Sharif Digital Repository

In industries there are many nonlinear processes which cannot be easily controlled with classical methods. Model predictive control is a useful method for nonlinear processes which not only has high efficiency, but also extension of this control to interferential multi variable case, with constraint on the controlled and manipulated variables and other problematic dynamic specifications such as slow dynamics and inverse response is very simple. Industrial polymerization processes are regarded as significant nonlinear processes. Optimization and control of polymerization reactors have considerable importance in process applicability and in economics. The molecular structure of polymer such as... 

In this research UHMWPE/MWCNT nanocomposites with different concentrations of nanotubes (0.5, 1.5, 2.5, 3.5 wt %) were prepared via in situ polymerization using a novel Bi-supported Ziegler-Natta catalytic systems. Magnesium etoxide and Multi wall carbon nanotubes 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. Support of catalyst on MWCNT was investigated using Fourier Transform Infrared Spectroscopy (FTIR). The results confirmed interaction between catalyst and hydroxyl groups on the surface... 

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... 

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... 

In the industry, there are nonlinear processes that can not be controlled with classical methods. Also, there are many processes that are more than one controlled variable that with classical methods, the design of a multiple input - multiple output controler is very difficult for them as well as the constraints on the inputs and outputs of the process exist, using classical controllers will be far more difficult. A model-based predictive control method for controlling nonlinear processes is useful in addition to having very high efficiency, extended to multi-mode interference together with constraints on the control variables and other controlled Problem with dynamic properties such as... 

In this research UHMWPE/CB nanocomposites were prepared via in situ polymerization using Bi-supported Ziegler-Natta catalytic systems. Magnesium etoxide and carbon black were used as supports of catalyst. TiCl4 accompanied by triisobutyl aluminum and diisobutyl phthalate (DIBP) constituted Ziegler-Natta catalytic system. Preparation of catalyst and polymerization were done in slurry phase under the argon atmosphere. Then, structural, thermal and mechanical properties of produced nanocomposites with different CB content were evaluated by SEM, DSC, TGA, DMTA and tensile tests. Scanning Electron Microscopy (SEM) images also certified very good dispersion of CBs throughout PE matrix.... 

In the present thesis, intracellular fluid flows have investigated for study cell motions. It is due to firmly relation between the cell motion and these flows. Generally, the cell firstly adheres to a surface, then, moves forward with the effects of the internal fluid flows. In this study, the cell structure is invided to two general parts; the front part of the cell and the cell body. The front part of the cell plays a essential roles in the cell motion, however, the cell body is considered as a extra cargo that is carried by the front of the cell. Therefor, in the present modellings, the front part is only considered. Here, using four different models for the front part of the cell, many... 

A new technique for surface modification of flat sheet hemodialysis membranes has been investigated. This new strategy presents a dynamic surface modification for membranes in order to assess the hydrophilicity, antifouling, and biocompatibility effects of two functional monomers on dialysis membrane. PSF membranes containing polyvinylpyrrolidone were prepared via phase inversion technique. Afterward, free radical polymerization combined with surface polymerization used to introduce acrylic acid and 2-hydroxyethyl methacrylate onto polysulfone membrane surface. Various monomer concentrations were selected to obtain an optimum condition. Field emission scanning electron microscope (FE-SEM),... 

The purpose of this study is the implementation of multi-model predictive control (MMPC) approach for the co-polymerization system of methyl methacrylate - vinyl acetate. Simpler development of local models and controllers and also convenience of understanding the model and controller structure are the main reasons for using this approach. In the first step, RGA analysis has been used for pairing input and output variables. Then the performance of PI controller on the system has been investigated. For designing model predictive controller (MPC) the nonlinear model has been linearized at operational point and the controller has been designed in MPC toolbox of MATLAB software R2013a. In the... 

Ultra high molecular weight polyethylene has attracted the attention of numerous researchers and industries. This polymer due to its strong properties can be used in advanced military industries, medical engineering and cases in which high strength and high abrasion resistance is required. Present study aims to fabricate UHMWPE/Molybdenum disulfide composites, using in-situ polymerization. Before carrying out the polymerization process, nanoparticles of molybdenum disulfide underwent various processes such as oxidation, pickling, ultrasonic and thermal shock, in order to increase the interlayer distance and creating functional groups on the surface, then various analyzes, such as XRD, FESEM,... 

Hydrogels are crosslinked hydrophilic polymers that are capable of imbedding large amounts of water or biological fluids usually to equilibrium. Because of their unique properties, these materials have become ubiquitous and indispensable materials in many applications in recent years. Synthetic methods have produced numerous hydrogel materials with excellent properties. However, their nonbiodegradability might pose long-term environmental problems and limit their use. As a consequence, various research groups have put considerable amounts of effort and resources toward development of new absorbent materials from natural polymers such as polysaccharides. In this research, new hydrogel... 

Atom transfer radical polymerization (ATRP) is a convenient approach to synthesis of polymer with narrow molecular weight distribution. ATRP of acrylamide (AAm) is taken into consideration because of the intrinsic properties of acrylamide such as water solubility and biocompatibility. As reported in many recent works, polymerization of acrylamide by this method didn’t provide monomodal molecular weight distributions. In best condition with strong ligands such as Me4Cyclam, polymerization was carried out in a short time with high yield but polymerization was not highly controlled. It was shown that polymerization of acrylamide under typical ATRP condition displayed a much lower ATRP... 

This project is devoted to experimental investigation of increasing on production of polyethylene/clay nanocomposites (PECNs) and polypropylene/clay nanocomposites (PPCNs) via in-situ polymerization method. First of all we produced bi-supported Ziegler-Natta catalyst to polymerized polyolefins nanocomposites. Bentonite type clay and Magnesiumethoxide (Mg (OEt)2) were used as the support of Tetrachloridetitanium (TiCl4). Catalyst support and polymerization process have been done in slurry phase using Triisobutylaluminum (TiBA) as the co-catalyst. The efficiency of preapared bi-supported Ziegler-Natta was reasonably high (average 200 (gr. Product/mmol Ti. h) for PECNs and 195 (gr. Product/mmol... 

The Electron Paramagnetic Resonance(EPR) is a retrospective and accurate dosimetry method to measure irradiated-induced radical population in the matter for determination the induced dose in the matter. The dose uncertainties will be about 1 percent. in the first stage of the present research, the response of EPR system to a reference sample has been measured. Then, responses due to the other samples has been compared with it and the secondary sample dose has been calculated. The reference sample usually is alanine. Unlike the perturbation theory forecast,the EPR signal intensity response to dose for alanine is not linear. In this thesis, first, the alanine samples (with pellet form) have... 

At the first part of project, different kinds of monodithiocarbamates were synthesized.In order to prepare these compounds two methods have been used:Reactions of amines and carbon disulfide in water and finally addition of Michael acceptors.Reaction of amines and carbon disulfide, then addition of alkyl halides under solvent-free conditions.Dithiocarbamate salts are prepared in ether by using CF3SO3CH3 as the methylation agent with resulted monodithiocarbamates at the first part of the project. These salts are found to be ionic liquids, which is important class of organic compounds.At the second part of project, the Michael additions of amines with divinyl sulfone are investigated in... 

In this study preparation of polymeric membrane for grey water treatment is examined. Grey water is the wastewater that is produced by household activities such as baths, showers and sinks. These sources make 50 to 80 percent of total household wastewater. Because of low contamination of these kind of wastewater, they can be treated with Nanofiltration membrane process. Membrane used for treatment is thin composite polyamide membrane. This membrane is made with interfacial polymerization reaction of Piperazine and m-phenylenediamine as amine monomer and trimesoyl chloride as chloride acid monomer on a Polysulfone ultrafiltration membrane. In order to promote the flux, Polyethylene glycol is... 

Due to outstanding advantages of polymeric insulators such as: hydrophobicity, impact resistance and lower weight, their application in the high voltage transmission and distribution lines is increased significantly, in recent years. The most important feature of these insulators is their hydrophobicity. Contamination and aging are some of the factors that weaken this important feature and reduce the reliability of these insulators. Due to aging effects partial discharges start on the surface of the composite insulators and increase by impact of external factors. This thesis examines the occurrence of partial discharge signals on polymeric insulators under: varying amounts of contamination,... 

Nowadays, regarding the wide achievements in micro scale technology, it is possible to manufacture a micro robot. Micro swimmer have extensive applications in different fields especially in medical sciences. One of the most important problems of the micro robot is their propulsion system. The locomotion of microorganisms in fluids is ubiquitous and plays an important role in numerous biological processes. The physics of swimming governing life under the microscope is very different from the one we experience in the macroscopic world. This project is aimed at designing a propulsion system for a micro swimmer based on the swimming mechanism of the eukaryotic Spermatozoa. Simplicity to build is... 

In the present research the methods and challenges to ocular drug delivery have been investigated with more emphasis on ocular diseases that do not have any approved treatment. Periocular route is a promising alternative to the common routes of ocular drug delivery especially for treatment of posterior eye diseases. Based on barriers for efficient drug delivery to the eye, magnetic drug targeting revealed to be influential to eliminate some obstacles of this route which has not been worked before. It is hypothesized that the particles can pulled into the eye or will be trapped inside the sclera tissue or even if it is not happened, they can stay behind the sclera and magnetic force can... 

Most used polymers, such as hydrolyzed polyacrylamide, are not able to withstand high levels of salinity and high temperature of the reservoirs. To overcome these problems, in this project, new types of microstructures based on modified acrylamide with hydrophilic groups (malic anhydride monomer) and hydrophobic groups (styrene monomer) using inversible mini-emulsion were synthesized. The structure of the synthesized terpolymer was investigated using methods of FT-IR and 1H NMR. The micro-structure and the particle-size of the terpolymer particles were studied with the scanning electron microscopy (FE-SEM) and differential light scattering (DLS) method and the results showed that the average...