Effect of Prestrain on Dynamic Mechanical Properties of HTPB Propellant during Aging Process

The accelerated aging tests of HTPB (hydroxy-terminated polybutadiene binder) propellant under the interaction of thermal and prestrain were adopted to study the effect of prestrain on the mechanical properties of composite solid propellant. The dynamic mechanical parameters of HTPB propellant at different prestrain levels were obtained through dynamic mechanical tests and the temperature spectra of storage modulus, loss modulus and loss factor were analyzed. The results show that the prestrain during aging process has great influence on the dynamic mechanical properties of HTPB propellant. At the same aging time, with the increase of the prestrain, the flexibility of polymer chain decreases, as a result, the glass transition temperature of HTPB propellant increases. Besides, the activation energy of the glass relaxation process and the mechanical loss increase. For the HTPB propellant aged without prestrain, with the increase of aging time, the mechanical loss of HTPB propellant decreases due to the leading role of the oxidative crosslinking reaction of binder matrix. However, for the HTPB propellant aged under 15% prestrain level, the mechanical loss increases with the increase of aging time. Because the accumulated damage of binder matrix and the damage of interface between filler/matrix plays a dominant role in the mechanical loss of the propellant.