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    Effect of system of initiators on the process cycle of nonisothermal resin transfer molding - Numerical investigation

    , Article Composites Part A: Applied Science and Manufacturing ; Volume 41, Issue 1 , 2010 , Pages 138-145 ; 1359835X (ISSN) Shojaei, A ; Farrahinia, H ; Pishvaie, S.M.R ; Sharif University of Technology
    The role of initiators with different reactivities on the process cycle of nonisothermal resin transfer molding (RTM) was examined using the numerical simulation. A new process model was developed based on flow, heat and mass transfer equations combined with an appropriate mechanistic kinetics model which elucidates the functions of the initiators in the system. The process cycle of RTM with both single initiator and dual-initiator (combination of two initiators) was analyzed. The numerical simulations revealed that the single initiator with high reactivity reduces the cycle time, but there is a risk of incomplete mold filling and nonuniform temperature distribution. For dual-initiator... 

    Comparison of the batch and breakthrough properties of stable and plain alginate microcapsules with a chelating resin and an ion exchanger in Ag+ adsorption

    , Article Industrial and Engineering Chemistry Research ; Volume 47, Issue 17 , 5 August , 2008 , Pages 6742-6752 ; 08885885 (ISSN) Outokesh, M ; Niibori, Y ; Mimura, H ; Ahmadi, S. J ; Sharif University of Technology
    A comparative study on the uptake properties of alginate microcapsules containing Cyanex 302 extractant, Lewatite TP 214 chelating resin, and Amberlite 200CT strongly acidic ion exchanger has been conducted using Ag+ as the target ion. The study resulted in an analytical formula, as well as three phenomenological breakthrough formulas that are also applicable in other fixed-bed operations. It also demonstrated a close similarity of the uptake properties of alginate microcapsules (MCs) and the chelating resins. Advantages of MCs over chelating resins include ease of preparation, ability to immobilize different extractants, and, most remarkably, an enormous distribution factor (Kd ≈ 106... 

    A theoretical analysis on resin injection/compression molding

    , Article Key Engineering Materials ; Volume 334-335 I , 2007 , Pages 209-212 ; 10139826 (ISSN) Shojaei, A ; Spah, A ; Sharif University of Technology
    Trans Tech Publications Ltd  2007
    In the present investigation, mold filling process of resin injection/compression molding (RI/CM) is compared with resin transfer molding (RTM) for simple mold geometry. To do this, analytical solutions are obtained for RI/CM in unidirectional flow. Based on the analytical solutions, flow front progression and pressure distribution are compared with RTM at different fiber content. The results indicate that the RI/CM reduces the mold filling time significantly, particularly for composite parts with higher fiber content  

    Characterization of reinforcing effect of alumina nanoparticles on the novolac phenolic resin

    , Article Polymer Composites ; Vol. 35, Issue 7 , July , 2014 , pp. 1285-1293 ; ISSN: 02728397 Etemadi, H ; Shojaei, A ; Sharif University of Technology
    Very fine alumina nanoparticles were loaded in novolac type phenolic resin (PF) using solution mixing method. The concentration of nanoalumina in PF was varied between 2.5 to 20 wt%. All the compounds were compression molded and then subjected to scanning electron microscopy (SEM), tensile, flexural, and dynamic mechanical analysis (DMA) tests. SEM analysis showed that the nanoalumina were dispersed uniformly at low concentrations, however, at high concentrations, dispersion was suppressed leading to agglomerates in the composites. Mechanical testing revealed that the nanoalumina had a great influence on the strength and stiffness of PF resin particularly at concentrations below 5 wt%.... 

    Loading rate-induced transition in toughening mechanism of rubber-modified epoxy

    , Article Journal of Macromolecular Science, Part B: Physics ; Volume 49, Issue 3 , 2010 , Pages 602-614 ; 00222348 (ISSN) Abadyan, M ; Khademi, V ; Bagheri, R ; Motamedi, P ; Kouchakzadeh, M. A ; Haddadpour, H ; Sharif University of Technology
    The effect of loading rate on toughening mechanisms of rubber-modified epoxy resin was investigated using amine-terminated butadiene acrylonitrile (ATBN) rubber. Rubber-modified samples were tested at various loading rates in the range of 1-1000 mm/min. At low loading rates, modified resin exhibited a high fracture toughness, which decreased by increasing the rate of loading. At higher loading rate a transition region was observed, where the fracture toughness did not change noticeably with increasing the loading rate. Beyond the transition region, the resin fracture toughness dropped dramatically to the level of unmodified epoxy. Fractography of the damage zone showed different toughening... 

    Effects of asphaltene, resin and crude oil type on the interfacial tension of crude oil/brine solution

    , Article Fuel ; Volume 223 , July , 2018 , Pages 261-267 ; 00162361 (ISSN) Lashkarbolooki, M ; Ayatollahi, S ; Sharif University of Technology
    Elsevier Ltd  2018
    In recent years, the behavior of crude oil interfacial tension (IFT) as a function of salt concentration have been investigated. The results found in literature are highly controversial, thus the current experimental study aimed to clarify the reasons behind this by developing a methodology based on extracting asphaltene and resin from three different crude oils and performing elemental analysis on them. In addition, the effect of salinity on the IFT of three studied crude oil was compared with the synthetic crude oil consisted of different weight percent (wt%) of asphaltene and resin in toluene. The obtained results revealed that the IFT of crude oil as a function of salinity depended not... 

    Comments on the " A comparative study of chelating and cationic ion exchange resins for the removal of palladium (II) complexes from acidic chloride media"

    , Article Journal of Hazardous Materials ; Volume 229-230 , 2012 , Pages 461-462 ; 03043894 (ISSN) Alahyari, S. A ; Khanchi, A. R ; Outokesh, M ; Tayebi, A ; Sharif University of Technology

    Experimental and theoretical study on the mechanical properties of novolac phenolic resin nanocomposites: Effects of nanoclay and multiwallwed carbon nanotube

    , Article ECCM 2012 - Composites at Venice, Italy, Proceedings of the 15th European Conference on Composite Materials, 24 June 2012 through 28 June 2012 ; 2012 ; 9788888785332 (ISBN) Jahanmard, P ; Shojaei, A ; Faghihi, M ; Sharif University of Technology
    European Conference on Composite Materials, ECCM  2012
    The present work focused on the characterization of mechanical properties of novolac phenolic resin (PF) filled with two types of clays, including modified and unmodified ones, and multiwalled carbon nanotube (MWCNT). It was found that the solution mixing method is able to disperse the nanoparticles within the PF resin appropriately. It was also shown that the unmodified clay (Closite Na+) has the highest influence on the mechanical properties possibly due to the good level of dispersion as well as the good interfacial interaction. Theoretical analysis based on the rubber elasticity theory showed that the nanoparticles influence the evolution of crosslinking density and network structure  

    Effect of asphaltene and resin on interfacial tension of acidic crude oil/ sulfate aqueous solution: Experimental study

    , Article Fluid Phase Equilibria ; Volume 414 , 2016 , Pages 149-155 ; 03783812 (ISSN) Lashkarbolooki, M ; Ayatollahi, S ; Sharif University of Technology
    Elsevier  2016
    Although the capability of using sulfate anion as a wettability modiffier is well established, no systematic investigation on the effect of sulfate ions and natural surfactants in the crude oil including asphaltene and resin on the interfacial tension (IFT) of acidic crude oil (ACO)/sulfate were performed. In this regards, the fluid/fluid interactions are tested through the IFT measurements for ACO, asphaltene and resin extracted from ACO in the presence of sulfate salts including Na2SO4, MgSO4 and CaSO4 while the concentration of each salt ranges between 0 and 45000 ppm. The obtained results demonstrate that the capability of asphaltene molecules is higher for IFT reduction compared with... 

    Numerical simulation of three-dimensional flow and analysis of filling process in compression resin transfer moulding

    , Article Composites Part A: Applied Science and Manufacturing ; Volume 37, Issue 9 , 2006 , Pages 1434-1450 ; 1359835X (ISSN) Shojaei, A ; Sharif University of Technology
    In compression resin transfer moulding (CRTM), resin flows inside a mould filled with fibrous reinforcement as a result of resin injection and mould compression. This process facilitates the resin flow through the fibrous reinforcement particularly for high fiber content parts. This paper presents the numerical simulation of filling process of CRTM in full three-dimensional domain. A mathematical model of three-dimensional resin flow inside the CRTM mould is presented. An effective elastic modulus is introduced for multi-layer preforms connecting the mould closing speed to deformation rate of individual layers. Control volume/finite element method (CV/FEM) is used and the numerical algorithm... 

    Hybrid Fiber Reinforced Composite Phenolic Foam

    , M.Sc. Thesis Sharif University of Technology Marii Notash, Mahsa (Author) ; Foronchi, Masoud (Supervisor) ; Dadbeen, Susan (Supervisor)
    Phenolic foam are common among the polymeric foams, they can be prepared from resole resin, it is possible to apply an external thermal reservoir to achieve curing and expansion simultaneously, or use an acid as curing agent, without external heating, and utilize heat of curing reaction for expansion of foaming mixture. Because of economic aspect of view and ease of processing the latter method is preferable. However, the existing problem is that the resole resin must be so active to react with acid curing agent and produce suitable heat. Also,physical properties of resin such as viscosity have a great importance to the efficiency of resin in foam processing.In the present work, resole... 

    Preparation and Characterization of Phenolic Resin-nanodiamond Nanocomposites

    , M.Sc. Thesis Sharif University of Technology Sheikhhasani, Sina (Author) ; Shojaei, Akbar (Supervisor) ; frounchi, Massoud (Supervisor)
    Recently nanodiamond has drawn a vast attention of researchers due to exceptional mechanical properties. However, nanodiamond tendency to aggregation in polymer matrix restricts its reinforcement properties. In this research, novolac phenolic resin nanocomposites reinforced by nanodiamond were prepared by solution blending method and their mechanical properties were investigated. In order to prevent nanodiamond aggregation, ultrasonic treatment was used and nanodiamond surface was modified with acid and amine functional groups. FTIR and TGA were performed in order to investigate nanodiamond surface and confirmation of existence of acid carboxylic and oleylamine (OLA) groups. Produced... 

    Catalytic graphitization behavior of phenolic resins by addition of in situ formed nano-Fe particles

    , Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 101 , 2018 , Pages 50-61 ; 13869477 (ISSN) Rastegar, H ; Bavand Vandchali, M ; Nemati, A ; Golestani Fard, F ; Sharif University of Technology
    Elsevier B.V  2018
    This work presents the catalytic graphitization process of phenolic resins (PR's) by addition of in situ nano-Fe particles as catalyst. Pyrolysis treatments of prepared compositions including various contents of nano-Fe particles were carried out at 600–1200 °C for 3 h under reducing atmosphere and graphitization process were evaluated by different techniques such as X-Ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Microscopy (HRTEM), Simultaneous Thermal Analysis (STA) and Raman spectroscopy that mainly performed to identify the phase and microstructural analysis, oxidation resistance and extend of graphitized carbon... 

    One-step hydrothermally synthesized ferrite@polymeric nanoparticles for decolorization of crystal violet

    , Article Desalination and Water Treatment ; Volume 108 , 2018 , Pages 299-310 ; 19443994 (ISSN) Alijani, H ; Beyki, M. H ; Kaveh, R ; Fazli, Y ; Sharif University of Technology
    Desalination Publications  2018
    An efficient dye decolorization platform was developed through one-step hydrothermally route based on magnetic polymeric resin and employed in aqueous crystal violet (CV) adsorption. The polymer nanohybrid composed of ZnFe2O4 and hydroxybenzoic acid–resorcinol resin as metal and organic fragment, respectively. Several techniques such as X-ray diffraction, N2 – adsorption desorption, vibration sample magnetometer, field emission scanning electron microscopy and Fourier transform infrared spectroscopy were employed for characterization of as-prepared nanohybrid. CV adsorption showed low equilibrium time within 10 min with the adsorption capacity of 83.3 mg g–1. Regeneration of the sorbent... 

    Use of rubber modification technique to improve fracture-resistance of hoop wound composites

    , Article Materials and Design ; Volume 30, Issue 6 , 2009 , Pages 1976-1984 ; 02641275 (ISSN) Abadyan, M ; Khademi, V ; Bagheri, R ; Haddadpour, H ; Kouchakzadeh, M. A ; Farsadi, M ; Sharif University of Technology
    Toughness improvement of an epoxy resin and respective hoop wound composite were investigated systematically using amine-terminated butadiene acrylonitrile (ATBN) liquid rubber. Rubber modification improves fracture toughness of epoxy resin with slight reduction in the glass transition temperature (Tg), flexural and compressive properties of resin. Impact resistance of composite is improved by rubber modification similar to modified resin. Interlaminar shear strength (ILSS), compressive modulus and strength, and flexural strength of composite decreased slightly with rubber modification. To interpret the data, the void content of composite samples was determined and the damaged surfaces of... 

    Breakthrough curves for adsorption and elution of rhenium in a column ion exchange system

    , Article Hydrometallurgy ; Volume 85, Issue 1 , 2007 , Pages 17-23 ; 0304386X (ISSN) Mozammel, M ; Sadrnezhaad, S. K ; Badami, E ; Ahmadi, E ; Sharif University of Technology
    Impure rhenium and molybdenum bearing solution was passed through a column of Varian strong base anionic resin for selective adsorption of rhenium and molybdenum ions from the solution. Elution of molybdenum and rhenium was carried out using 2 N NaOH and 0.2 N NH4SCN, respectively. The effect of resin bed height on breakthrough time was investigated. Experimental and theoretical curves were compared with good agreement. The results showed that the behavior pattern of these curves was repeatable and almost constant. © 2006 Elsevier B.V. All rights reserved  

    An experimental study of saturated and unsaturated permeabilities in resin transfer molding based on unidirectional flow measurements

    , Article Journal of Reinforced Plastics and Composites ; Volume 23, Issue 14 , 2004 , Pages 1515-1536 ; 07316844 (ISSN) Shojaei, A ; Trochu, F ; Ghaffarian, S. R ; Karimian, S. M. H ; Lessard, L ; Sharif University of Technology
    Unidirectional experiments were carried out for the evaluation of the unsaturated permeability of the reinforcement during the injection and the saturated permeability. Saturated permeability was found to govern the permanent flow established after filling of the cavity. The unsaturated permeability was evaluated by a linear regression in function of the position of the resin front during transient flow experiments performed at constant injection pressure. The difference between these two permeability values is also related to the pore structure of the fiber bed  

    Simulation of the three-dimensional non-isothermal mold filling process in resin transfer molding

    , Article Composites Science and Technology ; Volume 63, Issue 13 , 2003 , Pages 1931-1948 ; 02663538 (ISSN) Shojaei, A ; Ghaffarian, S. R ; Karimian, S. M. H ; Sharif University of Technology
    Elsevier BV  2003
    Numerical simulation of resin transfer molding (RTM) is known as a useful method to analyze the process before the mold is actually built. In thick parts, the resin flow is no longer two-dimensional and must be simulated in a fully three-dimensional space. This article presents numerical simulations of three-dimensional non-isothermal mold filling of the RTM process. The control volume/finite element method (CV/FEM) is used in this study. Numerical formulation for resin flow is based on the concept of nodal partial saturation at the flow front. This approach permits to include a transient term in the working equation, removing the need for calculation of time step to track the flow front in... 

    Effects of rubber curing ingredients and PhenolicResin on mechanical, thermal, and morphological characteristics of rubber/phenolic-resin blends

    , Article Journal of Applied Polymer Science ; Volume 108, Issue 6 , 2008 , Pages 3808-3821 ; 00218995 (ISSN) Derakhshandeh, B ; Shojaei, A ; Faghihi, M ; Sharif University of Technology
    This article examines the physical and mechanical characteristics of mixtures of two different synthetic rubbers, namely styrene-butadiene rubber (SBR) and nitril-butadiene rubber (NBR), with novolac type phenolicresin (PH). According to Taguchi experimental design method, it is shown that the addition of PH increases the crosslinking density of rubber phase probably due to its curative effects. Thermal analysis of the blends indicates that, contrary to NBR/PH blend, thermal stability of SBR/PH blend is dependent on sulfur content due to predominant polysulfidic crosslinks formed in SBR. Slight shift in glass-transition temperature (Tg) of pure SBR and NBR vulcanizates by the addition of PH... 

    Study and Preparation of Paper Filter for Air Treatment in Internal Combustion Process

    , M.Sc. Thesis Sharif University of Technology Zare Shervedani, Ali (Author) ; Musavi, Abbas (Supervisor) ; Hamzeh, Yahya (Supervisor)
    Air filter paper is a combination of cellulosic, polymeric and resin materials with a certain permeability to air, which is used to prevent dust from entering the internal combustion process.The purpose of this research was to study and make air filter paper, based on which 4 samples of automobile air filter paper were produced. Samples with a combination of 2 types of cellulose fibers, imported short Kraft fibers and long Bangladeshi Kenaf fibers (skin) and one type of polymer fibers, Polyester fibers with a type of self-networking water-based Acrylic resin with glass conversion temperature (Tg) About 33 degrees Celsius and in the range of 20% by weight with a mass of about 120 g/m2 were...