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    In-situ preparation and characterization of ultra-high molecular weight polyethylene/diamond nanocomposites using bi-supported Ziegler-Natta catalyst: effect of nanodiamond silanization

    , Article Materials Today Communications ; Volume 14 , March , 2018 , Pages 53-64 ; 23524928 (ISSN) Haddadi, S. A ; Ramezani Saadatabadi, Ahmad ; Amini, M ; Kheradmand, A ; Shsrif University of Technology
    Elsevier Ltd  2018
    Abstract
    In this study, reinforcement of ultra-high molecular weight polyethylene (UHMWPE) was investigated using the sol-gel surface modified diamond nanoparticles (NDs). Nanocomposite samples were synthesized via in-situ polymerization using bi-supported Ziegler-Natta catalyst. Fourier transform infrared spectroscopy, thermogravimetric analysis and contact angle measurements proved the proper silanization (∼1.9%) of NDs. Characterization of the catalysts revealed decrease in the activity of catalysts in presence of NDs which were responsible for the lower average molecular weight of the samples. Field emission scanning electron microscopy revealed an improved dispersion of the modified NDs in... 

    Kinetic and morphological investigation on the magnesium ethoxide-based ziegler-natta catalyst for propylene polymerization using typical external donors

    , Article Macromolecular Symposia ; Volume 285, Issue 1 , 2009 , Pages 52-57 ; 10221360 (ISSN) Dashti, A ; Ramezani Saadat Abadi, A ; Hiraoka, Y ; Kim, S. Y ; Taniike, T ; Terano, M ; Sharif University of Technology
    2009
    Abstract
    Kinetic and morphological aspects of slurry propylene polymerization using a MgCl2-supported Ziegler-Natta catalyst synthesized from a Mg(OEt)2 precursor in the presence and absence of two different external donors are investigated. The kinetic profiles show similar trend in presence and absence of donors. The Mg(OEt)2-based catalyst show a mild activation and a long-standing activity with good replication of the catalyst particles. The results show that synthesized Mg(OEt)2-based Ziegler-Natta catalyst presents a highly stable polymerization activity and good replication due to the uniform Ti distribution all over the catalyst particles. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim  

    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... 

    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
    Abstract
    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... 

    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
    Abstract
    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... 

    Investigation Properties of Polypropylene/Carbon Nanotube Nanocomposites Prepared via in Situ Polymerization Using Bi-Supported Ziegler Natta Catalyst

    , M.Sc. Thesis Sharif University of Technology Jafari Esfad, Narjes (Author) ; Ramezani Saadatabadi, Ahmad (Supervisor)
    Abstract
    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... 

    Preparation and study of bi-supported Ziegler-Natta catalyst with nano graphene oxide and magnesium ethoxide supports for polymerization of polyethylene

    , Article Polymer Science - Series B ; Volume 58, Issue 3 , 2016 , Pages 271-277 ; 15600904 (ISSN) Kheradmand, A ; Ramazani SaadatAbadi, A ; Khorasheh, F ; Baghalha, M ; Bahrami, H ; Sharif University of Technology
    Maik Nauka-Interperiodica Publishing  2016
    Abstract
    In this study, we have reported the preparation of bi-supported Ziegler-Natta catalysts using magnesium ethoxide and graphene oxide as support. The polymerization process was carried out in slurry phase using triisobutylaluminum as a co-catalyst.The XRD analysis of TiCl4/graphene oxide/Mg(OEt)2 catalyst demonstrated that the space between the layers of graphene oxide had increased to 0.2 nm.The catalyst was characterized by XPS, BET, BJH, SEM, and TGA. The catalyst activity was studied for various Al/Ti molar ratios, and the catalyst activity was optimum at Al/Ti molar ratio of 315. © 2016, Pleiades Publishing, Ltd  

    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... 

    Effects of nano graphene oxide as support on the product properties and performance of Ziegler-Natta catalyst in production of UHMWPE

    , Article Polymers for Advanced Technologies ; Volume 26, Issue 4 , 2015 , Pages 315-321 ; 10427147 (ISSN) Kheradmand, A ; Ramazani, S. A ; Khorasheh, F ; Baghalha, M ; Bahrami, H ; Sharif University of Technology
    John Wiley and Sons Ltd  2015
    Abstract
    The synthesis of mono- and bi-supported Ziegler-Natta catalysts using magnesium etoxide Mg(OEt)2 and graphene oxide (GO) as catalyst support for production of Ultra High Molecular Weight Polyethylene (UHMWPE) is reported in this investigation. Nano-graphene oxide was prepared by the modified Hummer's method and its structure was analyzed by XRD and FTIR indicating the presence of hydroxyl groups on graphene oxide and the formation of an exfoliated structure. The activity of TiCl4/Mg(OEt)2, TiCl4/Mg(OEt)2-GO, and TiCl4/GO catalysts in terms of grams of PE produced per mmol of Ti per hour was experimentally obtained for catalysts with different ratios of co-catalyst (triisobutylaluminium) to... 

    A stacked neural network approach for yield prediction of propylene polymerization

    , Article Journal of Applied Polymer Science ; Volume 116, Issue 3 , May , 2010 , Pages 1237-1246 ; 00218995 (ISSN) Monemian, S. A ; Shahsavan, H ; Bolouri, O ; Taranejoo, S ; Goodarzi, V ; Torabi Angaji, M ; Sharif University of Technology
    2010
    Abstract
    Prediction of reaction yield as the most important characteristic process of a slurry polymerization industrial process of propylene has been carried out. Stacked neural network as an effective method for modeling of inherently complex and nonlinear systems-espe-cially a system with a limited number of experimental data points-was chosen for yield prediction. Also, effect of operational parameters on propylene polymerization yield was modeled by the use of this method. The catalyst system was Mg(OEt)2/DIBP/TiCl 4/PTES/AlEt3, where Mg(OEt)2, DIBP (diisobutyl phthalate), TiCl4, PTES (phenyl triethoxy silane), and triethyl aluminum (AlEt3) (TEAl) were employed as support, internal electron... 

    Kinetic and morphological study of a magnesium ethoxide-based Ziegler-Natta catalyst for propylene polymerization

    , Article Polymer International ; Volume 58, Issue 1 , 2009 , Pages 40-45 ; 09598103 (ISSN) Dashti, A ; Ramazani Saadatabadi, A ; Hiraoka, Y ; Kim, S. Y ; Taniike, T ; Terano, M ; Sharif University of Technology
    2009
    Abstract
    Background: Kinetic andmorphological aspects of slurry propylene polymerization using a MgCl2-supported Ziegler-Natta catalyst synthesized from a Mg(OEt)2 precursor are investigated in comparison with a ball-milled Ziegler-Natta catalyst. Results: The two types of catalyst show completely different polymerization profiles: mild activation and long-standing activity with good replication of the catalyst particles for the Mg(OEt)2-based catalyst, and rapid activation and deactivation with severe fragmentation of the catalyst particles for the ball-milled catalyst. The observed differences are discussed in relation to spatial distribution of TiCl4 on the outermost part and inside of the... 

    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
    Abstract
    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... 

    Effect of exfoliated molybdenum disulfide oxide on friction and wear properties of ultra high molecular weight polyethylene

    , Article Polymers for Advanced Technologies ; Volume 29, Issue 12 , 2018 , Pages 3085-3096 ; 10427147 (ISSN) Amini, M ; Ramazani S. A., A ; Afkhami Varjouy, A ; Faghihi, M ; Sharif University of Technology
    John Wiley and Sons Ltd  2018
    Abstract
    The aim of this work is to investigate the effect of molybdenum disulfide on tribological properties of Ultra-high-molecular-weight polyethylene (UHMWPE). UHMWPE/MoS2 nano-composites were prepared using in-situ polymerization and Ziegler-Natta catalytic system. Studies showed that, in order to obtain the optimum tribological properties, interlayer distance between nanosheets should be as high as possible. Therefore, the nanosheets were subjected to oxidation using the required oxidants followed by thermal shock and ultrasound. Fourier-transform infrared spectroscopy (FTIR) analysis was used to determine the formation of functional groups which indicate the formation of S═O bond in the... 

    SiO 2 -covered graphene oxide nanohybrids for in situ preparation of UHMWPE/GO(SiO 2 ) nanocomposites with superior mechanical and tribological properties

    , Article Journal of Applied Polymer Science ; Volume 136, Issue 31 , 2019 ; 00218995 (ISSN) Haddadi, S. A ; Saadatabadi, A. R ; Kheradmand, A ; Amini, M ; Ramezanzadeh, M ; Sharif University of Technology
    John Wiley and Sons Inc  2019
    Abstract
    The modified Hummer technique was used in the preparation of graphene oxide (GO) nanosheets, and then SiO 2 decorated GO [GO(SiO 2 )] nanosheets were synthesized via the sol–gel method. Then, ultrahigh-molecular-weight polyethylene (UHMWPE) nanocomposites loaded with 0.5, 1, 1.5, and 2 wt % of GO(SiO 2 ) were prepared using magnesium ethoxide/GO(SiO 2 )-supported Ziegler–Natta catalysts via the in situ polymerization. Morphological study of the prepared polymer powders was assessed using field-emission scanning electron microscopy, which showed that GO(SiO 2 ) nanohybrids have been uniformly dispersed and distributed into the UHMWPE matrix. Also, the neat UHMWPE and its nanocomposites were... 

    Production and characterization of UHMWPE/fumed silica nanocomposites

    , Article Polymer Composites ; Volume 33, Issue 10 , 2012 , Pages 1858-1864 ; 02728397 (ISSN) Ramazani, A ; Saremi, M. G ; Amoli, B. N ; Izadi, H ; Sharif University of Technology
    Wiley  2012
    Abstract
    Ultrahigh-molecular-weight polyethylene (UHMWPE)/fumed silica nanocomposites were prepared via in situ polymerization using a bi-supported Ziegler-Natta catalytic system. Nanocomposites with different nanoparticle weight fractions were produced in order to investigate the effect of fumed silica on thermal and mechanical properties of UHMWPE/fumed silica nanocomposites. The viscosity average molecular weight (M) of all samples including pure UHMWPE as the reference sample and nanocomposites were measured. Scanning electron microscope (SEM) images showed the homogenous dispersion of nanoparticles throughout the UHMWPE matrix while no nanoparticle cluster has been formed. Crystallization... 

    Preparation and investigation of tribological properties of ultra-high molecular weight polyethylene (UHMWPE)/graphene oxide

    , Article Polymers for Advanced Technologies ; Volume 27, Issue 9 , 2016 , Pages 1172-1178 ; 10427147 (ISSN) Bahrami, H ; Ramazani S. A., A ; Shafiee, M ; Kherad Mand, A ; Sharif University of Technology
    John Wiley and Sons Ltd 
    Abstract
    This article has been devoted to investigation of the tribological properties of ultra-high molecular polyethylene/graphene oxide nanocomposite. The nanocomposite of ultra-high molecular polyethylene/graphene oxide was prepared with 0.5, 1.5, and 2.5 wt% of graphene oxide and with a molecular weight of 3.7 × 106 by in-situ polymerization using Ziegler–Natta catalyst. In this method, graphene oxide was used along with magnesium ethoxide as a novel bi-support of the Ziegler–Natta catalyst. Analyzing the pin-on-disk test, the tribological properties of the nanocomposite, such as wear rate and mean friction coefficient, were investigated under the mentioned contents of graphene oxide. The... 

    Investigation of in situ prepared polypropylene/clay nanocomposites properties and comparing to melt blending method

    , Article Materials and Design ; Volume 31, Issue 1 , 2010 , Pages 76-84 ; 02641275 (ISSN) Baniasadi, H ; Ramazani S. A. A ; Javan Nikkhah, S ; Sharif University of Technology
    Abstract
    The morphological, physical and mechanical properties of polypropylene/clay nanocomposites (PPCNs) were prepared by in situ polymerization are investigated. Non-modified scmectite type clay (e.g. bentonite) was used to prepare bi-supported Ziegler-Natta catalyst of TiCl4/Mg(OEt)2/clay. Exfoliated PPCNs were obtained by in situ intercalative polymerization of propylene using produced bi-supported catalyst. X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) micrograph were used to assess the clay morphology and dispersion of clay. The crystalline structures of PPCNs were characterized by differential scanning calorimetry (DSC). The mechanical properties of PPCNs were... 

    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
    2009
    Abstract
    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... 

    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
    2009
    Abstract
    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...