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Simple and green oxidation of cyclohexene to adipic acid with an efficient and durable silica-functionalized ammonium tungstate catalyst
, Article Catalysis Communications ; Vol. 43 , 5 January , 2014 , pp. 169-172 ; Mahmoodi Hashemi, M ; Sharif University of Technology
Abstract
A novel silica-functionalized ammonium tungstate interphase catalyst has been reported as a non-nitric acid route for adipic acid production from one-pot oxidative cleavage of 30% hydrogen peroxide and catalytic amounts of p-toluenesulfonic acid (PTSA). The catalyst has been simply prepared by commercially available starting material. The structure of the catalyst has been investigated using FT-IR spectroscopy, atomic absorption, TEM, SEM and XRD analysis. The catalyst has shown good to high activity even up to 10 runs of reaction. Simple preparation of the catalyst, avoids using harmful phase transfer catalyst (PTC) and/or chlorinated additives are among the other benefits of this work
Effective mechanical properties of unidirectional composites in the presence of imperfect interface
, Article Archive of Applied Mechanics ; Vol. 84, issue. 6 , June , 2014 , pp. 807-819 ; Print ISSN: 0939-1533 ; Toozandehjani, H ; Sharif University of Technology
Abstract
In this paper, the equivalent inclusion method is implemented to estimate the effective mechanical properties of unidirectional composites in the presence of an imperfect interface. For this purpose, a representative volume element containing three constituents, a matrix, and interface layer, and a fiber component, is considered. A periodic eigenstrain defined in terms of Fourier series is then employed to homogenize non-dilute multi-phase composites. In order to take into account the interphase imperfection effects on mechanical properties of composites, a stiffness parameter in terms of a matrix and interphase elastic modulus is introduced. Consistency conditions are also modified...
Piezoelectric composites with periodic multi-coated inhomogeneities
, Article International Journal of Solids and Structures ; Volume 47, Issue 21 , October , 2010 , Pages 2893-2904 ; 00207683 (ISSN) ; Weng, G. J ; Kargarnovin, M. H ; Shodja, H. M ; Sharif University of Technology
Abstract
A new, robust homogenization scheme for determination of the effective properties of a periodic piezoelectric composite with general multi-coated inhomogeneities is developed. In this scheme the coating does not have to be thin, the shape and orientation of the inclusion and coatings do not have to be identical, their centers do not have to coincide, their properties do not have to remain uniform, and the microstructure can be with the 2D elliptic or the 3D ellipsoidal inclusions. The development starts from the local electromechanical equivalent inclusion principle through the introduction of the position-dependent equivalent eigenstrain and electric field. Then with a Fourier series...
On variations of the interphase thickness and the slope of strengthening by clay addition in exfoliated polymer-clay nanocomposites
, Article Polymer (United Kingdom) ; Volume 90 , 2016 , Pages 302-308 ; 00323861 (ISSN) ; Khederlou, Kh ; Payandehpeyman, J ; Bagheri, R ; Sharif University of Technology
Elsevier Ltd
Abstract
Polymer-clay nanocomposites (PCNs) have received intensive attention in recent years because of their wide domain of applications. The present report provides an approach to calculate the thickness of nanometric interphase region in exfoliated PCNs based on the information about their macroscopic modulus and their nanoclay content. First, the concept of interphase region in PCNs is explained with an “algae explanation”. Then, a series of parametric finite element simulations together with analytical equations are employed to derive an explicit relationship between the interphase thickness and the PCN macroscopic modulus. The obtained analytical model considers the structural impact of the...
Investigating Effects of Interphase on Mechanical Properties of Particulate Metal-Matrix Nanocomposites Using Surface Elasticity
, M.Sc. Thesis Sharif University of Technology ; Naghdabadi, Reza (Supervisor)
Abstract
Due to ignoring the effect of length scale and neglecting the details at nanosize, classical methods are not sufficiently accurate to determine the properties of nanostructured materials. More reliable results can be obtained, using surface elasticity theory. Lots of analytical, experimental and numerical investigations have been done on the effect of interphase on the mechanical properties of polymer nanocomposites whereas metal matrix nanocomposites are in the first stages of analytical and numerical researches and have attracted so much attention.
The main objective of this research is to investigate the effects of interphase as well as coating, on the mechanical behavior of metal...
The main objective of this research is to investigate the effects of interphase as well as coating, on the mechanical behavior of metal...
The Effect of Structural Defects of Graphene Reinforced Polymer Nanocomposites on Mechanical Properties
, M.Sc. Thesis Sharif University of Technology ; Naghd Abadi, Reza (Supervisor)
Abstract
Nanocomposites are widely used due to unique properties such as low density and high strength in many industries such as electronics, telecommunications, aerospaces, Petrochemicals and shipbuildings. Meanwhile, due to the importance of economic issues, polymer based nanocomposites are the most used type of nanocomposites. The purpose of this thesis is studing the structural defects of graphene-reinforced nanocomposite polymers on the mechanical properties of these materials. Defects created in nanocomposites can be divided into two categories after construction. The first category is the defects that are created in the graphene structure when it is synthsis, and the second happen at the...
Study of the Surface Effect on the Behavior of a FG Multiphase Nano-sphere with Spherical Anisotropy due to Some Nonuniform Eigenstrain Field
, M.Sc. Thesis Sharif University of Technology ; Mohammadi Shodja, Hossein (Supervisor)
Abstract
The elastic field is one of the challenges in optimizing the lifetime and capacity of the lithiumion batteries. Graphite nanoparticles have been widely used in Li-ion batteries, due to their mechanical, thermal and electrical properties. During the lithiation, chemical reactions occurred in the electrolyte, which forms a solid electrolyte interphase(SEI) in the surrounding of nanoparticles as well as stress fields inside the nanoparticles. Therefore, the purpose of this research is to examine the effects of the surface/interface on diffusion induced stresses(DIS) within core-shell nanosphere due to non-uniform distribution of eigenstrain fields. Due to the mechanical behavior of the phases,...
Study of the Surface Effect on the Behavior of a FG Multiphase Nano-Sphere with Spherical Anisotropy Due to some Nonuniform Eigenstrain Field
, M.Sc. Thesis Sharif University of Technology ; Mohammadi Shodja, Hossein (Supervisor)
Abstract
The elastic field is one of the challenges in optimizing the lifetime and capacity of the lithium-ion batteries. Graphite nanoparticles have been widely used in Li-ion batteries, due to their mechanical, thermal and electrical properties. During the lithiation, chemical reactions occurred in the electrolyte, which forms a solid electrolyte interphase(SEI) in the surrounding of nanoparticles as well as stress fields inside the nanoparticles. Therefore, the purpose of this research is to examine the effects of the surface/interface on diffusion induced stresses(DIS) within core-shell nanosphere due to non-uniform distribution of eigenstrain fields. Due to the mechanical behavior of the phases,...
Investigating the effect of carbon nanotube defects on the column and shell buckling of carbon nanotube-polymer composites using multiscale modeling
, Article International Journal for Multiscale Computational Engineering ; Volume 7, Issue 5 , 2009 , Pages 431-444 ; 15431649 (ISSN) ; Naghdabadi, R ; Sharif University of Technology
2009
Abstract
Carbon nanotube (CNT)-reinforced polymer composites have attracted great attention due to their exceptionally high strength. Their high strength can be affected by the presence of defects in the nanotubes used as reinforcements in practical nanocomposites. In this article, a new three-phase molecular structural mechanics/finite element (MSM/FE) multiscale model is used to study the effect of CNT vacancy defects on the stability of single-wall (SW) CNT-polymer composites. The nanotube is modeled at the atomistic scale using MSM, whereas the interphase layer and polymer matrix are analyzed by the FE method. The nanotube and polymer matrix are assumed to be bonded by van der Waals interactions...
Hierarchical multiscale modeling of nanotube-reinforced polymer composites
, Article International Journal for Multiscale Computational Engineering ; Volume 7, Issue 5 , 2009 , Pages 395-408 ; 15431649 (ISSN) ; Naghdabad, R ; Sharif University of Technology
2009
Abstract
A finite element-based hierarchical multiscale modeling scheme is presented and used for the analysis of nanotube-reinforced polymer composites. The scheme presented here consists of micro- and macroscale boundary value problems linked together using a computational homogenization scheme. Using the presented hierarchical multiscale scheme, we have studied nanotube-reinforced polymer composites, and the elastic properties are determined. Using different representative volume elements (RVEs) representing different volume fractions of aligned nanotubes, the effect of the nanotube volume fraction and the existence of an interphase layer on the effective elastic modulus of the nanocomposite are...
Investigation of the interphase effects on the mechanical behavior of carbon nanotube polymer composites by multiscale modeling
, Article Journal of Applied Polymer Science ; Volume 117, Issue 1 , March , 2010 , Pages 361-367 ; 00218995 (ISSN) ; Naghdabadi, R ; Sharif University of Technology
2010
Abstract
In this article, a multiscale modeling procedure is implemented to study the effect of interphase on the Young's modulus of CNT/polymer composites. For this purpose, a three-phase RVE is introduced which consists of three components, i.e., a carbon nanotube, an interphase layer, and an outer polymer matrix. The nanotube is modeled at the atomistic scale using molecular structural mechanics. Moreover, three-dimensional elements are employed to model the interphase layer and polymer matrix. The nanotube and polymer matrix are assumed to be bonded by van der Waals interactions based on the Lennard-Jones potential at the interface. Using this Molecular Structural Mechanics/Finite Element...
Influence of martensite volume fraction on tensile properties of triple phase ferrite-bainite-martensite steels
, Article Materials Science and Engineering A ; Volume 530, Issue 1 , 2011 , Pages 440-445 ; 09215093 (ISSN) ; Ekrami, A ; Sharif University of Technology
2011
Abstract
This paper presents the effect of martensite volume fraction (VM) on mechanical properties of AISI 4340 steel with ferrite-bainite-martensite microstructures. The steel bars were austenitized at 900°C for 1h followed by intercritical annealing at 740°C for 100min and quenching into a salt bath with temperature of 300°C and holding at different times to obtain triple phase (TP) microstructures with 34vol.% fraction ferrite and various martensite (or bainite) contents. Presence of three phases in adjacent to each other was confirmed by metallographic analysis and TEM studies. TEM observation also indicates higher density of dislocations within ferrite near martensite colonies compared to that...
Mechanical properties and structure of solvent processed novolac resin/layered silicate: Development of interphase region
, Article RSC Advances ; Volume 5, Issue 98 , Jun , 2015 , Pages 80875-80883 ; 20462069 (ISSN) ; Shojaei, A ; Sharif University of Technology
Royal Society of Chemistry
2015
Abstract
Composites of phenol-formaldehyde (PF) resin with Closite Na+ and Closite 30B up to 20 wt% loadings were prepared by solution mixing. Tensile testing showed that both pristine and organically modified clays increased considerably the mechanical properties of PF resin at 2.5 wt% loading followed by marginal improvement or even sacrificed properties at high loadings. DMA and DSC analyses suggested development of a highly crosslinked and well adhered interphase around silicate layers. A novel three-phase model considering the interphase region was proposed to predict composite modulus. The model was successfully employed to correlate morphological characteristics and mechanical properties of...
Contribution of ordered-inordered phenomenon within the interphase region toward increasing elastic modulus in CNT/polymer nanocomposites
, Article Materials Science and Technology Conference and Exhibition 2015, MS and T 2015, 4 October 2015 through 8 October 2015 ; Volume 1 , October , 2015 , Pages 595-602 ; 9781510813939 (ISBN) ; Goodarzi Hosseinabadi, H ; NACE International ; Sharif University of Technology
Association for Iron and Steel Technology, AISTECH
2015
Abstract
Exceptional mechanical properties of carbon nanotubes (CNTs) such as high elastic modulus, stiffness and tensile strength have made them as promising reinforcement in polymer nanocomposite systems. The characteristics of CNTs/polymer interphase region directly affect the efficiency of nanotubes for improving the nanocomposite mechanical properties. In this work, the influence of chains alignment within the interphase region on elastic response of the nanocomposite is assessed using a novel ordered-inordered approach. The applicability of the presented approach is examined by implementing the approach on a series of reported data available in the literature. The effects of CNT content,...
Synthesis of Conductive Magnetite Nanocomposite based on Polyaniline/Poly(maleic acid-co-acrylic acid) with Core-Shell Structure
, Article Advances in Polymer Technology ; 2016 ; 07306679 (ISSN) ; Najafi Moghadam, P ; Mahmoodi Hashemi, M ; Sharif University of Technology
John Wiley and Sons Inc
2016
Abstract
In this study, a new type of magnetite nanocomposite with a core-shell structure was synthesized using Fe3O4 nanoparticles as a core and polyaniline (PANI) as a shell. For this propose, the surface of Fe3O4 was chemically modified with hexamethylenediisocyanate (HMDI) to improve its compatibility and interphase interaction with the polymeric matrix. Thereafter, the PANI was reacted with modified Fe3O4 to anchor them to PANI by covalent bands which acted as a shell. In the second step, the poly (maleic acid-co-acrylic acid) (P(MAc-co-AA)) as polymeric dopant for the PANI was synthesized. Finally, the PANI anchored to Fe3O4 was immersed in an aqueous solution of poly (maleic...
Roll bonding of AA5052 and polypropylene sheets: bonding mechanisms, microstructure and mechanical properties
, Article Journal of Adhesion ; 2016 , Pages 1-25 ; 00218464 (ISSN) ; Akbarzadeh, A ; Sharif University of Technology
Taylor and Francis Inc
2016
Abstract
Structural, microstructural and mechanical properties in roll bonding of AA5052 and polypropylene sheets have been evaluated in this study. The surface roughness of the AA5052 sheets, rolling temperature and the surface energy of polymer were selected as the bonding variables. The findings indicated that an increase in the surface energy of polypropylene by grafting maleic anhydride would result in higher bonding strength due to chemical interaction between the AA5052 and the maleic anhydride grafted polypropylene (PP-g-MAH). In fact, this reaction caused the formation of an interphase layer at the polymer side of the interface and the diffusion of aluminum into the PP-g-MAH layer. It was...
Enhanced mechanical properties of chitosan/nanodiamond composites by improving interphase using thermal oxidation of nanodiamond
, Article Carbohydrate Polymers ; Volume 167 , 2017 , Pages 219-228 ; 01448617 (ISSN) ; Shojaei, A ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
Polymer composite films based on chitosan (CS) and nanodimaond (ND) were prepared using solution casting method. ND with variable contents of carboxylic functional group was prepared using thermal oxidation at temperature of 420 °C under air atmosphere at various durations of 1.5 and 4.5 h. The interfacial interaction between NDs and CS and morphological evolution of CS in presence of NDs were investigated by Fourier transform infrared (FTIR), differential scanning calorimeter (DSC) and X-ray diffraction (XRD) analyses. A significant improvement in tensile strength (∼85%) and tensile modulus (∼125%) of CS was achieved by oxidized ND (OND) obtained at higher oxidation time of 4.5 at low...
Roll bonding of AA5052 and polypropylene sheets: bonding mechanisms, microstructure and mechanical properties
, Article Journal of Adhesion ; Volume 93, Issue 7 , 2017 , Pages 550-574 ; 00218464 (ISSN) ; Akbarzadeh, A ; Sharif University of Technology
Taylor and Francis Inc
2017
Abstract
Structural, microstructural and mechanical properties in roll bonding of AA5052 and polypropylene sheets have been evaluated in this study. The surface roughness of the AA5052 sheets, rolling temperature and the surface energy of polymer were selected as the bonding variables. The findings indicated that an increase in the surface energy of polypropylene by grafting maleic anhydride would result in higher bonding strength due to chemical interaction between the AA5052 and the maleic anhydride grafted polypropylene (PP-g-MAH). In fact, this reaction caused the formation of an interphase layer at the polymer side of the interface and the diffusion of aluminum into the PP-g-MAH layer. It was...
A novel lifetime prediction method for lithium-ion batteries in the case of stand-alone renewable energy systems
, Article International Journal of Electrical Power and Energy Systems ; Volume 103 , 2018 , Pages 115-126 ; 01420615 (ISSN) ; Dufo López, R ; Roshandel, R ; Bernal Agustin, J. L ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
This paper presents a mathematical formulation of lithium-ion batteries, including aging and temperature effects. The model is developed by integrating the simplified single particle model (SSPM) and reduced-order model (ROM) to predict solid electrolyte interphase growth (SEI). Results show agreement with the experimental data at 25 °C operating temperature and moderate cycling currents. A maximum error of 3.6% in finding the battery discharged Ah is observed in harsh operating conditions, including 60 °C and approaching the end of life of the battery. Due to the typical operating conditions of stand-alone renewable energy systems, more accurate estimations are expected. Finally, this...
Modeling the interphase region in carbon nanotube-reinforced polymer nanocomposites
, Article Polymer Composites ; 2018 ; 02728397 (ISSN) ; Jam, J. E ; Arab, B ; Firouz-Abadi, R. D ; Sharif University of Technology
John Wiley and Sons Inc
2018
Abstract
Carbon nanotubes are regarded as ideal fillers for polymeric materials due to their excellent mechanical properties. Mechanical analysis without consideration of nanotube–matrix interphase, may not give precise predictions. In this work, the impacts of interphase on the behavior of polymer-based nanocomposites are studied. For this purpose, a closed-form micromechanical interphase model considering the diameter of nanotube, the thickness of interphase, and mechanical properties of nanotube and polymer is proposed to estimate the overall mechanical properties of nanotube-reinforced polymer nanocomposites. Furthermore, the effective elastic constants of the nanocomposites for a wide range of...