Synthesis of Polyol Tetrabromophthalate and Its Use as a Component for Preparing Foamed Polyurethanes of Reduced Flammability

A procedure was suggested for preparing brominated polyols of reduced viscosity for the synthesis of foamed polyurethanes of reduced flammability. The flame-retarding action of the synthesized polyol tetrabromophthalate in polyurethane was studied in comparison with that of other widely used flame retardants. Evaluation of the effect exerted on the flammability of the polurethane compound by the polyol tetrabromophthalate synthesized, melamine, and aluminum hydroxide shows that all the samples containing flame retardants are self-extinguishing. The shortest combustion time was observed for the sample containing 6% polyol tetrabromophthalate synthesized. The sample containing as a flame retardant additive solely the synthesized polyole tetrabromophthalate also exhibits the highest performance as a heat-insulating material from the viewpoint of thermal conductivity.

     

Band-Gap Determination from Photoconductivity Excitation Spectra

Journal of Applied Spectroscopy - The possibility to determine the direct and indirect band gap from the photoconductivity spectrum is shown. The band gap determined from the photoconductivity...     

Strengthened Wiegold Conjecture in the Theory of Nilpotent Lie Algebras

Mathematical Notes - In the present paper, we strengthen the assertion of the Wiegold conjecture for nilpotent Lie algebras over an infinite field by proving that if there exists a subset of a...     

Regio- and Stereoselective Addition of Selenium Dichloride to Alkyl Propiolates

Russian Journal of Organic Chemistry - The reaction of selenium dichloride with methyl and ethyl propiolates leads to formation of anti-Markovnikov adducts. The regio- and stereoselective synthesis...     

Integral Representations of a Pulsed Signal in a Waveguide

Acoustical Physics - The problem of pulsed excitation of an acoustic waveguide with a constant cross section is considered. Absorption is ignored. As the most general model of such a waveguide,...     

Shock waves in gas flows with nanoparticles

Journal of Thermal Analysis and Calorimetry - The paper focuses on the analytical analysis of the propagation of a normal shock wave in an adiabatic gas flow with nanoparticles. A modified...     

Formation and Characterization of Concentration Inhomogeneities in Melt-Grown Crystals

Crystallography Reports - The specific features of the formation of concentration inhomogeneities in crystals grown by the Czochralski method (GaSb:Te, Ge:Ga) and by the Bridgman method...     

Study of Wide-Gap Semiconductors Using Electron-Beam Induced Current Method

Crystallography Reports - The studies of wide-gap semiconductor materials using electron-beam induced current (EBIC) method are reviewed. The main methods for measuring the diffusion length of...     

Unbounded Solutions to Systems of Differential Equations at Resonance

Journal of Dynamics and Differential Equations - We deal with a weakly coupled system of ODEs of the type $$\begin{aligned} x_j'' + n_j^2 \,x_j + h_j(x_1,\ldots ,x_d) = p_j(t), \qquad...     

Monodromy-Quasifree Singular Points of the Sturm–Liouville Equation of Standard Form on the Complex Plane

Differential Equations - For the Sturm–Liouville equation of standard form on the complex plane, we study the existence of potentials with monodromy-quasifree singular points, i.e., singular...