Search for: phase-separation
Total 72 records
Fabrication, characterization, and electrochemical performance of the hdpe/sepiolite nanocomposite as a novel separator for li-ion batteries, Article Express Polymer Letters ; Volume 15, Issue 11 , 2021 , Pages 1063-1080 ; 1788618X (ISSN) ; Pircheraghi, G ; Sharifi, H ; Sharif University of Technology
BME-PT and GTE 2021
Separators are one of the most critically important components of lithium-ion batteries to ensure the safe performance of the battery. Commercial polyolefin separators have high thermal shrinkage and low electrolyte uptake, which confines the application of the battery. By using the thermally induced phase separation (TIPS) method, we successfully prepared HDPE/sepiolite nanocomposite separators with high thermal stability and electrolyte wettability. The sepiolite nanofibers are modified with the Vinyltriethoxysilane (VTES) as a coupling agent for better dispersion and interaction in the HDPE matrix. The purpose of fabricating this separator is to decrease the thermal shrinkage and...
Preparation and Characterization of Polymeric Nanocomposite Membrane used in Li-Ion Batteries, M.Sc. Thesis Sharif University of Technology ; Pircheraghi, Gholamreza
In Lithium ion batteries, the separator is membrane that placed between the cathode and the anode is one of critical components. Its primary function is to effectively transport ionic charge carriers between two electrodes as an efficient ionic conductor as well as to prevent the electric contact between them as a good electric insulator. The separator does not involve directly in any cell reactions, but its structure and properties play an important role in determining the battery performance. Commercially available polyolefin separators low cost, good electric resistance, high electrochemical stability, and effectively prevent thermal runaway caused by the electrical short-circuits or...
Formation of clusters in the 2D t-J model: The mechanism for phase separation, Article Journal of Physics Condensed Matter ; Volume 18, Issue 20 , 2006 , Pages 4935-4944 ; 09538984 (ISSN) ; Langari, A ; Mutter, K. H ; Sharif University of Technology
The emergence of phase separation is investigated in the framework of a 2D t-J model by means of a variational product ansatz, which covers the infinite lattice by two types of L × L clusters. Clusters of the first type are completely occupied with electrons, i.e. they carry maximal charge Qe = L2 and total spin 0, and thereby form the antiferromagnetic background. Holes occur in the second type of clusters - called 'hole clusters'. They carry a charge Qh
0.5) it turns out that hole clusters are occupied with an even...
Separation control of aero boundary layer in supercavitating bodies and its effect on pressure drag reduction, Article 2005 ASME Fluids Engineering Division Summer Meeting, FEDSM2005, Houston, TX, 19 June 2005 through 23 June 2005 ; Volume 2005 , 2005 , Pages 19-27 ; 0791837602 (ISBN); 9780791837603 (ISBN) ; Yazdani, M ; Sharif University of Technology
Supercavitation is known as the way of viscous drag reduction for the projectiles, moving in the liquid phase. In recent works, there is distinct investigation between cavitation flow and momentum transfer far away from the cavity surface. In fact such methodologies consider cavitation flow statically, rather than taking dynamic effects of overall flow into account. However, it seems that there is strong connection between overall flow and what takes place in the sheet cavity where a constant pressure distribution is assumed. Thereby, in order to configure the system conditions which may be cause of cavity perturbation and so system oscillation, we need to use proper methodologies in which...
Study on the Exfoliation of Graphite into Graphene by Electrochemical Method and Its Application in Thermoplastic Polyurethane Nanocomposite, M.Sc. Thesis Sharif University of Technology ; Pircheraghi, Gholamreza
Graphene is two dimensional nanomaterial, single layer of carbon atoms that exhibited excellent properties like high electrical conductivity and stiffness, but producing graphene and obtaining a good dispersion of graphene in a polymer matrix is still a major challenge. In this study by using the electrochemical route several graphene with different degree of oxidation produced in different electrolyte medium. According to XRD data, product of electrochemical exfoliation in dilute HNO3 medium includes 50% few-layer graphene (5 layers) and 25% GO and the rest are multi-layer graphene. Nonsolvent induced phase separation method were used to prepare TPU/Graphene nanocomposite. Different methods...
Simulating Dynamics of Immiscible Liquids Separation Using Microfluidics, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Aliasghar
Most of industrial and laboratory processes are faced with liquid-liquid emulsions particularly aqueous-organic ones in their different product streams which determine the need to perform phase separation due to enviromental problems or need to increase the product purity. In this project, due to presence of a water-hexane two phase flow mixture in the outflow of a microractor that performs Lithium-Bromine exchange reaction, a capillary microchip separator has been designed in order to separate water through capillary channel and hexane through main channel outlet using interfacial forces and wettability effects. To obtain a desired phase separation, the pressure drop through main channel...
Phase segregation susceptibility of ZA27 alloy at different shear rates, Article 9th International Conference on Semi-Solid Processing of Alloys and Composites, S2P 2006, Busan, 11 September 2006 through 13 September 2006 ; Volume 116-117 , 2006 , Pages 225-230 ; 10120394 (ISSN); 3908451264 (ISBN); 9783908451266 (ISBN) ; Aashuri, H ; Shalchi, B ; Sharif University of Technology
Trans Tech Publications Ltd 2006
Back extrusion technique was employed to characterize phase segregation tendency of mechanically stirred ZA27 alloy at different deformation rates. Variation of segregation intensity with ram diameter was found to follow opposite trends at low and high ram speeds. At sufficiently high ram speeds, small rams are of better performance in minimizing segregation whereas at low ram speeds, large rams result in less pronounced segregation. In addition, increasing ram speed invariably decreases segregation degree. Back extrusion at very high shear rates provided via a Drop Extruder Apparatus capable of displacing ram at speeds in excess of 1m/s results in production of very homogeneous products in...
Fabrication and characterization of maleic anhydride grafted polypropylene membranes with high antifouling properties, Article Journal of Applied Polymer Science ; Volume 133, Issue 36 , 2016 ; 00218995 (ISSN) ; Mousavi, S. A ; Farhadi, F ; Sharif University of Technology
John Wiley and Sons Inc 2016
In this study, maleic anhydride grafted polypropylene microporous flat-sheet membranes were prepared via a thermally induced phase separation method with a mixture of dibutyl phthalate and dioctyl phthalate as a diluent. The effects of the polymer composition and coagulation bath temperature on the morphology and performance of the fabricated membranes were investigated. The hydrophilicity results of the membranes demonstrated that membrane modification reduced the water contact angle by about 45°, whereas the pure water flux was enhanced about four times. The antifouling behavior of the fabricated membranes was also investigated in a membrane bioreactor. The results show that the pure water...
Bio-based UV curable polyurethane acrylate: Morphology and shape memory behaviors, Article European Polymer Journal ; Volume 118 , 2019 , Pages 514-527 ; 00143057 (ISSN) ; Shojaei, A ; Sundararaj, U ; Sharif University of Technology
Elsevier Ltd 2019
Smart bio-based shape memory polymers with high performance and fast response have the exciting potential to meet the growing need in biomedical applications. In this study, novel fast response UV-curable shape memory polyurethane acrylates (SMPUAs) comprising polycaprolactone diols (PCL-Diol), hexamethylene diisocyanate (HDI) and hydroxy-methyl methacrylate (HEMA) were synthesized by two-step bulk polymerization. Two series of PUAs with almost the same amount of hard segment content (HSC) were prepared with varying soft-segment molecular weight (2000, 3000, and 4000 g/mol) and different molar ratios of constituents. A mono-functional reactive diluent was used to control HSC and reduce the...
A mechanistic understanding of the water-in-heavy oil emulsion viscosity variation: effect of asphaltene and wax migration, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 608 , 2021 ; 09277757 (ISSN) ; Hemmati, M ; Safari, M ; Rahimi, A ; Rahmani, O ; Aminpour, S. M ; Beiranvand Pour, A ; Sharif University of Technology
Elsevier B.V 2021
The role of emulsions as a prevalent phenomenon is broadly investigated in the petroleum industry since forming the emulsion has many severe harmful implications. Heavy components of crude oil such as wax and asphaltene make the water-in-oil (w/o) emulsion more stable, while the role of these components on the emulsion viscosity has not been fully understood. In this regard, to find a proper demulsifier to break these emulsions, it is necessary to know the mechanisms of emulsion formation by heavy oil components. In this study, the effects of waxy-oil and asphaltenic-oil on w/o emulsion were investigated by measuring volume and viscosity of the formed emulsion after an elapsed time, followed...
Porous Structured of Polystyrene by Phase Separation in Liquid Nitrogen for Immersed Solvent Supported µ-extraction of Polycyclic Aromatic Hydrocarbons, M.Sc. Thesis Sharif University of Technology ; Bagheri, Habib
Porous materials using polymers have been developed for a variety of industrial applications. These structures mostly contain well-aligned microchannels and exhibit good mechanical properties and high porosity.There are several ways to prepare porous polymeric structures, such as sintering, stretching, track etching and phase separation processes. In this work Phase separation method using anti-solvent of selected polymer in liquid nitrogen was used to fabricate the porous structures. Considering physical and chemical peroperties of polycyclic aromatic hydrocarbons, porous polystyrene make to be good sorbents. Solvent supported microextraction technique was applied to extract polycyclic...
Numerical Investigation of Turbulent Flow Inside De-Oiling Hydrocyclones Using Large Eddy Simulation Approach, M.Sc. Thesis Sharif University of Technology ; Farhanieh, Bijan
Hydrocyclones are used for separating different materials from liquids in a variety of applications. Compactness, efficiency, reliability and low maintenance costs are their noteworthy characteristics. Dewatering and deoiling hydrocyclones used for refining crude oil or oily waste water in offshore platforms are examples of liquid-liquid hydrocyclones. Separation process in hydrocyclones is based on the fact that swirl flow induces a centrifugal force and leads to separation due to density difference. The density difference in liquid-liquid mixtures is smaller than solid-liquid types and trying to separate one liquid from another takes much more effort than the other type. Increase of...
Phase Separation in Binary Liquid Crystal Mixtures, M.Sc. Thesis Sharif University of Technology ; Ejtehadi, Mohammad Reza
Phase separation of a 50:50 binary system composed of two prolate ellipsoids with different axis ratios is investigated through molecular dynamics simulation. The system can be considered as a coarse-grained model of a binary liquid crystal mixture. Phase separation has been detected in the system by changing the density as the control parameter. The system goes through two different phase changes, one being the phase change due to phase separation and the other one due to orientational phase transition. In the latter case coexistence of the two particles results in simultaneous phase transition
Construction of Suitable Polymeric Membrane by Thermal Induce Phase Separation (TIPS) for using in the Membrane Bioreactor (MBR), M.Sc. Thesis Sharif University of Technology ; Farhadi, Fathollah ; Mousavi, Abbas
In this study, the response surface methodology (RSM) based on the central composite design (CCD) were used to prepare a polypropylene grafted maleic anhydride (PP-g-MA) microporous flat sheet membrane via thermally induced phase separation (TIPS) method. Mixture of dibutyl phthalate (DBP) and dioctyl phthalate (DOP) were used as diluent. The effect of the polymer composition and coagulation bath temperature on the morphology and performance of the fabricated microporous membranes in a bioreactor (MBR) were investigated. Analysis of variance (ANOVA) was used to determine which variables and interactions between variables have a significant effect on our responses. The ANOVA revealed that the...
Structural analysis of Y3Ba5Cu8O 19-δ high-Tc superconductor by ab initio density functional theory, Article Physica C: Superconductivity and its Applications ; Volume 497 , 15 February , 2014 , 2014, Pages 84-88 ; ISSN: 09214534 ; Rasti, M ; Akhavan, M ; Sharif University of Technology
The details of the crystal structure of the recently discovered Y 3Ba5Cu8O18+δ (Y358) superconductor have been determined by ab initio density functional theory. Total energy calculation has been performed for three different suggested structures with different oxygen content. The structure with a center of inversion symmetry and the highest oxygen concentration has the lowest total energy. Thus, it is the best choice for the Y358 crystal structure. By investigating the detailed structure, it is seen that this compound is arranged either of YBa2Cu3O7 and YBaCu2O 5 or YBaCu2O5 and BaCuO2 substructural blocks in the c direction. The difference between the total energy of Y358 compound and the...
Effects of nucleation agents on the preparation of transparent glass-ceramics, Article Journal of the European Ceramic Society ; Volume 32, Issue 11 , August , 2012 , Pages 2989-2994 ; 09552219 (ISSN) ; Nemati, A ; Baghshahi, S ; Sharif University of Technology
Formation of transparent glass-ceramic in the system MgO-SiO 2-Al 2O 3-K 2O-B 2O 3-F with and without addition of LiF and NaF has been investigated. Crystallization of glass-sample was conducted by controlled thermal heat-treatment, at determined nucleation and crystallization temperatures. In this regard, the effects of addition of LiF and NaF were investigated on the crystallization behavior and transparency of the samples. Low transmission (less than 80% at 600. nm) was observed in the basic composition (K).The addition of NaF and LiF caused more intense phase separation in the system. The results indicated that the glass-ceramic can remain transparent if fine grains with nano size are...
Experimental study and thermodynamic modeling for purification of extracted algal lipids using an organic/aqueous two-phase system, Article RSC Advances ; Volume 5, Issue 2 , 2015 , Pages 1153-1160 ; 20462069 (ISSN) ; Pazuki, G ; Vossoughi, M ; Sharif University of Technology
Royal Society of Chemistry 2015
The extraction and purification of lipids from the microalgae Chlorella vulgaris have been investigated. First, a mixture of hexane and ethanol was used to extract lipids from the algal biomass. Ultrasonication was employed to disrupt the cell wall and increase the extraction performance. Under these conditions, over 90% of the fatty acids in the biomass were extracted. Second, a biphasic system was formed by adding water and hexane to the extracted crude oil. In this way, fatty acids were mainly distributed in the organic phase (mostly hexane and ethanol) while most of the contaminants remained in the aqueous phase (mostly water and ethanol). Equilibrium distribution data between the phases...
A combined micro-solid phase-single drop microextraction approach for trace enrichment of volatile organic compounds, Article Analytical Methods ; Volume 7, Issue 16 , Jun , 2015 , Pages 6514-6519 ; 17599660 (ISSN) ; Zare, M ; Piri Moghadam, H ; Es haghi, A ; Sharif University of Technology
Royal Society of Chemistry 2015
An attempt was made to combine μ-solid phase extraction and headspace single drop microextraction techniques and use their advantages for trace determination of some volatile organic compounds in aqueous samples. After performing the two-step preconcentration approach, the desired analytes were determined by gas chromatography-mass spectrometry. A resorcinol-formaldehyde-based xerogel was used as the extraction medium in the μ-solid phase extraction (μ-SPE) method. Then, the extracted BTEX was eluted with a rather large amount of methanol. To remove the laborious process including solvent evaporation and further reconstitution, which is usually accompanied by loss of analytes and accuracy,...
Biodegradable polyurethane acrylate/HEMA-grafted nanodiamond composites with bone regenerative potential applications: Structure, mechanical properties and biocompatibility, Article RSC Advances ; Volume 6, Issue 11 , 2016 , Pages 8743-8755 ; 20462069 (ISSN) ; Shojaei, A ; Abdekhodaie, M. J ; Sharif University of Technology
Royal Society of Chemistry
The present study demonstrates HEMA-grafted nanodiamond (ND-HEMA)/acrylate-terminated polyurethane-acrylate diluents (APUA) composites as promising materials for bone implant applications. Neat APUA and APUA composites containing ND-HEMA at different loadings up to 2 wt% were prepared by an in situ polymerization method. Morphological analysis demonstrated that ND-HEMAs were actually in the form of tightly bound aggregates which led to formation of big agglomerates at a concentration of 2 wt%. It was also suggested that ND-HEMAs were preferentially localized in the continuous soft domain of APUA; however it interacted by both soft and hard domains. Moreover, ND-HEMAs caused considerable...
TPU/graphene nanocomposites: effect of graphene functionality on the morphology of separated hard domains in thermoplastic polyurethane, Article Polymer ; Volume 148 , 18 July , 2018 , Pages 169-180 ; 00323861 (ISSN) ; Pircheraghi, G ; Sharif University of Technology
Elsevier Ltd 2018
Graphene nanoplatelets with different surface functional groups and polarity were prepared by Hummer's method and electrochemical exfoliation of graphite in two aqueous acids. The XRD, FTIR and sedimentation tests performed to characterize the polarity of the prepared graphenes. The highest polarity was associated with the sample prepared by Hummer's method and the sample synthesized by electrochemical exfoliation in nitric acid medium showed the moderate polarity. Meanwhile, the sample prepared in sulfuric acid medium showed the lowest polarity. Then thermoplastic polyurethane (TPU)/graphene nanocomposite films were fabricated with solvent exchange method. While the dispersion state and...