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Oxygen-barrier properties of poly(lactic acid)/poly(vinyl acetate-co-vinyl alcohol) blends as biodegradable films
, Article Journal of Applied Polymer Science ; Volume 125, Issue SUPPL. 2 , September , 2012 , Pages E20-E26 ; 00218995 (ISSN) ; Dadbin, S ; Frounchi, M ; Sharif University of Technology
Wiley
2012
Abstract
The oxygen-barrier properties of poly(lactic acid) (PLA)/poly(vinyl acetate-co-vinyl alcohol) [P(VAc-co-VA)] were investigated. P(VAc-co-VA)s with vinyl alcohol (VA) contents of 5, 10, and 15 mol % were prepared with the acid-catalyzed hydrolysis of poly(vinyl acetate). The obtained copolymers with various contents of VA were blended with PLA at 5/95, 10/90, and 15/85 compositions. Films of the blends were prepared by a solution-casting method with chloroform as the cosolvent. Although the blend with 5% VA in the copolymer appeared to be miscible, the blends with 10 and 15% VA content in the copolymer were immiscible, as verified by dynamic mechanical analysis. The oxygen-barrier properties...
Producing ultrafine-grained aluminum rods by cyclic forward-backward extrusion: Study the microstructures and mechanical properties
, Article Materials Letters ; Volume 74 , May , 2012 , Pages 147-150 ; 0167577X (ISSN) ; Zaeem, M. A ; Dehghani, K ; Shivaee, H. A ; Sharif University of Technology
2012
Abstract
A cyclic forward-backward extrusion (CFBE) process was used as a severe plastic deformation (SPD) technique to produce ultrafine-grained aluminum rods. Yield strength and tensile strength of the specimens increased by increasing the number of CFBE cycles, while elongation to break decreased due to an increase in the grain refinement and microhardness. According to transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) results, the average grain size was reduced from 120 μm to 315 nm after only 3 cycles of CFBE
Antioxidant, antifungal, water binding, and mechanical properties of poly(vinyl alcohol) film incorporated with essential oil as a potential wound dressing material
, Article Journal of Applied Polymer Science ; Vol. 131, issue. 20 , 2014 ; Nateghpoor, B ; Dadfar, S. M. M ; Dadfar, S. M. A ; Sharif University of Technology
Abstract
In this study, the properties of poly (vinyl alcohol)(PVA) films incorporated with Zataria multiflora essential oil (ZMO) as a potential antioxidant/antibacterial material was investigated. PVA films were prepared from PVA solutions (2% w/v) containing different concentrations of ZMO. Water solubility, moisture absorption, water swelling, and water vapor permeability for pure PVA films were 57 ± 1.1, 99 ± 3.2%, 337 ± 8%, and 0.453 ± 0.015 g mm/m2 h, respectively. Incorporation of ZMO into PVA films caused a significant decrease in water swelling and moisture absorption and increase in solubility and water vapor permeability. Tensile strength, elastic modulus, and elongation at break for pure...
Evaluating the effects of different plasticizers on mechanical properties of starch/ clay nanocomposites
, Article Advanced Materials Research ; Volume 829, 2014 , 2014 , Pages 279-283 ; ISSN: 10226680 ; ISBN: 9783037859070 ; Mousavi, S. M. A ; Emam Djomeh, Z ; Bagheri, R ; Sharif University of Technology
Abstract
Nano-biocomposites are a new class of hybrid materials composed of nano-sized filler (nanofiller) incorporated into a bio-based matrix. Such an association between eco-friendly biopolymers and nano-objects, with the aim to obtain synergic effects, is one of the most innovating routes to enhance the properties of these bio-matrices. In recent years, there has been an increasing interest in Starch as an inexpensive and renewable source has been used as a filler for environmentally friendly plastics for about two decades. However, the poor mechanical properties of starch based biopolymers, leads to use of nanoparticles as reinforcing materials. In the present study, the influence of a...
Production and characterization of UHMWPE/fumed silica nanocomposites
, Article Polymer Composites ; Volume 33, Issue 10 , 2012 , Pages 1858-1864 ; 02728397 (ISSN) ; Saremi, M. G ; Amoli, B. N ; Izadi, H ; Sharif University of Technology
Wiley
2012
Abstract
Ultrahigh-molecular-weight polyethylene (UHMWPE)/fumed silica nanocomposites were prepared via in situ polymerization using a bi-supported Ziegler-Natta catalytic system. Nanocomposites with different nanoparticle weight fractions were produced in order to investigate the effect of fumed silica on thermal and mechanical properties of UHMWPE/fumed silica nanocomposites. The viscosity average molecular weight (M) of all samples including pure UHMWPE as the reference sample and nanocomposites were measured. Scanning electron microscope (SEM) images showed the homogenous dispersion of nanoparticles throughout the UHMWPE matrix while no nanoparticle cluster has been formed. Crystallization...
Preparation of ethylene vinyl acetate copolymer/graphene oxide nanocomposite films via solution casting method and determination of the mechanical properties
, Article Polymer - Plastics Technology and Engineering ; Volume 54, Issue 2 , Jan , 2015 , Pages 218-222 ; 03602559 (ISSN) ; Sedaghat, S ; Ramazani S. A, A ; Baniasadi, H ; Sharif University of Technology
Taylor and Francis Inc
2015
Abstract
Ethylene vinyl acetate/graphene oxide (EVA/GO) nanocomposite films were prepared via solution casting method. The morphological studies investigated using SEM and XRD methods and the results confirmed the formation of likely exfoliation structures and good interaction between matrix and fillers. The results of permeability measurements showed that films have good resistance against oxygen. Mechanical measurements revealed that Young’s modulus and tensile strength of EVA have improved with introducing GO because of proper dispersion of GO into matrix and good interaction between them; however, elongation at break decreased due to formation of strong and rigid polymer/filler network preventing...
Effect of poly (propylene-g-maleic anhydride) on the morphological, rheological, and mechanical properties of PP/HDPE blend
, Article Journal of Thermoplastic Composite Materials ; Volume 22, Issue 5 , 2009 , Pages 519-530 ; 08927057 (ISSN) ; Abdi Valami, M ; Khak, M ; Sharif University of Technology
2009
Abstract
In this study, the morphological, rheological, and mechanical properties of PP/HDPE blend compatibilized with poly (propylene-g-maleic anhydride) were studied. Necessary blends were prepared using a counter current twin-screw extruder. The blend composition ranged from 10 to 50 wt% of dispersed phase (HDPE) and compatibilizer (MAPP) with two Concentration ranges 10, 20 wt% were used for PP/HDPE (80/20) blend with respect to the dispersed phase (HDPE). The results of morphological studies shows a droplet dispersion morphology in the composition to 50wt% HDPE content, which indicates that HDPE forms a dispersed phase and PP forms a continuous phase in these composition region. Addition of the...
In situ synthesized TiO2-polyurethane nanocomposite for bypass graft application: In vitro endothelialization and degradation
, Article Materials Science and Engineering C ; Volume 114 , May , 2020 ; Bagheri, R ; Pourjavadi, A ; Ghanbari, H ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
The in vitro endothelial response of human umbilical vein endothelial cells was investigated on a poly (caprolactone)-based polyurethane surface vs an in situ TiO2-polyurethane nanocomposite surface, which has been produced as scaffolds for artificial vascular graft. The in situ synthesis of TiO2 nanoparticles in polyurethane provided surface properties that facilitated cellular adhesion, cell sensing, cell probing and especially cell migration. Cells on the nanocomposite surface have elongated morphology and were able to produce more extracellular matrix. All of these advantages led to an increase in the rate of endothelialization of the nanocomposite scaffold surface vs pure polyurethane....
Mechanical performance of styrene-butadiene-rubber filled with carbon nanoparticles prepared by mechanical mixing
, Article Materials Science and Engineering A ; Volume 528, Issue 24 , September , 2011 , Pages 7161-7172 ; 09215093 (ISSN) ; Shojaei, A ; Sharif University of Technology
2011
Abstract
Reinforcement of styrene-butadiene-rubber (SBR) was investigated using two different carbon blacks (CBs) with similar particle sizes, including highly structured CB and conventional CB, as well as multi-walled carbon nanotube (MWCNT) prepared by mechanical mixing. The attempts were made to examine reinforcing mechanism of these two different classes of carbon nanoparticles. Scanning electron microscopy and electrical conductivity measurement were used to investigate morphology. Tensile, cyclic tensile and stress relaxation analyses were performed. A modified Halpin-Tsai model based on the concept of an equivalent composite particle, consisting of rubber bound, occluded rubber and...