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Rostami M.,Amirkabir University of Technology | Mohseni M.,Amirkabir University of Technology | Ranjbar Z.,Institute for Colorants
Pigment and Resin Technology | Year: 2011

Purpose - The purpose of this paper is to investigate the effect of different PHS on the surface chemistry of fumed silica treated with aminopropyltrimethoxysilane (APTMS). Design/methodology/approach - The reaction conditions involved variation of pH ranging from acidic to alkaline. Different analytical techniques including FT-IR spectroscopy, thermogravimetric analysis (TGA), CHN and Zeta potential analyses were employed to investigate the surface chemistry of treated particles. In addition, the stability of silanised silica dispersions were studied using turbidimetric and rheometric measurements. Findings - It was revealed that in all conditions silica was more or less chemically grafted by the silane. When the pH of treating bath was adjusted to 1-2 prior and during the reaction, 58 percent grafting was observed, as obtained by CHN and TGA analyses. At very alkaline conditions, however, the grafting content declined to 29 percent. The variations in grafting were dependent on the silane hydrolysis and its further condensation with the silica surface. Zeta potential measurements showed a drastic change from -27.1 mv to +18.01 mv (at pH 7) for the untreated particle and the one with the highest grafting, respectively. The dispersion stability of differently treated particles varied in solvents with different Hansen solubility parameters (HSP). Moreover, due to the variations of surface chemistry of particles, their rheological behaviours were significantly influenced. Originality/value - The results obtained in this work showed that the surface chemistry of fume silica could be tuned with treating method. The highest content of grafting led to a better dispersion in solvents having greater hydrogen bonding component and to an inferior dispersion in solvents with higher polar component. © Emerald Group Publishing Limited.


Zamani Ketek Lahijania Y.,Amirkabir University of Technology | Mohseni M.,Amirkabir University of Technology | Bastani S.,Institute for Colorants
Tribology International | Year: 2014

This work describes the mechanical behavior of different nanocomposite films containing non-treated and silane treated nanosilica loaded into a UV cured urethane acrylate resin. Nanoindentation, nanoscratch, micro-hardness and dynamic mechanical thermal analysis were utilized to assess the coatings. It was demonstrated that the surface treated nanoparticles had stronger interfacial interaction with the polymeric matrix and had improved storage modulus. Nanoindentation and microindentation results suggested that a homogenous reinforced structure was formed in the bulk and surface of hybrid coatings filled with treated nanosilica. This resulted in films with high abrasion resistance. © 2013 Elsevier Ltd.


Rostami M.,Amirkabir University of Technology | Rostami M.,Institute for Colorants | Mohseni M.,Amirkabir University of Technology | Ranjbar Z.,Institute for Colorants
International Journal of Adhesion and Adhesives | Year: 2012

Surface treatment of nanosilicas with silane coupling agents is a common method by which the interfacial interaction of these particles can be enhanced. This is because of interactions taking place between the silane and silica, as well as the interactions between the organic part of the silane with the polymeric matrix. Therefore, interfacial interaction of silane grafted silica plays a key role to ensure a better reinforcing effect. The present work is an attempt to quantitatively predict the interfacial bonding strength between differently amino silane treated nanosilicas and a polyurethane coating matrix. This was based on the data deduced from tensile strength and dynamic mechanical thermal (DMTA) experiments of differently loaded untreated and treated nanosilicas loaded films. Using a predefined linear model taking into account the yield stresses of the particle loaded polyurethane and that of the matrix itself, an interaction bonding strength parameter was obtained. It was shown that this parameter was directly proportional to the amino silane content on nanosilica. However, for higher loadings of silicas the model best fit the data deviated from linearity and obeyed a second order equation, in which the second power term attributing the extent of interfacial strength was systematically increased. These results were in good agreement with the storage modulus and glass transition temperature values revealed by DMTA analysis. © 2012 Elsevier Ltd. All rights reserved.


Yahyaei H.,Amirkabir University of Technology | Mohseni M.,Amirkabir University of Technology | Bastani S.,Institute for Colorants
Journal of Sol-Gel Science and Technology | Year: 2011

This work aims at studying the abrasion resistance of differently formulated organic-inorganic hybrid coatings prepared by sol-gel method. The organic phase contained UV curable urethane acrylate oligomers and monomers having different functionalities. The inorganic phase was composed of tetraethyl orthosilicate (TEOS) and 3-methacryloxy propyltrimethoxy silane (MEMO). Through a Taguchi experimental design, the impact of influencing parameters such as molar ratio of precursors, hydrolysis ratio (R), post-curing temperature, post-curing time and weight percentage of inorganic to organic part were investigated. Very high transparency of hybrid coatings indicated that nano sized inorganic phase had formed. MEMO could facilitate the connection of two phases, preventing macro phase separation. However, high levels of MEMO lead to 'defect structure' in silica network as well as to decreased transparency and mechanical properties. The optimum condition in which highly transparent films with great abrasion resistance occurred was observed at equimolar ratio of water to alkoxide and TEOS: MEMO ratio being unity. Statistical analysis revealed that thermal post-curing was not significantly important. © 2011 Springer Science+Business Media, LLC.


Ferdosian F.,Amirkabir University of Technology | Ebrahimi M.,Amirkabir University of Technology | Jannesari A.,Institute for Colorants
Thermochimica Acta | Year: 2013

The curing behavior and kinetics of epoxy nanocomposites based on solid epoxy, diaminodiphenylmethane (DDM) and nano organoclay were studied. The curing kinetics of epoxy nanocomposites waselucidated by non-isothermal differential scanning calorimetry. The fitting model was used to calculatethe kinetic parameters. The kinetics of the curing reaction was also evaluated by two different isoconver-sional models. The kinetic parameters calculated from fitting model were almost the same for neat epoxysystem and nanocomposite systems indicating that the curing kinetics was not affected by the presenceof nanoclay particles. However, the isoconversional models showed that the incorporation of nanoclayparticles into the epoxy/DDM system had a significant effect on the trend of activation energy during thecuring process. Therefore, it can be concluded that using isoconversional models would be a preferredmethod to elaborate the effect of nanoparticles on the curing mechanism of nanocomposite systems. © 2013 Elsevier B.V. All rights reserved.


Salavati-Niasari M.,University of Kashan | Javidi J.,University of Kashan | Davar F.,University of Kashan | Fazl A.A.,Institute for Colorants
Journal of Alloys and Compounds | Year: 2010

Dysprosium carbonates nanoparticles were synthesized by the reaction of Dy(CH3COO)36H2O and sodium hydroxide by a sonochemical method. Dysprosium oxide nanoparticles with average size about 12nm were prepared from calcination of Dy2(CO3) 3xH2O nanoparticles. Dy(OH)3 nanoparticles were synthesized by facial hydrothermal processing from Dy2O3 nanoparticles. The as-synthesized nanoparticles were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), X-ray photoelectron spectrum (XPS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and photoluminescence (PL). The PL result showed one broad emission band centered at 390 nm (λex = 300nm) of the pure Dy2O3 nanoparticles. The role of surfactant, calcination temperature and sonication time were investigated on the morphology and particle size of the products. © 2010 Elsevier B.V. All rights reserved.


Gharagozlou M.,Institute for Colorants | Ganjkhanlou Y.,Iranian Materials and Energy Research Center
Micro and Nano Letters | Year: 2012

In the current work, titanium dioxide and iron-doped titanium dioxide (0-3) nanocrystals were prepared with the Pechini-type sol-gel method. The same procedure as well as spin-coating technique was applied for preparation of thin films. The prepared samples were characterised by X-ray diffractometery (XRD) and X-ray photoelectron spectroscopy techniques. The crystallographic and microstructural parameters of nanopowders were refined from XRD patterns utilising the Rietveld refinement method. It was found that with incorporation of iron in TiO2 structure, a highly distorted brookite phase was generated and the amount of anatase phase was decreased. The rutile phase disappeared with addition of iron; however, in higher concentration of iron (3), it reappeared. The results also indicate that the crystallite size of brookite phase as well as microstrain of anatase and brookite phases were amplified with iron doping. The results of the photocatalytic test of prepared thin films are in agreement with the prediction of photocatalytic activity of samples based on their phase's constituents and structure. © 2012 The Institution of Engineering and Technology.


Zori M.H.,Institute for Colorants
Journal of Inorganic and Organometallic Polymers and Materials | Year: 2011

In this work, TiO 2 nanoparticles were prepared by microemulsion (ME)/heat treated method and its photodecomposition property of methylene blue. Microemulsion (ME) consisted of water, cyclohexane and an anionic surfactant such as bis (2-ethylhexyl) sodium sulfosuccinate (AOT). Titanium tetraisopropoxide (TTIP) was dropped into the ME solution and then then TiO 2 nanoparticles were formed by the hydrolysis reaction between TTIP in the organic solvent and the water in the core of ME. The smallest diameter of the particles was 20 nm in the system of cyclohexane with surfactant when the molar ratio of water to surfactant was 2. The effect of the process parameters (water/surfactant ratio, different temperatures) on the final characteristics has been investigated, in terms of structural phase and particle size. The TiO 2 nanoparticles were characterized by means of X-ray diffraction, Transmission and scanning electron microscopy, Fourier-Transformed infrared and differential thermal analysis. TiO 2 nanoparticles prepared in this condition were collected as amorphous powder, and converted to anatase phase at less than 350 °C, which is lower than the ordinal phase transition temperature. The crystallite size and crystallinity increase with an increase of heat treated s temperature. The particles are shown to have a spherical shape and have a uniform size distribution. The size of nanoparticles raises with an increase of water/surfactant ratio. In the photocatalytic decomposition of methylene blue, the photocatalytic activity is mainly determined by the crystallinity of TiO 2. In addition, the TiO 2 heat treated at 350 °C shows the highest activity on the photocatalytic decomposition of methylene blue (k = 1.7 × 10 -2 min -1). © 2010 Springer Science+Business Media, LLC.


Nourmohammadian F.,Institute for Colorants | Gholami M.D.,Institute for Colorants
Synthetic Communications | Year: 2010

To one pot synthesis of coumarins with benzimidazol or benzoxazol moieties, three different microwave irradiations based procedures are reported here which take place within a few minutes. In spite of fairly well yield of the products using solvent free procedures, 25-30% further yields were achieved within 3 minutes at 110C using 2mL n-pentanol as solvent.


Sobhani S.,Institute for Colorants | Jannesari A.,Institute for Colorants | Bastani S.,Institute for Colorants
Journal of Applied Polymer Science | Year: 2012

To achieve a stable blend of a bisphenol A type epoxy resin and poly(dimethylsiloxane) (PDMS), reaction between hydroxyl (OH) groups of the epoxy and silanol groups of hydroxyl-terminated(HT) PDMS has been investigated. The chemical structures of the HTPDMS-modified epoxies were characterized by Fourier transform infrared (FTIR) and 1H- and 13C-NMR spectroscopy. To allow further understanding of the influence of viscosity and content of HTPDMS on the blend morphology, four different viscosities of HTPDMS were used in three content levels. The morphologies of modified epoxy resins were observed with optical microscopy. The modified epoxies were cured with a cycloaliphatic polyamine. The morphologies of modified epoxies were investigated by using scanning electron microscopy (SEM)/energy dispersive X-ray (EDX) technique. The cured films showed droplet in matrix morphology with different mean droplets size which was influenced by the viscosity and the content of the incorporated HTPDMS. To illustrate the effect of the morphologies of the cured samples on mechanical properties, tensile strength tests were performed. The introduction of HTPDMS into the epoxy altered the tensile behavior according to its viscosity and content. Surface properties of the cured films were evaluated by sessile drop method. The results clearly indicate that the hydrophilic surface of the epoxy turns to a hydrophobic one due to the modification with HTPDMS. © 2011 Wiley Periodicals, Inc.

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