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21.
Simultaneous study of cure kinetics and rheology of montmorillonite/vinyl ester resin nanocomposites
Shahin Akhlaghi Mohammadreza Kalaee Effat Jowdar Ali Nouri Saeedeh Mazinani Mehdi Afshari Mohamadhosein Navid Famili Navid Amini Toktam Behrouz 《先进技术聚合物》2012,23(3):534-544
In this work, the effect of quaternary ammonium salt containing nanoclay content (1–5 wt%) on phase morphology, rheology, cure kinetics, and mechanical properties of the vinyl ester resin (VER)‐based nanocomposites was studied. The morphological characterization including d‐spacing measurement, microscopy observation and phase‐height image processing were performed on the prepared nanocomposites using small angel X‐ray scattering (SAXS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). According to the results obtained from these techniques, it was concluded that an intercalated morphology existed for all the nanocomposites. The kinetic analyses of the isothermal curing followed by storage modulus obtained from the rheometry experiments are shown to be an affective rheological characteristic to investigate the cure behavior of VER/clay nanocomposites. In addition, the most important finding regarding the effect of nanoclay on the cross‐linking behavior of VER systems lays on the chemisorption and physisorption of the reacting monomers and initiator molecules on the nanoclay platelets surface which is found to be responsible for the retardation of the cure reaction caused by organoclay. Eventually, the mechanical characterizations were performed through the tensile, flexural and impact analysis tests. In this case, a considerable improvement of the bulk mechanical responses such as tensile and flexural strengths and also the corresponding moduli were observed for the nanocomposites. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
22.
MR Eskildsen AB Abrahamsen PL Gammel DJ Bishop NH Andersen K Mortensen PC Canfield 《Pramana》2002,58(5-6):903-905
We compare the results of small angle neutron scattering on the flux line lattice (FLL) obtained in the borocarbide superconductor
LuNi2B2C with the applied field along the c- and a-axes. For H‖c the temperature dependence of the FLL structural phase transition from square to hexagonal symmetry was investigated. Above
10 K the transition onset field. H
2(T), rises sharply, bending away from H
c2(T) in contradiction to theoretical predictions of the two merging. For H‖a a first order FLL reorientation transition is observed at H
tr=3–3.5 kOe. Below H
tr the FLL nearest neighbor direction is parallel to the b-axis, and above H
tr to the c-axis. This transition cannot be explained using nonlocal corrections to the London model. 相似文献
23.
The energetic charged particles penetration in the plasmasphere are carried out using the updated version of 3D Stanford PIC code. We considered slow and fast wind streams to know the penetration of the energetic charged particles (electrons and ions) having different velocities into four regions i.e. cusp, plasmasphere, sunward, and tailward sides. It is observed that the ion penetrations are higher than electrons for solar slow wind streams in the plasmasphere, while it is reverse for the solar fast streams. Also, the results show that the percentage of penetration of the energetic charged particles (both electrons and ions) are the same into the cusp and subsolar point reconnection region. It is different for the higher speed of fast streams; so that the penetrated electrons reached about 10–20 times than penetrated ions. The results show that for the tailward reconnection region, the penetration of ions is 2–3 times higher than the penetration of electrons, but it is the same for the case of higher solar fast speed. 相似文献
24.
A new polysulfide polymer was synthesized from methylene dichloride and sodium tetrasulfide by an interfacial polycondensation technique using two quarternary ammonium salts as phase transfer catalysts. The synthesized polymers were characterized by FT-IR, X-ray and elemental analysis. Thermal properties were evaluated by thermogravimetric analysis and differential scanning calorimetry. The solvent resistance of the polymer was investigated by the swelling method. 相似文献
25.
Summary : Poly(alkyltetrasulfide) is prepared via reaction of ethylene dichloride with sodium tetrasulfide (Na2S4) in the presence of methyl tributyl ammonium chloride as phase transfer catalyst (PTC). The polysulfide polymer is characterized by CHN analysis, FT-IR, TGA, DTA and DSC techniques. 相似文献
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The semileptonic decay width of heavy baryons such as (Λ
b
→ Λcev) has been estimated in the framework of a nonrelativistic field theoretic quark model where four component quark field
operators along with a harmonic oscillator wave function are used to describe translationally invariant hadronic states. The
present estimation does not make an explicit use of heavy quark symmetry and has a reasonable agreement with the experimentally
measured decay width, polarisation ratio and form factors with the harmonic oscillator radii and quark momentum distribution
inside the hadron as free parameters. 相似文献
29.
S. Sankar MR. Manikandan S.D. Gopal Ram T. Mahalingam G. Ravi 《Journal of Crystal Growth》2010,312(19):2729-2733
The microbial free single crystals of α and γ glycine were grown from gel at room temperature in a new chemical route. These crystals showed a superior quality than the solution grown crystals. The metastable α-form and the stable γ-form of glycine were crystallized in silica gel by solubility reduction method. The form of crystallization is confirmed by single crystal and powder X-ray diffraction analyses. The crystals of α and γ glycine were found to crystallize in monoclinic and hexagonal crystal systems, respectively. For analyzing the functional group and thermal stability of α and γ glycine crystals, spectroscopic and thermal analyses have been carried out. The dielectric studies were performed to find the dielectric constant of the grown crystals and the results are discussed. Second harmonic generation efficiency of the crystal was measured by Kurtz’s powder method using Nd:YAG laser and it was found to be 2.68 times that of potassium dihydrogen phosphate crystals. 相似文献
30.
Raman and resonance-Raman spectra of the I?3 ion isolated within CsI crystals have been studied using 647 nm and 488 nm exciting radiation. Sample temperatures between 300 and 20 K have been used. Eleven overtones of the symmetric stretching mode (nν1) have been observed in the resonance-Raman spectrum excited by the 488 nm Ar+ laser line. Bands centred at 153, 170, 264 and 304 cm?1 have been assigned as ν3, 2ν2, ν1+ν3 and 2ν3(Σ+) respectively. The remaining structure between the nν1 lines has been assigned as due to combinations of these lines with the lattice vibrations of the CsI crystal. 相似文献