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    Synthesis of polypropylene/clay nanocomposites using bisupported Ziegler-Natta catalyst

    , Article Journal of Applied Polymer Science ; Volume 115, Issue 1 , 2010 , Pages 308-314 ; 00218995 (ISSN) Ramazani, S. A. A ; Tavakolzadeh, F ; Baniasadi, H ; Sharif University of Technology
    In this article, preparation of polypropylene/clay nanocomposites (PPCNC) via in situ polymerization is investigated. MgCl2/montmorillonite bisupported Ziegler-Natta catalyst was used to prepare PPCNC samples. Montmorillonite (MMT) was used as an inert support and reinforcement agent. The nanostructure of the composites was characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy techniques. Obtained results showed that silica layers of the MMT in these PPCNC were intercalated, partially exfoliated, and uniformly dispersed in the polypropylene matrix. Thermogravimetric analysis showed good thermal stability for the prepared PPCNC. Differential... 

    Fabrication of porous gelatin-chitosan microcarriers and modeling of process parameters via the RSM method

    , Article International Journal of Biological Macromolecules ; Volume 88 , 2016 , Pages 288-295 ; 01418130 (ISSN) Karimian, S. A. M ; Mashayekhan, S ; Baniasadi, H ; Sharif University of Technology
    Elsevier B.V 
    Porous gelatin-chitosan microcarriers (MCs) with the size of 350 ± 50 μm were fabricated with blends of different gelatin/chitosan (G/C) weight ratio using an electrospraying technique. Response surface methodology (RSM) was used to study the quantitative influence of process parameters, including blend ratio, voltage, and syringe pump flow rate, on MCs diameter and density. In the following, MCs of the same diameter and different G/C weight ratio (1, 2, and 3) were fabricated and their porosity and biocompatibility were investigated via SEM images and MTT assay, respectively. The results showed that mesenchymal stem cells (MSCs) could attach, proliferate, and spread on fabricated porous MCs... 

    In situ polymerization of polyethylene/clay nanocomposites using a novel clay-supported ziegler-natta catalyst

    , Article Polymer Composites ; Volume 30, Issue 10 , 2009 , Pages 1388-1393 ; 02728397 (ISSN) Ramazani Saadatabadi, A ; Tavakolzadeh, F ; Baniasadi, H ; Sharif University of Technology
    Polyethylene/clay nanocomposites (PECNC) were synthesized via in situ Ziegler-Natta catalyst polymerization. Activated catalyst for polymerization of ethylene monomer has been prepared at first by supporting of the cocatalyst on the montmorillonite (MMT) smectite type clay and then active complex for polymerization formed by reaction of TiCl4 and aluminum oxide compound on the clay. Acid wash treatment has been used for increasing hydroxyl group and porosity of the clay and subsequently activity of the catalyst. The nano- structure of composites was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Obtained results show that silica layers of the mineral clay... 

    Preparation and Properties of Ethylene-vinyl Acetate/linear Low-density Polyethylene/Graphene Oxide Nanocomposite Films

    , Article Polymer - Plastics Technology and Engineering ; Volume 54, Issue 11 , 2015 , Pages 1152-1158 ; 03602559 (ISSN) Bahmanyar, M ; Ramazani, S. A ; Baniasadi, H ; Sharif University of Technology
    Taylor and Francis Inc  2015
    Ethylene-vinyl acetate-based nanocomposites with 18 and 28 wt% vinyl acetate were prepared via solution casting method. To improve the mechanical and barrier properties of ethylene-vinyl acetate, linear low-density polyethylene, and graphene oxide were introduced to matrix. The morphological studies indicated that the graphene oxide diffraction peak disappeared in all prepared nanocomposites, probably due to its exfoliation; also proper dispersion and good interaction between nanofillers and polymer matrix were achieved. By introducing low amount of graphene oxide into the matrix, the mechanical and thermal properties and oxygen permeability were improved especially for those with 28 wt%... 

    Investigation of Thermomechanical Properties of UHMWPE/Graphene Oxide Nanocomposites Prepared by in situ Ziegler-Natta Polymerization

    , Article Advances in Polymer Technology ; Volume 34, Issue 4 , February , 2015 ; 07306679 (ISSN) Bahrami, H ; Ramazani, A.S.A ; Kheradmand, A ; Shafiee, M ; Baniasadi, H ; Sharif University of Technology
    John Wiley and Sons Inc  2015
    The graphene-based Ziegler-Natta catalyst has been used to prepare ultrahigh molecular weight polyethylene/graphene oxide (UHMWPE/GO) nanocomposite via in situ polymerization. The morphological investigations have been conducted using X-ray diffraction patterns and scanning electron microscopy method. The obtained results indicated that no diffraction peak is detected in a GO pattern, which could be due to the exfoliation of graphene nanosheets in the UHMWPE matrix. Morphological investigations indicated that GO nanosheets are dispersed almost uniformly in polymeric matrix, and that there should exist a good interaction between nanofillers and matrix. The mechanical properties of the... 

    Preparation of ethylene vinyl acetate copolymer/graphene oxide nanocomposite films via solution casting method and determination of the mechanical properties

    , Article Polymer - Plastics Technology and Engineering ; Volume 54, Issue 2 , Jan , 2015 , Pages 218-222 ; 03602559 (ISSN) Bahmanyar, M ; Sedaghat, S ; Ramazani S. A, A ; Baniasadi, H ; Sharif University of Technology
    Taylor and Francis Inc  2015
    Ethylene vinyl acetate/graphene oxide (EVA/GO) nanocomposite films were prepared via solution casting method. The morphological studies investigated using SEM and XRD methods and the results confirmed the formation of likely exfoliation structures and good interaction between matrix and fillers. The results of permeability measurements showed that films have good resistance against oxygen. Mechanical measurements revealed that Young’s modulus and tensile strength of EVA have improved with introducing GO because of proper dispersion of GO into matrix and good interaction between them; however, elongation at break decreased due to formation of strong and rigid polymer/filler network preventing... 

    Design and fabrication of conductive nanofibrous scaffolds for neural tissue engineering: Process modeling via response surface methodology

    , Article Journal of biomaterials applications ; Volume 33, Issue 5 , 2018 , Pages 619-629 ; 15308022 (ISSN) Soleimani, M ; Mashayekhan, S ; Baniasadi, H ; Ramazani, A ; Ansarizadeh, M ; Sharif University of Technology
    NLM (Medline)  2018
    Peripheral nervous system in contrary to central one has the potential for regeneration, but its regrowth requires proper environmental conditions and supporting growth factors. The aim of this study is to design and fabricate a conductive polyaniline/graphene nanoparticles incorporated gelatin nanofibrous scaffolds suitable for peripheral nervous system regeneration. The scaffolds were fabricated with electrospinning and the fabrication process was designed with Design-Expert software via response surface methodology. The effect of process parameters including applied voltage (kV), syringe pump flow rate (cm3/h), and PAG concentration (wt%), on the scaffold conductivity, nanofibers diameter,... 

    Investigation of properties of polyethylene/clay nanocomposites prepared by new in situ ziegler-natta catalyst

    , Article Materials and Design ; Volume 30, Issue 7 , 2009 , Pages 2309-2315 ; 02641275 (ISSN) Nikkhah, S. J ; Ramazani Saadat Abadi, A ; Baniasadi, H ; Tavakolzadeh, F ; Sharif University of Technology
    This paper is devoted to investigation of morphological and physical-mechanical properties of polyethylene (PE)/clay nanocomposites prepared via in situ polymerization method using bi-supported Ziegler-Natta catalyst. Bentonite type clay and MgCl2 (ethoxide type) were used as the support of TiCl4. Catalyst support and polymerization process have been done in slurry phase using Triisobutylaluminum as the co-catalyst. The microstructure of the nanocomposites was examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD and TEM indicated that almost fully exfoliated PE/clay nanocomposites were produced successfully using this method. According to permeability... 

    Alginate/cartilage extracellular matrix-based injectable interpenetrating polymer network hydrogel for cartilage tissue engineering

    , Article Journal of Biomaterials Applications ; Volume 36, Issue 5 , 2021 , Pages 803-817 ; 08853282 (ISSN) Shojarazavi, N ; Mashayekhan, S ; Pazooki, H ; Mohsenifard, S ; Baniasadi, H ; Sharif University of Technology
    SAGE Publications Ltd  2021
    In the present study, alginate/cartilage extracellular matrix (ECM)-based injectable hydrogel was developed incorporated with silk fibroin nanofibers (SFN) for cartilage tissue engineering. The in situ forming hydrogels were composed of different ionic crosslinked alginate concentrations with 1% w/v enzymatically crosslinked phenolized cartilage ECM, resulting in an interpenetrating polymer network (IPN). The response surface methodology (RSM) approach was applied to optimize IPN hydrogel's mechanical properties by varying alginate and SFN concentrations. The results demonstrated that upon increasing the alginate concentration, the compression modulus improved. The SFN concentration was...