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1.
Tatiana B. Mikenas Vladimir A. Zakharov Lyudmila G. Echevskaya Mikhail A. Matsko 《Journal of polymer science. Part A, Polymer chemistry》2007,45(22):5057-5066
The effects of polymerization temperature, polymerization time, ethylene and hydrogen concentration, and effect of comonomers (hexene‐1, propylene) on the activity of supported catalyst of composition LFeCl2/MgCl2‐Al(i‐Bu)3 (L = 2,6‐bis[1‐(2,6‐dimethylphenylimino)ethyl] pyridyl) and polymer characteristics (molecular weight (MW), molecular‐weight distribution (MWD), molecular structure) have been studied. Effective activation energy of ethylene polymerization over LFeCl2/MgCl2‐Al(i‐Bu)3 has a value typical of supported Ziegler–Natta catalysts (11.9 kcal/mol). The polymerization reaction is of the first order with respect to monomer at the ethylene concentration >0.2 mol/L. Addition of small amounts of hydrogen (9–17%) significantly increases the activity; however, further increase in hydrogen concentration decreases the activity. The IRS and DSC analysis of PE indicates that catalyst LFeCl2/MgCl2‐Al(i‐Bu)3 has a very low copolymerizing ability toward propylene and hexene‐1. MW and MWD of PE produced over these catalysts depend on the polymerization time, ethylene and hexene‐1 concentration. The activation effect of hydrogen and other kinetic features of ethylene polymerization over supported catalysts based on the Fe (II) complexes are discussed. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5057–5066, 2007 相似文献
2.
Lyudmila Kondakova Victor Yanishpolskii Valentin Tertykh Tat'yana Buglova 《Analytical sciences》2007,23(1):97-101
Galactose oxidase from Fusarium graminearum IMV-1060 adsorbed on, and covalently bound to, silica carriers has been used for analytical determinations of D-galactose and galactose-containing sugars. Using a flowing oxygen electrode of the Clark-type, sensor system for enzymatic analysis of water solutions of galactose-containing carbohydrates was made. Measurements were taken both in the pulse and continuous modes of a substrate flowing through a column with an immobilized biocatalyst. The linear measurement ranges for galactose-containing carbohydrates concentrations were determined. 相似文献
3.
Methods of preparing diverse metallosupramolecular polymers containing 2,2′-bipyridine and 2,2′:6′,2″-terpyridine moieties in main chains and their properties have been considered and analyzed. It has been shown that these polymers offer new possibilities for the design of materials possessing valuable specific characteristics. 相似文献
4.
5.
T. P. Pogrebnaya V. G. Solomonik V. N. Vinogradova M. I. Godneva 《Theoretical and Experimental Chemistry》1987,22(6):693-697
The geometric structure, force fields, and vibrational spectra of M2O and MOH (M=Li, Na) molecules have been investigated. The size of the d basis on the oxygen atom has a significant influence only on the frequency of the deformation vibration 3. Experimentally unknown constants of the molecules considered have been evaluated.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 22, No. 6, pp. 724–728, November–December, 1986. 相似文献
6.
I. B. Rabinovich N. V. Karyakin É. S. Dzharimova S. A. Siling I. I. Ponomarev S. V. Vinogradova 《Russian Chemical Bulletin》1984,33(4):716-723
Conclusions The reaction of phthalonitrile condensation with m-phenylenediamine is thermodynamically allowed at temperatures from 250° to 500°K, and its equilibrium is almost completely shifted toward the formation of the macroheterocycle.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 779–787, April, 1984. 相似文献
7.
Russian Chemical Bulletin - 相似文献
8.
9.
I.S. Vinogradova 《Journal of solid state chemistry》1983,49(2):129-133
A deuteron magnetic resonance study of a single crystal of NaDSeO3 at room temperature is reported. The observed electric field gradient tensors correspond to two nonequivalent hydrogen bonds. The quadrupole coupling constants () and asymmetry parameters (η) are found to be 172.8 and 0.07 kHz for D(1), and 152.5 and 0.08 kHz for D(2). D(2) are ordered, but D(1) are found to be dynamically disordered. The DMR results are consistent with recent X-ray reinvestigation. No phase transitions have been encountered in the temperature range 336 to 77 K. 相似文献
10.
V. V. Korshak S. V. Vinogradova V. A. Vasnev G. D. Markova T. V. Lecae 《Journal of polymer science. Part A, Polymer chemistry》1975,13(12):2741-2749
The effect of conditions of polycondensation on the structure of polymers formed from monomers with symmetric and asymmetric functional groups by nonequilibrium polycondensation has been studied for the system with acceptor-catalytic polyesterification of β-hydroxyethyl ethers of bisphenols and terephthalic acid chloride in the presence of triethylamine. Polymers with statistical or regular arrangement of diol residues in the chain can be produced in such systems, depending on the way in which starting compounds are introduced in the reactor. A difference in the reactivity of functional groups in an asymmetric monomer is not sufficient to produce polycondensation polymers with a regular structure. Gradual introduction of the symmetric monomer is essential to yield polymers with predominant “head-to-head” (“tail-to-tail”) configurations. Some properties of the resulting polymers have been studied. Polymers with ordered residues of the asymmetric monomers in the macromolecules have higher softening temperatures and an increased tendency for crystallization than the statistic polymers. 相似文献