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An Investigation into Effects of Components Ratio and Nano/micro Sized ZnO Particles on Evolution of Transesterification Reaction, Compatiblization and Modification of PET/PC Blends Structure
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Reza (Supervisor) ; Pircheraghi, Gholamreza (Supervisor)
Abstract
Polycarbonate (PC) and polyethylene-terephthalate (PET) are important engineering thermoplastics. During last decades these polymers and their blends have been studied extensively due to their wide range of applications. Blends of PET and PC combine mechanical properties and chemical resistance together, which make applicable in various components such as automotive, electrical and of medical parts. It has been accepted that PET/PC immiscible blends are subjected to transesterification reactions during thermal processing, which produces PET-PC copolymer chains. In fact, scissioning and substitution of ester/carbonate functional groups of PC and PET at the interface, transforms the initial...
Control of Formation, Dispersion and Morphology of TiB2 Particles in Al-TiB2 Metal Matrix In-Situ Composite through Optimization of Melt Condition
, M.Sc. Thesis Sharif University of Technology ; Varahram, Naser (Supervisor) ; Davami, Parviz (Co-Advisor)
Abstract
A study has been carried out on the formation of TiB2 particles in an aluminum based in-situ metal matrix composite by mixing master alloys containing Ti and B i.e., Al-10Ti and Al-8B with a Ti:B weight ratio of 5:2. It was shown that the microstructure of the composite was greatly affected by the controlling factors of the in-situ reaction like temperature, reaction time and stirring of the melt. An increasing reaction time leads to the dissolusion of the primary phases (AlB2 and Al3Ti) and the increase in TiB2 volume fraction. Optical microscope and SEM images were used to study these changes and XRD analysis was applied to confirm these observations. The act of melt stirring in short...
Application of a Thermo-Plastic Constitutive Model for Coupled THM Analysis of Behavior of Saturated Soils
, M.Sc. Thesis Sharif University of Technology ; Pak, Ali (Supervisor)
Abstract
Effects of temperature on the behavior of soils and rocks have been studied widely in recent years. Following the need for understanding the effects of temperature on the behavior of clayey soils, several experimental and numerical studies on thermo-mechanical behavior of clayey soils have been carried out and a number of thermo-mechanical constitutive models have been developed for saturated and unsaturated clayey soils. In this research, a two-yield surface thermo-plastic constitutive model developed by Abuel-Naga et al. (2007, 2009), has been chosen for THM analysis of the behavior of saturated clayey soils. This constitutive model is based on Modified Cam-Clay (MCC) model. The MCC model...
Comparison of Mechanical Properties of Al-TiB2 Composite in as Cast, Heat Treated and Extruded Condition
, M.Sc. Thesis Sharif University of Technology ; Varahram, Naser (Supervisor) ; Davami, Parviz (Supervisor)
Abstract
This research focused on mechanical properties of Al-TiB2 composite in as cast, heat treated and extruded condition. The composites were produced by mixing Al-Ti and Al-B master alloyes. Since some engineering parts during service are supposed to tolerate severe wear conditions, in this research abrasive wear condition was wxamined using pin on disk method. In a fixed load and abrasive disk, composites showed better resistance against wear in comparison with matrix alloy. Furtheremore, T6 heat treatment made composites more resistant against abrasive wear. Finally the best wear resistance was accompolished when composite was extruded and then heat treated. While increase in reinforcement...
Study of the Poly (vinyl acetate)/SiO2 Nanocomposites Produced by in Situ Polymerization
, M.Sc. Thesis Sharif University of Technology ; Ramazani Saadat Abadi, Ahmad (Supervisor)
Abstract
The main object of this thesis is synthesizing poly(vinyl acetate)/ colloidal silica nanocomposites via emulsion and in-situ polymerization methods. At the first, nanocomposites were produced in the presence of poly(vinyl alcohol) as the protective colloid, ammonium persulphate as the initiator and sodium bicarbonate as the buffer in an aqueous solution. Then, structural, thermal, rheological, mechanical and surface properties of produced nanocomposites with various colloidal silica content (0.5 %, 1 %, 1.5 %) were evaluated by DLS, FTIR, SEM-EDS, DSC, TGA, dynamic and steady rheological tests, tensile and shear mechanical tests, AFM and static water contact angle. The particle size of...
Investigation of Toughening Mechanisms in Al/Al3Ti In-Situ Hot Extruded Composites
, M.Sc. Thesis Sharif University of Technology ; Madaah Hosseini, Hamid Reza (Supervisor)
Abstract
In this study in-situ Al/Al3Ti was fabricated by mechanical alloying, hot extrusion and subsequent heat treatment. First, initial pure powders of Al and Ti were mechanically alloyed with 5 weight percentages of Ti for 40 hours. The as-hot extruded samples containing 5 wt% of initial Ti particles, were exposed to heating at 600 oC for various time intervals up to 10 hours. Microstructure analysis by OM and SEM proved that in-situ Al3Ti phase was formed as a layer around Ti particles by solid reactive diffusion between Al and Ti particles. After 10 hours of heating, all the Ti particles were consumed and transformed to Al3Ti. Mechanical properties of samples were investigated by Brinell...
The Study of Permeable Reactive Barriers Made of Nano Zero Valent Iron, for In-situ Groundwater Remediation
, M.Sc. Thesis Sharif University of Technology ; Abrishamchi, Ahmad (Supervisor) ; Vossoughi, Manoochehr (Supervisor)
Abstract
In present research in-situ groundwater remediation by permeable reactive barriers is considered and the main goal is to find the optimal dimension of reactive walls and also to find the most efficient reactive media. Here, computer simulation is done via MODFLOW. Different barrier lengths, widths, depths and distances between trenches have been considered and contaminant removal percentage calculated in all situations. Based on the research achievements increasing the barrier length has led to reduction of contaminant removal percentage because flow gradient and flow density decrease by length increase. As the results show, contaminant removal percentage increases by width increase because...
Study of Mechanical Properties of High Tempreture Al Nano-composites with Al2O3-Al3Ti based on theThermal Degradation of Aluminium Titanate
, M.Sc. Thesis Sharif University of Technology ; Madaah Hosseini, Hamid Reza (Supervisor)
Abstract
In this study, in situ Al-Al3Ti-Al2O3 nanocomposite has been fabricated on thermal decomposition of tialite (Al2TiO5 or AT) precursor in the aluminum matrix through powder metallurgy method. The high-temperature mechanical property of Al-Al3Ti-Al2O3 on this procedure has been investigated. In the first step nano-structured tialite were synthesized through citrate sol-gel methods. Then 3.5 wt.% tialite powder was mixed with aluminum by high energy vibratory milling for 3 hours. In the next step, green compacts of mechanically milled powder mixtures were sintered at 530°С for 6 hours under argon atmosphere. In the final step, hot extrusion as a consolidation method reduces the sample voids,...
Investigation of Hydraulic Fracturing Effect on Production of Natural Reservoir Fractures
, M.Sc. Thesis Sharif University of Technology ; Jamshidi, Saeeid (Supervisor) ; Pak, Ali (Co-Advisor)
Abstract
Hydraulic fracturing process as one of the most important ways to inhanse of production requires careful study and investigation and due to its importance has been studied for decades. The effect of this process on the production at oil and gas industry has many complexities and these complexities with the complex structure of natural gaps, would be multiplied. In this thesis effect of hydraulic fracturing operation on the production of natural fractures at naturaly fractured reservoirs from two aspects of hydraulic and geomechanics will be investigated. First we provide models for fractures network by using UDEC software after that investigate the effect of hydraulic farcture on the natural...
, M.Sc. Thesis Sharif University of Technology ; Vossoughi, Manoochehr (Supervisor)
Abstract
One of the subjects that have been title for many research proposals in recent years is application of Nano Zero Valent Iron (NZVI) particles in contaminant removal from groundwater sources. Despite many studies being done, field application of this particles in a practical scale is not widespread yet which is due to many challenges like rapid settlement of particles or their unclear behavior through field application. The main purpose of this thesis in the first place is to find a practical and productive method for stabilization of particles and enhancement of their transport properties. To reach this goal, application of a natural polymer like starch has been studied as a solution. To...
Numerical Modeling of Diagnostic Fracture Injection Test
, M.Sc. Thesis Sharif University of Technology ; Shad, Saeed (Supervisor) ; Zivar, Davood (Co-Supervisor)
Abstract
Diagnostic Fracture Injection Test (DFIT) uses to identify the characteristics of the reservoir, including minimum horizontal stress, permeability, initial reservoir pressure, etc. The general steps of this process include fluid injection, fracture initiation in the matrix, fracture propagation and its closure due to fluid leak-off. The results of DFIT are analyzed in two stages based on the fracture closure event. The objective of this study is to investigate the effect of leak-off mechanisms on pressure-dependent leak-off (PDL), tip extension and fracture storage. To do so, different methods are used for identifying the cooperating parameters at each step. In order to analyze DFIT, a...
Numerical Modeling of Cone Penetration Tests in Saturated Clayey Soil under Undrained Conditions
, M.Sc. Thesis Sharif University of Technology ; Ahmadi، Mohammad Mehdi (Supervisor)
Abstract
This study aims to numerical modeling of piezocone penetration test (CPTu) in saturated clayey soils under undrained conditions using FLAC-2D software. According to the available studies, measuring excess pore water pressure during the piezocone penetration test can play an important role in determining the characteristics and engineering parameters of clayey soils. In many geotechnical problems, the initial state of existing stresses in the ground and are an important parameter that must be known for designs and analysis. The relationship between vertical and horizontal effective stress under zero lateral deformation is usually expressed by the coefficient of lateral earth pressure at...
Hydrogel Design and Development for Osteoarthritis Treatment
, M.Sc. Thesis Sharif University of Technology ; Yaghmaei, Soheyla (Supervisor) ; Mashayekhan, Shohreh (Supervisor)
Abstract
"osteoarthritis" is one of the most common joint diseases. This disease has a close relationship with factors such as aging, weight gain, genetics, mechanical pressures, and severe injuries. Although the mechanism of this disease is not fully understood, inflammation is one of the main causes of its exacerbation and progression. controlling inflammation can greatly help in controlling the disease. One of the common treatment methods for osteoarthritis is intra-articular injection of hyaluronic acid and triamcinolone as anti-inflammatory drug. Hyaluronic acid is the main component of synovial fluid, with its viscosupplementation property, prevents bones from rubbing against each other in the...
In-Situ Synthesis of Zif-8 Nanocomposite Coating on Carbon Steel and Investigating the Effect of Adding Mbt on Corrosion Behavior and Sic Nanoparticles on Mechanical Properties
, M.Sc. Thesis Sharif University of Technology ; Abachi, Parvin (Supervisor) ; Dolati, Abolghasem (Supervisor)
Abstract
Nowadays, metal-organic frameworks have received a lot of attention due to their properties and characteristics such as controllable structure, high specific surface area and the tunable porosity size and have found many applications. One group of metal-organic frameworks are zeolitic imidazolate frameworks which ZIF-8 is a member of this family, and many studies have been conducted on it. In the present study, ZIF-8 nanocomposite coating was applied to the plain carbon steel substrate by synthesis at room temperature and immersion method, and its corrosion behavior and mechanical properties were investigated. The effect of Mercaptobenzothiazole (MBT) inhibitor on corrosion behavior and...
Synthesis, Characterization and Optimization of an In situ Forming Hydrogel Derived from Extracellular Matrix for Cardiac Tissue Engineering Applications
, M.Sc. Thesis Sharif University of Technology ; Mashayekhan, Shohreh (Supervisor) ; Baheiraei, Nafiseh (Supervisor) ; Pourjavadi, Ali (Co-Supervisor)
Abstract
Myocardial Infarction occurs due to sudden blockage in a coronary artery and causes necrosis of myocardial tissue. Since myocardium is unable to self-regenerate, cardiac tissue engineering has become a promising therapeutic approach for MI treatment by restoring heart function via combination of cells, biomaterials and signaling factors. For this purpose, myocardial extracellular matrix (ECM) is an attractive biomaterial providing better biomimetic for cultured cells. In this project, we synthesized an in situ forming hydrogel derived from myocardial ECM and for improving mechanical and electrical properties of ECM hydrogel we added oxidized alginate (OA) with 5% oxidation degree and APTMS...
Fabrication of in Situ Forming Hydrogels Composed of Acellular Cartilage Matrix with Improved Mechanical Properties for Recovery of Local Damages in Articular Cartilage
, M.Sc. Thesis Sharif University of Technology ; Mashayekhan, Shohreh (Supervisor) ; Hassanzadeh, Zabihollah (Co-Supervisor)
Abstract
Since cartilage has limited self-regeneration, in-situ forming hydrogels can act as an ideal scaffold for cartilage tissue engineering to fill the defect gap due to their ability to homogeneously encapsulate the desired cells, efficient mass transfer and minimally invasive characteristics. In this project, an injectable hydrogel with improved structure by adding silk fibroin (SF) nanofibers and better biochemical properties by employing the cartilage extracellular matrix (ECM) was fabricated. The in-situ forming hydrogel is consisted of different concentrations of ionic crosslinked alginate incorporated with different concentrations of SF nanofibers and 1% w/v enzymatically crosslinked...
Fabrication of in Situ Forming Bioadhesive Hydrogel for Cartilage Tissue Engineering
, M.Sc. Thesis Sharif University of Technology ; Mashayekhan, Shohreh (Supervisor) ; Hasanzadeh, Zabihollah (Supervisor)
Abstract
In recent years, many efforts have been made in tissue engineering and new methods for the treatment of cartilage damage, with an emphasis on their non-invasive and less aggressive nature. Meanwhile, injectable and in situ forming hydrogels have been considered as a less invasive nature. On the other hand, lack of enough mechanical properties in these hydrogels is one of their main problem. In this study, gelatin and alginate was used to fabricate hydrogel as interpenetrating network (IPN) hydrogel and silica nano particles were also used to increase mechanical properties in the fabricating of hydrogels. Gelatin is also combined with dopamine in order to induce bio adhesive properties of...
Fabrication & Characterization of Al-Al3Ti-Al2O3 Nano-composites Based on the Thermal Degradation of Aluminium Titanate & Facile Study on the Correlation between Microstructure & Their Mechanical Properties
, M.Sc. Thesis Sharif University of Technology ; Maddah Hosseini, Hamid Reza (Supervisor)
Abstract
In this study insitu Al-Al3Ti-Al2O3 nanocomposite has been fabricated based on thermal decomposition of tialite (Al2TiO5) precursor in aluminium matrix through powder metallurgy method. Also the effect of high energy mechanical milling and hot extrusion on this procedure has been investigated. In the first step nano-structured tialite were synthesized through citrate sol gel methods. Then, different volume fraction of tialte was mixed with aluminium by high energy vibratory milling. The results of X-ray differaction analysis, scanning electron microscopy and differential thermal analysis showed that mechanical milling can degrade stability of tialite and cause strain-induced decomposition,...
Investigation Properties of Polypropylene/Carbon Nanotube Nanocomposites Prepared via in Situ Polymerization Using Bi-Supported Ziegler Natta Catalyst
, M.Sc. Thesis Sharif University of Technology ; Ramezani Saadatabadi, Ahmad (Supervisor)
Abstract
In this research polypropylene/carbon nanotube nano composites were prepared via in situ polymerization using Bi-supported Ziegler-Natta catalytic systems. Magnesium etoxide and Multi wall carbon nanotubes(MWCNT) functionalized by hydroxyl groups were used as supports of catalyst. TiCl4 and TiBA were used as catalyst and co catalyst respectively. After defining the polymerization optimum conditions and considering its parameters constant, nano composites with different carbon nanotube contents were produced by changing the polymerization time. Scanning Electron Microscopy (SEM) images certified very good dispersion of MWCNTs throughout polypropylene matrix. The thermal properties behavior of...
Manufacturing and Investigation the Properties of Polyethylene/ Fumed Silica Nanocomposites Via in situ Polymerization
, M.Sc. Thesis Sharif University of Technology ; Ramazani Saadatabadi, Ahmad (Supervisor)
Abstract
In this research UHMWPE/FUMED SILICA nanocomposites with different concentrations of nano fumed silica (0.5, 1.5, 2.5, 4.5 wt %) were prepared via in situ polymerization using a novel Bi-supported Ziegler-Natta catalytic systems. Magnesium etoxide and Fumed Silica functionalized by hydroxyl groups were used as supports of catalyst. TiCl4 accompanied by triethylaluminum constituted Ziegler-Natta catalytic system. Preparation of catalyst and polymerization were done in slurry phase under the argon atmosphere. Scanning Electron Microscopy (SEM) images also certified very good dispersion of fumed silica throughout PE matrix. Intrinsic viscosity measurements showed high molecular weight for...