Storage-life prediction and relationship between maximum elongation and stabilizer depletion for a composite modified double base propellant (CMDB) propellant

In an effort to predict the storage life of a composite modified double base propellant (CMDB propellant) at 298.15 K, we investigated the relationship between the maximum elongation of the propellant and its stabilizer depletion. Thermally accelerated aging experiments were carried out at 323.15 K, 333.15 K, 343.15 K, and 353.15 K. The change in the amounts of N-methyl-4-nitroaniline (MNA) content and the maximum elongation of the propellant at different thermal aging temperatures were measured and analyzed. A modified exponential aging model for CMDB propellant was proposed. With the use of both MNA content and maximum elongation as aging indicators, the storage life of CMDB propellants at 298.15 K was predicted using the modified Arrhenius equation. The aging mechanism of CMDB propellant was analyzed, and a correlation function model for the relationship between the maximum elongation and stabilizer depletion was established. The results show that the maximum elongation and MNA content decrease with aging time as the aging temperature increases. The fitting correlation coefficients of the modified exponential aging model exceed 0.97. The storage life of CMDB at 298.15 K is estimated to be 20.84 years and 19.19 years, based on the MNA content and maximum elongation, respectively. The validity of the correlation function is validated by comparing the prediction results of the correlation function and the aging model for the maximum elongation under different aging times. The overall error is less than 15%, indicating the validity for predicting the maximum elongation of CMDB propellant based on the consumption of MNA.