Search for: polyesters
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    Synthesis, chemical and thermal characterization of poly(cis-2-butenylene oxalate) [electronic resource]

    , Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Volume 46, Issue 3-4, 2000 Pourdjavadi, A. (Ali) ; Zohuriaan-Mehr, M. J ; Rezai, N ; Sharif University of Technology
    A non-terminated, low molecular weight, highly crystalline, linear aliphatic polyester was successfully synthesized via ester-interchange polycondensation of cis-2-butene-1,4-diol and diethyl oxalate by using of lead (II) oxide as the catalyst. No decarboxylation occurred during the optimized polymerization. Structural and Chemical identification was performed by elemental analysis, FTIR, 'H-NMR, and Mass spectroscopy. Some macrocyle species were detected in the product, according to GPC. Fragmentation patterns were suggested for the main m/e's of the mass spectrum. Thermal characterization was performed by DSC and TGA. It was found that the overall thermal stability of the polyester is... 

    GMR in multilayered nanowires electrodeposited in track-etched polyester and polycarbonate membranes

    , Article Journal of Magnetism and Magnetic Materials ; Volume 308, Issue 1 , 2007 , Pages 35-39 ; 03048853 (ISSN) Nasirpouri, F ; Southern, P ; Ghorbani, M ; Iraji zad, A ; Schwarzacher, W ; Sharif University of Technology
    Commercially available track-etched polyester membranes were used as templates to electrodeposit Co-Ni-Cu/Cu multilayered nanowires, giving room-temperature current perpendicular to plane (CPP) giant magnetoresistance (GMR) values of up to ∼12%. In contrast to similar nanowires electrodeposited in track-etched polycarbonate membranes, the GMR obtained in multilayered nanowires electrodeposited in the polyester membranes increased with decreasing Cu-layer thickness tCu, for tCu in the 2-7 nm range, indicating a lack of ferromagnetic coupling through pinholes, etc. Transmission electron micrographs showed clear evidence for smooth, parallel layer interfaces in the nanowires. © 2006 Elsevier... 

    Morphology development and mechanical properties of unsaturated polyester resin containing nanodiamonds

    , Article Polymer International ; Volume 66, Issue 6 , 2017 , Pages 950-959 ; 09598103 (ISSN) Hashemi, M ; Shojaei, A ; Sharif University of Technology
    Unsaturated polyester/styrene (UP) resin was filled with nanodiamonds (NDs) containing carboxyl and methacrylate functionalities using mechanical mixing. Field emission SEM exhibited a uniform dispersion of tightly bound aggregates of nanosized spherical NDs with good interfacial interaction. Rheological measurements exhibited a step increment in the shear viscosity of a UP/ND suspension at 0.6 wt% ND resembling a percolation state at this loading. Shear viscosity data supported by dynamic mechanical analysis results suggested the development of effective ND particles in which ND aggregates were covered by only polyester macromolecules. Accordingly, the morphology of UP/ND composites... 

    Preparation and Characterization of Unsaturated Polyester Resin/Nanodiamond Nanocomposites

    , M.Sc. Thesis Sharif University of Technology Hashemi, Mohammad Jafar (Author) ; Shojaei, Akbar (Supervisor)
    In recent decades, nano-structured materials have been allocated specific position for wide use in various fields. The nano-diamonds has attracted the attention of many researchers. The inherent characteristics of a diamond like spherical structure of nanoparticles and carbon atoms which have used their full capacity in the chemical bonds,also the same surface as the radiography particles which have empty orbital, provides an ability to perform a variety of surface modification on the particle . This article introduces the nanocomposites based on polymer, constituents specification and discuss properties of nanocomposites after mixing components together. Lots of studies was on... 

    A new homologous series of linear aliphatic unsaturated hydroxypolyesters a polyol soft segments for polyurethanes: Synthesis and characterization [electronic resource]

    , Article Journal of Applied Polymer Science ; Volume 68, Issue 2, pages 173–183, 11 April 1998 Pourdjavadi, A. (Ali) ; Rezai, Nasrin ; Zohurian, M. J ; Sharif University of Technology
    Synthesis and characterization of a new series of low molecular weight (MW = 500–3000) OH-terminated linear aliphatic unsaturated polyesters based on cis-2-butene-1,4-diol and oxalic to sebacic acid were investigated. Direct polycondensation and transesterification methods were used for the syntheses. The latter was recognized to be the preferable method due to its lower reaction temperature and time, lower diol/diacid ratio, absence of decarboxylation, and formation of a product with low polydispersity (Mw/Mn = 1.3–2.7). Elemental analysis, GPC, FTIR, 1H-NMR, DSC, and WAXD were used for the investigations. A segmented polyurethane based on poly (cis-2-butylene adipate) glycol was also... 

    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... 

    Enhancing seebeck coefficient and electrical conductivity of polyaniline/carbon nanotube–coated thermoelectric fabric

    , Article Journal of Industrial Textiles ; 2021 ; 15280837 (ISSN) Amirabad, R ; Ramazani Saadatabadi, A ; Pourjahanbakhsh, M ; Siadati, M. H ; Sharif University of Technology
    SAGE Publications Ltd  2021
    In this work, flexible thermoelectric fabrics, polyester/yarn fabrics coated with polyaniline/carbon nanotube (PANI/CNT) nanocomposite, were fabricated by sequential processing: (I) polyaniline/carbon nanotube nanocomposites preparation by a one-step in-situ polymerization and (II) dip coating of a mixture solution of CNT-doped PANI on a polyester/yarn fabric. Nanocomposites were synthesized with various CNT content (0.5, 2.5, 5, and 10 wt%) and characterized using different methods. The Seebeck coefficient and electrical conductivity measurements were used to determine their thermoelectric properties. The results revealed significant improvement in both electrical conductivity and the... 

    A comprehensive study on the fabrication and properties of biocomposites of poly(lactic acid)/ceramics for bone tissue engineering

    , Article Materials Science and Engineering C ; Volume 70 , 2017 , Pages 897-912 ; 09284931 (ISSN) Tajbakhsh, S ; Hajiali, F ; Sharif University of Technology
    Elsevier Ltd  2017
    The fabrication of a suitable scaffold material is one of the major challenges for bone tissue engineering. Poly(lactic acid) (PLA) is one of the most favorable matrix materials in bone tissue engineering owing to its biocompatibility and biodegradability. However, PLA suffers from some shortcomings including low degradation rate, low cell adhesion caused by its hydrophobic property, and inflammatory reactions in vivo due to its degradation product, lactic acid. Therefore, the incorporation of bioactive reinforcements is considered as a powerful method to improve the properties of PLA. This review presents a comprehensive study on recent advances in the synthesis of PLA-based biocomposites... 

    Nano reengineering of horseradish peroxidase with dendritic macromolecules for stability enhancement

    , Article Enzyme and Microbial Technology ; Volume 50, Issue 1 , 2012 , Pages 10-16 ; 01410229 (ISSN) Khosravi, A ; Vossoughi, M ; Shahrokhian, S ; Alemzadeh, I ; Sharif University of Technology
    A simple bio-conjugation procedure to surround a single horseradish peroxidase (HRP) enzyme molecule with dendritic polyester macromolecules (polyester-32-hydroxyl-1-carboxyl bis-MPA dendron, generation 5) was proposed. The characterization of resultant nanoparticles entitled HRP dendrozyme, was performed by transmission electron microscopy, dynamic light scattering, gel permeation chromatography and Fourier transform infrared spectroscopy. The results showed that HRP nanoparticles were spherical in shape and have an average size of 14 ± 2. nm in diameter. Furthermore, bio-conformational characterization of HRP dendrozyme was performed by means of circular dichroism and fluorescence... 

    The impact of morphology on thermal properties and aerobic biodegradation of physically compatibilized poly (lactic acid)/co-plasticized thermoplastic starch blends

    , Article Polymers for Advanced Technologies ; Volume 29, Issue 12 , 2018 , Pages 2880-2889 ; 10427147 (ISSN) Esmaeili, M ; Pircheraghi, G ; Bagheri, R ; Altstädt, V ; Sharif University of Technology
    John Wiley and Sons Ltd  2018
    Recently, the use of biodegradable polymers became the applicable solution to reduce the environmental concerns, which are created by plastic wastes as well as restrictions of petroleum-based synthetic polymers. By this point of view, polylactic acid (PLA) as a biodegradable and bio-based polymer is resolving both aforementioned issues. While, the high cost of PLA and its slow biodegradation rate make researchers to blend it with a faster one, for instance, thermoplastic starch (TPS). Adding TPS into PLA can influence on the morphological structure, thermal stability, and biodegradability. In this study, the well-tuned co-plasticized TPS via sorbitol/glycerol mixture was melt mixed with PLA... 

    Gamma irradiated electro-conductive polylactic acid/polyaniline nanofibers

    , Article Synthetic Metals ; Volume 259 , 2020 Ashraf, S. S ; Frounchi, M ; Dadbin, S ; Sharif University of Technology
    Elsevier Ltd  2020
    In this study, polyaniline nanoparticles (PANI NPs) in emeraldine base (EB) form were prepared by a modified method and characterized by FTIR and UV–vis spectroscopies. The average size of the nanoparticles was 140 nm measured by DLS method. The nanoparticles were embedded into polylactic acid (PLA) nanofibers prepared by electrospinning method. It was found that inclusion of PANI NPs in PLA resulted in reduced diameter of the fibers during the electrospinning process. Also, the surface of nanofibers appeared smooth in FE-SEM images without formation of beads. Improvement in mechanical and electrical properties of PLA/PANI nanofibers over the neat PLA nanofibers implied a good dispersion of... 

    Synthesis and characterization of biodegradable acrylated polyurethane based on poly(ε-caprolactone) and 1,6-hexamethylene diisocyanate

    , Article Materials Science and Engineering C ; Vol. 42 , 2014 , pp. 763-773 ; ISSN: 09284931 Alishiri, M ; Shojaei, A ; Abdekhodaie, M. J ; Yeganeh, H ; Sharif University of Technology
    A series of biodegradable acrylic terminated polyurethanes (APUs) based on poly(ε-caprolactone) diol (PCL), aliphatic 1,6-hexamethylene diisocyanate (HDI) and hydroxyethyl methyl acrylate (HEMA) was synthesized as potential materials for hard tissue biomedical applications. PCLs with low molecular weights of 1000 and 2000 g/mol were employed to provide different amounts of end capped urethane acrylate in APUs. To control crosslink density, a mixture of two different reactive diluents including mono-functional HEMA and bi-functional ethylene glycol dimethacrylate (EGDMA) with different weight ratios was incorporated into the APUs, called here PUAs. Morphological characteristics and mechanical... 

    Utilization of molecular dynamics simulation coupled with experimental assays to optimize biocompatibility of an electrospun PCL/PVA scaffold

    , Article PLoS ONE ; Volume 12, Issue 1 , 2017 ; 19326203 (ISSN) Sarmadi, M ; Shamloo, A ; Mohseni, M ; Sharif University of Technology
    Public Library of Science  2017
    The main focus of this study is to address the possibility of using molecular dynamics (MD) simulation, as a computational framework, coupled with experimental assays, to optimize composite structures of a particular electrospun scaffold. To this aim, first, MD simulations were performed to obtain an initial theoretical insight into the capability of heterogeneous surfaces for protein adsorption. The surfaces were composed of six different blends of PVA (polyvinyl alcohol) and PCL (polycaprolactone) with completely unlike hydrophobicity. Next, MTT assay was performed on the electrospun scaffolds made from the same percentages of polymers as in MD models to gain an understanding of the... 

    Thermal resistance, tensile properties, and gamma radiation shielding performance of unsaturated polyester/nanoclay/PbO composites

    , Article Radiation Physics and Chemistry ; Volume 146 , 2018 , Pages 5-10 ; 0969806X (ISSN) Bagheri, K ; Razavi, M ; Ahmadi, J ; Kosari, M ; Abolghasemi, H ; Sharif University of Technology
    Elsevier Ltd  2018
    Composites of unsaturated polyester containing 5 wt% nanoclay and different amounts of lead monoxide particles (0, 10, 20, and 30 wt%) were prepared. XRD patterns showed the exfoliation of nanoclay layers in the polymer. Morphological properties of the composites were studied using SEM micrographs. The prepared composites were investigated for their thermal resistance and mechanical properties using thermogravimetric analysis and tensile testing method, respectively. Addition of lead monoxide to the polymer worsened its thermal resistance and tensile properties, whereas the observed negative effects could be moderated by the clay nanoparticle. Gamma attenuation performance of the composites... 

    An innovative high performance pervious concrete with polyester and epoxy resins

    , Article Construction and Building Materials ; Volume 228 , 2019 ; 09500618 (ISSN) Tabatabaeian, M ; Khaloo, A ; Khaloo, H ; Sharif University of Technology
    Elsevier Ltd  2019
    Pervious concrete (PC) has been detecting application in pavement and concrete structures such as dams, small retaining walls, and etc during the past decades. Also, in recent years, the types of resins have been introduced to apply in concrete owing to the enhancing in mechanical and durability characteristics. However, few studies have investigated the mechanical behavior of high performance pervious concrete (HPPC) incorporated by polyester and epoxy resins as polymeric composites, where ordinary cement material has been completely deleted. The purpose of this investigation is to compare the mechanical properties, permeability, and durability of HPPCs made by polymeric composites (i.e.... 

    Fabrication and characterization of core-shell electrospun fibrous mats containing medicinal herbs for wound healing and skin tissue engineering

    , Article Marine Drugs ; Volume 17, Issue 1 , 2019 ; 16603397 (ISSN) Zahedi, E ; Esmaeili, A ; Eslahi, N ; Shokrgozar, M. A ; Simchi, A ; Sharif University of Technology
    MDPI AG  2019
    Nanofibrous structures mimicking the native extracellular matrix have attracted considerable attention for biomedical applications. The present study aims to design and produce drug-eluting core-shell fibrous scaffolds for wound healing and skin tissue engineering. Aloe vera extracts were encapsulated inside polymer fibers containing chitosan, polycaprolactone, and keratin using the co-axial electrospinning technique. Electron microscopic studies show that continuous and uniform fibers with an average diameter of 209 ± 47 nm were successfully fabricated. The fibers have a core-shell structure with a shell thickness of about 90 nm, as confirmed by transmission electron microscopy. By... 

    In vitro study of hydroxyapatite/polycaprolactone (HA/PCL) nanocomposite synthesized by an in situ sol-gel process

    , Article Materials Science and Engineering C ; Volume 33, Issue 1 , 2013 , Pages 390-396 ; 09284931 (ISSN) Rezaei, A ; Mohammadi, M. R ; Sharif University of Technology
    Hydroxyapatite (HA) is the most substantial mineral constituent of a bone which has been extensively used in medicine as implantable materials, owing to its good biocompatibility, bioactivity high osteoconductive, and/or osteoinductive properties. Nevertheless, its mechanical property is not utmost appropriate for a bone substitution. Therefore, a composite consist of HA and a biodegradable polymer is usually prepared to generate an apt bone scaffold. In the present work polycaprolactone (PCL), a newly remarkable biocompatible and biodegradable polymer, was employed as a matrix and hydroxyapatite nanoparticles were used as a reinforcement element of the composite. HA/PCL nanocomposites were... 

    Fabrication of chitosan/poly(lactic acid)/graphene oxide/TiO2 composite nanofibrous scaffolds for sustained delivery of doxorubicin and treatment of lung cancer

    , Article International Journal of Biological Macromolecules ; Volume 110 , 2018 , Pages 416-424 ; 01418130 (ISSN) Samadi, S ; Moradkhani, M ; Beheshti, H ; Irani, M ; Aliabadi, M ; Sharif University of Technology
    Elsevier B.V  2018
    In this work, the synthesized graphene oxide/TiO2/doxorubicin (GO/TiO2/DOX) composites were loaded into the chitosan/poly(lactic acid) (PLA) solutions to fabricate the electrospun chitosan/PLA/GO/TiO2/DOX nanofibrous scaffolds via electrospinning process. The synthesized composites and nanofibers were characterized using X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. Three-factor three-level central composite design was used to determine the influence of PLA to chitosan ratio, TiO2/DOX content and GO/TiO2/DOX content on the release of DOX from nanofibrous scaffolds. Drug loading efficiency and drug release behavior from... 

    Accelerated full-thickness wound healing via sustained bFGF delivery based on a PVA/chitosan/gelatin hydrogel incorporating PCL microspheres

    , Article International Journal of Pharmaceutics ; Volume 537, Issue 1-2 , 2018 , Pages 278-289 ; 03785173 (ISSN) Shamloo, A ; Sarmadi, M ; Aghababaie, Z ; Vossoughi, M ; Sharif University of Technology
    Elsevier B.V  2018
    Herein, a hybrid hydrogel/microsphere system is introduced for accelerated wound healing by sustained release of basic fibroblast growth factor (bFGF). The hydrogel is composed of a mixture of PVA, gelatin and chitosan. The double-emulsion-solvent-evaporation method was utilized to obtain microspheres composed of PCL, as the organic phase, and PVA, as the aqueous phase. Subsequently, various in-vitro and in-vivo assays were performed to characterize the system. BSA was used to optimize the release mechanism, and encapsulation efficiency in microspheres, where a combination of 3% (w/v) PCL and 1% (w/v) PVA was found to be the optimum microsphere sample. Incorporation of microspheres within... 

    Fabrication and evaluation of a bilayer hydrogel-electrospinning scaffold prepared by the freeze-gelation method

    , Article Journal of Biomechanics ; Volume 98 , 2020 Kamali, A ; Shamloo, A ; Sharif University of Technology
    Elsevier Ltd  2020
    This study presents a bilayer structure as a skin scaffold comprised of an electrospun sheet layer made of polycaprolactone and polyvinil alcohol and a porous hydrogel layer made of chitosan and gelatin. The hydrogel layer was fabricated by employing the freeze-gelation technique. The bilayer structure was achieved by pouring the hydrogel solution on the electrospun sheet at the bottom of a mold followed by the freeze-gelation technique to obtain a porous structure in the hydrogel. The hydrogel and hydrogel-electrospun samples were characterized by scanning electron microscopy, swelling, tensile strength, in vitro and in vivo analyses. From a mechanical strength standpoint, the combination...