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    Microwave-induced Cannizzaro reaction over neutral γ-alumina as a polymeric catalyst [electronic resource]

    , Article Reactive and Functional Polymers ; 01/2002; 51(1):49-53 Pourjavadi, A. (Ali) ; Soleimanzadeh, B ; Marandi, G. B
    Abstract
    γ-Alumina is used to catalyze the Cannizzaro reaction in the absence of any base under microwave irradiation in high yields. In the case of terephthalaldehyde the reaction is carried out with high selectivity  

    Modified Chitosan. 2. H-chitoPAN, a novel pH-responsive superabsorbent hydrogel [electronic resource]

    , Article Journal of Applied Polymer Science ; Volume 90, Issue 11, pages 3115–3121, 9 December 2003 Pourjavadi, A. (Ali) ; Mahdavinia, G. R ; Zohuriaan-Mehr, M. J
    Abstract
    Chitosan was modified with polyacrylonitrile (PAN) through ceric-initiated graft copolymerization. The chitosan-g-PAN product was saponified using sodium hydroxide aqueous solution to prepare a novel superabsorbent hydrogel, H-chitoPAN. Duration of completing the saponification reaction as well as the water absorbency capacity of the hydrogel was decreased with increasing the alkaline concentration. Either chitosan-g-PAN or H-chitoPAN was characterized by FTIR spectroscopy and DSC, TGA, and DTG thermal methods. According to FTIR, all the nitrile groups were converted to carboxylate and carboxamide groups. Both modified chitosans exhibited enhanced thermal stability over chitosan. The... 

    Modified CMC.2. Novel carboxymethylcellulose-based poly (amidoxime) chelating resin with high metal sorbtion capacities [electronic resource]

    , Article Reactive and Functional Polymers ; Volume 61, Issue 1, August 2004, Pages 23–31 Zohurian Mehr, M. J. (Mohammad Jalal) ; Pourjavadi, A ; Sadeghi, M ; Sharif University of Technology
    Abstract
    Carboxymethylcellulose sodium salt (CMC) was doubly modified to prepare a novel poly(acrylamidoxime) chelating resin. Acrylonitrile was firstly graft polymerized onto CMC using cerium ammonium nitrate as an initiator. The polyacrylonitrile (PAN) grafted CMC was then amidoximized via treatment with hydroxylamine to prepare the ion exchange resin. The sorption capacity of the resin towards bivalent metal ions was evaluated while varying the pH, the loading of the PAN and the initial metal ion concentration. The adsorption kinetics were investigated for the cupric ion. The chelating resin exhibited very high metal sorption capacity in comparison with either synthetic or polysaccharide-based... 

    Modified CMC: part 1- optimized synthesis of carboxymethylcellulose-g-polyacrylonitrile [electronic resource]

    , Article Iranian Polymer Journal ; Vol. 14, No 2, 131-138, 2005 Zohurian Mehr, M. J. (Mohammad Jalal) ; Pourjavadi, A ; Sadeghi, M
    Abstract
    As the first part of a continued research on conversion of carboxymethyl cellulosesodium salt (CMC) to useful biopolymer-based materials, large numbers of cyanide functional groups were introduced onto CMC by grafting with polyacrylonitrile (PAN). The graft copolymerization reactions were carried out under nitrogen atmosphere using ceric ammonium nitrate (CAN) as an initiator. Evidence of grafting was obtained by comparing FTIR spectra of CMC and the graft copolymer as well as solubility characteristics of the products. The synthetic conditions were systematically optimized through studying the effective factors including temperature and concentrations of initiator, acrylonitrile monomer,... 

    Modified carrageenan. 1. H-carragPAM, a novel biopolymer-based superabsorbent hydrogel [electronic resource]

    , Article Journal of Bioactive and Compatible Polymers ; September 2005 Vol. 20 no. 5 475-490 Hosseinzadeh, H. (Hossein) ; Pourjavadi, A ; Mahdavinia, G. R ; Zohuriaan-Mehr, , M. J
    Abstract
    A novel kappa-carrageenan (C)-based superabsorbing hydrogel was synthesized through graft copolymerization of acrylamide (AAm) onto a C substrate in the presence of a crosslinking agent. The crosslinked C-poly(AAm) polymer graft was partially hydrolyzed in alkaline medium to yield a superabsorbent resin, H-carragPAM. The resin structure was confirmed using FTIR spectroscopy. The variables of graft copolymerization (monomer, initiator, polysaccharide and crosslinker concentration, reaction temperature and time as well as stirrer speed) that affected on the ultimate water-swelling capacity were optimized. The time-temperature variation of the copolymerization was investigated in terms of the... 

    Design, modeling and optimization of a novel two DOF polymeric electro-thermal micro-actuator

    , Article Applied Mechanics and Materials ; Vol. 307 , 2013 , pp. 112-116 ; ISSN: 16609336 ; ISBN: 9783037856598 Sheikhbahaie, R ; Alasty, A ; Salarieh, H ; Sharif University of Technology
    Abstract
    In this paper, design, simulation and optimization of a novel electrothermally-activated polymeric microactuator capable of generating combination of bidirectional lateral and rotational motions are presented. The composite structure of this actuator is consisted of a symmetric meandered shape silicon skeleton, a SU8 thermal expandable polymer and a thin film chrome layer heater. This actuator is controlled by applying appropriate voltages on its four terminals. With the purpose of dimension optimization, a numerical parametric study is executed. The modeled actuator which is 1560 ?m long, 156 ?m wide and 30 ?m thick, demonstrates a remarkable lateral displacement of 23 ?m at power... 

    Optimization of operating conditions in ultrafiltration process for produced water treatment via Taguchi methodology

    , Article Desalination and Water Treatment ; Volume 54, Issue 10 , June , 2015 ; ISSN: 19443994 Reyhani, A ; Sepehrinia, K ; Seyed Shahabadi, S. M ; Rekabdar, F ; Gheshlaghi, A ; Sharif University of Technology
    Abstract
    This paper describes how to find optimal operating conditions of three controlling parameters, i.e. temperature, transmembrane pressure (TMP), and cross-flow velocity (CFV) for maximizing the permeate flux and total organic carbons (TOC) rejection, and minimizing the fouling resistance using Taguchi method in ultrafiltration (UF) treatment of the real produced water. At first, the optimal operating conditions were found at a temperature of 45°C, TMP = 4 bar, and CFV of 2.25 m/s. To determine the most significant parameters affecting the response parameters, an analysis of variance was employed. In the second stage, performance of applied polymeric membrane in the UF system was studied under... 

    Property investigation of polypropylene/multiwall carbon nanotube nanocomposites prepared via in situ polymerization

    , Article Polymer International ; Vol. 63, issue. 4 , April , 2014 , pp. 689-694 ; ISSN: 09598103 Jafariesfad, N ; Ramazani, S. A ; Azinfar, B ; Sharif University of Technology
    Abstract
    In this study, polypropylene/carbon nanotube nanocomposites were prepared via in situ polymerization using a bi-supported Ziegler-Natta catalytic system. In this system, magnesium ethoxide and multiwall carbon nanotubes (MWCNTs) are jointly used as catalyst supports. SEM images reveal the distribution and quite good dispersion of MWCNTs throughout the polypropylene (PP) matrix. The thermal properties of the samples were examined using DSC and TGA tests. The results show that the crystallization temperature of the nanocomposites significantly increases while the melting point is not markedly affected. In addition, the thermal stability is improved. The melt rheological properties of PP/MWCNT... 

    Preparation of conductive polyaniline/graphene nanocomposites via in situ emulsion polymerization and product characterization

    , Article Synthetic Metals ; Vol. 196 , 2014 , pp. 199-205 Baniasadi, H ; Ramazani, S. A ; Mashayekhan, S ; Ghaderinezhad, F ; Sharif University of Technology
    Abstract
    This work, which is a part of our ongoing studies on developing conductive scaffolds for nerve tissue engineering, reports synthesis of highly conductive binary-doped polyaniline nanoparticles and polyaniline/graphene nanocomposites. The samples were synthesized through chemical oxidation of aniline via in situ emulsion polymerization method in presence of hydrochloric acid and sodium dodecyl sulfate. Graphene nanosheets were also prepared via modified Hummer's method followed by chemical reduction using hydrazine monohydrate. Electrical conductivity measurements using a standard four-point probe technique with FTIR and UV-vis studies revealed that conductive binary-doped emeraldine salt... 

    Optimization of uhmwpe/graphene nanocomposite processing using ziegler-natta catalytic system viaresponse surface methodology

    , Article Polymer - Plastics Technology and Engineering ; Vol. 53, Issue. 9 , June , 2014 , pp. 969-974 ; ISSN: 03602559 Shafiee, M ; Ramazani, S. A. A ; Sharif University of Technology
    Abstract
    Optimization of operational conditions for the preparation of Ultrahigh-molecular-weight polyethylene (UHMWPE)/Graphene nanocomposites with Ziegler-Natta catalyst was carried out via response surface methodology (RSM). This study deals with the optimization of process variables to optimize the productivity and molecular weight. A three-factor, three-level Box-Behnken design with temperature (X1), monomer pressure (X2), and [Al]/[Ti] molar ratio (X3) as the independent variables were selected for the study. The dependent variables were productivity and molecular weights of the final nanocomposites. It was developed by using the three parameters at three levels including 50, 60, and 70°C for... 

    In situ preparation and property investigation of polypropylene/fumed silica nanocomposites

    , Article Polymer Composites ; Vol. 35, issue. 1 , January , 2014 , pp. 37-44 ; ISSN: 02728397 Azinfar, B ; Ahmad Ramazani, S. A ; Jafariesfad, N ; Sharif University of Technology
    Abstract
    We present the preparation of polypropylene (PP)/fumed silica (FS) nanocomposites via in situ polymerization in this article. The approach includes preparation and utilization of a bisupported Ziegler-Natta catalytic system in which magnesium ethoxide and FS are used as conjugate supports of the catalyst. Catalyst preparation and polymerization processes are carried out in the slurry phase and under argon atmosphere. Scanning electron microscopy images show a good dispersion of the FS throughout the PP matrix. Results from differential scanning calorimetry reveal that the crystallization temperature of prepared nanocomposites increases by increasing FS loading. Also, crystal content of... 

    In-situ electro-polymerization of graphene nanoribbon/polyaniline composite film: Application to sensitive electrochemical detection of dobutamine

    , Article Sensors and Actuators, B: Chemical ; Vol. 196 , June , 2014 , pp. 582-588 ; ISSN: 09254005 Asadian, E ; Shahrokhian, S ; Zad, A. I ; Jokar, E ; Sharif University of Technology
    Abstract
    The present paper demonstrates the capability of narrow graphene nanoribbons (GNRs) in constructing new sensing platforms. Graphene nanoribbons have been synthesized via a simple solvothermal route through unzipping of carbon nanotubes, which was confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy analysis. These narrow carbon sheets were used to form a composite film by in-situ electro-polymerization with aniline. The produced graphene nanoribbon/polyaniline (GNR/PANI) composite film showed impressive performance in electrochemical determination of dobutamine (DBT). Under optimal conditions, in comparison to... 

    Silver nanoparticles-polyaniline nanocomposite for microextraction in packed syringe

    , Article Chromatographia ; Vol. 77, issue. 5-6 , 2014 , pp. 397-403 ; ISSN: 00095893 Bagheri, H ; Banihashemi, S ; Sharif University of Technology
    Abstract
    A rapid, convenient and reliable method for microextraction in packed syringe (MEPS) of the loop diuretic furosemide (FUR) in urine along with high-performance liquid chromatography (HPLC) was developed. A nanocomposite based on silver nanoparticles/polyaniline (Ag-NPs/PANI) was synthesized and used as the MEPS packing material. This nanocomposite was prepared conveniently using interfacial polymerization without the need for any templates or functional dopants. The feasibility of the synthesized nanocomposites was examined by isolation of FUR from diluted urine samples. After extraction, the analyte was desorbed by 200 μL of methanol. It was then dried and the residue was dissolved in 30 μL... 

    Functionalized poly(amidoamine) dendrimer as a strong ionic Brønsted acid organocatalyst for protection/deprotection of aldehydes

    , Article Phosphorus, Sulfur and Silicon and the Related Elements ; Vol. 189, issue. 12 , 2014 , pp. 1794-1801 ; ISSN: 10426507 Pourjavadi, A ; Hosseini, S. H ; Sharif University of Technology
    Abstract
    Poly(amidoamine) dendrimer (PAMAM) was successfully functionalized by chlorosulfonic acid to form an strong ionic acid catalyst. The resulting polymeric catalyst was shown to be an efficient catalyst for the synthesis of 1,1-diacetyl from aldehydes under free solvent conditions at room temperature. Also, the deprotection of the resulting aldehydes was investigated under catalytic conditions. The Hammett acidity function of catalyst showed that catalyst is a strong Brønsted acid. Due to the multi-functional nature of PAMAM, the catalyst has high loading level of acidic protons  

    Preparation and characterization of UHMWPE/graphene nanocomposites using bi-supported ziegler-natta polymerization

    , Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Vol. 63, issue. 16 , 2014 , p. 815-819 Shafiee, M ; Ramazani, S. A ; Sharif University of Technology
    Abstract
    Ultrahigh-molecular-weight polyethylene (UHMWPE)/graphene nanocomposites with molecular weights as high as 3 × 106 g/mol were prepared via in situ polymerization using a bi-supported Ziegler-Natta catalytic system. Effects of [Al]/[Ti] molar ratio, temperature, monomer pressure, and polymerization time on productivity of the catalyst have been investigated. Increasing [Al]/[Ti] molar ratio from 128 to 320, increased productivity from 1667 g PE/mmol Ti.h to maximum value which was 2420 g PE/mmol Ti.h. Further [Al]/[Ti] ratio decreased the productivity. Reaction temperature effect investigation reveals that the optimal activity was obtained at 60°C. the polymerization productivity increases... 

    Towards greater mechanical, thermal and chemical stability in solid-phase microextraction

    , Article TrAC - Trends in Analytical Chemistry ; Volume 34 , 2012 , Pages 126-138 ; 01659936 (ISSN) Bagheri, H ; Piri-Moghadam, H ; Naderi, M ; Sharif University of Technology
    Abstract
    Solid-phase microextraction (SPME) is a fast, solvent-free technique, which, since its introduction in the 1990s, has been increasingly applied to sample preparation in analytical chemistry. Conventional SPME fibers are fabricated by making a physical bond between the usual silica substrate and the polymeric coatings. However, some applications are limited, as the lifetime and the stability of conventional SPME fibers cannot meet the demands of analyzing relatively non-volatile compounds with more polar moieties. There have been attempts to analyze less volatile compounds by increasing the thermal, physical and chemical stability of the fibers. In this review, we present some new... 

    Novel nano-porous hydrogel as a carrier matrix for oral delivery of tetracycline hydrochloride

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 392, Issue 1 , December , 2011 , Pages 16-24 ; 09277757 (ISSN) Bardajee, G. R ; Pourjavadi, A ; Soleyman, R ; Sharif University of Technology
    Abstract
    A novel nano-porous hydrogel (NPH) was synthesized via graft copolymerization of sodium acrylate (Na-AA) and acrylamide (AAm) onto salep backbones and its application as a carrier matrix for oral delivery of tetracycline hydrochloride (TH) was investigated. The Taguchi method as a strong experimental design tool was used for synthesis optimization. The swelling behavior of optimum hydrogel was measured in various media. The hydrogel formation was confirmed by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetrical analysis (TGA). The study of the surface morphology of the hydrogels using SEM and AFM showed a nanoporous (average pore size: 180. nm) structure for the sample... 

    A simple granulation technique for preparing high-porosity nano copper oxide(II) catalyst beads

    , Article Particuology ; Volume 9, Issue 5 , 2011 , Pages 480-485 ; 16742001 (ISSN) Ahmadi, S. J ; Outokesh, M ; Hosseinpour, M ; Mousavand, T ; Sharif University of Technology
    Abstract
    A simple and efficient method was developed for fabricating spherical granules of CuO catalyst via a three-step procedure. In the first step, copper oxide nanoparticles were synthesized by hydrothermal decomposition of copper nitrate solution under supercritical condition. Then, they were immobilized in the polymeric matrix of calcium alginate, and followed by high-temperature calcination in an air stream as the third step, in which carbonaceous materials were oxidized, to result in a pebble-type catalyst of high porosity. The produced CuO nanoparticles were characterized by transmission electron microscopy (TEM) that revealed an average size of 5 nm, X-ray diffractometry (XRD), and thermo... 

    Electrocatalytic Oxidation of 1-Propanol and 2-Propanol on Electro-active Films Derived from Ni II-(N,N′-bis(2-Hydroxy, 3-Methoxy Benzaldehyde)-1,2-Propandiimine) Modified Glassy Carbon Electrode

    , Article Electrocatalysis ; Volume 2, Issue 3 , Volume 2, Issue 3 , 2011 , Pages 163-171 ; 18682529 (ISSN) Jafarian, M ; Rashvand avei, M ; Gobal, F ; Rayati, S ; Mahjani, M. G ; Sharif University of Technology
    Abstract
    Complexes of Ni II-(N,N′-bis(2-hydroxy, 3-methoxy benzaldehyde)-1,2-propandiimine) can be electro-polymerized onto GC electrode in an alkaline solution to give an electro-active film strongly adhered on the electrode surface. In alkaline solution, this poly-(Ni II{sal-1,2-pn(3-OMe) 2})/GC film shows the typical voltammetric response of a surface-immobilized redox couple, as can be anticipated for the Ni 2+/Ni 3+ transitions into the film. In addition, the film exhibits a potent and persistent electro-catalytic activity towards the oxidation of 1- and 2-propanol. In CV studies, in the presence of these alcohols, poly-(Ni II{sal-1,2-pn(3-OMe) 2})/GC electrode shows a new oxidation peak for the... 

    Correlations for prediction of specific surface area and bulk and apparent densities of porous styrene-divinylbenzene copolymers

    , Article Journal of Applied Polymer Science ; Volume 120, Issue 4 , 2011 , Pages 1942-1949 ; 00218995 (ISSN) Nodehi, A ; Hajiebrahimi, M ; Parvazinia, M ; Shahrokhi, M ; Abedini, H ; Sharif University of Technology
    Abstract
    Macroporous styrene-divinylbenzene copolymers with different degree of crosslinking were prepared by suspension polymerization in presence of different binary mixtures of toluene and heptane, as diluent. Specific surface area, bulk and apparent densities, and pore volume of the resulting beads were determined experimentally. Applying the least square method to the experimental data, correlations for prediction of these properties were obtained. Effects of divinylbenzene concentration, diluent to comonomer volume ratio, and composition of the diluent mixture were considered in developing the aforementioned correlations. The influence of the reaction recipe on porous structure of the samples...