Investigation of Gas Formation Processes in Cotton Fabrics Impregnated with Binary Compositions of Ethyl Silicate - Flame Retardant System

The use of complex fire-retardant coatings based on ethyl silicate gel - diammonium hydrogen phosphate reduces the process of smoke formation during thermal exposure to treated tissue samples, which is promising for improving the fire safety of textile materials. The compositions are easy to obtain, they do not require specific processing conditions, do not contain toxic substances. This allows us to offer developed compositions for fire protection of textile materials used in facilities with a large number of people.

Three-Component Efficient Synthesis of 2-Amino-3-cyano-4H-pyrans Catalyzed by Diammonium hydrogen phosphate in Aqueous Media

Background: The present method is facile, green and effective for the synthesis of 2-amino-3-cyano-4H-pyran derivatives which are obtained by one-pot three-component condensation reactions of aromatic aldehydes, malononitrile and methyl acetoacetate using diammonium hydrogen phosphate (DAHP) in aqueous ethanol at room temperature. Methods: 2-Amino-3-cyano-4H-pyrans were synthesized through a one-pot three-component tandem Knoevenagel cyclocondensation reaction of aromatic aldehydes, malononitrile, and methyl acetoacetate in the presence of 10 mol% of DAHP as a catalyst under aqueous ethanol medium at room temperature. All obtained structures were confirmed by their physical constant, IR, 1H NMR, 13C NMR spectroscopy, also elemental analyses for new derivatives. Results: Three-component synthesis of 2-amino-3-cyano-4H-pyrans catalyzed by DAHP with aromatic aldehydes, malononitrile and methyl acetoacetate in aqueous ethanol medium at room temperature was prepared. The achieved derivatives (nine entries) were well synthesized in excellent yields. Conclusion: The present method is straightforward, quick, and most efficient green protocol for the synthesis of 2-amino3-cyano-4H-pyran derivatives using highly inexpensive, easily handle and, nontoxic DAHP as an efficient catalyst in aqueous ethanol medium at room temperature.

Supercapacitor Electrodes from Viscose-Based Activated Carbon Fibers: Significant Yield and Performance Improvement Using Diammonium Hydrogen Phosphate as Impregnating Agent

Viscose fibers were impregnated with different concentrations of diammonium hydrogen phosphate (DAHP), carbonized, activated, and tested as high-performance electrode materials for supercapacitors. The yield of these activated carbon fibers (ACFs) could be increased by a factor of 14 by using DAHP compared to ACF without impregnation. These specific activation procedures yielded a high specific surface area of more than 2700 m2·g−1 with a pore size distribution (PSD) suitable for use as a supercapacitor electrode. The electrode materials were implemented in symmetric supercapacitors using TEMA BF4 as electrolyte and cyclic voltammetry measurements showed high specific capacitances of up to 167 F·g−1. Furthermore, the devices showed high energy densities of up to 21.4 W·h·kg−1 and high-power densities of up to 8.7 kW·kg−1. The supercapacitors featured high capacity retention (96%) after 10,000 cycles. These results show that ACFs made of viscose fibers, previously impregnated with DAHP, can be used as high-performance electrodes in supercapacitors for energy storage applications.

Synthesis of Carbonate and Fluorine Substituted Nanocrystalline Hydroxyapatite by Mechanochemical Method

The present work is aimed at the synthesis of fluorine substituted and carbonate substituted hydroxyapatites (FHA, CHA) by the mechanochemical method. The shortest milling time required for the synthesis of FHA and CHA using calcium hydroxide and diammonium hydrogen phosphate as precursors was estimated. In addition to the Ca and P precursors, ammonium carbonate and ammonium fluoride were used for carbonate and fluorine substitutions, respectively. Thermal stability of the synthesized FHA and CHA was evaluated. The phase composition and crystallite size were evaluated by the X-Ray Diffraction (XRD). Fourier Transform Infrared Spectroscopy (FTIR) technique was employed to confirm the functional groups corresponding to the FHA and CHA. Thermal stability of the FHA and CHA was determined by the XRD and FTIR studies on the FHA and CHA powders annealed at 900 °C. From the XRD and FTIR results, it is observed that the 30 min milling time is the shortest time for the complete formation of FHA and CHA. The powders synthesized with a minimum milling time of 30 min exhibited better thermal stability.