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    Synthesis and Characterization of High Molecular Weight Polyacrylamide and Cationic Polyacrylamide

    , M.Sc. Thesis Sharif University of Technology Abdollahi Banouei, Zohreh (Author) ; Frounchi, Masoud (Supervisor) ; Dadbin, Susan (Supervisor)
    In many industrial processes there is an urgent need for flocculation of suspensions that can’t flocculate easily through the time so flocculants are wildly used in these industries. Polymeric flocculants because of less needed dose are economically used. Polymeric flocculants divided to three categories: nonionic, anionic and cationic those are almost from polyacrylamide group. Studying mechanisms of flocculation, one of the main factors that enhance flocculation is molecular weight of polymer. Hence one of the goals of this work is to improve molecular weights of synthesized polymers as much as possible that is followed by viscometery, NMR, DSC and FTIR studies and ended with jar test.... 

    Thermal degradation behavior and kinetic analysis of ultra high molecular weight polyethylene based multi-walled carbon nanotube nanocomposites prepared via in-situ polymerization

    , Article Journal of Macromolecular Science, Part A: Pure and Applied Chemistry ; Volume 49, Issue 9 , 2012 , Pages 749-757 ; 10601325 (ISSN) Shariati, J ; Saadatabadi, A. R ; Khorasheh, F ; Sharif University of Technology
    T&F  2012
    Thermal degradation behavior of multi-wall carbon nanotubes (MWCNTs)/ultra high molecular weight polyethylene (UHMWPE) nanocomposites, with different nanotubes contents (0.5, 1.5 and 3.5 wt%) prepared via in-situ polymerization technique have been investigated using thermal gravimetric analysis (TGA). TGA spectra revealed that these nanocomposites had enhanced thermal stability and no significant mass loss (<0.4 wt%) occurred up to 350°C. Thermal degradation of these UHMWPE/MWCNT nanocomposites was investigated in terms of parameters such as the onset temperature of degradation (T 10), the decomposition temperature at 50% wt loss (T 50), the degradation temperature of maximum rate of the... 

    High performance Dyneema® fiber laminate for impact resistance/macro structural composites

    , Article Journal of Thermoplastic Composite Materials ; Volume 25, Issue 4 , 2012 , Pages 403-414 ; 08927057 (ISSN) Karbalaie, M ; Yazdanirad, M ; Mirhabibi, A ; Sharif University of Technology
    UHMWPE composite materials are increasingly used in armors design due to their high strength-to-weight ratios and energy absorption capacities. In this study the effect of production parameters upon the terminal ballistic properties of UHMWPE composite were examined under different conditionings. The composite armor plate laminates were produced by hot pressing with three different pressing times from 10-30 minutes and the laminates conditioned at +115, +125, and +135°C. The molding temperature of SK66 fiber composite has the main direct effect on the ballistic absorption energy, so the relation of molding temperature with the adhesive bonding force between layers, the thickness of the... 

    Investigation of the applicability of nano silica particles as a thickening additive for polymer solutions applied in EOR processes

    , Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Vol. 36, Issue. 12 , 2014 , Pages 1315-1324 ; ISSN: 15567036 Zeyghami, M ; Kharrat, R ; Ghazanfari, M. H ; Sharif University of Technology
    In past decades, many attempts have been made to use water-soluble polymers as a mobility control agent to improve sweep efficiency of enhanced oil recovery processes. However, sensitivity of the thickening behavior of these polymers to some harsh conditions, such as high salinity, has cast serious doubt on their applicability in reservoir conditions. By expansion of nanotechnology, scientists discovered that nanoparticles can be utilized as thickening and rheology control agents in many polymer solutions. In this study, hydrophilic fumed silica is added to hydrolyzed polyacrylamide and sulfonated polyacrylamide solutions. The effect of the addition of nano silica on the thickening and... 

    Interdiffusion versus crystallization at semicrystalline interfaces of sintered porous materials

    , Article Polymer ; Volume 156 , 2018 , Pages 54-65 ; 00323861 (ISSN) Salari, M ; Pircheraghi, G ; Sharif University of Technology
    Elsevier Ltd  2018
    Sintering process at temperature intervals close to the melting point of polymers is greatly important due to its role in synthesizing porous materials. During sintering, particles of polymeric materials coalesce throughout a process called interdiffusion. On the contrary, crystallization strongly affects the interdiffusion process at temperature intervals below and close to the melting point. Apparently, the outcome of the contention between these two factors would determine the interfacial width. Therefore, the current study presents a model, which takes both crystallization and interdiffusion into account, to predict sintering kinetic. Consequently, interfacial strength was assessed with... 

    Experimental investigation of asp flooding in fractured heavy oil five-spot systems

    , Article 74th European Association of Geoscientists and Engineers Conference and Exhibition 2012 Incorporating SPE EUROPEC 2012: Responsibly Securing Natural Resources, 4 June 2012 through 7 June 2012 ; 2012 , Pages 3924-3928 ; 9781629937908 (ISBN) Sedaghat, M. H ; Ghazanfari, M. H ; Masihi, M ; Rashtchian, D ; Sharif University of Technology
    European Association of Geoscientists and Engineers, EAGE  2012
    Although alkaline-surfactant-polymer flooding is proved to be efficient for oil recovery from heavy oil reservoirs, the displacements mechanism/efficiency of this process in fractured systems needs to more discussion, especially in five-spot patterns. In this work, several ASP flooding test were performed on fractured micromodels which were initially saturated with heavy oil at constant flow rate and different fracture geometrical characteristics conditions. The ASP solutions are constituted from 5 polymers i.e. four synthetic polymers include three hydrolyzed polyacrylamide with different molecular weight as well as a non-hydrolyzed polyacrylamide and a biopolymer, 2 surfactants i.e. a... 

    Optimization of industrial CSTR for vinyl acetate polymerization using novel shuffled frog leaping based hybrid algorithms and dynamic modeling

    , Article Computers and Chemical Engineering ; Volume 35, Issue 11 , November , 2011 , Pages 2351-2365 ; 00981354 (ISSN) Pakravesh, H ; Shojaei, A ; Sharif University of Technology
    Industrial scale continuous stirred tank reactor (CSTR) for production and grade transitions of poly vinyl acetate (PVAc) at the different reactor sizes was investigated. Such reactor is known to show oscillatory behavior and to have periodic limit points, particularly at high molecular weights. Four efficient novel hybrid optimization methods which use variable population size genetic algorithm (VPGA), bacterial optimization algorithm (BO) and shuffled frog leaping method (SFL) were introduced for this kind of reactors. These algorithms can reliably find dynamically stable points with desired conditions for PVAc production. The dynamic modeling combined with the new hybrid optimization... 

    Amine-functionalized magnetic nanocomposite particles for efficient immobilization of lipase: effects of functional molecule size on properties of the immobilized lipase

    , Article RSC Advances ; Volume 5, Issue 42 , Apr , 2015 , Pages 33313-33327 ; 20462069 (ISSN) Esmaeilnejad Ahranjani, P ; Kazemeini, M ; Singh, G ; Arpanaei, A ; Sharif University of Technology
    Royal Society of Chemistry  2015
    A cost-effective design of reusable enzyme-functionalized particles with better catalytic activity is of great scientific interest due to their applications in a wide range of catalytic reactions in several industrial processes. In this work, a systematic approach for preparing amine-functionalized magnetic nanocomposite particles through the surface modification of core/shell type Fe3O4 cluster@SiO2 particles by the small molecules of 3-(2-aminoethyl)aminopropyltrimethoxysilane (AAS) or the large molecules of polyethyleneimine (PEI) with two different molecular weights, as the support materials for enzyme immobilization, has been demonstrated. The functional... 

    High molecular weight polyacrylamide nanoparticles prepared by inverse emulsion polymerization: reaction conditions-properties relationships

    , Article Colloid and Polymer Science ; Volume 294, Issue 3 , 2016 , Pages 513-525 ; 0303402X (ISSN) Tamsilian, Y ; Ramazani S. A ; Shaban, M ; Ayatollahi, S ; Tomovska, R ; Sharif University of Technology
    Springer Verlag  2016
    High molecular weight polyacrylamide (PAM) nanoparticle dispersions are products with wide application possibilities, the most important of which is in petroleum industry such as drilling fluid and flooding agent in enhanced oil recovery. For that aim, it is necessary to achieve complete control of the final dispersion and polymer properties during the synthesis step. In this work, PAMs were synthesized by inverse emulsion polymerization of aqueous acrylamide solution in cyclohexane in the presence of emulsifier mixture of Span 20 and Span 80. We present a comprehensive study of the effects of variation of all important reaction conditions (agitation rate, reaction time and temperature,... 

    Investigation of the combination of TiO2 nanoparticles and drag reducer polymer effects on the heat transfer and drag characteristics of nanofluids

    , Article Canadian Journal of Chemical Engineering ; Volume 96, Issue 6 , 2018 , Pages 1430-1440 ; 00084034 (ISSN) Paryani, S ; Ramazani Ahmad, S. A ; Sharif University of Technology
    Wiley-Liss Inc  2018
    To compensate for drag increment due to the addition of nanoparticles to heat-transfer fluids, it seems that one could add drag reducer polymeric agents to these fluids. So, in this work, experiments were carried out for solutions of two types of polyacrylamide (FLOPAAM 3330S and FLOPAAM 3630S) at three distinct concentrations (25, 40, and 55 ppm), and TiO2-water nanofluid at concentrations of 0.015, 0.02, 0.025, and 0.03 L/L. The steady state turbulent convective heat transfer and the friction factor of the suspension of TiO2 in a dilute solution of very high molecular weight, polyacrylamide (hybrid fluid), in a coiled tube were analyzed. Experimental measurements were carried out from a... 

    Layer-by-layer self assembly deposition and characterization of TiO 2 nanoparticles by using a short chain polycation

    , Article EPJ Applied Physics ; Volume 48, Issue 1 , 2009 , Pages 10602p1-10602p7 ; 12860042 (ISSN) Rahman, M ; Taghavinia, N ; Sharif University of Technology
    Using low molecular weight polyethylenimine (PEI), transparent thin films of TiO2 nanoparticles were prepared by layer-by-layer self assembly method. UV-visible spectrophotometry was employed in a quantitative manner to monitor the adsorbed mass of TiO2 and PEI after each dip cycle. The adsorption of both TiO2 and PEI showed a saturation dip time of 10 min. The effect of dip time on the growth mode and surface morphology was investigated by scanning electron microscopy (SEM) and non-contact atomic force microscopy (AFM). It was found that growth proceeds in the form of laterally broad islands in case of short dip times, and taller but laterally smaller islands in case of longer dip times. A... 

    The role of mixed reaction promoters in polyol synthesis of high aspect ratio ag nanowires for transparent conducting electrodes

    , Article Journal of Electronic Materials ; Volume 49, Issue 8 , 2020 , Pages 4822-4829 Amiri Zarandi, A ; Khosravi, A ; Dehghani, M ; Tajabadi, F ; Taghavinia, N ; Sharif University of Technology
    Springer  2020
    In recent years, thin silver nanowires (Ag NWs) with diameters smaller than 150 nm have been synthesized by implementation of NaCl or FeCl3 as reaction promoters and high molecular weight polyvinylpyrrolidone (PVP) as the capping agent. However, the yield of Ag NWs still remains low, mostly due to the insufficient aspect ratio (AR) of the synthesized nanostructures and the production of Ag nanoparticles, which is an undesirable by product. This study proposes a modified technique to alleviate the problem by using a mixture of FeCl3/CuCl2 as the reaction promoter and two different types of PVP with molecular weight of 360 k and 40 k as the capping agents. The appropriate mixtures of... 

    Improvement of polymer flooding using in-situ releasing of smart nano-scale coated polymer particles in porous media

    , Article Energy Exploration and Exploitation ; Volume 30, Issue 6 , 2012 , Pages 915-940 ; 01445987 (ISSN) Ashrafizadeh, M ; Ramazani, S. A. A ; Sadeghnejad, S ; Sharif University of Technology
    The main purpose of this paper is modeling and simulation of in-situ releasing of smart nano-sized core-shell particles at the water-oil interface during polymer flooding. During the polymer flooding process, when these nano-particles reach the water-oil interface, migrate to the oil phase and the hydrophobic layer of them dissolves in this phase. After dissolution of this protective nano-sized layer, the hydrophilic core containing a water-soluble ultra high molecular weight polymer diffuses back into the water phase and with dissolving in this phase, dramatically increases viscosity of flooding water in the neighborhood of the water-oil interface. In this study, two different... 

    Preparation of ultrahigh-molecular-weight polyethylene/carbon nanotube nanocomposites with a Ziegler-Natta catalytic system and investigation of their thermal and mechanical properties

    , Article Journal of Applied Polymer Science ; Volume 125, Issue SUPPL. 1 , 2012 , Pages E453-E461 ; 00218995 (ISSN) Amoli, B. M ; Ramazani, S. A. A ; Izadi, H ; Sharif University of Technology
    Wiley  2012
    In this research, ultrahigh-molecular-weight polyethylene (UHMWPE)/multiwalled carbon nanotube (MWCNT) nanocomposites with different nanotube concentrations (0.5, 1.5, 2.5, and 3.5 wt %) were prepared via in situ polymerization with a novel, bisupported Ziegler-Natta catalytic system. Magnesium ethoxide [Mg(OEt) 2] and surface-functionalized MWCNTs were used as the support of the catalyst. Titanium tetrachloride (TiCl 4) accompanied by triethylaluminum constituted the Ziegler-Natta catalytic system. Preparation of the catalyst and the polymerization were carried out in the slurry phase under an argon atmosphere. Support of the catalyst on the MWCNTs was investigated with Fourier transform... 

    Study of molecular conformation and activity-related properties of lipase immobilized onto core-shell structured polyacrylic acid-coated magnetic silica nanocomposite particles

    , Article Langmuir ; Volume 32, Issue 13 , 2016 , Pages 3242-3252 ; 07437463 (ISSN) Esmaeilnejad Ahranjani, P ; Kazemeini, M ; Singh, G ; Arpanaei, A ; Sharif University of Technology
    American Chemical Society 
    A facile approach for the preparation of core-shell structured poly(acrylic acid) (PAA)-coated Fe3O4 cluster@SiO2 nanocomposite particles as the support materials for the lipase immobilization is reported. Low- or high-molecular-weight (1800 and 100 000, respectively) PAA molecules were covalently attached onto the surface of amine-functionalized magnetic silica nanoacomposite particles. The successful preparation of particles were verified by scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA), zeta potential measurement, and Fourier-transform infrared (FTIR) techniques. Once lipase is covalently...