermal conductivity of the NTH. Results show that the randomly dispersed NTHs can hardly promote heat transfer because effective heat transfer channels are lacking. Strikingly, surface functionalization has an adverse effect on the thermal conductivity due to the presence of additional voids. The presence of voids answers a long-standing open question that functionalization of the heat conductive filler only slightly improves the thermal conductivity of the polymer composite. Additionally, the transverse thermal conductivity degrades in the presence of the NTH and exhibits no clear correlation with the filler content or the distribution pattern. Overall, this study provides an in-depth understanding of the heat transfer within the polymer nanocomposites, which opens up possibilities for the preparation of highly conductive polymers.
... Al. Ostaz et al. [21] estimated the mechanical properties of a polyethylene-matrix composite reinforced with singlewalled CNTs using MD simulation. One of their results is that elastic constants are the same for SWCNT under various loadings. ...
In this study, the mechanical and thermal properties of carbon nanotube-reinforced polymeric nano-composite have been predicted by simulating molecular dynamics (MD). The polymer matrix is of epoxy polymer type with EPON828 resin along with EpiCure Curing Agent-3234 hardener which is reinforced with a single-walled carbon nanotube (SWCNT). Mechanical and thermal properties such as density, elastic modulus, Poisson’s ratio, and coefficient of thermal expansion (CTE) for various states, including the cross-linking degree of resin and hardener molecules 10–65%, carbon nanotubes (CNTs) with different diameters, and weight fraction of carbon nanotubes of 0.5, 1 and 2% have been estimated. The cell’s stiffness matrix in all cases was extracted, and thermo-mechanical properties were obtained using it. The placement of carbon nanotubes in a representative cell is completely random which has a random orientation, and the cell is dynamically analyzed separately under constant temperature and constant pressure conditions at the specified time, and after equilibration, its properties are extracted. The results show an obvious increase in the elastic modulus by increasing cross-linking degrees and an increase in the elastic modulus, and a significant decrease in the nano-composite CTE when the weight fraction of CNTs has increased. The experimental studies and simulation of other researchers were examined to validate the simulation that, the results are in good agreement with each other.
... Single-walled nanotube (SWCNT) is a CNT that exhibits electric properties that are different from multi-walled carbon nanotube (MWNT). SWCNT has various applications in polymers [24], high-performance supercapacitors [25], catalysts [26], gas-discharge tubes in telecom networks [27], energy conversion [28], drug delivery [29], sensors [30], etc. Motivated by the wide applications of the SWCNT in various fields of science and engineering, some interesting mathematical models [31][32][33][34][35][36][37][38][39] have been developed to study the peristaltic transport of SWCNT suspended nanofluids with permeable walls [31]; MHD slip flow over stretching surface [32]; induced magnetic field and heat flux [33]; variable viscosity and wall properties [34]; velocity and thermal slips in the mixed convection [35]; micropolar fluid in a rotating fluid [36]; curved channel with variable viscosity [37]; radiative nanofluid flow with double stratification [38]. Raza et al. [39] examined the effect of the induced magnetic field and different types of carbon nanotubes on heat transfer characteristics of saltwater transported by using a peristaltic pump through a permeable channel. ...
This article analyzes the flow of single-walled carbon nanotubes (SWCNTs) suspended water-based ionic solution driven by combined effects of electroosmosis and peristalsis mechanisms. The analysis is performed in the presence of the transverse magnetic field, thermal radiation, mixed convection, and the slip boundary condition imposed on the channel walls. Poisson–Boltzmann ionic distribution is linearized by employing the Debye–Hückel approximation. The scaling analysis of the problem is rendered subject to the lubrication approach. The resulting nonlinear system of equations is executed to obtain approximate solutions using regular perturbation techniques and the graphical results are computed for various flow properties. Pumping and trapping phenomena are also discussed under the effects of pertinent parameters. Computed results show that a reduction in EDL thickness intensifies the fluid velocity as well as temperature. Improvement in thermal conductivity of base fluid is noticed with increasing SWCNTs volume fraction. It is further examined that axial velocity magnifies with Helmholtz–Smoluchowski velocity.
... Thereby, the resolution and sharpness of the image will get affected. The structure of pores cannot be displayed clearly because of the overlap in optical imaging (Al-Ostaz et al., 2008). As a result, it is difficult to observe the structure of micro-pores (<10 μm) clearly using polarized light microscopy, especially with the image based quantitative analysis of the micro-pores (Liu et al., 2018;Bultreys et al., 2016). ...
Understanding the occurrences of different fractions of organic matter in shale reservoirs is very important for the evaluation of shale oil. Lacustrine organic-rich shale samples from the first member of the Cretaceous Qingshankou Formation in the Songliao Basin were analyzed with confocal laser scanning microscopy (CLSM) and fluorescence spectral analysis. The results show that the occurrences of different organic components are related to the fabric of samples and vary with depth. The bulk content of light components is significantly higher than heavy components and exhibits a positive relationship with quartz and feldspar contents. Both light and heavy components are distributed parallel with the lamination in microscopic view in laminated samples, and randomly in massive samples. The maximum radius of light components in most of the samples is larger than 20 µm, while it is smaller for heavy components, indicating the micro fractionation from clay/organic lamina to quartz/feldspar lamina. The depth of enrichment of light components corresponds to the oil maturity of organic matter. Both the distribution of light and heavy components fits the same fractal model, with fractal dimensions ranging between 2.2 and 2.5. The CLSM results confirm that it can be a reliable tool for the “sweet spot” exploration.
