Use of organosilicon compounds as modifiers of epoxy compositions

Organosilicon compounds used to improve the strength and adhesion properties, as well as the thermal stability, of epoxy compositions are reviewed. Properties of composition on the basis of bisphenol A-based ED-20 resin cured with a KrOOT-1 silicon-containing amine are described.     

Influence of free surface energy of polymers on formation of their interphase contact with oxyethylated isononylphenol

The interconnection of the surface energy characteristics of polymers in a wide range of acid-base constituents of the free surface energy and their adhesive interaction with adducts of ethylene oxide and isononylphenol was investigated. It was shown that the content of the polar groups in the polymer surface layer and the length of the oxyethylene chain additively influence the wetting ability and the work of adhesion. The peculiarities of the adhesive interaction of high pressure polyethylene with oxyethylated compounds depending on the thermal oxidation of polymer and the acidity parameters of the surface were revealed.     

On a Construction of Green's Function for Systems with Distributed Parameters

We propose a method for constructing Green's function and particular solutions of dynamical systems with distributed parameters. The proposed method is illustrated with an example of classical equations of mathematical physics and more difficult problems of elasticity dynamics.     

On the classical solutions of the liouville equation in a four-dimensional euclidean space

In terms of Fueter analytic functions, a classical solution of the Liouville equation in a fourdimensional Euclidean space depending on two arbitrary complex functions is obtained and discussed.     

Investigations of 2-substituted imidazoles. 2. Synthesis and electrophilic substitution of 1-methyl-2-(thienyl-2)imidazole. A convenient method of methylation of 2-R-imidazoles

We have synthesized 2-(thienyl-2)imidazole and its N-methyl derivative. The latter product was obtained by nitration, bromination, acylation, and formylation, occurring as a rule on the thiophene ring. A general method for methylating 2-R-imidazoles with methyl iodide KOH-dimethoxy ethane is proposed.For Communication 1 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1414–1418, October, 1991.     

Synthesis and methylation products of 4(5)-(2-furyl)imidazole

Bromination of 2-acetylfuran with copper(II) bromide in a mixture of ethyl acetate and chloroform leads selectively to furacyl bromide, the nucleophilic substitution of bromine in which by OAc and subsequent use of the Weidenhagen reaction enabled the synthesis of 4(5)-(2-furyl)imidazole. On N-methylation of this imidazole in KOH–acetone 2 isomers are formed, the 1-methyl-4- and 1-methyl-5-(2-furyl)imidazoles. It was established that, unlike alkylation of 4(5)-phenylimidazole, the main product of the reaction is 1-methyl-5-(2-furyl)imidazole.     

Electroluminescent characteristics of InGaAsSb/GaAlAsSb heterostructure Mid-IR LEDs at high temperatures

The electroluminescent characteristics of an InGaAsSb/GaAlAsSb heterostructure LED emitting at 1.85 μm are studied in the temperature range 20–200°C. It is shown that the emission power exponentially drops as P ≅ 0.4exp(2.05 × 10³/T) with a rise in temperature primarily because of an increase in the Auger recombination rate. It is found that band-to-band radiative recombination goes in parallel with recombination through acceptor levels, the latter causing the emission spectrum to broaden. With a rise in temperature, the activation energy of the acceptor levels decreases by the law ΔE≅ 32.9 − 0.075T and the maximum of the LED’s emission spectrum shifts toward the long-wavelength range (hν _max = 0.693 − 4.497 × 10⁻⁴ T). Based on the dependence E _g = hν _max − 0.5kT and experimental data, an expression is derived for the temperature variation of the bandgap in the In_0.055Ga_0.945AsSb active area, E _g ≅ 0.817 − 4.951 × 10⁻⁴ T, in the range 290 K < T < 495 K. The resistance of the heterostructure decreases exponentially with rising temperature as R ₀ ≅ 5.52 × 10⁻²exp(0.672/2kT), while cutoff voltage U _cut characterizing the barrier height of a p−n junction decreases linearly with increasing temperature (U _cut = −1.59T + 534). It is found that the current through the heterostructure is due to the generation-recombination mechanism throughout the temperature interval.