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Hossein Roghani‐Mamaqani Vahid Haddadi‐Asl Mohammad Najafi Mehdi Salami‐Kalajahi Mohammad Najafi Mehdi Salami‐Kalajahi 《American Institute of Chemical Engineers》2011,57(7):1873-1881
Tailor‐made polystyrene nanocomposite with mixed free and clay‐attached polystyrene chains was synthesized using atom transfer radical polymerization. Vinylbenzyl trimethylammonium chloride having a double bond, which could be incorporated into polystyrene chains by a grafting through process, was used as a nanoclay modifier. Conversion and molecular weight evaluation was carried out using gas chromatography and gel permeation chromatography, respectively. The thermogravimetric analysis results confirmed the elevated thermal stability of the nanocomposites in comparison with the neat polystyrene sample. Additionally, the Tg increases by clay loading was confirmed by differential scanning calorimetry (DSC). The difference in the degradation temperature of C? Br bond in attached and free polystyrene chains was well revealed in DSC thermograms. Finally, a lower clay loading resulted in an exfoliated structure as proved by X‐ray diffraction and transmission electron microscopy results. © 2010 American Institute of Chemical Engineers AIChE J, 2011 相似文献
23.
Seyed‐Ataollah Mirshafiei‐Langari Vahid Haddadi‐Asl Hossein Roghani‐Mamaqani Masoud Sobani Khezrollah Khezri 《Polymer Composites》2013,34(10):1648-1654
Polystyrene nanocomposite with mixed free and anchored chains was synthesized by atom transfer radical polymerization. Attachment of 3‐(trimethoxysilyl)propyl methacrylate with a double bond on the nanoporous silica aerogel surface results in a double bond grafted silica aerogel which could be incorporated into the polystyrene chains by a grafting‐through process. Conversion and molecular weight evaluation was carried out using gas chromatography and gel permeation chromatography, respectively. Double bond containing silica aerogel has an inconsiderable effect on conversion. There is no considerable discrepancy between the molecular weights of the free and anchored chains. Addition of silica aerogel with pendant CC bonds leads to increase of apparent rate constant of polymerization and also molecular weights. This is mainly because of initiator trapping in silica aerogel pores. Every percent of double bond containing silica aerogel with respect to styrene results in trapping of about 0.08 mol of ethyl alpha‐bromoisobutyrate among the silica pores. POLYM. COMPOS., 34:1648–1654, 2013. © 2013 Society of Plastics Engineers 相似文献
24.
An attempt was made to prepare polyvinyl chloride (PVC)/thermosetting polyurethane (PU) blends via direct formation of the thermosetting minor phase from its reactants during blending into PVC. Chemorheological approaches were employed in order to investigate the formation reaction of PU. The results of chemorheological analyses were utilized to adjust appropriate reactive blending temperature. PVC/PU reactive blending process was carried out in a laboratory internal mixer. PVC and PU reactive mixture were fed into the internal mixer using two different feed orders. In the first method, porous particles of PVC and liquid mixture of PU monomers were premixed in a high-speed mixer at ambient temperature. The blending was then followed by processing the prepared paste in the preheated internal mixer. In the second method, PVC was loaded into the internal mixer. Afterward, PU reactive compound was introduced into the PVC after torque equilibrium. For both feed orders, the PU content of blends and rotor speed were among parameters studied. The mechanical properties of PVC/PU blends prepared by reactive blending and pure PVC showed that incorporation of PU elastomer into PVC through the proposed reactive blending technique resulted in an increase in the elongation at break and toughness of the brittle PVC. 相似文献
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Roya Mohammadzadeh Kakhki Samira Hedayat Fatemeh Ahsani 《Journal of Inorganic and Organometallic Polymers and Materials》2018,28(6):2264-2274
In this paper Co3O4 doped nanoclinoptilolite was synthesized and characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDX) techniques. The adsorption efficiency for removing of methylene blue was about 95% in 10 min. The effect of some factors such as adsorbent dose, concentration of analyte and pH was investigated for enhancing the removing efficiency. Moreover Freundlich and Langmuir patterns were plotted for this new nanocomposite. Maximum of adsorption capacity was obtained from slope of Langmuir and was about 25 mg/g. The kinetic study for methylene blue shows a second order kinetic with rate constant about 0.02 g/mg/min. The prepared nanocomposite was successfully applied for removing some color compounds such as methylene blue, methyl green, and methyl red and also binary dye mixtures. 相似文献
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The overall efficiency of photovoltaic (PV) systems connected to the grid depends on the efficiency of direct current (DC) of the solar modules to alternate current (AC) inverter conversion. The requirements for inverter connection include: maximum power point, high efficiency, control power injected into the grid, high power factor and low total harmonic distortion of the currents injected into the grid. An approach to power factor control and reactive power regulation for PV systems connected to the grid using field programmable gate array (FPGA) is proposed. According to the grid demands; both the injected active and reactive powers are controlled.In this paper, a new digital control strategy for a single-phase inverter is carried out. This control strategy is based on the phase shift between the inverter output voltage and the grid voltage, and the digital sinusoidal pulse width modulation (DSPWM) patterns, in order to control the power factor for a wide range of the inverter output current and consequently the control and the regulation of the reactive power will be achieved. The advantage of the proposed control strategy is its implementation around simple digital circuits.In this work, a simulation study of this strategy has been realized using Matlab/Simulink and PSIM. In order to validate its performance, this control has been implemented in a FPGA. Experimental tests have been carried out demonstrating the viability of this control in order to control the power factor and the injected power into the grid. 相似文献
29.
Koopialipoor Mohammadreza Murlidhar Bhatawdekar Ramesh Hedayat Ahmadreza Armaghani Danial Jahed Gordan Behrouz Mohamad Edy Tonnizam 《Engineering with Computers》2020,36(1):283-294
Engineering with Computers - The stability of retaining walls against overturning is analyzed in this study using artificial intelligence methods. Five input parameters including wall height, wall... 相似文献
30.
Ali Zockaie Hedayat Z. Aashtiani Mehrnaz Ghamami Yu Nie 《Computer-Aided Civil and Infrastructure Engineering》2016,31(2):132-144
This article studies the problem of locating fuel stations to minimize the extra cost spent in refueling detours, which belongs to a class of discretionary service facility location problems. Unlike many studies of similar problems in the literature, the proposed model considers capacity constraints and compares different ways to incorporate them in the formulation. Note that ignoring the capacity constraint results in nonoptimal and unrealistic solutions. The proposed models are solved using both an off‐the‐shelf solver (CPLEX) and a specialized meta‐heuristic method (Simulated Annealing) developed in this study. The solution methods are tested and compared in two case studies; a test benchmark network and a large‐scale network. An effort to overcome the memory limitation of CPLEX through more compact formulation was partially successful: it results in a model that is less tightly bounded by its linear relaxation and hence is much more difficult to solve. In contrast, the Simulated Annealing algorithm scales better and is able to consistently yield high‐quality solutions with a reasonable amount of computation time. 相似文献