Time filter

Source Type

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 | 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.

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.

Kowsari E.,Amirkabir University of Technology | Ansari V.,Amirkabir University of Technology | Moradi A.,Islamic Azad University at Tehran | Zare A.,Amirkabir University of Technology | And 2 more authors.
Journal of Polymer Research | Year: 2015

A poly(amide-imide) (PAI) bearing imidazole groups on the polymer chain was synthesized via direct polycondensation of a synthesized diacid-diimide and 4,4′-(1,4-Phenylenediisopropylidene) bisaniline (PDBA). Diacide-diimide was synthesized by the condensation of an amino acid compound, (S)-(+)-Histidine hydrochloride monohydrate and 3,3′,4,4′-Benzophenone tetracarboxylic dianhydride (BTDA). On the other hand, a sulfonated polyimide (SPI) was also synthesized by the solution imidization of sulfonated, (4,4-diaminostilbene-2,2-disulfonic acid) (DSDSA) and non-sulfonated, 4,4′-(1,4-Phenylenediisopropylidene) bisaniline (PDBA) diamines in reaction with a six-membered naphthalene base dianhydride, 1,4,5,8-Naphthalenetetracarboxylic dianhydride (NTDA). A strong and flexible SPI membrane with good uniformity and proper thermal and mechanical properties was achieved. The SPI was then blended with different amounts of PAI and doped with phosphoric acid (PA), in order to investigate the blending influence of PAI in PA-doped blend membranes compared to the pure SPI membrane. It was found that a proper amount of PAI could effectively improve the water uptake, IEC and proton conductivity of the PA doped SPI/PAI membranes. Nevertheless the excess PAI negatively affected the membrane properties. The pure SPI with an IEC of 1.76 meq.g−1 showed a proton conductivity of 29.4 mS cm−1 at 120 °C, while PA doped SPI/PAI-10 % (w/w) as the most optimal PAI containing sample, with an IEC of 2.23, showed a proton conductivity of 69.7 mS cm−1 at 140 °C. The proton conductivity measurements were performed at 40 % relative humidity. © 2015, Springer Science+Business Media Dordrecht.

Discover hidden collaborations