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    Adhesion modification of polyethylenes for metallization using radiation-induced grafting of vinyl monomers

    , Article Surface and Coatings Technology ; Volume 201, Issue 16-17 , 2007 , Pages 7519-7529 ; 02578972 (ISSN) Shojaei, A ; Fathi, R ; Sheikh, N ; Sharif University of Technology
    The present paper demonstrates the performance of the radiation grafting technique as a chemically based surface pretreatment method to adhesion modification of polyethylene surfaces toward the metallic layer. Gamma irradiation over a dose range of 4-10 kGy is used for grafting of vinyl monomers including acrylamide (AAm) and 1-vinyl-2-pyrrolidone (NVP) onto the surface of three different polyethylenes including low density polyethylene (LDPE) and two kinds of high density polyethylenes, namely HDPE-1 and HDPE-2. The grafting yield is evaluated based on the weight increase of the samples. It is found that the grafting yield is dominated by the crystallinity of the polyethylene, so that lower... 

    Preparation of highly rubber-toughened nylons

    , Article Iranian Polymer Journal (English Edition) ; Volume 16, Issue 7 , 2007 , Pages 459-468 ; 10261265 (ISSN) Bordbar, H ; Yousefi, A. A ; Ramezani saadatabadi, A ; Sharif University of Technology
    Nylon 6 and 66 were toughened with EPDM-g-MA and SEBS-g-MA and steadystate rheological behaviour of rubbers, nylons and their blends and mechanical properties of nylons and their rubber-toughened blends were investigated. The EPDM maleic grafting preparation was performed In the framework of this study where SEBS-g-MA was obtained from a commercial source. The results showed the ultratoughened SEBS-g-MA blends, whereas EPDM blends under the same blending conditions did not show a significant improvement in toughness. In case of EPDM toughened blends an average of some micrometers was observed for the dispersed EPDM particles. Impact and tensile properties of the toughened blend with 20% of... 

    Synthesis and properties of biodegradable hydrogels of κ-carrageenan grafted acrylic acid-co-2-acrylamido-2-methylpropanesulfonic acid as candidates for drug delivery systems

    , Article Reactive and Functional Polymers ; Volume 67, Issue 7 , 2007 , Pages 644-654 ; 13815148 (ISSN) Pourjavadi, A ; Barzegar, Sh ; Zeidabadi, F ; Sharif University of Technology
    Novel types of highly swelling hydrogels were prepared by grafting crosslinked polyacrylic acid-co-poly-2-acrylamido-2-methylpropanesulfonic acid (PAA-co-PAMPS) chains onto κ-carrageenan through a free radical polymerization method. Here, we propose a mechanism for κ-carrageenan-g-PAA-co-PAMPS formation and confirm the hydrogel structure using FTIR spectroscopy. The effect of grafting variables (i.e. concentration of methylenebisacrylamide (MBA), acrylic acid/-2-acrylamido-2-methylpropanesulfonic acid (AA/AMPS) weight ratio, ammonium persulfate (APS), κ-carrageenan, neutralization percent and reaction temperature) were systematically optimized to achieve a hydrogel with a maximum swelling... 

    Irradiation mediated synthesis of a superabsorbent hydrogel network based on polyacrylamide grafted onto salep

    , Article Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms ; Volume 266, Issue 18 , September , 2008 , Pages 3932-3938 ; 0168583X (ISSN) Rezanejade Bardajee, G ; Pourjavadi, A ; Soleyman, R ; Sheikh, N ; Sharif University of Technology
    The synthesis and swelling behavior of a new superabsorbent hydrogel based on natural salep grafted with polyacrylamide is described. The new biopolymer was synthesized via simultaneous crosslinking and graft copolymerization of acrylamide monomer onto a salep backbone using radiochemical methods. Various parameters such as relative contents of salep and acrylamide, as well as total dose of γ-rays were examined. The best synthesis condition is reported and a mechanism for superabsorbent hydrogel formation suggested. Factors affecting the swelling behavior of hydrogel were also studied. © 2008 Elsevier B.V. All rights reserved  

    Grafting of acrylamide onto kappa-carrageenan via γ-irradiation: Optimization and swelling behavior

    , Article Radiation Physics and Chemistry ; Volume 77, Issue 2 , 2008 , Pages 131-137 ; 0969806X (ISSN) Rezanejade Bardajee, G ; Pourjavadi, A ; Sheikh, N ; Sadegh Amini Fazl, M ; Sharif University of Technology
    The Taguchi method, a robust experimental design for optimization, was used for the synthesis of a superabsorbent hydrogel network using γ-rays as an initiator, energy source and crosslinker at the same time. Nine different samples of superabsorbent hydrogels were prepared in various conditions from kappa-carrageenan (κC) and acrylamide by γ-irradiation at room temperature. Considering the results of nine trials and according to analysis of variance (ANOVA), a new experimental condition with the concentrations of κC and acrylamide 1.5 g and 0.028 mol (2 g in total volume of 50 mL H2O), respectively, as well as γ-ray at the optimum total dose (7 kGy) was proposed. After preparing the desired... 

    Synthesis and absorbency of gelatin-graft-poly(sodium acrylate-co- acrylamide) superabsorbent hydrogel with saltand pH-responsiveness properties

    , Article E-Polymers ; 2006 , Pages 1-15 ; 16187229 (ISSN) Pourjavadi, A ; Sadeghi, M ; Mahmodi Hashemi, M ; Hosseinzadeh, H ; Sharif University of Technology
    European Polymer Federation  2006
    In this article, we synthesize a novel gelatin-based superabsorbent hydrogel via graft copolymerization of mixtures of acrylic acid (AA) and acrylamide (AAm) onto gelatin backbones. The polymerization reaction was carried out in an aqueous medium and in the presence of ammonium persulfate (APS) as an initiator and N,N-methylene bisacrylamide (MBA) as a crosslinker. The hydrogel structures were confirmed by FTIR spectroscopy. The effect of grafting variables, i.e. concentration of MBA and APS, AA/AAm weight ratio, and reaction time and temperature, was systematically optimized to achieve a hydrogel with swelling capacity as high as possible. The swelling behavior of these absorbent polymers... 

    Modified CMC: Part1-optimized synthesis of carboxymethyl cellulose-g-polyacrylonitrile

    , Article Iranian Polymer Journal (English Edition) ; Volume 14, Issue 2 , 2005 , Pages 131-138 ; 10261265 (ISSN) Zohuriaan Mehr, M. J ; Pourjavadi, A ; Sadeghi, M ; Sharif University of Technology
    As the first part of a continued research on conversion of carboxymethyl cellulose-sodium 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,... 

    Novel cationic-modified salep as an efficient flocculating agent for settling of cement slurries

    , Article Carbohydrate Polymers ; Volume 93, Issue 2 , April , 2013 , Pages 506-511 ; 01448617 (ISSN) Pourjavadi, A ; Fakoorpoor, S. M ; Hosseini, S. H ; Sharif University of Technology
    A new cationic flocculant was synthesized by graft copolymerization of acrylamide (AM) and 3-(methacryloylamino)propyl]trimethylammonium chloride (MAPTAC) onto salep using free radical polymerization initiated by ammonium persulfate (APS) to produce cationic salep [S-g-P(AM-co-MAPTAC)]. Reaction parameters (monomers/salep ratio, concentration of reactants, MAPTAC/AM ratio, and APS) were optimized using a full factorial experimental design to obtain the highest settling rate for cement suspensions. The best performing product was characterized by gel permeation chromatography (GPC), FTIR, 1H NMR spectroscopy, and thermogravimetric analysis (TGA). The resulted cationic flocculant may be... 

    Novel highly swelling nanoporous hydrogel based on polysaccharide/protein hybrid backbone

    , Article Journal of Polymer Research ; Volume 18, Issue 3 , 2011 , Pages 337-346 ; 10229760 (ISSN) Bardajee, G. R ; Pourjavadi, A ; Soleyman, R ; Sharif Unviersity of Technology
    Novel high capacity swelling nanoporous hydrogel (NPH) was synthesized via graft copolymerization of acrylamide (AAm) onto kappa-carrageenan (kC, as a polysaccharide) and gelatin (as a protein) hybrid backbone, after hydrolysis of this system. The Taguchi method as a strong experimental design tool was used for its optimized synthesis. The Taguchi method was applied for the experimental and standard 9 orthogonal array (OA) with four factors and three levels for each factor. A series of NPHs were synthesized by proposed conditions of Qualitek-4 Software. Considering the results of 9 trials according to analysis of variance (ANOVA), optimum conditions were proposed. The swelling behavior of... 

    Synthesis of new electromagnetic nanocomposite based on modified Fe3O4 nanoparticles with enhanced magnetic, conductive, and catalytic properties

    , Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Volume 65, Issue 8 , 2016 , Pages 384-390 ; 00914037 (ISSN) Pourjavadi, A ; Doroudian, M ; Afshar Saveh, Z ; Doulabi, M ; Sharif University of Technology
    Taylor and Francis Inc  2016
    A new method for the fabrication of an electromagnetic nanocomposite based on Fe3O4 and polyaniline (PANI) is offered. The authors focused on improvement of the physical and electromagnetic properties of the nanocomposite using a new synthetic method. Supermagnetic Fe3O4 nanoparticles were synthesized through coprecipitation method. As a chemical modification, the third generation of poly (amidoamine) dendrimer was grafted on the surface of the nanoparticles. PANI was grafted from -NH2 functional groups of dendrimer via in situ polymerization of aniline. Finally, Au nanoparticles were loaded on the nanocomposite and its catalytic activity for reduction reactions was studied  

    Synthesis and characterization of a new nanocomposite by filling of CNT with CoFe2O4 Magnetic nanoparticles and grafting to polymer

    , Article Nano ; Volume 4, Issue 6 , 2009 , Pages 371-376 ; 17932920 (ISSN) Sepahvand, R ; Adeli, M ; Actinchap, B ; Bahari, A ; Sharif University of Technology
    In this work, the synthesis and characterization of a new nanocomposite from carbon nanotubes-graft-polymer (CNTs-g-P) is reported. The products were obtained by the filling of multi-walled carbon nanotubes (MWCNTs) (inner diameter 2040 nm) with CoFe2O4 magnetic nanoparticles, been grafted with poly (caprolactone). The filling process was carried out by using acid treatment through wet chemistry. The structure and the properties of the new nanocomposite were studied with TEM, VSM, TGA, and spectroscopic techniques. © 2009 World Scientific Publishing Company  

    Ethylenediamine grafting to functionalized NH2-UiO-66 using green aza-Michael addition reaction to improve CO2/CH4 adsorption selectivity

    , Article Industrial and Engineering Chemistry Research ; Volume 57, Issue 20 , April , 2018 , Pages 7030-7039 ; 08885885 (ISSN) Molavi, H ; Ahmadi Joukani, F ; Shojaei, A ; Sharif University of Technology
    American Chemical Society  2018
    Three versions of zirconium-based metal organic frameworks, NH2-UiO-66, GMA-UiO-66, and EDA-UiO-66, were synthesized and employed as adsorbent for CO2/CH4 separation. GMA-UiO-66 was synthesized via a ring opening reaction between the amine species in the framework and epoxy groups in glycidyl methacrylate (GMA), while the green aza-Michael addition reaction was used for the first time to functionalize GMA-UiO-66 with ethylenediamine (EDA). The products were characterized by BET, XRD, TGA, FESEM, ICP-OES, 1H NMR, mass spectroscopy, and FTIR-ATR methods to monitor their textural properties before and after functionalization. The results indicated that GMA was successfully grafted to the... 

    Solute dispersion by electroosmotic flow through soft microchannels

    , Article Sensors and Actuators, B: Chemical ; Volume 255, Part 3 , February , 2018 , Pages 3585-3600 ; 09254005 (ISSN) Hoshyargar, V ; Khorami, A ; Ashrafizadeh, S. N ; Sadeghi, A ; Sharif University of Technology
    Elsevier B.V  2018
    We study the hydrodynamic dispersion (HD) by electroosmotic flow in soft microchannels. Considering a fully developed flow in a slit microchannel of low surface potential and adopting the Taylor dispersion theory, we derive analytical solutions for the solute concentration field and the effective dispersion coefficient. We also conduct numerical analyses to broaden the paper's scope to high surface potentials and to specify a criterion for the validity of the Debye-Hückel linearization in soft microconduits as well as to investigate the broadening of an analyte band from the time of injection. It is demonstrated that the effective dispersion coefficient of a neutral solute band is generally... 

    Polyacrylamide-grafted magnetic reduced graphene oxide nanocomposite: preparation and adsorption properties

    , Article Colloid and Polymer Science ; 2019 ; 0303402X (ISSN) Pourjavadi, A ; Nazari, M ; Kohestanian, M ; Hosseini, S. H ; Sharif University of Technology
    Springer Verlag  2019
    Magnetic reduced graphene oxide/polymer nanocomposites were prepared by in situ polymerization and grafting of polyacrylamide on the surface of functionalized magnetic reduced graphene oxide (rGO). Graphene oxide nanosheets were decorated with Fe3O4 nanoparticles, reduced and functionalized with 3-(trimethoxysilyl)propyl methacrylate, and then grafted with polyacrylamide. Grafting of polyacrylamide makes magnetic rGO hydrophilic and highly water dispersible. The prepared material was used as adsorbent for removal of an anionic dye, Congo red, and a maximum adsorption capacity up to 166.7 mg g−1 was obtained. The kinetics and isotherm of adsorption and the effect of experimental condition on... 

    Amino-silane-grafted NH2-MIL-53(Al)/polyethersulfone mixed matrix membranes for CO2/CH4 separation

    , Article Dalton Transactions ; Volume 48, Issue 36 , 2019 , Pages 13555-13566 ; 14779226 (ISSN) Ahmadijokani, F ; Ahmadipouya, S ; Molavi, H ; Arjmand, M ; Sharif University of Technology
    Royal Society of Chemistry  2019
    Mixed-matrix membranes (MMMs) are promising candidates for carbon dioxide separation. However, their application is limited due to improper dispersion of fillers within the polymer matrix, poor interaction of fillers with polymer chains, and formation of defects and micro-voids at the interface of both phases, which all result in the decline of the gas separation performance of MMMs. In this work, we present a new method to overcome these challenges. To this end, a series of MMMs based on polyethersulfone (PES) as the continuous polymer matrix and MIL-53-derived MOFs as the dispersed filler were prepared. FTIR-ATR, XRD, TGA, FESEM, and N2 adsorption/desorption analyses were employed to... 

    Synthesis and investigation of swelling behavior of grafted alginate/alumina superabsorbent composite

    , Article Starch/Staerke ; Volume 60, Issue 9 , 9 September , 2008 , Pages 457-466 ; 00389056 (ISSN) Pourjavadi, A ; Farhadpour, B ; Seidi, F ; Sharif University of Technology
    In this study a novel alginate-g-poly(acrylic acid)/alumina composite was synthesized and characterized. Preparation of the composite hydrogels involved free radical polymerization of a combination of alginate, acrylic acid (AA) and distilled water, in appropriate amounts and N,N-methylene bisacrylamide (MBA) as crosslinking agent. The composite formation was confirmed by Fourier transform infrared spectroscopic (FTIR). The surface morphologies of the synthesized hydrogels were assessed by scanning electron microscopy. Systematically, the different variables of the graft copolymerization were optimized to achieve maximum swelling capacity. The swelling of superabsorbent hydrogels was... 

    Novel nanoporous superabsorbent hydrogel based on poly(acrylic acid) grafted onto salep: Synthesis and swelling behavior

    , Article Starch/Staerke ; Volume 60, Issue 9 , 9 September , 2008 , Pages 467-475 ; 00389056 (ISSN) Pourjavadi, A ; Soleyman, R ; Rezanejade Barajee, G ; Sharif University of Technology
    Hydrogels of poly(acrylic acid) grafted onto salep with excellent water absorption and water retention abilities under neutral conditions were successfully synthesized for the first time and employed for different applications. The effect of reaction variables to achieve maximum swelling capacity was investigated. In our procedure, ammonium persulfate (APS) as a water-soluble initiator and methylenebisacrylamide (MBA) as a suitable crosslinking agent were used and the best synthesis conditions described. The structure of the final product was confirmed by Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy SEM and TGA analysis and a mechanism for superabsorbent... 

    Tuning electrokinetic flow, ionic conductance, and selectivity in a solid-state nanopore modified with a pH-responsive polyelectrolyte brush: A molecular theory approach

    , Article Journal of Physical Chemistry C ; Volume 124, Issue 34 , 2020 , Pages 18513-18531 Sadeghi, M ; Saidi, M. H ; Moosavi, A ; Kröger, M ; Sharif University of Technology
    American Chemical Society  2020
    We use an efficient molecular theory approach to study electrokinetic flow within a pH-responsive nanopore grafted with a polyelectrolyte (PE) brush. The flow rate, migration and convective conductance, electric potential and velocity fields, species distributions and the degree of ionization of the weak PE functional groups and nanopore selectivity are obtained and interpreted while considering pH-induced surface charges. The theory is generally based on writing the overall free energy of the system including the entropies arising from the conformations of flexible, excluded volume chains, the mixing of mobile species, electrostatic contribution, and the free energy due to the chemical... 

    Hydrolyzed collagen-based hydrogel with salt and pH-responsiveness properties

    , Article Journal of Applied Polymer Science ; Volume 106, Issue 4 , 2007 , Pages 2371-2379 ; 00218995 (ISSN) Pourjavadi, A ; Salimi, H ; Kurdtabar, M ; Sharif University of Technology
    A novel hydrolyzed collagen-based hydrogel has been prepared by grafting the binary mixture of acrylamide and 2-acrylamido-2-methylpropanesulfonic acid onto the collagen backbone in the presence of a cross-linking agent. Its physicochemical properties in aqueous solution were studied. The effect of reaction variables on both gel content and swelling capacity was investigated to achieve a hydrogel with improved absorbency and gel content. The absorbency under load of optimized hydrogel was also investigated by using an absorbency under load tester at various applied pressures. The swelling ratio in various salt solutions was also determined and additionally, the swelling of hydrogels was... 

    Modification of isotactic polypropylene by the free-radical grafting of 1,1,1-trimethylolpropane trimethacrylate

    , Article Journal of Applied Polymer Science ; Volume 104, Issue 2 , 2007 , Pages 950-958 ; 00218995 (ISSN) Mousavi Saghandikolaei, S. A ; Frounchi, M ; Dadbin, S ; Augier, S ; Passaglia, E ; Ciardelli, F ; Sharif University of Technology
    The chemical modification of isotactic polypropylene was performed by the free-radical-promoted grafting of 1,1,1-trimethylolpropane trimethacrylate (TMPTMA) in the presence of dicumyl peroxide (DCP) as the initiator. The reaction was carried out both in a batch internal mixer and in a corotating twin-screw extruder; the effects of the peroxide and monomer concentrations on the extent of modification in terms of the grafting efficiency and polymer chain structure variations were investigated. The modified samples were characterized with Fourier transform infrared to determine the structure of the grafted groups and the degree of functionalization, with gel permeation chromatography and the...