Study on elongation master curve of thermal aging composite modified double base propellant

In order to predict the maximum elongation of composite modified double base (CMDB) propellants under different aging time, temperature and strain rate, systematic uniaxial tensile characterization was performed across six controlled temperatures (233.15 K, 253.15 K, 273.15 K, 283.15 K, 298.15 K, 323.15 K) and three decades of strain rates (3.3 × 10^-4 s^-1, 3.3 × 10^-3 s^-1 and 3.3 × 10^-2s^-1) through accelerated aging protocols. The maximum elongation of CMDB propellants under different temperatures and strain rates during aging was obtained, and the aging mechanism of CMDB propellants was analyzed in combination with scanning electron microscopy experiments. The elongation master curve was constructed based on time-temperature equivalent principle, and the elongation master curve model considering aging effect was established combining with existing theories. The results show that the maximum elongation of CMDB propellant decreases monotonically with the aging time, and the microscopic damage in the tensile section gradually increases. The aging time has little effect on the temperature and rate-related properties of the material. By comparing the predicted results of the elongation master curve model considering the aging effect with the experimental results, It is shown that the elongation master curve model considering the aging effect can describe the elongation master curve under different aging time.