ABSTRACT
The present work reports synthesis, characterization and theoretical insights on novel hydroxymethyl-bishomocubanone derivatives. Twelve new bishomocubanes (BHCs) were synthesized and fully characterized by various spectroscopic techniques and single crystal X-ray analysis. The densities of the title compounds were found in the range of 1.34-1.59 g/cm3. Density-functional theory (DFT) based calculations at B3LYP/6-311++G(d,p) level of theory were performed on ten selected BHC based cage compounds. Propulsive and ballistic properties of newly synthesized hydroxymethyl-bishomocubanone derivatives in solid and liquid propulsion systems were calculated, and the results suggested that these compounds are superior to conventional fuel RP1 and binder HTPB. The detonation parameters revealed that these compounds are not explosive in nature and safe to use as solid propellants. Furthermore, kinetic and thermal stabilities of the title compounds were determined by HOMO-LUMO energy gap, ESP maps, impact sensitivity (h50) and bond dissociation energies (BDEs) followed by thermogravimetric analysis (TGA) and differential thermogravimetry analysis (DTA). Three compounds, a dinitroazide (Isp,vac= 310.98s), a dinitrate (Isp,vac = 309.51s), and a dinitronitrate (Isp,vac= 309.20s) were found to be excellent candidates for volume limited applications.
ABSTRACT
Novel 1,4-disubstituted cubane derivatives have been designed and selected ones have been successfully synthesized and characterized by various analytical and spectroscopic techniques, including single-crystal X-ray analysis. A detailed computational study at B3LYP/6-311++G(d,p) level of theory revealed that all newly designed 1,4-disubstituted cubane derivatives possess higher densities, higher density-specific impulse and superior ballistic properties when compared to conventional fuels, for example, RP-1. These compounds also exhibit acceptable kinetic and thermodynamic stabilities which were evaluated in terms of their HOMO-LUMO energy gap and bond dissociation energies, respectively, and are superior to TEX and many other compounds containing explosophoric groups. These results provide novel insights into the possible application of cubane-based energetic materials.
Subject(s)
Explosive Agents , Models, Theoretical , ThermodynamicsABSTRACT
The accurate measurement of temperature in sooty flames remains a challenging task. In this study, the procedure for calibration and use of a consumer-grade digital single-lens reflex (DSLR) camera for the measurement of temperature in sooty flames using color-ratio pyrometry (CRP) is elucidated. Owing to the necessity of acquiring RAW images for CRP, investigations conducted thus far have been limited to stable flames. In this work, the potential of a CANON EOS 550D DSLR camera for measuring temperature during a transient process such as a droplet combustion event at frame rates up to 50 fps is demonstrated. The spectral response curves of the camera-lens system were obtained with the help of a tunable laser source and a laser power meter, which were subsequently used to generate lookup tables for blackbody as well as soot radiation. Soot radiation was assumed to vary with wavelength (λ) as λ-α, where α is the soot dispersion exponent. The blackbody lookup table was validated against blackbody calibration data from 1023 to 1773 K. Experiments were conducted on a candle flame as well as a McKenna flat flame burner with ethylene-air mixtures of equivalence ratios 2.1 and 2.3. For estimating temperatures using CRP, soot particles were classified as nascent and mature soot with soot dispersion exponent (α) values of 4 and 1.38, respectively. The CRP results were found to yield a decent match with thermocouple measurements as well as data reported in the literature.
ABSTRACT
This work provides new insights for the liquid-phase decomposition of bis(triaminoguanidinium) azotetrazolate (TAGzT). The liquid-phase decomposition process was investigated using a combined experimental and computational approach. Sub-milligram samples of TAGzT were heated at rates of about 2000 K s-1 to a set temperature (230 to 260 °C) where liquid-phase decomposition occurred under isothermal conditions. Fourier transform infrared (FTIR) spectroscopy and time-of-flight mass spectrometry (ToFMS) were used to acquire transmittance spectra and mass spectra of the evolved gas-phase species from the rapid thermolysis, respectively. FTIR spectroscopy was also used to acquire the transmittance spectra of the condensate and residue formed from the decomposition. N2, NH3, HCN, N2H4, triaminoguanidine and 3-azido-1,2,4-triazol-4-ide anion were identified as products of liquid-phase decomposition. Quantum chemical calculations were used for confirming the identity of the species observed in experiments and for identifying elementary chemical reactions that formed these species. Based on the calculated free energy barriers of these elementary reactions, important reaction pathways were identified for the formation of each of the product species.
