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971.
H. H. Le I. Kolesov Z. Ali M. Uthardt O. Osazuwa S. Ilisch H.-J. Radusch 《Journal of Materials Science》2010,45(21):5851-5859
Composites based on highly branched ethylene-1-octene copolymer (EOC) and carbon black (CB) with different dispersion degree
of CB were prepared. The method of the online measured electrical conductance/resistance was used to monitor the change of
the electrical conductance/resistance of the composites during the preparation processes, i.e. mixing and cross-linking. It
was found that the kinetics of thermally stimulated shape-memory recovery of CB filled EOC is strongly influenced by the filler
dispersion degree, which actually affects the heat transfer in the composites. Using a special arrangement of experiments
the Joule heating stimulated shape-memory behaviour was quantified. CB dispersion degree and related electrical resistivity
determine the extent of the Joule heating stimulated shape-memory behaviour. Composite collected at the maximum in the online
measured conductance–time characteristics showed the best shape-memory effect owing to the highest electrical conductivity
in the solid state. The CB filled EOC showed a negative thermal coefficient of resistivity (NTC) effect, which accelerates
the temperature increase and shape-memory recovery of the composites when applying a voltage. 相似文献
972.
A series of cobalt and manganese catalysts supported on SBA-15 with different loading of Mn+2 and Co+2 were synthesized. These samples were characterized by SEM and XRD techniques. The catalytic activity of these samples was evaluated in the oxidation of ethylbenzene (EB) to produce acetophenone (AP) and benzoic acid (BA) in the liquid phase using tert-butylhydroperoxide (TBHP) as an oxidant. The effects of Co-Mn loading, TBHP: EB molar ratio and temperature on acetophenone and benzoic acid yields were studied by Box-Behnken experimental design to optimize the production of acetophenone and benzoic acid in liquid system. 相似文献
973.
H. M. Ali A. M. Ramadan M. A. Yousef 《Polymer-Plastics Technology and Engineering》2013,52(1-2):61-71
Commercial hydroxyethyl cellulose (HEC) was cyanoethylated with acrylonitrile in nonaqueous medium in the presence of sodium hydroxide under a variety of conditions. Variables studied included the amount of acrylonitrile and the reaction temperature. The reaction was proved by NMR and its extent was measured by determining the nitrogen content. The physical properties of the obtained derivatives—i.e., the electric properties and the apparent viscosity at various rates of shear—were investigated. It was found that the extent of reaction was increased by increasing the amount of acrylonitrile as well as the reaction temperature. The products were water soluble and their apparent viscosity increased with increasing nitrogen content. The same holds true for the dielectric constant and dielectric loss. 相似文献
974.
Yusheng Zhao Michael J. Gordon Ali Tekeei Fu‐Hung Hsieh Galen J. Suppes 《应用聚合物科学杂志》2013,130(2):1131-1138
A theoretical model was developed to simulate the polyurethane foaming process for a rigid foam. In the model, multiple ordinary differential equations were solved by MATLAB and the model was able to predict temperature profiles by inputting foam recipe information. This initial study on foam modeling focusses on reaction kinetic parameters that were fitted to experimental temperature data as a function of time. The modeling was able to accurately model temperature profiles of single‐polyol polyurethane formulations and was able to accurately predict temperature profiles of mixtures based on pure component kinetic parameters. A primary goal of this work is to expedite the ability to develop new foam formulations by simulation—especially for incorporation of new bio‐based polyols into formulations. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1131‐1138, 2013 相似文献
975.
976.
The Tunable Porous Structure of Gelatin–Bioglass Nanocomposite Scaffolds for Bone Tissue Engineering Applications: Physicochemical,Mechanical, and In Vitro Properties 下载免费PDF全文
Unidirectional freeze‐casting method is used to fabricate gelatin–bioglass nanoparticles (BGNPs) scaffolds. Transmission electron microscopy (TEM) images show that sol–gel prepared BGNPs are distributed throughout the scaffold with diameters of less than 10 nm. Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetric are used to evaluate the physicochemical properties of BGNPs. Scanning electron microscopy (SEM) micrographs present an oriented porous structure and a homogeneous distribution of BGNPs in the gelatin matrix. The lamellar‐type structure indicates an improvement of mechanical strength and absorption capacity of the scaffolds. Increasing the concentration of BGNPs from 0 to 50 wt% have no noticeable effect on pore orientation, but decreases porosity and pore size distribution. Increase in BGNPs content improves the compressive strength. The absorption and biodegradation rate reduces with augmentation in BGNPs concentration. Bioactivity is evaluated through apatite formation after immersion of the nanocomposites in simulated body fluid and is verified by SEM–energy‐dispersive X‐ray spectroscopy (EDS), an element map analysis, X‐ray powder diffractometer, and FTIR spectrum. SEM images and methyl thiazolyl tetrazolium assay confirm the biocompatibility of scaffolds and the supportive behavior of nanocomposites in cellular spreading. The results show that gelatin–(30 wt%)bioglass nanocomposites have incipient physicochemical and biological properties. 相似文献
977.
Abdulaziz Ali Alghamdi Abdulellah Alsolami Abdel-Basit Mohammed Al-Odayni Abdelhabib Semlali Taieb Aouak 《Designed Monomers and Polymers》2018,21(1):145-162
A series of poly(acrylic acid)/poly(methyl vinyl ketone) (PAA/PMVK) blends with different compositions were prepared by the solvent casting method. The miscibility of this pair of polymers was investigated by differential scanning calorimetry(DSC), Fourier transform infra-red (FTIR) and X-Ray diffraction (XRD) techniques. An in-vitro cytotoxicity test of the drug-carrier system via MTT (3-(4,5-demethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay revealed no significant cytotoxic effects at concentrations up to 100 µg· ml?1. The STX/PAA-50 drug carrier systems were also prepared by solvent casting of solutions containing the sulfamethoxazole (STX) used as drug model and PAA/PMVK blend in N.N-dimethylformamide then crosslinked with acidified ethylene glycol. The release dynamic of STX from the prepared hydrogels was investigated in which the diffusion through the polymer matrix, the enhancement of the water solubility of STX, the influence of the initial drug concentration, the pH of the medium, and the effect of the degree of swelling of the polymer matrix on the release dynamic was evaluated. According to the total gastrointestinal transit time estimated by Belzer, the estimate distribution of STX released in the different organs indicated that the performance is obtained with the drug – carrier-system containing equal ratios of polymer and 10 wt% of STX (STX-10/PAA-50). 相似文献
978.
Elnaz Akbari Zolkafle Buntat Aria Enzevaee Mahsa Khoshkhooy Yazdi Mahdi Bahadoran Ali Nikoukar 《Nanoscale research letters》2014,9(1):402
Carbonaceous materials have recently received attention in electronic applications and measurement systems. In this work, we demonstrate the electrical behavior of carbon films fabricated by methane arc discharge decomposition technique. The current-voltage (I-V) characteristics of carbon films are investigated in the presence and absence of gas. The experiment reveals that the current passing through the carbon films increases when the concentration of CO2 gas is increased from 200 to 800 ppm. This phenomenon which is a result of conductance changes can be employed in sensing applications such as gas sensors. 相似文献
979.
Sefer Bora Lisesivdin Nadir Ali Khan Simone Mazzucato Naci Balkan Michael John Adams Ville-Markus Korpij?rvi Mircea Guina Gabor Mezosi Marc Sorel 《Nanoscale research letters》2014,9(1):22
We report the observation of room-temperature optical gain at 1.3 μm in electrically driven dilute nitride vertical cavity semiconductor optical amplifiers. The gain is calculated with respect to injected power for samples with and without a confinement aperture. At lower injected powers, a gain of almost 10 dB is observed in both samples. At injection powers over 5 nW, the gain is observed to decrease. For nearly all investigated power levels, the sample with confinement aperture gives slightly higher gain. 相似文献
980.
Ghasem Sargazi Daryoush Afzali Ali Ghafainazari Hamideh Saravani 《Journal of Inorganic and Organometallic Polymers and Materials》2014,24(4):786-790
Metal-organic framework (MOF) has been shown to potential applications due to the high porous hybrid structure. Cobalt MOF was synthesized rapidly by ultrasound energy with about 3,000 m2/g surface area by BET method. Furthermore, this component is crystalline with significant thermal stability, on account of X-ray diffraction and thermal analysis, respectively. Based on high roughness, crystallinity, and unreported type of FTIR spectrum, a new structure of Co-MOF structure was proposed. 相似文献