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141.
142.
Synthesis and architecture study of a reactive polybutadiene polyamine as a toughening agent for epoxy resin
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In this study, a novel reactive toughener for the epoxy resin was developed and compared with traditional hydroxyl‐terminated polybutadiene (HTPB). For this purpose, the highly reactive aliphatic amine‐terminated polybutadiene (ATPB) was synthesized at ambient conditions by nucleophilic substitution amination. The characterizations of the product were provided by Fourier transform infrared and 1H NMR spectroscopy. According to the mechanical test results, incorporation of ATPB into epoxy networks can significantly toughen the epoxy matrix. The addition of 10 phr ATPB increased the critical stress intensity factor (KIC) and critical strain energy release rate (GIC) of the epoxy from 0.85 to 2.16 MPa m1/2 and from 0.38 to 3.02 kJ m?2, respectively. Furthermore, unlike HTPB, the presence of the ATPB did not deteriorate the tensile strength of the matrix. The toughening and failure mechanisms were discussed based on the epoxy network morphological characteristics. The reduction in cross‐linking density and glass transition temperature of the epoxy system upon modification with liquid rubbers was confirmed by dynamic mechanical analysis. This article opens up the possibility of utilizing reactive flexible diamines with polybutadiene backbone as effective toughening agents for thermoset polymers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44061. 相似文献
143.
Hamid Jadidi Hamzeh Shahrajabian Mehdi Moghri 《Journal of Inorganic and Organometallic Polymers and Materials》2016,26(4):881-888
Nanocomposite foams contain very fine cells because of the fillers in nano scale. Due to the limited size of the cells, the mechanical and physical properties of nanocomposite foams are improved compared to polymer foams. In this study PVC/clay nanocomposite foams containing various concentrations of nano-clay (1, 3 and 5 phr) were successfully prepared. The samples were placed under CO2 gas pressure at 5 MPa, by immersing in glycerin bath at 60, 70, 80 °C and 20, 30, 40 s, respectively, to form foams. The density and the cell size as a factor of nano-clay content, foaming time and temperature were investigated using Archimedes method and scanning electron microscopy, respectively. The minimum density was obtained in the sample containing 1 phr nanoclay prepared at 80 °C and 40 s. The minimum cell size was related to the sample containing 5 phr nanoclay at 60 °C and 20 s. 相似文献
144.
Mehdi Salih Shihab Abbas Hadi Alshukrawi Wedad Hamad Aldahhan 《Protection of Metals and Physical Chemistry of Surfaces》2016,52(6):1086-1092
In the present work, sodium 4-[(4-formylbenzylidene) amino] benzoiate (4) was synthesized and its structure was confirmed using spectroscopic techniques. Prepared compound was successfully applied as a corrosion inhibitor for C1010 carbon steel in 3.5% NaCl solution at 25°C. Different electrochemical measurements such as linear polarization resistance (LPR), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) were used to evaluate the suggested inhibitor (4). The results of different electrochemical measurements show that inhibition efficiencies obtained from EIS curves are in consistence with the results of potentiodynamic polarization and LPR measurements due to increase corrosion inhibition efficiency by increasing the concentration of organic inhibitor (4). Semi-empirical calculations with PM3 method were used to find relationship between molecular structure and inhibiting effect of suggested inhibitor (4). 相似文献
145.
Jalal?Basiri?Parsa Taher?Mehdi?Panah Farideh?Nabizadeh?ChianehEmail author 《Korean Journal of Chemical Engineering》2016,33(3):893-901
This study deals with the performance and modeling of the electro-coagulation process for ciprofloxacin (CIP) removal by using aluminum electrode as anode in a continuous electrochemical reactor. The initial pH, temperature, current density, time and flow rate were selected as independent variables in response surface methodology (RSM) involving a five-level central composite design (CCD), while CIP removal efficiency was considered as the response function. The result of optimization showed that the maximum amount of CIP removal efficiency (88%) presented at the optimal condition of pH=5.6, t=100min, T=25.5 °C, I=5.6mA/cm2 and V=25.9 mL/min. In addition, the mineralization of the CIP was investigated by chemical oxygen demand (COD) and total organic carbon (TOC) measurements that showed 77% COD removal and 49%TOC removal. 相似文献
146.
Elaheh Abdollahi Mehdi Salami-Kalajahi Ali Mohammadi Ali Khalafi-Nezhad 《Designed Monomers and Polymers》2016,19(1):56-66
Diethyl-dithiocarbamic acid 2-[4-(2-diethylthiocarbamoylsulfanyl-2-phenyl-acetyl)-2,5-dioxo-piperazin-1-yl]-2-oxo-1-phenyl-ethyl ester as a novel di-functional reversible addition–fragmentation chain transfer (RAFT) agent was synthesized based on 2,5-diketopiperazine. The RAFT agent was designed based on the propagating core (R group) approach and characterized by 1H NMR, 13C NMR, FT-IR, elemental analysis, and melting point technique. Then, ethyl methacrylate was synthesized via free radical and RAFT polymerizations. To investigate the effect of the RAFT agent on the kinetic of polymerization, molecular weight, and polydispersity index (PDI) of polymers and also monomer conversion were monitored. Also, synthesized polymers were characterized by 1H NMR, 13C NMR, FT-IR, and TGA. Characterization analyses of synthesized RAFT agent were consistent with the structure. NMR and FTIR analyses confirmed end group incorporation of RAFT agent into polymer structure. According to results, poly(ethyl methacrylate) with low PDI (1.14) was obtained. Kinetic study indicated well-controlled polymerization of ethyl methacrylate by synthesized RAFT agent. TGA results showed that RAFT agent could reduce termination reactions and so reduce head-to-head bonds and chain-end unsaturation by keeping the concentration of radicals low enough. 相似文献
147.
Syed Jafar Mehdi Hector Rosas-Hernandez Elvis Cuevas Susan M. Lantz Steven W. Barger Sumit Sarkar Merle G. Paule Syed F. Ali Syed Z. Imam 《International journal of molecular sciences》2016,17(9)
Currently, the lack of new drug candidates for the treatment of major neurological disorders such as Parkinson’s disease has intensified the search for drugs that can be repurposed or repositioned for such treatment. Typically, the search focuses on drugs that have been approved and are used clinically for other indications. Kinase inhibitors represent a family of popular molecules for the treatment and prevention of various cancers, and have emerged as strong candidates for such repurposing because numerous serine/threonine and tyrosine kinases have been implicated in the pathobiology of Parkinson’s disease. This review focuses on various kinase-dependent pathways associated with the expression of Parkinson’s disease pathology, and evaluates how inhibitors of these pathways might play a major role as effective therapeutic molecules. 相似文献
148.
Mehdi Koohmishi 《Soils and Foundations》2019,59(6):2265-2278
The aggregate in the ballast layer of the railway track structure degrades due to the splitting of single particles and the abrasion of the angular corners, resulting in a ballast course comprised of degraded aggregate with a lower drainage potential. In the present study, the hydraulic conductivity of clean, degraded and clay-fouled degraded ballast specimens was evaluated considering the initial particle size distribution of aggregate and the degradation mechanism to investigate the permeability of ballast fouled by both internal and external factors. First, degraded ballast aggregate was generated by using a large-scale impact loading testing apparatus. Then, a large-scale constant head permeability test was performed to estimate the hydraulic conductivity of degraded ballast aggregate contaminated with clay. Based on the obtained results, the flow regime through extremely degraded ballast remained between a completely turbulent regime (observed in the case of clean ballast) and a laminar flow regime. Darcy’s law was shown to be valid for degraded aggregate samples contaminated with clay. While the degradation of the aggregate had the expected effect of reducing hydraulic conductivity, the abrasion of asperities was shown to have an even greater impact on hydraulic conductivity. Also, the further degradation of aggregate under impact loading was shown to accelerate the reduction in the permeability of clay-fouled degraded ballast to an unacceptable extent. 相似文献
149.
Mehdi Miansari Mehdi Rajabtabar Darvishi Davood Toghraie Pouya Barnoon Mojtaba Shirzad As'ad Alizadeh 《中国化学工程学报》2022,44(4):424-434
Heat exchangers are integral parts of important industrial units such as petrochemicals, medicine and power plants. Due to the importance of systems energy consumption, different modifications have been applied on heat exchangers in terms of size and structure. In this study, a novel heat exchanger with helically grooved annulus shell and helically coiled tube was investigated by numerical simulation. Helically grooves with the same pitch of the helical coil tube and different depth are created on the inner and outer wall of annulus shell to improve the thermal performance of heat exchanger. In the first section, thermal performance of the shell and coil heat exchanger with the helical grooves on its outer shell wall was compared with same but without helical grooves. At the second section, helically grooves created on both outer and inner wall of the annulus shell with different groove depths. The results showed that the heat exchanger with grooves on both inner and outer shell wall has better thermal performance up to 20% compared to the heat exchanger with grooves on only outer shell wall. The highest thermal performance achieves at lower flow rates and higher groove depths whereas the pressure drop did not increase significantly. 相似文献
150.
Khani Ali Eskandani Morteza Derakhshankhah Hossein Soleimani Khadijeh Nakhjavani Sattar Akbari Massoumi Bakhshali Jahanban-Esfahlan Rana Moloudi Kave Jaymand Mehdi 《Journal of Polymer Research》2022,29(4):1-10
Journal of Polymer Research - Derivatives of formyl pyrazole were synthesized by the reaction of acetophenone, 4-methyl acetophenone, 3-acetyl furan, 3-acetyl thiophen and phenyl hydrazine... 相似文献