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The present study focuses on modeling of carbon nanofibers (CNFs) and evaluating the effect of their reinforcement in
polypropylene (PP) matrix. A novel approach for modeling of CNF has been explained in this study. Molecular dynamics
(MD) simulation has been used to study the effect of CNF volume fraction (Vf) and aspect ratio (l/d) on mechanical...
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... thermal underwear, and carpets), sta- tionery, plastic parts and reusable containers of various types, laboratory equipment, loudspeakers, automotive components, and polymer banknotes. In this study, we have constructed several chains of PP, each containing seven units of propylene as shown in Figure 6. The simulation procedure consists of geometry optimiza- tion, dynamics, and forcite mechanical properties cal- culation. ...
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Fibre-reinforced polymer composite has many uses in structural components that required high strength, stiffness, and damping capacity. Cross and quasi-laminated epoxy composites with and without nano Al 2 O 3 were used in this investigation to determine flexural modulus, natural frequency, damping ratio, and mode shapes by using analytical, experi...
Citations
... This high increase is similar to that observed by Sharma et al., where they found that a 2% addition of carbon nanobers in a polypropylene matrix caused a 748% increase. 55 The negative Young's modulus observed in the y-direction indicates a negative strain due to the atoms stretching and expanding instead of being compressed. 60 Therefore, the effect of the addition of TiO 2 increases its mechanical properties in 2 directions. ...
Electrospun nanofibrous materials serve as potential solutions for several biomedical applications as they possess the ability of mimicking the extracellular matrix (ECM) of tissues. Herein, we report on the fabrication of novel nanostructured composite materials for potential use in biomedical applications that require a suitable environment for cellular viability. Anodized TiO2 nanotubes (TiO2 NTs) in powder form, with different concentrations, were incorporated as a filler material into a blend of chitosan (Cs) and polyvinyl alcohol (PVA) to synthesize composite polymeric electrospun nanofibrous materials. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), nanoindentation, Brunauer–Emmett–Teller (BET) analysis, and MTT assay for cell viability techniques were used to characterize the architectural, structural, mechanical, physical, and biological properties of the fabricated materials. Additionally, molecular dynamics (MD) modelling was performed to evaluate the mechanical properties of the polymeric PVA/chitosan matrix upon reinforcing the structure with TiO2 anatase nanotubes. The Young's modulus, shear and bulk moduli, Poisson's ratio, Lame's constants, and compressibility of these composites have been computed using the COMPASS molecular mechanics force fields. The MD simulations demonstrated that the inclusion of anatase TiO2 improves the mechanical properties of the composite, which is consistent with our experimental findings. The results revealed that the mineralized material improved the mechanical strength and the physical properties of the composite. Hence, the composite material has potential for use in biomedical applications.
... Considering the above, the present study aims to investigate the mechanical behaviour of a polymeric material reinforced with fullerenes C 60 . In view of the fact that experimental procedures (Ballav, 2005;Wondmagegn and Curran, 2006;Bronnikov et al., 2017;Zuev, 2011Zuev, , 2012 are excessively costly for the material characterization of polymer-fullerene nanocomposite systems, numerical techniques such as molecular dynamics (MD) (Sharma et al., 2015(Sharma et al., , 2016 seem to be very attractive for predicting and investigating their performance. Therefore, in the present study a hybrid numerical multiscale technique based on MD (Sharma et al., 2015(Sharma et al., , 2016, finite element method (FEM) (Tserpes and Papanikos, 2014) and unit cell methods (Marur, 2004) has been implemented to characterize the elastic mechanical properties of a polymeric material reinforced uniformly with molecules C 60 . ...
... In view of the fact that experimental procedures (Ballav, 2005;Wondmagegn and Curran, 2006;Bronnikov et al., 2017;Zuev, 2011Zuev, , 2012 are excessively costly for the material characterization of polymer-fullerene nanocomposite systems, numerical techniques such as molecular dynamics (MD) (Sharma et al., 2015(Sharma et al., , 2016 seem to be very attractive for predicting and investigating their performance. Therefore, in the present study a hybrid numerical multiscale technique based on MD (Sharma et al., 2015(Sharma et al., , 2016, finite element method (FEM) (Tserpes and Papanikos, 2014) and unit cell methods (Marur, 2004) has been implemented to characterize the elastic mechanical properties of a polymeric material reinforced uniformly with molecules C 60 . Among numerous candidate polymer materials, the polyamide-12 (PA-12) has been chosen as the matrix material of the investigated nanocomposite since it has already been experimentally demonstrated that the addition of graphene nanoplatelets or CNTs, which are analogous to fullerenes, at even small concentration up to 2 wt% within pure PA-12, may lead to significant improvements of its mechanical and electrical behaviour (Zuev, 2011;Chatterjee et al., 2011). ...
Purpose
The purpose of this paper is the computation of the elastic mechanical behaviour of the fullerene C60 reinforced polyamide-12 (PA-12) via a two-stage numerical technique which combines the molecular dynamics (MD) method and the finite element method (FEM).
Design/methodology/approach
At the first stage, the proposed numerical scheme utilizes MD to characterize the pure PA-12 as well as a very small cubic unit cell containing a C60 molecule, centrally positioned and surrounded by PA-12 molecular chains. At the second stage, a classical continuum mechanics (CM) analysis based on the FEM is adopted to approximate the elastic mechanical performance of the nanocomposite with significantly lower C60 mass concentrations. According to the computed elastic properties arisen by the MD simulations, an equivalent solid element with the same size as the unit cell is developed. Then, a CM micromechanical representative volume element (RVE) of the C60 reinforced PA-12 is modelled via FEM. The matrix phase of the RVE is discretized by using solid finite elements which represent the PA-12 mechanical behaviour predicted by MD, while the C60 neighbouring location is meshed with the equivalent solid element.
Findings
Several multiscale simulations are performed to study the effect of the nanofiller mass fraction on the mechanical properties of the C60 reinforced PA-12 composite. Comparisons with other corresponding experimental results are attempted, where possible, to test the performance of the proposed method.
Originality/value
The proposed numerical scheme allows accurate representation of atomistic interfacial effects between C60 and PA-12 and simultaneously offers a significantly lower computational cost compared with the MD-only method.
... There are very limited studies of Bis-GMA and TEGDMA dental composites, using MD because of their complexity. The authors have used MD simulations for exploring the properties of various nanomaterials [18][19][20][21][22][23][24][25][26][27][28]. Thus, in this work MD simulations have been used to predict the mechanical and dynamic properties of blends of dental resin and composites. ...
In this study, molecular dynamics simulations have been used to investigate the effects of organic/inorganic components on the properties of silica nanoparticle/hydroxyapatite fiber reinforced Bis-GMA/TEGDMA dental composite materials. Characterization at the atomic scale is highly important for an advancement of the understanding of properties of resin based materials. Various combinations of Bis-GMA/TEGDMA (20-80% by weight) were modelled using molecular dynamics. The silica nanoparticle weight percentage was varied from 0 to 11% and the hydroxyapatite fiber weight percentage was varied from 0 to 12%. It was observed that the radius of gyration, in various blends of resin, lie in the range of 16-17 Å and thus was approximately independent of Bis-GMA/TEGDMA weight percentage. It was found that a small percentage of silica nanoparticle improved the mechanical properties significantly because of an increase in the volumetric hydrogen bonds and polymer chain contraction. As the weight percentage of TEGDMA in dental resin blends was increased from 20 to 80%, the hydrogen bonds per unit volume were found to decrease from 1.3 × 10 −3 to 0.3 × 10 −3 Å −3. The elastic and shear moduli of dental composites containing varying percentage of hydroxyapatite fibers (0-12%) increased by 8.13 and 10% respectively. In comparison to the hydroxyapatite fibers, the silica nanoparticles provided significant mechanical reinforcement effect. The diffusion coefficient falls approximately by 46%, from 1.15 × 10 −11 to 0.62 × 10 −11 m 2 /s with an increase in the silica nanoparticle weight percentage from 0 to 11 %. This indicated a strong dependency on change in chain conformation as well as hydrogen bonds. These findings will be of great importance in improving the understanding of the mechanical and dynamic properties of dental materials at the atomic/nanoscale.
... Gu and Sansoz [47] studied the effects of the CNFCA on the mechanical properties of CSCNF by a molecular dynamics simulation (MDS). MDS was utilized by Sharma et al. [48] in order to explore the volume fraction, aspect ratio and CNFCA effects on the mechanical properties of CSCNF reinforced polymers. About the CNFs reinforcing NCs damping properties, Finegan et al. [49] studied loss factor and storage modulus of CNFs reinforcing polymer NCs as a function of simply CNF volume fraction by means of a simple analytical model and experimentally by dynamic mechanical thermal analyzer. ...
Damping properties of polymer matrix nanocomposites (NC) reinforced by vapor grown carbon fiber (VGCF) are investigated by presenting a multi-stage analytical micromechanical model. A third phase as interphase is considered due to the complex chemical and physical state in the region near to matrix/fiber interface. Both uniform and graded properties of the interphase through the thickness are considered. Acceptable agreements in comparison with experiments and appropriate mesh sensitivity analysis prove the efficiency and accuracy of the proposed model. The effects of various meaningful parameters, including the interphase bonding strength, thickness and types and also the VGCF volume fraction, aspect ratio, orientation, diameter, waviness and cone angle are investigated. Stored and dissipated energy in the NC constituents are obtained as well. It is concluded that the NCs reinforced by long nanofiber possess greater storage and loss modulus than the NCs owing short fiber. However, the specific damping capacity picks lower values. Higher bonding strength and lower thickness of the interphase enhance the NC effective damping properties. Increasing VGCF diameter, waviness and cone angle result declining in the damping properties. The interphase portion in the stored and dissipated energy increases by decreasing the interphase bonding strength and increasing the interphase thickness.
This chapter provides the details of molecular dynamics (MD) simulation procedure for nanofiber‐ and nanoparticle‐reinforced polymer composites. MD simulation has been used to study the effect of carbon nanofiber (CNF) volume fraction (V f) and aspect ratio (l/d) on mechanical properties of CNF reinforced polypropylene (PP) composites. CNF composition in PP was varied by volume from 0% to 16%. Aspect ratio of CNF was varied from l/d = 5 to 100. Results show that with only 2% addition by volume of CNF in PP, E 11 increases 748%. Increase in E 22 is very less in comparison to the increase in E 11. With the increase in the CNF aspect ratio (l/d) until l/d = 60, the longitudinal loss factor (η 11) decreases rapidly. MD simulations have also been used to investigate the effects of organic/inorganic components on the properties of silica nanoparticle/hydroxyapatite fiber (HAF) reinforced bis‐GMA/ tri‐ethylene glycol di‐methacrylate (TEGDMA) dental composite materials. Various combinations of bis‐GMA/TEGDMA (20–80% by weight) were modeled using MD. The silica nanoparticle weight percentage was varied from 0% to 11% and the hydroxyapatite fiber weight percentage was varied from 0% to 12%. It was observed that the radius of gyration, in various blends of resin, lie in the range of 16–17 Å and thus was approximately independent of bis‐GMA/TEGDMA weight percentage. It was found that a small percentage of silica nanoparticle improved the mechanical properties significantly because of an increase in the volumetric hydrogen bonds and polymer chain contraction. In comparison to the HAFs, the silica nanoparticles provided significant mechanical reinforcement effect. The diffusion coefficient falls approximately by 46%, from 1.15 × 10−11 to 0.62 × 10−11 m2/s with an increase in the silica nanoparticle weight percentage from 0% to 11%. This indicated a strong dependency on change in chain conformation as well as hydrogen bonds.
In material research, the development of polymer nanocomposite is rapidly emerging as a multidisciplinary research activity whose results could broaden its application in various industries ranging from biomedical to aerospace. This chapter mainly focuses on nanocomposites, especially those nanocomposites of biogenic carbon nanofibers (CNF). It deals with the properties and applications of CNF nanocomposites. The chapter discusses the fabrication methods of CNF composites. There are different ranges of polymers available which are used in the field of nanotechnology. The wide ranges of natural and synthetic polymers generally used are described. In the preparation of any composite there are three main material constituents: matrix, re‐enforcement material (CNF), and interfacial region. The thermal conductivity and mechanical properties of CNF composites also decide their applications as sensors and electrode materials.
In the present study an effort is made to numerically characterize the elastic mechanical behaviour of a polymer-based nanocomposite made of nylon-12, also known as polyamide-12 (PA-12), which is uniformly reinforced with C60 or C70 fullerenes. For this purpose, a numerical study is conducted in two stages.
In the first one, a molecular dynamics (MD) approach is formulated to provide numerical solutions regarding the elastic properties of the nanocomposites under investigation, for a wide range of concentrations of the C60 or C70 reinforcing agents up to 8% by weight. During the analysis, appropriate cubic representative volume elements (RVEs) are developed which contain at its centers single fullerene nanocrystals surrounded by PA-12 polymer chains, in accordance with the assumed uniform nanoparticle distribution.
In the second stage, the reinforcing ability of the most spherical fullerene C60 in nylon-12 matrix is only tested. Given the high computational cost of the MD-only simulations for small C60 mass fractions, a classical continuum mechanics (CM) method, grounded on the finite element method (FEM), is developed. The proposed method pre-requires the utilization of some MD data regarding the RVE of a nanocomposite of a rather high C60 mass fraction, in order to develop a same sized, continuum, equivalent volume unit. Then, nanocomposite RVEs of higher filler concentrations are treated in a continuum manner, by placing centrally the developed volume unit in perfect contact with the surrounded PA-12 matrix. Both components are discretized with appropriate solid finite elements to realize the simulations.
The performance of the MD-only as well as the FEM-MD combined method is investigated through comparisons with relevant experimental measurements.
In this study, molecular dynamics simulations have been used to investigate the effects of organic/inorganic components on the properties of silica nanoparticle/hydroxyapatite fiber reinforced Bis-GMA/TEGDMA dental composite materials. Characterization at the atomic scale is highly important for an advancement of the understanding of properties of resin based materials. Various combinations of Bis-GMA/TEGDMA (20–80% by weight) were modelled using molecular dynamics. The silica nanoparticle weight percentage was varied from 0 to 11% and the hydroxyapatite fiber weight percentage was varied from 0 to 12%. It was observed that the radius of gyration, in various blends of resin, lie in the range of 16–17 Å and thus was approximately independent of Bis-GMA/TEGDMA weight percentage. It was found that a small percentage of silica nanoparticle improved the mechanical properties significantly because of an increase in the volumetric hydrogen bonds and polymer chain contraction. As the weight percentage of TEGDMA in dental resin blends was increased from 20 to 80%, the hydrogen bonds per unit volume were found to decrease from 1.3 × 10−3 to 0.3 × 10−3 Å−3. The elastic and shear moduli of dental composites containing varying percentage of hydroxyapatite fibers (0–12%) increased by 8.13 and 10% respectively. In comparison to the hydroxyapatite fibers, the silica nanoparticles provided significant mechanical reinforcement effect. The diffusion coefficient falls approximately by 46%, from 1.15 × 10−11 to 0.62 × 10−11 m2/s with an increase in the silica nanoparticle weight percentage from 0 to 11 %. This indicated a strong dependency on change in chain conformation as well as hydrogen bonds. These findings will be of great importance in improving the understanding of the mechanical and dynamic properties of dental materials at the atomic/nanoscale.
The aim of the present study is to propose a multiscale computational technique for the prediction of the elastic mechanical properties of nanoreinforced composites. The proposed method utilizes a molecular dynamics (MD) based numerical scheme to capture the mechanical behaviour of the nanocomposite at nanoscale and then a classical continuum mechanics (CM) analysis based on the finite element method (FEM) to characterise the microscopic performance of the nanofilled composite material. The material under investigation is polyamide 12 (PA 12) randomly reinforced with fullerenes C60. At the first stage of the analysis, in order to capture the atomistic interfacial effects between C60 and PA 12, a very small cubic unit cell containing a C60 molecule, centrally positioned and surrounded by PA 12 molecular chains, is simulated via MD. Inter- and intra-molecular atomic interactions are described by using the Condensed Phase Optimized Molecular Potential for Atomistic Simulation Studies (COMPASS). According to the elastic properties data arisen by the MD simulations, an equivalent finite element volume with the same size as the unit cell is developed. At the second stage, a CM micromechanical representative volume element (RVE) of the C60 reinforced PA 12 is developed via FEM. The matrix phase of the RVE is discretised by using solid finite elements which represent the PA 12 mechanical behaviour while each C60 location is meshed with equivalent solid finite elements. Several multiscale simulations are performed to study the effect of the nanofiller volume fraction on the mechanical properties of the C60 reinforced PA 12 composite. Comparisons with other corresponding experimental results are attempted, where possible, to test the performance of the proposed method.
