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71.
Jaber Nasrollah Gavgani Mohsen Shahrousvand Mohammad Mohammadi Aslzadeh 《Colloid and polymer science》2013,291(10):2299-2309
The polymerization of styrene (St) was carried out with varying amounts of methanol in aqueous medium. As methanol content decreased (to 50 %), the phase of polymerization mixture (methanol/water/monomer) changed to a heterogeneous state; the homogeneous state was obtained in samples that contain 75 and 100 % methanol. In order to verify the mechanism of polymerization in heterogeneous and homogeneous mixtures, the nucleus formation rate during polymerization, the stability equilibrium of the media and seeded particles, and the size of particles and their growth in polymerization were experimentally being monitored. With the homogeneous mixture in 75 wt% methanol, dumbbell, triangle, and peanut-like particles have been formed. On the other hand, the characteristics of the polymerization products were different from those typically obtained in the emulsion polymerization and in the sample with 100 wt% methanol dispersion polymerization. In the sample with 100 % methanol and in one with 50 % methanol, monodispersed spherical particles are formed in the final conversion. Thus, homogeneity in the aqueous methanol mixture can be a critical factor in determining the polymerization modes between dispersion and emulsion polymerization. 相似文献
72.
Reza Sepahvand Mohsen Adeli Bandar Astinchap Roya Kabiri 《Journal of nanoparticle research》2008,10(8):1309-1318
Metal-carbon nanotube-graft-polymer (MCNT-g-P) nanocomposites were synthesized and characterized successfully. In this work, multiwall carbon nanotubes (MWCNT) were
opened using HNO3/H2SO4 mixture and filled by metal nanoparticles such as silver nanoparticles through wet chemistry method. Then MWCNT containing
metal nanoparticles were used as macroinitiator for ring opening polymerization of ε-caprolactone and MCNT-g-P nanocomposites were obtained. Length of grafted polymer arms onto the MWCNT was controlled using MWCNT/ε-caprolactone ratio.
Structure and properties of nanocomposites were evaluated by TEM, DSC, TGA, and spectroscopy methods. 相似文献
73.
Mohsen M. Mostafa Rafaat M. El-Shazly Tawfik H. Rakha Mohamed H. Abdel-Rahman 《Transition Metal Chemistry》2002,27(2):237-237
Other Index
Forthcoming articles 相似文献74.
Measurement and modeling of three-dimensional sound intensity variations due to shallow-water internal waves 总被引:1,自引:0,他引:1
Badiey M Katsnelson BG Lynch JF Pereselkov S Siegmann WL 《The Journal of the Acoustical Society of America》2005,117(2):613-625
Broadband acoustic data (30-160 Hz) from the SWARM'95 experiment are analyzed to investigate acoustic signal variability in the presence of ocean internal waves. Temporal variations in the intensity of the received signals were observed over periods of 10 to 15 min. These fluctuations are synchronous in depth and are dependent upon the water column variability. They can be explained by significant horizontal refraction taking place when the orientation of the acoustic track is nearly parallel to the fronts of the internal waves. Analyses based on the equations of vertical modes and horizontal rays and on a parabolic equation in the horizontal plane are carried out and show interesting frequency-dependent behavior of the intensity. Good agreement is obtained between theoretical calculations and experimental data. 相似文献
75.
76.
Rani Warsi Sullivan Mohsen Razzaghi Jutima Simsiriwong 《Mathematical Methods in the Applied Sciences》2011,34(2):140-146
The objective of this paper is to present an algorithm from which a rapidly convergent solution is obtained for Volterra integral equations of Hammerstein type. Such equations are often encountered when describing the response of viscoelastic materials where the time dependency of the material properties is often expressed in the form of a convolution integral. Frequently, singularity is encountered and often ignored when dealing with the constitutive equations of viscoelastic materials. In this paper, the singularity is incorporated in the solution and the iterative scheme used to solve the equation converges within six iterations to a typical toleration error of 10?5. The algorithm is applied to the strain response of a polymer under impulsive (constant) loading and the results show excellent correlation between the experimental and analytical solution. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
77.
Mehdi Ramezani Mehdi Dehghan Mohsen Razzaghi 《Numerical Methods for Partial Differential Equations》2008,24(1):1-8
In this work the combined finite difference and spectral methods have been proposed for the numerical solution of the one‐dimensional wave equation with an integral condition. The time variable is approximated using a finite difference scheme. But the spectral method is employed for discretizing the space variable. The main idea behind this approach is that we can get high‐order results. The new method is used for two test problems and the numerical results are obtained to support our theoretical expectations. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007 相似文献
78.
Lobna Abdel‐Mohsen Ebaid Nassr 《国际化学动力学杂志》2010,42(6):372-379
Kinetics of aquation of some Fe(II) Schiff base amino acid complexes was followed spectrophotometrically. The Schiff base ligands were derived from salicylaldehyde and isoleucine, leucine, serine, methionine, tryptophan, or histidine. The reaction was studied in aqueous media, aqua–propanol mixtures, and in the presence of different concentrations of KBr. Moreover, the activation parameters were calculated and discussed for structures and other physical properties observed. The reaction was acid catalyzed and the general rate equation was suggested as follows: rate = kobs [complex], where kobs = k2 [H+]. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 372–379, 2010 相似文献
79.
Mir Ali Farajzadeh Leila Goushjuii Mohsen Mazloom Farsibaf Ali Ranji 《Mikrochimica acta》2008,160(1-2):179-183
A gas chromatographic technique is reported for the determination of a secondary antioxidant, Irgafos 168, in polymeric samples.
Irgafos 168 [tris(2,4-di-tert-butyl phenyl)phosphite] is extracted by dissolution/precipitation, saponified to 2,4-di-tert-butyl phenol by refluxing in the presence of methanolic potassium hydroxide, and determined by gas chromatography-flame ionization
detection. The method’s repeatability is good, and the relative standard deviation is 7.5% (between runs) and 15.5% (between
days). This method was applied to the determination of Irgafos 168 in commercial polymers, and the obtained results were in
relatively good agreement with those obtained by the previously reported spectrophotometric method.
Correspondence: Mir Ali Farajzadeh, Department of Chemistry, Faculty of Science, Urmia University, Urmia, Iran 相似文献
80.
The DPAC technique was applied to measure the quadrupole moments of the 300 ps, 5/2− states in75,77As. The isotopes were implanted in α-Ga. The following results were obtained: Q(5/2−)=30(10) fm2 for75As, and Q(5/2−)<75 fm2 for77As. 相似文献