access deny [1302]
En
    access deny [1002]
    access deny [1003]
  • آزمایشگاه پلیمر
  • کارگاه شکل دهی پلیمرها

access deny [1028]

access deny [1001]

Effect of nanoparticle network formation on electromagnetic properties and cell morphology of microcellular polymer nanocomposite foams

Mehrnoosh Taghavimehr, Mohammad Hossein Navid Famili, Mehran Abbasi Shirsavar
Journal PapersPolymer Testing , 2020 March 4, {Pages 106469 }

Abstract

Adding high loadings of nanoparticles can remarkably alter the functionality of polymer nanocomposite foams. Therefore, this dramatic change was studied at the percolation threshold as a point to predict the properties of foamed nanocomposites using the viscoelastic characteristics of un-foamed ones. In this research, the effect of incorporating 10–40 wt% of ZnO nanoparticles on rheological properties of PS/ZnO samples was investigated. Then, these samples were foamed at processing temperatures of 80 and 120 ?C to study morphology and electromagnetic properties. First, the rheological study showed that the storage modulus of nanocomposites increased significantly above 20 wt% of nanoparticles. A connected network of nanoparticles al

Numerical Simulation and Visual Evaluation of the Mixing of Polymer Fluids in Twin Screw Extruder Based on Components Miscibility

Ebrahim Khalaj, FAMILI MOHAMAD HOSSEIN NAVID, Faezeh Ghodratpour
Journal Papers , Volume 32 , Issue 100508, 2019 January 1, {Pages 55-64 }

Abstract

Hypothesis The morphological attributes of polymer blends have a significant influence on the final properties of the blend. Many attempts have been made to simulate morphological changes of a blend in various equipments، using several mathematical models and numerical simulations. In this study، mixing of non-Newtonian fluids was simulated using a power-law rheological model in a typical twin screw extruder in three dimensions. Modified marker and cell (MAC) method was used for simulation. In modified MAC، for simulation of polymeric fluids flow، power law rheological model was used to generalize velocity equations to non-Newtonian fluids. Interfacial tension and viscosity ratios were used to introduce the effect of miscibility paramet

Effect of processing method on migration of antioxidant from HDPE packaging into a fatty food simulant in terms of crystallinity

Zahra Maghsoud, M Rafiei, MH Navid Famili
Journal PapersPackaging Technology and Science , Volume 31 , Issue 3, 2018 March , {Pages 141-149 }

Abstract

Migration of additives from plastic packaging into food products is generally considered to be affected by polymer crystallinity. In the present work, migration of Irganox 1010 from high density polyethylene into a fatty food simulant (ethanol 95%) was studied for samples prepared with different percent crystallinities. For this purpose, 2 different processing techniques, injection and compression molding, were used, and the preparation conditions were changed to obtain high density polyethylene samples with crystallinities in the range of 50 to 70%. Migration analysis was carried out at 121?C for 2?hours, and then at 40?C for 238?hours using high performance liquid chromatography. In general, the injection molded specimens had lower crysta

Mixing challenges for SiO2/polystyrene nanocomposites

Hajir Kourki, Mohammad Hossein Navid Famili, Mehrzad Mortezaei, Milad Malekipirbazari
Journal PapersJournal of Thermoplastic Composite Materials , Volume 31 , Issue 5, 2018 May , {Pages 709-726 }

Abstract

Morphology of a nanocomposite, which has indisputable effects on its properties, is determined by its dynamic and thermodynamic conditions. While physical properties of the components of a nanocomposite as well as the interaction between them are the parameters controlling the morphology thermodynamically, their dynamic condition is related to the issues like intensity of mixing and geometry of mixer. In this research, we investigate the mixing process of solution casting method by studying the effects of mixing intensity on the dynamics of the particle structure and hereby its morphology using sedimentation test. In these experiments, mixing is performed at various durations, input energies, and energy types for suspensions containing diff

Analyzing and Comparing the Effect of System Dynamics on Agglomerations of CB/PS and TiO2/PS Nanocomposites Through Rheological Dielectric Method

Mona Janipour, Mohammad Hossein Navid Famili
Conference PapersInternational Seminar on Polymer Science and Technology , 2018 November 10, {Pages 394-397 }

Abstract

Various particles containing dipoles have different dielectric properties which would be applicable in varied industries like electronics, aerospace, food and etc. Carrying out dielectric and rheological experiments called “Rheo-dielectric” would result in dramatic achievement in macro and micro structures of polymeric composites. In this study we used TiO2 (as a ceramic material) and CB (as a conductive material) nanoparticles in PS (which is neutral) as a matrix to investigate the dispersion and agglomeration of each kind of nanocomposite and then compare them together. The dielectric experiments have been done at the frequency of 100?Hz and a sweep of shear strain has been imposed to the nanocomposites at the constant shear rate of

Janus Fiber Fabrication Using Electrospinning Process

Khadijeh Keshavarz Bahaghighat, Mohammad Hossein Navid Famili
Conference PapersInternational Seminar on Polymer Science and Technology , 2018 November 10, {Pages 502-504 }

Abstract

Arguably, one of the most versatile approaches toward anisotropic particles, cylinders, fibers, and fiber scaffolds is based on electrohydrodynamic (EHD) co-jetting. Electrospraying and electrospinning processes have been applied to polymer solutions to establish straightforward methods for the preparation of nano-/microparticles using high electrical voltages as driving forces for the transport of polymer solutions [1]. In this study, we have obtained the electrohydrodynamic method of Janus fiber. The precursor solutions of these fibers include polyvinylpyrrolidone (PVP) in blue and yellow, with a flow rate of 0.3?mL/h at 8?kV.

Numerical Simulation of Mixing Polymeric Fluids in Rotating Cylinder Rheometer

Ebrahim Khalaj, Mohammad Hossein N Famili, Faezeh Ghodratpour
Conference PapersInternational Seminar on Polymer Science and Technology , 2018 November 10, {Pages 324-327 }

Abstract

In this study, mixing of non-Newtonian polymeric fluids was simulated three dimensionally using a power-law rheological model in a rotational rheometer with coaxial cylinders. The simulation was performed by obtaining 3D components of velocity for each grid point using finite volume method and tracking the grid points in specified time intervals. To generalize the method to immiscible polymers, a modification was done by introducing interfacial tension and viscosity ratios of two fluids in solving velocity equations. The developed simulation method can be used to simulate the mixing of immiscible polymers.

Using the Rheo-Dielectric Method in Analyzing the Effect of System Dynamics on the Dispersion State of CB/PS Nanocomposites

Mona Janipour, Mohammad Hossein Navid Famili
Conference PapersInternational Seminar on Polymer Science and Technology , 2018 November 10, {Pages 391-393 }

Abstract

Simultaneous dielectric and dynamically mechanical investigations have a tremendous number of impressive accomplishments on microscopic properties of polymeric systems containing dipoles, specially nanocomposites. So far, a huge amount of research has been carried out to analysis such properties of nanocomposites by using dielectric and rheo-dielectric method. In this research we traced the percolation threshold and the changes in dielectric properties of nanocomposites of CB/PS through rheo-dielectric tests. We observed the remarkable differences of dielectric properties and also percolation threshold between before and after of imposing the oscillatory shears on CB/PS nanocomposites with three different volume fractions of nanoparticles.

Numerical Simulation of Mixing Polymeric Fluids in Twin Screw Extruder

Ebrahim Khalaj, Mohammad Hossein N Famili, Faezeh Ghodratpour
Conference PapersInternational Seminar on Polymer Science and Technology , 2018 November 10, {Pages 328-331 }

Abstract

In this study, mixing of non-Newtonian polymeric fluids was simulated three dimensionally using a power-law rheological model in a twin screw extruder. The simulation was performed by obtaining 3D components of velocity for each grid point using finite volume method and tracking the grid points in specified time intervals. To generalize the method to immiscible polymers, a modification was done by introducing interfacial tension and viscosity ratios of two fluids in solving velocity equations. The developed simulation method can be used to simulate the mixing of immiscible polymers.

3D Simulation of Velocity Field for Polymeric Fluids in Twin Screw Extruder by Finite Volume Method (FVM)

Ebrahim Khalaj, Mohammad Hossein N Famili, Faezeh Ghodratpour
Conference PapersInternational Seminar on Polymer Science and Technology , 2018 November 10, {Pages 332-335 }

Abstract

In this research, the velocity field of polymeric fluids is simulated in twin screw extruder by finite volume method (FVM). The simulation was three dimensional and the discretization performed using central difference method. For optimizing of the simulation, an Under Relaxation Factor (URF) parameter was considered. It was found that by using URF equal to 0.3, simulation had more rapid convergence. Considering a lower power law index (n) also had a similar effect.

A method for quantitative characterization of agglomeration degree in nanocomposites

A Golbang, MHN Famili, M Mokhtari Motameni Shirvan
Journal PapersComposites Science and Technology , Volume 145 , 2017 June 16, {Pages 181-186 }

Abstract

Dispersion and agglomeration control the macroscopic properties of nanocomposites; thus, quantitative characterization of particle dispersion and agglomeration is crucial. So far, methods such as image analysis or measurement of macroscopic properties have been insufficient. So, a novel methodology is introduced to predict particle dispersion and agglomeration degree quantitatively through the measurement of effective dielectric constant. This is done by taking into account the impact of inter-particle interactions in respect to microstructure for the calculation of effective dielectric constant. Inter-particle interaction is calculated as a function of inter-particle distance for random dispersion of particles in composites and as a functi

New polyvinyl chloride/thermoplastic polyurethane membranes with potential application in nanofiltration

Zahra Maghsoud, Mojgan Pakbaz, Mohammad Hossein Navid Famili, Seyed Siavash Madaeni
Journal PapersJournal of Membrane Science , Volume 541 , 2017 November 1, {Pages 271-280 }

Abstract

Due to favorable interactions between Polyvinyl chloride (PVC) and Thermoplastic Polyurethane (TPU) chain segments as revealed by viscosity measurement and differential scanning calorimetry (DSC), the ternary phase diagram of the PVC/TPU blend (for all compositions) was almost close to that of neat PVC. According to a simple diffusion model used for studying the kinetics of membrane formation, the PVC/TPU membrane structure was expected to be almost similar to that of PVC membrane which was supported by scanning electron microscope (SEM) micrographs. PVC membranes were impermeable to water up to a transmembrane pressure of 8?bar. Interestingly, adding TPU to PVC lowered the pressure at which the membrane showed permeability. Addition of 25?

Rheology and morphology study of immiscible linear low‐density polyethylene/poly (lactic acid) blends filled with nanosilica particles

Maryam Hoseini, Ali Haghtalab, Mohammad Hossein Navid Famili
Journal PapersJournal of Applied Polymer Science , Volume 134 , Issue 46, 2017 December 10, {Pages 45526 }

Abstract

The objectives of this study are to investigate the effect of silica nanoparticles on the morphology and rheological behavior of immiscible linear low‐density polyethylene/poly(lactic acid) (LLDPE/PLA) blends. Melt blending method is applied to prepare the blends and their nanocomposites. Scanning electron microscope and parallel plate rheometer were used to investigate morphology and rheological behavior of the blend nanocomposites. Scanning electron microscope results demonstrated a significant change in morphology behavior by incorporation of silica nanoparticles. A significant reduction in the PLA droplet for LLDPE/PLA (75/25) with 8 wt % silica was observed. The rheological studies illustrated that for all samples storage modulus an

Morphological Parameters in Relation to the Electromagnetic Properties of Microcellular Thermoplastic Polyurethane Foam in X-Band Frequency Ranges

Mohammad Hassan Moeini, Mohammad Hossein Navid Famili, Kayvan Forooraghi, Mazyar Soltani Alkouh, Mozafar Mokhtari Motameni Shirvan
Journal Papers̒Ulūm va Tiknuluzhī-i Pulīmir , Volume 30 , Issue 1, 2017 April , {Pages 19-30 }

Abstract

Vol. 30, No. 1, 19-30 April-May 2017 ISSN: 1016-3255 Online ISSN: 2008-0883 DOI: 10.22063/jipst. 2017.1459 microcellular foam, radar absorbing materials, thermoplastic polyurethane, foam morphology, electromagnetic properties

Modeling the rheological properties of highly nano-filled polymers

Hajir Kourki, Mehrzad Mortezaei, Mohammad Hossein Navid Famili, Milad Malekipirbazari
Journal PapersJournal of Composite Materials , Volume 51 , Issue 19, 2017 August , {Pages 2813-2824 }

Abstract

Organic and inorganic materials are usually added to polymers in order to achieve some benefits such as reducing the product cost, as well as achieving higher modulus and strength. Addition of these materials would change polymers’ behavior. Adding nano-materials to polymers on the other hand is a new challenge in the field of polymer composites where previous studies were unable to achieve good correlation with nano-composites at higher particle volume fractions. In this research, Yamamoto network theory is developed to investigate the behavior of highly nano-filled systems. For this purpose, five different types of sub-chain and two types of junctions are considered and the effect of particle size, concentration, and the model parameter

A REVIEW ON THE THERMODYNAMIC ASPECTS OF THERMOPLASTIC FOAMS

MOZAFFAR MOKHTARI, FAMILI MOHAMMAD HOSSEIN NAVID
Journal Papers , Volume 36 , Issue 300239, 2017 January 1, {Pages 20-Jan }

Abstract

Both physical and chemical foaming agents can be used in the two common methods for the production of polymeric foams. The physical foaming agent is dissolved in the polymer at a pressure and temperature beyond its critical condition. The foam structure is formed by a sudden pressure drop in the mixture in three steps; nucleation, growth, and coalescence. In the nucleation step, thermodynamic instability is formed in the mixture. This induces a tendency in the solvent molecules for a phase transition from a supersaturated state to a gas state in the direction of instability reduction. By overcoming the energy barrier, the free energy of the system is reduced and gas stable nuclei are formed in the free volumes of the polymer chains. Growth

Filler networking in the highly nanofilled systems

Hajir Kourki, Mehrzad Mortezaei, Mohammad Hossein Navid Famili
Journal PapersJournal of Thermoplastic Composite Materials , Volume 29 , Issue 8, 2016 August , {Pages 1047-1063 }

Abstract

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 i

Highly nanofilled polystyrene composite: Thermal and dynamic behavior

Hajir Kourki, Mohammad Hossein Navid Famili, Mehrzad Mortezaei, Milad Malekipirbazari, Mahdi Najjar Disfani
Journal PapersJournal of Elastomers & Plastics , Volume 48 , Issue 5, 2016 August , {Pages 404-425 }

Abstract

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 (Tg) 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 fr

Effect of Stabilization on Morphology Polystyrene and Supercritical Carbon Dioxide Thermoplastic Foams

Mozafar Mokhtari Motameni Shirvan, Mohammad Hossein Navid Famili
Journal Papers̒Ulūm va Tiknuluzhī-i Pulīmir , Volume 28 , Issue 6, 2016 January 1, {Pages 515 }

Abstract

Vol. 28, No. 6, 505-515 February-March 2016 ISSN: 1016-3255 Online ISSN: 2008-0883 thermoplastic microcellular foam, stabilization, temperature, foam morphology, nucleation

The relationship between electromagnetic absorption properties and cell structure of poly (methyl methacrylate)/multi-walled carbon nanotube composite foams

M Soltani Alkuh, MHN Famili, M Mokhtari Motameni Shirvan, MH Moeini
Journal PapersMaterials & Design , Volume 100 , 2016 June 15, {Pages 73-83 }

Abstract

The understanding of the effect of cell structure on the electromagnetic absorption properties can help to optimize foam structures for different applications. In this research, foams with different air volume percent, spherical and polygonal cell shapes, cell densities in the range of 104–1010?cell/cm3 and cell sizes ranging from 2.8 to 370.3?μm are produced using an automatic and controllable supercritical CO2 foaming system. The results showed that foaming of PMMA/MWCNT composites resulted in a 60% reduction in electromagnetic reflection and a 96% increase in specific electromagnetic absorption. The percolation threshold of foams with polygonal cell shape is found to occur at higher MWCNT loading than spherical cell shapes. Electromag

access deny [1428]

دروس نیمسال جاری

    access deny [1008]

دروس نیمسال قبل

    access deny [1009]
    access deny [1010]
    access deny [1263]

مهم

    access deny [1013]

جدید

    access deny [1012]