JOURNAL OF ENERGETIC MATERIALS
Year:2006 | Volume:1 | Issue:1|Papers Count:10

In this paper, at first, the amount of Impulse delivered to the plate due to an under water sta nd-off explosion of concentrated charge is calculated. Then the strain energy due to deformation of plate in the conical die is calculated. In the next stage, required energy is obtained by considering mechanical efficiency of the operations. Based on the results of this stage, required velocity and impulse is determined. Finally, required charge mass for cone explosive forming operations is obtained by equating required impulse and delivered Impulse of plate. Some experimental tests were designed and carried out. Experimental results of this investigation and experimental results of other researchers were compared to analytical results of presented model and commented upon.

Catalytic reductive alkylation of acetylhydrazine (AH) to dimethyl acetylhydrazine (DMAH) is a key step in the production of unsymmetrical dimethyl hydrazine (UDMH). The catalyst used for the process is Pd/C (5 wt.%). The catalyst may be deactivated due to polymerization of acetylhydrazone (AOH), an intermediate product, the kinetics of production and polymerization of AOH has been studied, in addition, the ways of preventing catalyst deactivation are proposed.

Composite Modified Double Base (CMDB)propellants are capable of prod ucing highest specific impulse along with wide flexibility of burning rates among the solid rocket propellants and therefore are preferred over conventional double base and composite propellants in many applications. High energy double base propellants contain high energy ingredients such as AP, AI, HMX and RDX These propellants are produced via different methods such as extrusion and casting. In this research, AP-CMDB propellants were studied and produced by solvent extrusion to increase the standard specific impulse to a minimum of 240 sec. Performance calculations for CMDB propellants were carried out using CEC software. According to these calculations and literature survey twelve formulations were determined and prepared by solvent extrusion process. Quality control and static tests were carried out over these propellants and Isp =260.4 sec (standard Isp = 251 sec) was obtained in comparison with 200 sec for conventional double base propellants. Finally the formulation of CMDB propellant was optimized with respect to mechanical and stability properties, calorific value and specific impulse.

The particle size factor is universal and concerns all reactive systems: fuels, oxidizers, propellants, pyrotechnics and explosives. In the pyrotechnics formulations particle size factor is very important. The heat of reaction is an important parameter of pyrotechnic composition, being one of the factors, which control maximum temperature obtained during combustion. This is especially important with pyrotechnic compositions containing potassium chlorate which are used to vaporized organic materials. The latter are decomposed at high temperatures and are thus sensitive to the amount of heat evolved. In this research the effect of potassium chlorate particle size on heat evolved and ignition temperature were studied. The particle size of potassium chlorate is prepared from chemical method with crystallizing of potassium chlorate saturated solutions. The heat of reaction was measured from direct calorimetric methods. The ignition temperature was determined from thermal analysis methods. The results indicate that with decrease of particle size, heat of reaction is increased and which more decrease of particle size the increase of heat evolved very rapidly. The considerable results indicate that 100 to 250 microns are the best potassium chlorate particle size for this pyrotechnic utilization's.

Ageing of a composite solid propellant based on polyether-urethane (PEU-P) was investigated at various temperatures between 25 to 70°e. GPC, FTIR, tensile tests and sol/gel analysis were utilized in determining the chemical and physical changes at different intervals during the curing and ageing periods of (PEU-P). GPC results showed that the MW of the sol increases, going through a maximum then decreases to a constant level. The results obtained from GPC, FTIR, tensile tests and gel analysis showed the end of poly merization (te) i.e. "the time to reach the constant level of gel percent, MW, mechanical properties and NCO termination" decreased with increasing temperature and showed linear plots of the te vs. 1/T. During the ageing period, gel content and maximum stress (σm) decreased and MW of the sol inreased. An ageing model based on Arrhenius equation was suggested (σm=k Ln t + a) and fitted to the experimental data and the lifetime of the (PEU-P) was predicted. The activation energy for the (PEU-P) ageing process was found to be 29kJ/mol.

In this research the synthesis of new compound, 2,6-bis (picrylamino)-3-nitropyridine was studied. For this purpose, two methods used, picrylation of 2,6-diamino-3-nitropyridine and nitration of 2,6-bis (picrylamino) pyridine (BPAP). The nitration of 2,6-bis (picrylamino)-3-nitropyridine due to interaction between the lone pairs of amines with pyridine ring, with nitro group, aborted, but, nitration of BPAP resulted in desired products, 2,6 –bis (picrylamino)-3- nitropyridine (BPNP). This product was separated and purified by thin layer chromatography method and reco gnized by JHNMR spectrum.

Cyclotetramethylene tetranitramine, known as HMX is one of the most important high explosives currently used extensively in various military applications. In this paper, at first, physical, chemical and various preparation methods of HMX were reviewed and Bachmann process was chosen as proper method. Then with consid eration of reaction conditions such as temperature, agititation speed and reaction time, effect of variation of nitric acid to ammonium nitrate molar ratio on product yeild have been examined. Infrared and NMR spectra have been used for product charactrization. The comparison of reresults with other references show that reaction yield in present work is more than previous reported data.