Iranian Journal of Chemical Engineering (IJChE)

Abstract Liners serve as both a barrier layer and an adhesive, bonding the insulation to the propellant. Plasticizer migration is a frequently observed phenomenon in solid propellants, often leading to detrimental effects on mechanical stability and performance.  Absorbent plasticizer liners have emerged as a next-generation solution, offering both anti-migration properties and adhesive capabilities. In this study, the anti-migration effects of three polyethers, including polyethylene glycol (PEG), polypropylene glycol (PPG), and polytetrahydrofuran (PTHF) as liners in the presence of plasticizers 1,2,4-butanetriol trinitrate (BTTN),  trimethylolethane trinitrate (TMETN), and triethylene glycol dinitrate (TEGDN), were studied using NPT-molecular dynamics simulation (NPT-MD) with the Compass III force field. The binding energy, solubility parameter, and radial distribution function of polyethers containing 20% plasticizers were calculated.  The mixture of PEG and TEGDN exhibited the highest binding energy and compatibility. The solubility parameter reflects the strength of non-bonded intermolecular forces, indicating compatibility. The radial distribution function analysis showed strengthened van der Waals interactions, confirming compatibility. Molecular dynamics simulation results showed that polyethylene glycol is a suitable liner with anti-migration properties in propellants.

Abstract 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) is one of the most powerful explosives of which the purity may have a significant effect on increasing the performance of rocket engines. In this research, the synthesis of high purity HMX is presented using the nitration of 1,5-diacetyl-3,7-dinitrooctahydro-1,3,5,7-tetrazocine (DADN) with a mixture of nitric acid and polyphosphoric acid. The nitration parameters including temperature, time, and the concentration of nitric acid, and polyphosphoric acid were optimized for the desirable purity and efficiency using the response surface method and central composite method (CCD). Based on the optimization, HMX was obtained with a purity of 99% and an efficiency of 92.9% at a temperature of 70°C and the time duration of 70 minutes with a molar ratio of polyphosphoric acid to nitric acid of 1:1:6.