Loading...
Search for: polyethylenes
0.007 seconds
Total 204 records

    Production of chlorosulfonated rubber from postconsumer polyethylene and evaluation of produced rubber properties

    , Article Polymer - Plastics Technology and Engineering ; Volume 47, Issue 5 , 2008 , Pages 508-514 ; 03602559 (ISSN) Moradi, A ; Ramazani, S. A. A ; Shahrokhi, M ; Sharif University of Technology
    2008
    Abstract
    In order to convert the postconsumer polyethylene to a valuable product, chlorosulfonation of virgin and highly degraded polyethylene has been carried out in the solution phase under atmospheric pressure. Produced chlorosulfonated polyethylene samples from virgin and degraded HDPE are compounded and cured at different temperatures and their mechanical properties are determined. The results show that degradation of used polyethylene does not have noticeable negative effects on the final mechanical properties of produced chlorosulfonated rubbers. Therefore, it can be concluded that chlorosulfonation can be considered as an effective new method for polyolefin recycling  

    Manufacturing and Investigating of Nano carbon/Polyethylene Nanocomposites via In-situ Polymerization

    , M.Sc. Thesis Sharif University of Technology Sadrani, Alaleh (Author) ; Ramezani Saadatabdi, Ahmad (Supervisor)
    Abstract
    In this research UHMWPE/CB nanocomposites were prepared via in situ polymerization using Bi-supported Ziegler-Natta catalytic systems. Magnesium etoxide and carbon black were used as supports of catalyst. TiCl4 accompanied by triisobutyl aluminum and diisobutyl phthalate (DIBP) constituted Ziegler-Natta catalytic system. Preparation of catalyst and polymerization were done in slurry phase under the argon atmosphere. Then, structural, thermal and mechanical properties of produced nanocomposites with different CB content were evaluated by SEM, DSC, TGA, DMTA and tensile tests. Scanning Electron Microscopy (SEM) images also certified very good dispersion of CBs throughout PE matrix.... 

    Synthesis of dithiocarbamates by Markovnikov addition reaction in PEG and their application in amidoalkylation of naphthols and indoles

    , Article Journal of the Brazilian Chemical Society ; Volume 26, Issue 7 , 2015 , Pages 1500-1508 ; 01035053 (ISSN) Halimehjani, A. Z ; Dadras, A ; Ramezani, M ; Shamiri, E. V ; Hooshmand, S. E ; Hashemi, M. M ; Sharif University of Technology
    Sociedade Brasileira de Quimica  2015
    Abstract
    Synthesis of dithiocarbamates by the one-pot three-component Markovnikov addition reaction of an amine, carbon disulfide and an alkyl vinyl ether or N-vinylpyrrolidone is reported in polyethylene glycol (PEG) under a mild and green procedure with high yields and completely regiospecific. Also, the products were used as efficient starting materials for amidoalkylation of electron-rich arenes such as naphthols and indoles  

    Experimental study and mathematical modeling of partitioning of β-amylase and amyloglucosidase in PEG-salt aqueous two-phase systems

    , Article Journal of Chemical and Engineering Data ; Volume 55, Issue 11 , 2010 , Pages 4968-4975 ; 00219568 (ISSN) Shahriari, S ; Vossoughi, M ; Taghikhani, V ; Safekordi, A. A ; Alemzadeh, I ; Sharif University of Technology
    2010
    Abstract
    In this study, the partitioning of β-amylase in aqueous two-phase systems (ATPS) containing polyethylene glycol (PEG) with a molar mass of 6000 and 10 000 and KH 2PO 4 at T = (301.65 and 304.65) K was experimentally studied. In addition, the partitioning of amyloglucosidase in ATPS containing polyethylene glycol with molar mass of 4000, 6000, and 10 000 in the presence of Na 2SO 4 at T = (301.65 and 305.65) K was investigated. The effects of molar mass of PEG, temperature, mass fractions of salt, and the length of the tie line on partition coefficients of the enzymes were also studied. The experimental results showed that while the partition coefficients of enzymes decrease with increasing... 

    Co-crystallization in ternary polyethylene blends: tie crystal formation and mechanical properties improvement

    , Article Polymer International ; Volume 65, Issue 12 , 2016 , Pages 1405-1416 ; 09598103 (ISSN) Eslamian, M ; Bagheri, R ; Pircheraghi, G ; Sharif University of Technology
    John Wiley and Sons Ltd  2016
    Abstract
    Understanding the co-crystallization behavior of ternary polyethylene (PE) blends is a challenging task. Herein, in addition to co-crystallization behavior, the rheological and mechanical properties of melt compounded high density polyethylene (HDPE)/low density polyethylene (LDPE)/Zeigler − Natta linear low density polyethylene (ZN-LLDPE) blends have been studied in detail. The HDPE content of the blends was kept constant at 40 wt% and the LDPE/ZN-LLDPE ratio was varied from 0.5 to 2. Rheological measurements confirmed the melt miscibility of the entire blends. Study of the crystalline structure of the blends using DSC, wide angle X-ray scattering, small angle X-ray scattering and field... 

    Binary and ternary blends of high-density polyethylene with poly(ethylene terephthalate) and polystyrene based on recycled materials

    , Article Polymers for Advanced Technologies ; Volume 22, Issue 5 , 2011 , Pages 690-702 ; 10427147 (ISSN) Razavi, S ; Shojaei, A ; Bagheri, R ; Sharif University of Technology
    Abstract
    Binary blends of recycled high-density polyethylene (R-HDPE) with poly(ethylene terephthalate) (R-PET) and recycled polystyrene (R-PS), as well as the ternary blends, i.e. R-HDPE/R-PET/R-PS, with varying amounts of the constituents were prepared by twin screw extruder. The mechanical, rheological, thermal, and scanning electron microscopy (SEM) analyses were utilized to characterize the samples. The results revealed that both R-HDPE/R-PET and R-HDPE/R-PS blends show phase inversion but at different compositions. The R-PET was found to have much higher influence on the properties enhancement of the R-HDPE compared to R-PS, but at the phase inverted situation, a significant loss in the tensile... 

    Long-term mechanical performance of polyethylene pipe materials in presence of carbon black masterbatch with different carriers

    , Article Polymer Testing ; Volume 91 , 2020 Gholami, F ; Pircheraghi, G ; Sarafpour, A ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    In this paper, two types of carbon black (CB) masterbatch with different carriers, i.e. HDPE and LDPE, are used to produce black compounds using three PE100 resins with various short chain branching distributions. Due to difference in short chain branch (SCB) distribution, the used polyethylene resins behave differently in microstructure development and long-term creep behavior. The microstructural analysis using different DSC techniques and rheological measurements revealed more sensitivity of the polyethylene resin with uniform comonomer distribution to the carbon black aggregates and their polymeric carriers. The Full Notched Creep Test (FNCT) was performed to determine the long-term... 

    Gas permeability measurement in polyethylene and its copolymer films

    , Article CHISA 2006 - 17th International Congress of Chemical and Process Engineering, Prague, 27 August 2006 through 31 August 2006 ; 2006 ; 8086059456 (ISBN); 9788086059457 (ISBN) Gholizadeh, M ; Razavi, J ; Mousavi, A ; Sharif University of Technology
    2006
    Abstract
    In this research, low density polyethylene (LDPE) and poly ethylene-co-vinyl acetate (EVA) were used as polymeric materials. The methods used to produce LDPE and EVA was Film Blowing and ThermalDry Phase Inversion. The amount of permeability, diffusivity and solubility of O2 and CO2 through above polymers were obtained and also the effect of temperature, pressure and film thickness for LDPE was measured. The Barometric method was considered and measurements were based on ASTM standard. To study film cross-section morphology in EVA, Scanning Electron Microscopy (SEM) was applied. From results we considered that the amount of permeability and solubility were decreased by increasing film... 

    Study of Mechanical Properties of PP/r-PET Composite Reinforced with Flax Fiber

    , M.Sc. Thesis Sharif University of Technology Yosefinezhad, Mehdi (Author) ; Shojaei, Akbar (Supervisor) ; Bagheri, Reza (Supervisor)
    Abstract
    Recycling of polymers, with the aim of environmental protection and economical benefits, is important procedure, which is constantly developing. In this study the effect of the incorporation of recycled PET(r-PET) and recycled polypropylene/Flax(r-PP/Flax) to PP at low (20wt %) and medium content (40wt %) of r-PET was investigated. Polymer compounds were prepared by twin screw extruder followed by injection moulding. The effect of r-PP/Flax and r-PET on PP was evaluated using different techniques such as scanning electron microscopy (SEM), differential scanning calorimetery (DSC), rheological behavior, and mechanical properties (tensile modulus, yield strength, and charpy notched impact... 

    Investigation Properties of Polyethylene/ Carbon Nanotube Nanocomposites Prepared Via in Situ Polymerization

    , M.Sc. Thesis Sharif University of Technology Meschi Amoli, Behnam (Author) ; Ramazani Saadatabadi, Ahmad (Supervisor)
    Abstract
    In this research UHMWPE/MWCNT nanocomposites with different concentrations of nanotubes (0.5, 1.5, 2.5, 3.5 wt %) were prepared via in situ polymerization using a novel Bi-supported Ziegler-Natta catalytic systems. Magnesium etoxide and Multi wall carbon nanotubes functionalized by hydroxyl groups were used as supports of catalyst. TiCl4 accompanied by triethylaluminum constituted Ziegler-Natta catalytic system. Preparation of catalyst and polymerization were done in slurry phase under the argon atmosphere. Support of catalyst on MWCNT was investigated using Fourier Transform Infrared Spectroscopy (FTIR). The results confirmed interaction between catalyst and hydroxyl groups on the surface... 

    Manufacturing and Investigation the Properties of Polyethylene/ Fumed Silica Nanocomposites Via in situ Polymerization

    , M.Sc. Thesis Sharif University of Technology Ghahri Saremi, Maysam (Author) ; Ramazani Saadatabadi, Ahmad (Supervisor)
    Abstract
    In this research UHMWPE/FUMED SILICA nanocomposites with different concentrations of nano fumed silica (0.5, 1.5, 2.5, 4.5 wt %) were prepared via in situ polymerization using a novel Bi-supported Ziegler-Natta catalytic systems. Magnesium etoxide and Fumed Silica functionalized by hydroxyl groups were used as supports of catalyst. TiCl4 accompanied by triethylaluminum constituted Ziegler-Natta catalytic system. Preparation of catalyst and polymerization were done in slurry phase under the argon atmosphere. Scanning Electron Microscopy (SEM) images also certified very good dispersion of fumed silica throughout PE matrix. Intrinsic viscosity measurements showed high molecular weight for... 

    Preparation and Investigating of Polyolephine/graphene Oxide Nanocomposites Via In-situ Ziegler-natta Polymerization

    , M.Sc. Thesis Sharif University of Technology Bahrami, Hiva (Author) ; Ramazani Saadatabadi, Ahmad (Supervisor)
    Abstract
    The main object of this thesis is preparation and investigation of polyolophine/graphene oxide nanocomposites by using bi-supported Ziegler-Natta catalytic system and in-situ polymerization. Magnesium ethoxide and graphene oxide were used as supports of catalyst. TiCl4 was accompanied by triisobutyl aluminum (tibia) and diisobutyl phthalate (DIBP) as an electron donor constituting Ziegler-Natta catalytic system. Preparation of catalyst and polymerization were taken place in slurry phase under the argon atmosphere. At the beginning of the polymerization experiment, several type of nanocomposites were made under various conditions (such as different Al/Ti molar ratio) to find optimum condition... 

    Microstructure-property characterization of a friction-stir welded joint between AA5059 aluminum alloy and high density polyethylene

    , Article Materials Characterization ; Vol. 98, issue , December , 2014 , p. 73-82 Khodabakhshi, F ; Haghshenas, M ; Sahraeinejad, S ; Chen, J ; Shalchi, B ; Li, J ; Gerlich, A. P ; Sharif University of Technology
    Abstract
    Aluminum alloys and high density polyethylene are utilized in a wide variety of industrial applications. In the present work the feasibility of friction stir butt welding between AA5059 alloy and high density polyethylene sheets is examined. The bonding mechanism, joint strength, and microhardness are considered in this study. Various welding parameters and tool alignment were investigated until sound joints were achieved by positioning approximately 85% of the rotating tool in the aluminum material on the advancing side (1.4 mm offset) at constant spindle speed and traverse speed of 710 rpm and 63 mm/min, respectively. The results indicate that AA5059 aluminum and high density polyethylene... 

    Parametric study of buried steel and high density polyethylene gas pipelines due to oblique-reverse faulting

    , Article Canadian Journal of Civil Engineering ; Volume 42, Issue 3 , 2015 , Pages 178-189 ; 03151468 (ISSN) Rahimzadeh Rofooei, F ; Hojat Jalali, H ; Khajeh Ahmad Attari, N ; Kenarangi, H ; Samadian, M ; Sharif University of Technology
    National Research Council of Canada  2015
    Abstract
    A numerical study is carried out on buried steel and high density polyethylene (HDPE) pipelines subjected to oblique-reverse faulting. The components of the oblique-reverse offset along the horizontal and normal directions in the fault plane are determined using well-known empirical equations. The numerical model is validated using the experimental results and detailed finite element model of a 114.3 mm (4==) steel gas pipe subjected to a reverse fault offset up to 0.6 m along the faulting direction. Different parameters such as the pipe material, the burial depth to the pipe diameter ratio (H/D), the pipe diameter to wall thickness ratio (D/t), and the fault–pipe crossing angle are... 

    Injectable polyethylene glycol-laponite composite hydrogels as articular cartilage scaffolds with superior mechanical and rheological properties

    , Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Volume 66, Issue 3 , 2017 , Pages 105-114 ; 00914037 (ISSN) Nojoomi, A ; Tamjid, E ; Simchi, A ; Bonakdar, S ; Stroeve, P ; Sharif University of Technology
    Taylor and Francis Inc  2017
    Abstract
    In this study, injectable PEG-based hydrogels containing Laponite particles with mechanical and structural properties close to the natural articular cartilage are introduced. The nanocomposites are fabricated by imide ring opening reactions utilizing synthesized copolymers containing PEG blocks and nanoclay through a two-step thermal poly-(amic acid) process. Butane diamine is used as nucleophilic reagent and hydrogels with interconnected pores with sizes in the range of 100–250 µm are prepared. Improved viscoelastic properties compared with the conventional PEG hydrogels are shown. Evaluation of cell viability utilizing human mesenchymal stem cells determines cytocompatibility of the... 

    Polyethylene quality control in an industrial scale fluidized bed reactor

    , Article Indian Journal of Chemical Technology ; Volume 25, Issue 1 , January , 2018 , Pages 21-30 ; 0971457X (ISSN) Vahidi, O ; Shahrokhi, M ; Sharif University of Technology
    National Institute of Science Communication and Information Resources (NISCAIR)  2018
    Abstract
    Polymer quality control in an industrial scale polyethylene fluidized bed reactor has been addressed. Since online measurements of polymer properties (melt index and density) are not available, they must be controlled indirectly via other available measurements. In the present paper, two algebraic equations correlating polyethylene melt index and density with the measureable concentrations of chemical components are obtained. Having the desired polyethylene properties and using these correlations, desired concentrations of chemical components are calculated and used via corresponding control loops. By using the infrequently available polyethylene property measurements, the correlation... 

    Superparamagnetic iron oxide nanoparticles with rigid cross-linked polyethylene glycol fumarate coating for application in imaging and drug delivery

    , Article Journal of Physical Chemistry C ; Volume 113, Issue 19 , 2009 , Pages 8124-8131 ; 19327447 (ISSN) Mahmoudi, M ; Simchi, A ; Imani, M ; Hafeli, U. O ; Sharif University of Technology
    2009
    Abstract
    Superparamagnetic iron oxide nanoparticles with proper surface coatings are increasingly being evaluated for clinical applications such as hyperthermia, drug delivery, magnetic resonance imaging, transfection, and cell/protein separation. To enhance the applicability of magnetic nanoparticles, two main problems must be overcome. First, as the drug coats the particle surface, a significant portion of it is quickly released upon injection (burst effect). Therefore, only small amounts of the drug reach the specific site after, for example, magnetic drug targeting. Second, once the surface-derivatized nanoparticles are inside the cells, the coating is likely digested, leaving the bare particles... 

    Control of a fluidized bed polyethylene reactor

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 27, Issue 3 , September and October , 2008 , Pages 87-101 ; 10219986 (ISSN) Vahidi, O ; Shahrokhi, M ; Mirzaei, A ; Sharif University of Technology
    2008
    Abstract
    In present paper, dynamic behavior and control of a fluidized bed reactor for polyethylene production has been considered. A double active sites model for Ziegler-Natta catalysts is used for simulation of polymerization reaction. Hydrodynamic behavior of the bed is modeled using a two phase model including bubble and emulsion phases in which bubble phase has plug flow pattern with differentially variable velocity and size through the bed and emulsion phase has the CSTR flow pattern. The reactor model is validated using industrial data. Conventional PID controllers with anti-windup are considered for control purposes. It has been shown that the control system has satisfactory performances... 

    Fabrication and Study of Mechanical Behavior of in Situ Microfibrillar- Reinforced Composites of Polypropylene/Recycled Poly (Ethylene Terephthalate)Toughened with Rubber Particles

    , M.Sc. Thesis Sharif University of Technology Motahari, Tayebeh (Author) ; Bagheri, Reza (Supervisor) ; Alizadeh, Reza (Supervisor)
    Abstract
    The use of polymers is increasing day by day due to low density, reasonable price and ability to produce different products. On the other hand, the accumulation of polymer wastes in nature is one of the environmental concerns in today's world, which is mainly due to the widespread use of polymers in the packaging industry and disposable applications. In order to solve this problem, recycling is recommended as the most appropriate and economical solution. Because in addition to consuming polymer waste, it also saves energy and reduces carbon footprint.Polyethylene terephthalate (PET) is one of the polymeric materials which; It has a special place in the packaging industry and is widely used... 

    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...