Aging Characteristics and Mechanisms of CMDB Propellants Under Vacuum Conditions

In order to explore the aging characteristics of CMDB propellants under vacuum conditions relevant to spacecraft storage or ground‐based applications, comparative accelerated aging tests were conducted under three conditions: vacuum 60°C, atmospheric 60°C and 70°C. Specimens were tested for uniaxial tensile strength, hardness, an NMR‐derived cross‐linking‐related parameter, and component content. The results show that under atmospheric 60°C, NG decreases by only 1.68%, stabilizer by 0.188%, cross‐linking density reduces by 0.196 Mc, maximum tensile strength declines by 2.169 MPa, maximum elongation decreases by 3.85%, and hardness increases by 1 HA. These changes are more obvious at 70°C, but the propellant remains viscoelastic. In contrast, under vacuum 60°C, NG drastically reduces from 36% to 19.54%, stabilizer reduces by 0.55%, cross‐linking density increases to 2.405 Mc, maximum tensile strength increases by 3.163 MPa, maximum elongation plunges by 11.984%, hardness increases by 4.13 HA, and the propellant exhibits brittle characteristics. The results indicate that vacuum conditions accelerate the migration and volatilization of liquid components (NG and stabilizer), increasing intermolecular forces of NC. Meanwhile, H + generated from thermal decomposition of NG creates a more acidic environment in the lower liquid component environment, inducing ‐OH groups on NC molecular chains to react and form ‐O‐ bonds, leading to chemical cross‐linking between adjacent NC molecules. These phenomena fundamentally cause the distinct vacuum aging behavior compared to atmospheric pressure.