f. abrishami

In this study, the synthesis, physicochemical properties and energetic performance of fused heterocycle based energetic materials with two or more rings are investigated. These compounds have been considered with a coplanar polycyclic structure, higher heats of formation (HOF) and ring-strain energy stored in the molecules. Good energetic performance, high thermal stability and low sensitivity toward destructive mechanical stimuli increase the safety of the synthesis, transfer, and storage of high- density energetic compounds. These properties make fused heterocyclic compounds a suitable alternative to conventional high-energetic materials for military and civilian applications Among the compounds studied, some of them have explosive performance comparable or higher than conventional explosives such as TNT, HMX, RDX or CL-20 and lower sensitivity to external stimuli. They are suitable candidate for replacement of conventional explosives. Because of their high specific impalse, some of them are suitable for use in high-performance propellant formulations. Also, the difference between melting point and decomposition temperature makes these fused heterocycles suitable as melt cast explosive.

In this study, the recent developments in the synthesis of some azo- linked high- nitrogen energetic heterocycles such as tetrazole, triazole, imidazole, pyrazole, triazine, tetrazine and their salts will be investigated. These energetic compounds generally exhibit desirable properties and performance, which in some cases are superior to the conventional energetic materials such as hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 2, 4, 6-trinitrotoluene (TNT) and 1,3,5-trinamino-2,4,6- trinitrobenzene (TATB).

One of the properties for liquid bipropellants is their hypergolicity. The required quantity for this purpose is ignition delay time (IDT). IDT is classified into two classes: physical and chemical. The chemical ignition delay time is the time interval between the contact of fuel droplet - oxidizer surface and appearance of the first flame. The most appropriate laboratory method for measuring the chemical ignition delay time is drop test. Considering the effective parameters on the ignition delay time (such as oxidizer to fuel ratio, temperature and pressure) and following the mechanical design, this system was manufactured with capability of temperature and the reaction chamber pressure adjustments. For calibration and standardization of the system, some liquid fuels (such as triethyl amine, unsymmetrical dimethyl hydrazine and Tonka-250 mixture) and some liquid oxidizers (such as strong nitric acid and conventional oxidizer AK27) were applied. Good repeatability and dispersity of the obtained results indicate the system accuracy.

Promote chemical technologies is an innovation that reduce or eliminate use or production of hazardous materials in the design, manufacture and use of chemical products. According to this law, reduce pollution at source is fundamentally different and more desirable than waste management and pollution control. Nowadays, this new approach known as green chemistry, which is: The design of chemical products and processes that reduce or destroy use and generate substances harmful to human health and the environment. In this article, chemical compounds containing the new tetrazoles includes N- oxide group, which belongs to high energetic compounds, has been discussed and compared with conventional explosives. In this comparison, it is seen that some -N-oxide compounds have better properties and performance compared to conventional explosives. So they could be suitable alternatives for propellants and explosives.