Time filter

Source Type

Ourang A.,Amirkabir University of Technology | Pilehvar S.,Polymer Engineering Group | Mortezaei M.,Polymer Engineering Group | Damircheli R.,Amirkabir University of Technology
Journal of Polymer Engineering | Year: 2017

In this work, polyacrylonitrile (PAN) was electrospun with and without magnetic nanoparticles (aluminum doped iron oxide) and was turned into magnetic nanofibers. The results showed that nanofibers diameter decreased from 700 nm to 300 nm by adding nanoparticles. Furthermore, pure PAN nanofibers were indicated to have low magnetic ability due to polar bonds that exist in their acrylonitrile groups. Obviously by adding only 4 wt% of the nanoparticles to PAN nanofibers, magnetic ability soared by more than 10 times, but at a higher percentage, it was shown to change just a little due to negative interaction among nanoparticles. This event relates to antiferromagnetically coupling of nanoparticles due to incomplete dispersion at higher percentage. © 2017 Walter de Gruyter GmbH, Berlin/Boston 2017.


Sahami M.,Shiraz BranchIslamic Azad UniversityShiraz Iran | Mazinani S.,Amirkabir Nanotechnology Research Institute Amirkabir University of TechnologyTehran Iran | Yeganeh J.K.,Polymer Engineering Group
Journal of Vinyl and Additive Technology | Year: 2016

The influences of organoclay on properties of chlorosulfonated polyethylene (CSPE) are scrutinized by loading different filler amounts to the polymeric matrix. In addition, cure characteristics of the prepared nanocomposites are determined by using rheometeric analysis. Although maximum and minimum torque values illustrate a slight increase with the organoclay incorporation, both scorch time and cure time of nanocomposites present a reduction in the presence of organoclay. The tensile strength and elongation at break of nanocomposites went through a maximum as a function of the organoclay content. As expected, the hardness, moduli at 100% and 300% elongations continuously increased along with increasing organoclay loading. The dispersion of organoclay in CSPE chaning was analyzed by X-ray diffraction and FESEM, methods. The best clay dispersion was achieved at 6 phr lauding by adding ENR 50. This was also observed in the stiffness of nanocomposites derived from both dynamic mechanical thermal analysis (DMTA) and tensile tests. © 2016 Society of Plastics Engineers.


Kaveh P.,Islamic Azad University at South Tehran | Mortezaei M.,Islamic Azad University at South Tehran | Mortezaei M.,Polymer Engineering Group | Barikani M.,Iran Polymer And Petrochemical Institute | Khanbabaei G.,Research Institute of Petroleum Industry RIPI
Polymer - Plastics Technology and Engineering | Year: 2014

In the present study, three thermoplastic polyurethanes (TPUs) based on poly(tetramethylene glycol) (PTMG) and poly(butylene adipate) (PBA) as polyols as well as their nanocomposites containing graphene oxide GO (0.3-1%) were prepared. TPUs had Tgs and Tms values in the range of -62.5 to -21.6°C and 5 to 10.8°C, respectively, increasing with enhancing PBA content in their formulations. Increasing of PBA moieties in TPUs resulted in higher crystallinity, elastic modulus and tensile strength values, while elongation at break and Helium permeability were decreased. Incorporation of GO into the TPUs improved crystallinity, mechanical properties and gas barrier values. © 2014 Copyright Composite Research Center.


Zamanian M.,Polymer Engineering Group | Mortezaei M.,Polymer Engineering Group | Salehnia B.,Amirkabir University of Technology | Jam J.E.,Polymer Engineering Group
Engineering Fracture Mechanics | Year: 2013

An epoxy resin was modified by the addition of different nanosilica particles. The particles were distributed into epoxy resin with ultrasonic instrument which gave a very well-dispersed phase of nanosilica particles. Tensile test and dynamic mechanical thermal analysis (DMTA) showed that Young's modulus increased and the glass transition temperature was unchanged. The fracture energy increased to about 620 J/m2 for the epoxy with 3.17 vol.% of 12-nm diameter nanoparticles. The responsible toughening mechanisms were recognized to be plastic deformation and plastic void growth. Finally, the toughening mechanisms have been quantitatively modeled and an excellent agreement between the results was found. © 2012 Elsevier Ltd. All rights reserved.


Kourki H.,Tarbiat Modares University | Famili M.H.N.,Tarbiat Modares University | Mortezaei M.,Polymer Engineering Group | Malekipirbazari M.,Tarbiat Modares University | Disfani M.N.,Baspar Gostar Aria Co
Journal of Elastomers and Plastics | Year: 2016

Highly filled systems, such as dental materials and tires, have some exceptional properties that make them very special for particular scientists and engineers. In this study, the thermal and dynamic properties of highly nanosilica-filled polystyrene were investigated. Thermal study predicts a phase in the filled system, named as adsorbed polymer, that has a different glass transition temperature (T g) compared with the neat polymer. The adsorbed polymer seems to be responsible for special thermal properties of the highly filled system. The dynamic properties of the filled system are observed to have a similar trend as the thermal behavior at different particle sizes and concentrations, both increasing linearly with the increase of volume fraction of adsorbed polymer. However, at higher volume fractions or for smaller particles, this trend changes and the filler networking mechanism is considered to be the reason for this change. Effect of the filler network is studied through the Han plot and it is found that the contribution of the filler network to the dynamic behavior of the highly filled system increases by reducing the particle size and increasing the particle loading. Beside the particle size and concentration, the effect of filler surface physics on dynamic and thermal behavior of the highly filled system is investigated and it is found that surface modification of the particle surface with nonpolar groups tends to lower Tg and volume fraction for the adsorbed phase and lower strength of the filler network. In this work, the samples were prepared using the method of stabilizing suspension in polymer solution. For viscoelastic investigation, the dynamic rheometry in sweep mode was chosen, also for studying the thermal behavior, differential scanning calorimetric tests were performed. In addition, in order to study the structure of filler in low and highly filled samples, atomic force microscopic imaging was employed. © SAGE Publications.


Ghodsi A.,Isfahan University of Technology | Fashandi H.,Isfahan University of Technology | Zarrebini M.,Isfahan University of Technology | Abolhasani M.M.,University of Kashan | Gorji M.,Polymer Engineering Group
RSC Advances | Year: 2015

This work reports a noticeable advancement in CO2 capture using gas-liquid membrane contactors (GLMC) composed of super-fine poly(vinylidene fluoride) hollow fiber membranes (PVDF HFMs). This is accomplished by incorporating large cavities as a sub-layer beneath the porous upper layer populated with macrovoids in a matrix of an interconnected network of pores. Superimposing rheological images on ternary phase diagrams is considered as a promising and comprehensive tool for interpretation of the observed morphologies in the HFs. Accordingly, the sub-layer cavities are found to evolve when the elastic modulus of HF outer layer (G′o) in contact with the bore fluid is not high enough to dampen the convective flow driven by the interfacial energy gradient. Implications of the impressive performance of the drawing process on the formation of the large cavities are discussed. Special attention is paid to the greater influence of increasing absorbent flow rate on enhancing CO2 capture efficiency of HFs with large cavities. © The Royal Society of Chemistry.


Kourki H.,Tarbiat Modares University | Mortezaei M.,Tarbiat Modares University | Mortezaei M.,Polymer Engineering Group | Navid Famili M.H.,Tarbiat Modares University
Journal of Thermoplastic Composite Materials | Year: 2016

Filler networking is considered as the most important parameter in controlling the mechanical and rheological properties of highly filled systems. Besides, the interparticle distance as a function of filler size and concentration seems to be the main parameter to govern the filler network strength or filler-filler interaction. In this article, considering the importance of filler networking, estimation of the interparticle distance for different values of filler size and concentration, investigation of the architecture of filler network in the nanocomposite for various filler sizes as well as analysis of the effects of filler size and concentration on the dynamic behavior of the filler networks are discussed and atomic force microscopic imaging is used to investigate the filler network parameters. In addition to the proposed filler network structure, the results suggest that the rheological properties of nanocomposites in the linear region could be related to the interparticle distance independent of filler size and concentration. On the other hand, by studying the linear and nonlinear viscoelastic properties of these highly filled systems, the results indicate that an increase in loss and storage modulus would occur by increasing the filler concentration and reducing the filler size. © The Author(s) 2014.


Kourki H.,Tarbiat Modares University | Mortezaei M.,Tarbiat Modares University | Mortezaei M.,Polymer Engineering Group | Navid Famili M.H.,Tarbiat Modares University
Journal of Composite Materials | Year: 2015

An accurate prediction of any process is the key to the control of that system. Modeling the rheological properties of nanocomposites would provide us a pattern for prediction of their properties as a function of process and material variables. In this study, the focus is to model and investigate the behavior of highly nanofilled systems, which is controlled by the filler-polymer and filler-filler interactions. In these systems, particles attract each other and form a network, which has a viscoelastic response to the applied stress or strain. Due to the filler-polymer interaction, polymer chains are adsorbed on the filler surface to create a secondary network, parallel with the filler-filler network. The third network in the system is the network of free polymer chains around the adsorbed ones. In this work, the behavior and contribution of these networks in the highly nanofilled systems are described. Furthermore, the relaxation time and the modulus of the filler network are estimated as a function of particle size and concentration. It is observed that the relaxation time and modulus of the filler network are increased with a reduction in particle size and an increase in particle concentration. For studying the parameters of the model, polymer adsorbed layer and available surface area of particles are estimated from the density of the nanocomposites. © SAGE Publications.


Amirshaghaghi A.,Polymer Engineering Group | Kokabi M.,Polymer Engineering Group
Iranian Polymer Journal (English Edition) | Year: 2010

Acrylamide (as monomer), N,N'-methylene-bis-acrylamide (as cross-linker), ammonium persulphate (as initiator), N,N,N',N'-tetramethylethyldiamine (as accelerator), and aluminium nitrate salt were used to produce a low temperature polymeric gel-net, in order to tailor the particle size of alumina powder. The monomers/salt ratio, metal ion/monomers interaction, furnace atmosphere, thermal stability and pore size of polymeric gel-net are the key factors to control the alumina particle size. Mercury porosimetry data and transmission electron microscopy (TEM) micrographs indicated that increasing the monomers/salt ratio from 1/1 to 3/1 resulted in polymeric gel-net with smaller pore size, and hence, nanopowders with narrower particle size distribution. The X-ray diffraction (XRD) patterns for nanopowders exhibited the amorphous phases below 1100°C and a single phase α-Al2O3 above 1100°C. Thermal analysis showed that for pre-oxidized samples below 200°C polymeric gel-net possesses better thermal stability at higher temperature in the presence of inert gas. Trapping of metal ions, with specific coordination numbers, into polymeric gel-net pores prevents their migration and reduces the nanopowder particles agglomeration. These observations were also confirmed by Fourier transform infrared (FTIR) and UV-vis spectrometry measurments. Polymeric gel-net inhibits the aggregation of Al2O3 nanopowder, improves its homogeneity, and provides a powder with narrower particle size distribution.


Pirouzfar V.,Islamic Azad University at Central Tehran | Mosalmani M.,Polymer Engineering Group | Mortezaei M.,Polymer Engineering Group
Iranian Polymer Journal (English Edition) | Year: 2015

Carbon–carbon composites have wide applications as ablative insulators. The carbon from thermal destruction of these composites acts as a layer and prevents reduction of volume and destruction of these composite parts. The amounts of carbon and ablation function of these composites are highly dependent on their polymer matrix. Among different thermally resistant polymers, phenolic resins are used extensively in making the insulations due to its low cost and appropriate processing. For production of carbon–carbon ablative composites, some resins with higher content of aromatic carbon and greater remaining carbon yield are used. This research investigates the effect of precursor material and blend composition in preparation and performance analysis of resole-pitch composites prepared through a blending technique. This study aims to investigate the role of each parameter using statistical analysis and modeling for investigation of design and optimization of the composite. The factorial methodology is used to optimize the carbon yield by implementing general factorial design considering the main parameters. The results of this study showed that the carbon yield and thermal resistance can be improved by polymerization of the resole in the presence of coal tar pitches. Resole polymerization with three types of tar pitches has increased the rate of thermochemical ablation by 24.30 %, although density of the carbon remaining after heat treatment has increased to some extent. The results of X-ray showed a structure similar to graphite for combination of the resole-pitch after pyrolysis up to 1000 °C, and finally by making the composite parts from synthesized resins and carbon fibers, improvement in thermal resistance of the parts against oxyacetylene flame is evaluated. The results of this research work hold that heat shields produced from the resole-tar and tar mixture provide greater heat resistance than composites produced from the resole. Therefore, the above-mentioned modification has greater ablative activity in the shields. © 2015, Iran Polymer and Petrochemical Institute.

Loading Polymer Engineering Group collaborators
Loading Polymer Engineering Group collaborators