No abstract

This paper has investigated the possibility to theoretically calculate a value of the specific impulse for highly energetic compositions using only two parameters – the heat of the reaction and the number of moles of gaseous decomposition reaction products. Specific impulse is one of the most important energetic characteristics of rocket propellant. It demonstrates the level of achieving the value of engine thrust and propellant utilization efficiency. Determining the specific impulse experimentally is a complex task that requires meeting special conditions. For the stage of synthesis of new promising components, the comparative analysis of energetic characteristics, forecasting the value of specific impulse, especially relevant are calculation methods. Most of these methods were first developed to determine the energetic characteristics of explosives. Since explosives and rocket propellants in many cases have similar energy content and similar chemical composition, some estimation methods can be used to assess the specific impulse of solid rocket propellant. The specific impulse has been calculated for 45 compositions based on environmentally friendly oxidizers (ammonium dinitramide, hydrazinium nitroformate, hexanitrohexaazaisowurtzitane) and polymer binders polybutadiene with terminal hydroxyl groups, glycidylazide polymer, poly-3-nitratomethyl-3-methyloxetane). It was established that the estimation data obtained correlate well with literary data. Deviation of the derived values of the specific impulse from those reported in the literature is from 0.4 % to 1.8 %. The calculation results could be used for preliminary forecasting of energetic characteristics for highly energetic compositions, selecting the most promising components, as well as their ratios.

Complexes of 2,6 dimethyl 3,5 pyridinedicarboxylic acid dihydrazide (DH) with copper(II) and cobalt(II) nitrates and sulfates have been studied by IR and UV spectroscopy, DTA, and X ray crystallogra phy. The complexation results in polynuclear compounds of the {[M(DH)(ROH) n ]An m } z composition (M = Cu 2+ , Co 2+ ; An = ; R = H, i Pr; n = 0.5-4, m = 1.2, z ≥ 4) containing bidentate DH bridges coordinated to the metal through the carbonyl oxygen atom and the amino group nitrogen atom of the hydrazide moiety.

No abstract

The growth of science and technology of polyurethanes leads to the development of new materials with more desirable properties. Modification of polyurethane (PU) by incorporating metal and functional groups are used extensively to improve various properties, such as enhanced thermal stability, fire retardancy, flexibility and solubility. In this investigation, a new metal-containing poly(urethane-semicarbazides) bearing a pyridine moiety have been synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), differential thermal analysis (DTA/TG) and tensile strength measurements. The results showed that the incorporation of metal ions into the polymer chain greatly influenced their mechanical and thermal properties. The tensile strength measurements on the PU films showed a marked difference in the elongation and tensile strength for compositions with various metal salts. The nature of the anion of the salt also affects the properties of the polymers, since the anions are able to form complexes with hydrogen atoms of urethane-semicarbazide PU segments. According to the results of DTA, introduction of metal ions leads to the increase of the thermal stability of metal-containing PU, as compared to the original PU. FTIR spectra data confirmed that the metal ions Cu2+, Co2+ are coordinated in the polymer metal chelates with hydrazide and urethane groups. The research results can be used to develop the new materials and methods for the preparation and designing of metal-containing polymers required in various areas, such as development of medical equipment, functional films and other related areas.