Sharif Digital Repository

The partition coefficients of L-Lysine HCL were measured in polymer-salt aqueous two-phase systems. These systems contain polyethylene glycol with nominal molecular weight of 4000 or 10000 and two different salts (di-potassium hydrogen phosphate or tri-sodium citrate 5,5-hydrate). The experimental data were obtained at temperatures 293.15, 298.15 and 303.15 K. The effects of temperature, pH, polymer and salt concentrations, polymer molecular weight and salt type on the partitioning of L-Lysine HCL were also studied. The results showed that salt concentration has a significant effect on the partition coefficient while temperature has a low effect. The experimental partition coefficients of... 

Increasing use of polymeric materials, especially in the packaging industry, besides the problems that exist in recycling these materials, has become a serious concern for the environment. The synthetic polymers are used widely in packaging industry so they have a considerable role in waste production in packaging industry. One way to solve this problem is adding a natural polymer to the synthetic polymer, as a result it becomes friendly environmentally. Starch is one of these natural polymers which is cheap and has the ability to complete degradation in the environment.using row starch in the polymeric compounds causes a severe drop in compound’s properties. For this reason, row starch must... 

Polymer flooding is a famous enhanced oil recovery method and is used to reduce mobility ratio of displacing fluid to displaced fluid by forming a stable front in displacing process. Due to high costs, polymer flooding faces economical risks and from this point of view, performance investigation of polymer flooding in laboratory scale was concerned. In this project, performance of 7 types of polymers which have different rheological properties were investigated in fractured/non-fractured carbonated and sandstone reservoirs. These polymers consists of 4 commercial polymers, one branched polymer, one synthetic polymer and one polymer composite which have different molecular weight,... 

Studying the behavior of materials at high strain rate is necessary for design and analysis of structures subjected to impact loading. Therefore, design and construction of apparatuses that enable us for testing various materials under impact loading is very important. The split Hopkinson pressure bar test -one of the most important impact tests- is utilized for dynamic loading at constant strain rates ranging from 100 to 10000 1/s.
In this thesis, first we explain about the behavior of materials at high strain rates and then focus on the behavior of polymers -that are widely used in different industries- under impact loading. Also, basic concepts of polymeric Hopkinson pressure bar and... 

In this study the main goal is to prepare a membrane to perform delayed drug release and absorbtion in the human body. To do so the supercritical method was used. A well-known biodegradable polymer was used. These kinds of polymers are used in drug delivery, wound dressing or scaffolding for cell culture. A membrane produced out of these kin of polymers is expected to have a good accordance with the goals.Ploy Vinyl alcohol, having very good bio degradable characteristics was used as the main polymer and Poly Ethylene Glycol (PEG) was used as an additive to make changes in the membrane structure. Also Dimethyl Sulfoxide, a polar solvent having the capability of solving both polymers is used.... 

One of the most important EOR methods in oil reservoirs is surfactant and polymer flooding. Surfactants cause decreasing in interfacial tension between oleic and aqueous phases. However, polymers give us efficient mobility control in displacing oil by increasing the viscosity of aqueous phase. Therefore, oil is displaced in aqueous phase by viscous forces.
One of the most important challenges in surfactant flooding is adsorption. The net surface charge distributed on the rock surface depends strongly on pH. When we inject surfactant in reservoir, electrostatic charge on rock surface causes the first-layer adsorption. After that we have had second-layer adsorption.
In this thesis we... 

In the present work, the experiments were carried out for two types of PAM (3330 and 3630) with three distinct concentrations (25, 40 and 55 ppm) and TiO_2-water nanofluid for four concentrations (1.5, 2, 2.5 and 3 vol. %), and the Nusselt number and friction factor for each of them expressed separately. The Reynolds number was in the range from 11000 to 21000. The steady state turbulent convective heat transfer and friction factor of the combination of TiO_2-water nanofluid and polymer 3330 in the coiled tube were investigated. The effects of the Reynolds number for 2 vol. % nanoparticles which consists of 25 ppm PAM (3330) determined at the constant temperature of 24°C. It was observed... 

Study of the recycling of acidic sludge waste produced from oil refineries and its application in road pavements is the one of the most important issues. Disposal of this sludge has always put the nature at risk. In this research, preliminary NPS bitumen was derived through neutralization and processes. NPS was modified by some thermoplastic elastomers such as SEBS, SBS, EVA, … and SBR and NBR rubbers. Also as a ionic and surface modified organoclay, C15A was used in three different weight percent. Rheological and performance behavior of pure bitumen and modified ones was studied using of standard tests for simulating traffic load. Behavior evaluation tests was included dynamic frequency... 

Joining metals to polymers is an increasing demand in industry mainly due to weight savings. Polymer-metal hybrid structures are widely used in aerospace and automotive industries. However, dissimilar joining of polymer to metal is very difficult due to large mechanical and physical properties differences. Since conventional methods for joining polymers to metals have various limitations, it is necessary to employ new practical and environmental friendly joining processes. In this study, the feasibility of joining an aluminum alloy (AA5052) to polypropylene (C30S) sheets via friction stir welding was examined. Lap joint configuration was determined as the optimized configuration by analyzing... 

In the world today, biological materials widely used are which requires proper packaging, the types of enzymes are used in various industries: food, pharmaceutical, cosmetics. Shelf Life of enzymes Limited and affected by internal and external factors a maximum of one year. Internal factors include water activity, pH, microbial flora, oxidation-reduction potential, chemistry and biochemistry products, product formulation, additives and the reaction with package. External factors such as relative humidity, light, gas atmosphere within the package, the storage conditions and temperature. Water activity and relative humidity are important factors in spoilage. Avoid drying, lipid reaction,... 

In this project, polymer nanocomposites containing graphene oxide were prepared and used for adsorption of several cationic and anionic dyes. In most cases, these nanocomposites were prepared as three-dimentional polymer networks which contain graphene oxide. Nanocomposites with direct grafting of polymer chains onto the surface of graphene oxide were also prepared. Graphene oxide is an oxidized carbonaceous material with unique properties. This material has high surface area, good mechanical strength and various functional groups. Polymeric compounds with different functional groups, structures and properties can be prepared and used. By preparing composites of graphene oxide and polymers,... 

Skin as the largest organ of the body is constructed of three distinctive layers referred to as epidermis, dermis, and hypodermis. Epidermis is the outermost layer of the skin and acts as body’s first barrier against infectious agents and contains mostly sweat glands. Dermis is the mid-layer of the skin which makes up to 70% of the skin and plays a significant role in maintaining body’s metabolism and is home to a huge part of skin’s vascular network, nerve cells and hair follicles. Hypodermis on other hand, is the deepest layer of the skin and mainly acts as a bonding layer between upper skin layers and the soft tissue underneath. Although skin is proved to have a profound ability to... 

Low salinity water flooding (LSWF) is a relatively new EOR method in which low salinity or modified ionic composition water is injected into the reservoir to alter its wettability toward a more water-wettable state to accelerate oil recovery. Ease of field deployment and relatively low cost, as well as laboratory results confirming the positive effect of this method in improving the oil recovery factor, have made this technique attractive in the oil industry.Despite the many advantages of this method, overcoming the mixing between low and high salinity water which occurs due to a high mobility ratio between these two fluids is essential because it negatively affects the efficiency of LSWF.... 

Achievements in the synthesis of polycatenanes promise new opportunities for having and designing new smart materials. However, the out-of-equilibrium dynamic of polycate-nane is largely unstudied. This research studies the interplay of poly[2]catenane topology and hydrodynamic interactions in pure shear flow using the MPCD method. To question the effect of topological interaction, we simulated systems with bonded rings alongside systems with poly[2]catenane. In order to investigate the effect of hydrodynamic interaction, each system was examined using the random solvent method as well. Our study shows the poly[2]catenane structure can control the shear and stress by twist and rotation...