Search for: hydrophobicity
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    Drag Reduction Using Geometrically Structured Surfaces for Non-newtonian Multi-phase Fluids

    , M.Sc. Thesis Sharif University of Technology Javaherchian, Javaneh (Author) ; Moosavi, Ali (Supervisor)
    With the advancement of the industry, microscale devices use due to its unique characteristics. On the other hand, it is essential to find ways to reduce drag inside microchannels because of The importance of energy. One of the methods is to optimize the contact surface using structured geometric surfaces. These hydrophobic surfaces reduce drag by trapping the air in roughness and creating a two-phase flow. The purpose of this project is to reduce the drag within the microchannel using structured geometric surfaces for non-Newtonian and multiphase flows. In most previous studies, with simplification, Newtonian and two-phase flows have been investigated. While most industrial fluids show... 

    PVDF/SiO2 Nanocomposite Coating with Different Wettability in Contact with Oil and Water for phase Separation Propose

    , M.Sc. Thesis Sharif University of Technology Hassani, Mohammad Ebrahim (Author) ; Dolati, Abolghasem (Supervisor)
    increased cohesion up to 4H pencil. Results of immersion test in water showed stability of coatings. Polarization test in naphtha and water mixture for stainless steel, copper and aluminum meshes demonstrated 98.89%, 86.25% and 66.6% protection efficiency respectively. In order to study of oil and water separation efficiency, mixtures of water and naphtha with different content of naphtha were used. Separation test for 200μm St.St mesh in different slopes demonstrated that changing of slop increase separation efficiency up to 95.5% for water and up to 100% for naphtha. Separation test for meshes with different pore size demonstrated that meshes with small pore size are more appropriate for... 

    Designing Drilling Mud Using Environmental Resistant Polymers and Investigation of Rheological Properties and Stability to Achieve Optimal Formulation

    , M.Sc. Thesis Sharif University of Technology Soleimanian, Alireza (Author) ; Ramezani, Ahmad (Supervisor) ; Goodarznia, Iraj (Supervisor)
    The purpose of this project is to design a water-based drilling fluid for use in high-pressure and high-pressure conditions (Deep Drilling). This goal is usually achieved by adding the resistant polymers to the ambient conditions (temperature stability) to the drilling fluid (here the blue base fluid), and then the rheological properties of the fluid are studied. The stability of the rheological properties of the fluid in high temperature and high pressure conditions is not constant. In this situation, a sequence of events occurs, for example, decreases with increasing viscosity and turbulence, and hence the reduction of drilling fractures and the efficiency of the bottom of the well is... 

    Preparation of Acrylamide Copolymers Containing Highly Hydrophobic Monomers and Study on Their Drag Reduction Properties

    , M.Sc. Thesis Sharif University of Technology Dadkhah, Parsa (Author) ; Ramazani Saadatabadi, Ahmad (Supervisor)
    With the rapid increase of energy consumption, energy problem has been a global issue, which must be faced with and solved. One way to prevent energy consumption is to reduce drag in the flow inside the pipes by using polymer additives; Because the Transportation of liquids using pipeline technology has its limitations, since turbulent flow inside the pipe involves a loss of energy. The net effect of this is that increasing the energy applied to the flow does not increase the flow rate. For this purpose, copolymers and terpolymers of hydrophilic acrylamide monomers along with hydrophobic styrene and hydrophilic maleic anhydride monomers were synthesized by reverse emulsion polymerization... 

    Preparation and Evaluation of Hydrophobic Pt Catalyst on Alumina and CNT to Produce Heavy Water Isotope

    , M.Sc. Thesis Sharif University of Technology Es’haghi Gorji, Zahra (Author) ; Kazemeini, Mohammad (Supervisor)
    Liquide phase catalytic exchange (LPCE) between liquid water and hydrogen is an important reaction for separation of the hydrogen isotope from liquid water. One of the application of this reaction is heavy water production. This method is mainly used hydrophobic catalysts with Pt active metal. The use of hydrophobic catalyst is necessary, because liquid water in the LPCE reaction, resulted in block the catalyst pores and loss of catalyst activity. Design of experiment has been done by using of Design Expert 7.0.0 for determination of number of tests and optimization of Pt weight percent. Alumina and carbon (included graphene, single-walled and multi-walled carbon nanotube) supported 5% wt Pt... 

    , M.Sc. Thesis Sharif University of Technology Bakhtiari, Fatemeh (Author) ; Mosavi, Abbas (Supervisor) ; Shojaei, Akbar (Co-Advisor)
    In this work nanocomposite CNT/polysulfone and CNT/polyethersulfone membranes for membrane contactor application in gas separation were fabricated. The two types of CNTs used for chemical and physical separation of H2S from a mixture of CH4 an H2S, had the outer diameter of 20-30nm and 50-100nm. One of the greatest concerns about using membrane contactors for gas separation applications is the wetting of membranes which consequently leads to decrease in separation performance. The aim of this study is to enhance the hydrophobicity of membranes by mixing hydrophobic carbon nanotubes in the polymeric matrix. The effect of factors like type of the polymer, diameter of the carbon nanotube and... 

    Synthesis, Characterization and Hydrophobicity of Teflon Coated Tungsten Nanostructure Thin Films

    , M.Sc. Thesis Sharif University of Technology Bayat, Amir (Author) ; Moshfegh, Ali Reza (Supervisor) ; Azimirad, Rouhollah (Supervisor)
    Hydrophobic and superhydrophobic surfaces find many applications in different fields of science. The aerospace industry is one such field that can take the advantage of superhydrophobicity for anti-icing coatings. In order to make hydrophobic and superhydrophobic surfaces on hydrophilic materials, two-step process is usually need, at first, making a rough surface and then modifying it with hydrophobic coatings with low surface free energy. In this research, we have used glancing angle deposition (GLAD) RF sputtering technique to fabricate Teflon coated tungsten on glass substrate for obtaining hydrophobic surface. GLAD approach is a method to grow structures such as nanorods and zigzag... 

    Numerical Modeling of Electroosmotic Flow of Viscoelastic Fluids in Hydrophobic Microducts

    , M.Sc. Thesis Sharif University of Technology Abdoli Farzaneh, Hassan (Author) ; Saeedi, Mohammad Hassan (Supervisor) ; Kazemzadeh Hannani, Siamak (Co-Advisor)
    The integrated development of small-scale electronic and mechanical systems has drawn attention, since they lead to increase in speed and decrease in volume of industry dimensions in the manufacturing sector. That is why microelectromechanical systems are highly considered. MEMS are widely used in Microfluidic systems that can be used in medicine, biology and drug injection. Due to the fact that consistent fluid velocity is necessary in biological applications, electroosmotic flow is more important than ever. To investigate the behavior of biofluids, Newtonian models cannot be used and it is required to use models that predict the behavior of these fluids accurately. In this research... 

    Development of Particulate Zinc-Iron/PTFE Composite and Nanocomposite Coatings Using Electrodeposition

    , M.Sc. Thesis Sharif University of Technology Mohagheghi Fard, Omid (Author) ; Ghorbani, Mohammad (Supervisor)
    Electrodeposition is an old, well known and conventional science surface modification method to improve the surface characteristics, decorative and functional, of a wide variety of materials. This science is considered in nanotechnology as a bottom-up method for fabrication of one, two and three-dimensional nanomaterials. A great variety of secondary components can be added to plating baths resulting in metallic matrix composite and nanocomposite coatings production. Low amounts of iron addition for alloying zinc coatings, significantly increases the corrosion resistance of this generally used metal economically. Superhydrophobic coatings on metallic substrates have shown, during the past... 

    Development of a Paper-based Microfluidic Device for Biological Assay

    , M.Sc. Thesis Sharif University of Technology Boodaghi, Miad (Author) ; Shamloo, Amir (Supervisor)
    All the biological diagnostic devices that are introduced to the consumers, must meet WHO criteria. Some of these criteria include being affordable, sensitive and deliverable to the user. In the last twenty years, there have been lots of efforts to use microfluidic devices for biological assay. Due to their expensive price and requirement of complex equipment for their fabrication, polymer-based microfluidic devices have not been able to be used in developing countries. It is to be hoped that introduction of paper for fabrication of microfluidic devices could make microfluidic devices meet WHO criteria. μPADs are divided into well-based and channel-based devices. In the present work, both... 

    Synthesis and Application of Acidic and Hydrophobic Ionic Liquids in Mannich Reaction and Esterification of Fatty Acids

    , M.Sc. Thesis Sharif University of Technology Karbalaie Reza, Mina (Author) ; Mahmoodi Hashemi, Mohammed (Supervisor)
    The current study deals with application of a surfactant-like Brønsted acidic ionic liquid (IL) 1-dodecyl-3-methylimidazolium hydrogensulfate (catalys 1) for Mannich reaction at room temperature. The reaction has been efficiently proceeds in water as solvent without using any harmful and expensive organic additives. Our observation has been shown that the reaction is selective for cyclohexanone and no product was observed by using cyclopentanone at room temperature. Density functional theory (DFT) calculations were performed to provide evidence about the nature of reactivity of the cyclohexanone/cyclopentanone. The activity of the catalyst 2 (1-dodecyl-2,3-dimethylimidazolium... 

    In Situ Preparation of Acrylamide-Styrene- Maleic Anhydride Nano Hydrogels and Investigation of their Properties

    , M.Sc. Thesis Sharif University of Technology Lalehgani, Zahra (Author) ; Ramazani Saadatabadi, Ahmad (Supervisor)
    Among the methods for increasing chemical oil extraction,the polymeric flood method has the most commercialization capability.However,most commonly used polymers such as Hydrolyzed Polyacrylamide (HPAM) are not able to withstand high levels of salinity and high temperatures.To overcome these problems,in this project,new types of polymer nanostructures were synthesized with hydrophobic groups consisting of styrene (hydrophilic monomer) and malic anhydride (hydrophilic monomer) acrylamide (hydrophilic monomer). These polymers were synthesized by reversible mini-emulsion by adjusting the synthesis conditions for the purpose of producing the terpolymer with suitable conditions for tolerating... 

    Preparation of Hydrophobically Modified Copolymer Nanostructures as Viscosity Increasing Agents for Enhanced Oil Recovery

    , Ph.D. Dissertation Sharif University of Technology Shaban, Masoom (Author) ; Ramazani Saadatabadi, Ahmad (Supervisor) ; Ahadian, Mohammad Mahdi (Supervisor)
    Among chemical enhanced oil recovery (CEOR) methods, polymer flooding has the highest commercial potential. However, the most widely used conventional polymers such as partially hydrolyzed polyacrylamide (HPAM) are not applicable for high temperature and high-salinity reservoirs. To overcome above mentioned problems, in this work, a series of water- soluble hydrophobically modified polymers (HMPs) nanostructures comprising styrene (hydrophobic monomer) and acrylamide (hydrophilic monomer) have been produced. The copolymers have been synthesized using inverse miniemulsion synthesis method by adjusting synthesis conditions to optimize solution characteristic of copolymers for applying under... 

    Application of Salt Fog Test and Lifetime Evaluation of Silicone Rubber Insulators in Atmospheric Conditions with Contamination and Humidity

    , M.Sc. Thesis Sharif University of Technology Eshaghi Maskouni, Mahdi (Author) ; Vakilian, Mehdi (Supervisor)
    Electricity distribution companies always strive to operate the power network efficiently and reliably so that their network be able to satisfy the growing needs for electricity. To achieve these goals in a power network, a comprehensive asset management plan with a sound policy for inspection, periodic maintenance, replacement, and disposal of depreciated equipment is required. One of the high-risk sectors of the electricity grid is the insulation section of distribution and transmission lines. In recent years, composite insulators have been used more widely because of their desirable characteristics such as: hydrophobicity, lower price, and lower weight if compared with the another... 

    Corrosion Behavior of Hydrophobic Silane Coating Prepared by Sol–gel Method on Carbon Steel

    , M.Sc. Thesis Sharif University of Technology Vaez Ghasemi, Fariba (Author) ; Dolati, Abolghasem (Supervisor)
    This project aims to study corrosion protection performance of silane coating based on tetraethylorthosilicate (TEOS), (3-Mercaptopropyl) trimethoxysilane (MPTS) and Hexamethyldisilazane (HMDS) on carbon steel substrate. Water contact angle (WCA) were measured to study hydrophobicity. The water contact angle increased from 60 degrees in carbon steel to 134.8 degrees in the sample containing 0.35 MPTS and 1.25 HMDS. Surface morphology was studied using Field emission scanning electron microscopy (FESEM) and chemical analysis was conducted using Fourier Transform Infrared Spectroscopy (FTIR). Corrosion resistance was studied by means of Electrochemical Impedance Spectroscopy (EIS) and tafel... 

    Investigating Asphaltene Biodegradability by Microorganism Considering Oil-Water Interface

    , M.Sc. Thesis Sharif University of Technology Iraji, Shohre (Author) ; Ayatollahi, Shahab (Supervisor) ; Taghikhani, Vahid (Supervisor)
    Asphaltine particle precipitation may lead to serious problems in petroleum industry; including wellbore transmissibility reduction. One of the proposed remedial methods is to make a use of the microorganisms which are able to consume the heavy hydrocarbon chains.
    Hydrophobicity of a cell surface is one of the parameters which greatly affect the microorganism adhesion to water insoluble hydrocarbons, in which results a higher hydrocarbon biodegradation. Consequently as the hydrophobicity of a cell surface increases; the microorganism tendency to bond with the hydrocarbon molecule enhances. The presence of a surface active agent, as an instance a chemical surfactant, will affect the... 

    The Investigation of Thermal and Rheological Properties of Hydrophobically Modified Polymer of Acrylamide

    , M.Sc. Thesis Sharif University of Technology Shahin Varnousfaderani, Ali (Author) ; Ramazani Saadatabadi, Ahmad (Supervisor)
    Among chemically enhanced oil recovery (CEOR) methods, polymer flooding has the highest commercial potential. However, the most widely used conventional polymers such as partially hydrolyzed polyacrylamide (HPAM) are not applicable for high-temperature and high-salinity reservoirs. To overcome above-mentioned problems, in this work, a series of water-soluble hydrophobically modified polymers (HMPs) nanostructures comprising 2-vinyl naphthalene (hydrophobic monomer) has been produced by freestyle method (without Surfactant), micellar (with Surfactant). The size of the particles was investigated using scanning electron microscopy (FE-SEM) and optical scattering (DLS). Results from FT-IR... 

    The Impact of Temperature on Surface Activity and Stability of Surface Modified Nano Particles

    , M.Sc. Thesis Sharif University of Technology Masoudi, Ghasem (Author) ; Mohammadi, Ali Asghar (Supervisor)
    Surface modification is an important property of nano particles. In this project surface of silica nano particles modified with hydrophobic and hydrophilic groups to imrprove surface activity of nano particles. Purpose of this project is to study surface activity of surface modified silica nano particles in different temperatures from 20 to 70 degree centigrade. Also effect of salt and time on the surface activity is studied. At first nano particles modified just with haydrophobic groups and then just with hydrophilic groups (hydrophobic and hydrophilic nano particles) and after that, the surface modification done with both hyadrophilic and hydrophobic groups (amphiphilic nanoparticles).... 

    The Effect of Hydrophobic Mismatch and Rigidity of Protein on the Cluster Formation of Transmembrane Proteins in Biomembranes

    , M.Sc. Thesis Sharif University of Technology Jafarinia, Hamid Reza (Author) ; Ahmadiyan, Mohammad Taghi (Supervisor) ; Jalali, Mir Abbas (Co-Advisor) ; Khoshnood, Atefeh (Co-Advisor)
    Membrane proteins aggregation is a very important biological phenomenon in a variety of cell functions. It has been suggested that aggregation behavior of membrane proteins is influenced by the shape of the hydrophobic domain of the proteins, proteins hydrophobic mismatch and bilayer curvature. However, in this study by means of coarse grained membrane simulations it has been found that in thermal equilibrium, protein-protein interactions also depend on protein rigidity and structural strength. Based on simulation results, we have observed stable large clusters even in the absence of hydrophobic mismatch between lipids and proteins. Interestingly, our results also indicate that proteins with... 

    Investigation on Hydrophobic Particle Mobility in Electrolyte Media under Various Electrokinetic Effects

    , M.Sc. Thesis Sharif University of Technology Shafiei Souderjani, Ali (Author) ; Seeadi, Mohammad Hassan (Supervisor) ; Kazemzadeh Hannani, Siamak (Co-Supervisor)
    Electrophoresis of colloidal and bio-particles, which is the motion of a charged particle under an electric field, is a powerful method for the characterization and separation of particles. Electrophoresis of particles could be in electrolyte and gel mediums. Additional drag force is exerted on the particle in a gel medium due to the 3D polymeric structure. Experimental research and molecular dynamics simulations have shown that the no-slip boundary condition is not valuable for many particles in micro and nano-devices. The Navier slip condition, which represents the amount of slip, must replace the no-boundary condition. Characterization of hydrophobicity for optimal design in microfluidic...