Dynamic mechanical properties of HTPB propellant aged under prestrain effect

To understand the effect of prestrain on the aging properties of solid propellant, the accelerated aging tests of HTPB (hydroxy-terminated polybutadiene binder) propellant under the interaction of thermal and prestrain were carried out at 343K and the dynamic mechanical tests were conducted. The dynamic mechanical parameters of HTPB propellant at different prestrain levels were obtained through dynamic mechanical analysis, including temperature spectra of storage modulus, loss modulus and tan δ. The glass transition temperature, the activation energy of the glass transition and the mechanical loss defined by tan δ curves were selected as analysis parameters. The analysis results show that the dynamic mechanical properties of HTPB propellant are greatly influenced by the prestrain during the aging process. At the same aging time, with the increase of the prestrain, the flexibility of HTPB polymer chain decreases, as a result, the glass transition temperature and the activation energy increase. Besides, the mechanical loss of HTPB propellant increases with the increase of prestrain, which is due to the aggravation of damage in the HTPB matrix and the dewetting damage of AP filler and HTPB matrix interface.