JOURNAL OF ENERGETIC MATERIALS
Year:2012 | Volume:6 | Issue:3 (13)|Papers Count:7

CL-20 is the most energetic conventional explosive available for military use. The over all aim of the high energy material research community is to increase the yield and reduce the cost of CL-20 synthesis. All synthetic methods used to prepare the CL-20, depended on the condensation reaction of benzylamine with glyoxal for the preparation of HBIW intermediate. In the presence of HCOOH catalyst and ethanol solvent, yield of 58% is reported. In this paper we investigated the effect of lewis acid catalyst on the yield of HBIW. The results showed that the more efficient catalyst such as BF3 and Mg (ClO4)2, increased the yield, 20% more than previously reported.

Oblique impact of cylindrical projectiles with blunt, conical and hemispherical noses with different aspect ratios on metallic targets with different thicknesses is investigated and penetration critical angle is determined. Circular targets of Al1100-H12 had a diameter of 240mm and thicknesses of 1, 2 and 3mm. Steel work hardened projectiles with blunt, conical and hemispherical noses are made with three different aspect ratios. Tests are conducted using a single stage gas gun. Results show that changing nose shape, changes the target failure mechanism and therefore, changes the target strength and the penetration critical angle. Aspect ratio of the projectile affects the ballistic performance of the target so that increase of this parameter results in increase of the penetration critical angle. The blunt nose projectile shows better ballistic performance and its penetration critical angle is greater than those of other projectiles. Finally, the penetration critical angle is slightly greater for conical nose projectile compared with semispherical one.

Different defensive methods are usually available to improve the resistance of existing critical buildings against catastrophic effects of explosion loads to ensure continuing services and protection of lives. The optimum retrofitting method is the one that through technical and economic considerations reduces the rate of damage to equipment, existing buildings and the possible human casualties. This paper presents a procedure to determine the best defensive retrofitting alternative using AHP and TOPSIS techniques. Application of developed procedure in retrofitting a group of critical concrete buildings identifies the specific method of "Adding Wall" as the best alternative against explosion loads of this type of buildings.

In this paper, preparation method of unsymmetrical di-methyl hydrazine with nano aluminum particles (50 and 130 nm) has been investigated. One of the important aspects of the research is the uniform dispersion of the nano particles in the fuel gel. Homogeneity of the fuel influences the quality of propellant combustion. The results showed that the combination of ultrasonic-mechanical-magnetic agitation is an appropriate method for the preparation of gel. Prepared gel following this method has appropriate stability and homogeneity. Rheological tests on the gel showed that the fuel gel has thixotropic and shear thinning properties. The modeling results showed that power law model is the best method for description of rheological behavior of gel. Index n of 0.56 and 0.63 have been obtained respectively for UDMH gel containing nano aluminum particle of 50 nm and 130 nm diameter at various temperatures.

Concentration of hydrogen peroxide to military grade (about 98 wt%) needs removal of impurities from hydrogen peroxide of commercial grade. In this research, separation of metallic impurities from hydrogen peroxide solution was studied and cations as Al, Fe, Pb, Zn and Cr were separated from commercial hydrogen peroxide using Amberlite IR-120 (strong cationic resin). The cations were separated in a vessel at constant stirring rate. The effects of pH, amount of resin, temperature and contact time on the separation process was studied. The amounts of metallic cations were measured by ICP method. For determination the amount of resin, certain concentrations of Mg2+ and Cr3+ were added to the solution and the results were followed. Results from separation of Cr3+ were compared with the Frendlich and Langmuir models and it has been shown that In a narrow limit of Cr3+ concentration, the models afford satisfactory results.

In this paper the Cross-linked double base propellant (XLDB) based on polyurethanes comprised of polycaprolactone (PCP) as binder and ammonium perchlorate (AP) and RDX as solid oxidizer have been prepared and characterized. Propellant burning rate were determined by the strand burner method (Crawford bomb). In the AP-based composition, the energy is enhanced and the pressure exponent reduced with increasing the AP content. When the AP is partially replaced by RDX, Isp is improved and the pressure exponent is decreased. The role of AP and RDX particle size was studied on the burning rate and mechanical properties of propellant. It will be find that the value of n (power low) decreases from 0.9 to 0.75 when the AP content increases from 10% to 20% and RDX amount decrease form 50% to 40%. By varying the AP particle size and RDX particle size up to 5 m, the exponent pressure reduce to 0.65<n<0.75. The mechanical properties of this propellant has been increased significantly by using of coarse & fine particle size of RDX (70.30).The result of this study revealed that fine size of RDX and AP (2-10 m) may be the most suitable for this propellant to meet desired burning rate for satisfactory ballistics utilization.

In this research, Polyisobutylene was produced via batch direct polymerization of isobutylene in a 1 liter reactor at low temperature. Various catalytic systems were investigated to produce desired polymer. The results showed that AlCl3/TiCl4 catalytic system is the best catalytic system to produce desired Polyisobutylene. In addition, effects of other important parameters such as temperature, amount of catalyst were investigated. The results showed that the temperature lowering to -30 oC caused production of polymer with desired characteristics. So, optimized condition consists of temperature of -35 oC in n-heptane as solvent and using a combination of 0.12 g of AlCl3 and 3 g of TiCl4 catalysts.