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951.
We investigate the enhanced alignment of lamellar microdomains under an electric field by addition of lithium chloride (LiCl) into polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) copolymers. A significant increase of dielectric contrast resulting from the formation of lithium-PMMA complexes markedly reduces the critical electric field strength required to overcome the preferential interactions of one block with the substrate, providing a route to achieve the complete alignment of microdomains in block copolymer thin films. 相似文献
952.
4-Chloro-2-methylquinolines in reaction with 3-aminopyridine yielded 4-quinolinamines, which upon cyclisation under Vilsmeier-Haak
conditions afforded the title compounds.
__________
Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 6, 901–904, June, 2005. 相似文献
953.
Dongre Sandeep Kumar Sunil Suresh S. Rangaswamy D. R. Sannappa J. 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(7):2825-2847
Journal of Radioanalytical and Nuclear Chemistry - The estimated mean value of activity of radionuclides (226Ra, 232Th, and 40K) in the forest environment of Shankaraghatta are... 相似文献
954.
A study on the thermo‐oxidative stabilization (cyclization) of polyacrylonitrile (PAN) terpolymers using dynamic mechanical thermal analysis (DMTA) is reported in this article. When the changes in viscoelastic properties were monitored in a rectangular tension mode, besides the tan δ peak characteristic of the glass transition observed below 200°C, the copolymer and the terpolymer displayed a second peak above 200°C due to the cyclization leading to the formation of ladder structures. The initiation temperature of the cyclization process as well as the peak temperature is found to depend on the acid value and the composition of the precursor polymer. The results presented show that monitoring the changes in viscoelastic properties during cyclization provides insight into the material properties as a result of the chemical changes that are taking place. These observations were confirmed by structural characterization using IR spectroscopy, and the observed chemical changes agree with the literature studies, as due to the thermal cyclization process. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
955.
Joy P. Dunkers Joseph L. Lenhart Sylvia R. Kueh John H. van Zanten Suresh G. Advani Richard S. Parnas 《Optics and Lasers in Engineering》2001,35(2)
The Polymer Composites group at the National Institute of Standards and Technology has efforts in both on-line flow and cure sensing for liquid composite molding. For our flow program, a novel fiber optic real-time sensor system has been developed that can sense resin at various locations on a single fiber using long-period gratings and a polychromatic source. The sensor operation and characterization will be discussed along with sensor performance during mold filling with various types of reinforcement. The cure sensing program focuses on the interface-sensitive fluorescence response of a dye molecule grafted to a high-index glass fiber. The fluorescence emission of the fluorophore undergoes a blue shift as the resin cures. The fluorescence sensor is made by grafting a silane functional fluorophore onto the surface of the glass with close attention to layer thickness. Fluorescence emission of the grafted fluorophore film is shown to be sensitive to epoxy resin cure, co-silane, and layer thickness. The response of the grafted fluorophore to cure on a high-index fiber is demonstrated. 相似文献
956.
Polarographic studies of potassium isobutyl xanthate at a mercury electrode reveal that the product of an anodic reaction is strongly adsorbed at the mercury surface, as indicated by a prewave. The adsorbed film greatly affects the characteristics of the anodic wave of xanthate in an aqeous medium. The current of total wave is proportional to the concentration of xanthate from 0.32 to 1.6 mM. 相似文献
957.
Azopyridine-containing hexacatenar silver complexes have been synthesized and their liquid crystalline and photoisomerization behaviours investigated. These silver complexes (1a-d) exhibit hexagonal columnar liquid crystalline phases, whose structures were confirmed using polarizing optical microscopy and small angle X-ray diffraction. 相似文献
958.
Effect of Al substitution on the magnetic properties of Ce(Ga1−x
Al
x
)2 (x=0, 0.1 and 0.5) system has been studied. The magnetic state of CeGa2 is found to be FM with a T
C of 8 K, whereas the compounds with x=0.1 and 0.5 are AFM and possess T
N of about 9 K. These two compounds undergo metamagnetic transition and the critical fields are about 1.2 T and 0.5 T. respectively
at 2 K. These variations are explained on the basis of helical spin structure in these compounds. 相似文献
959.
960.