Aging mechanical properties of HTPB propellant under thermal-mechanical coupled condition

In order to understand how pre-strain affects the aging mechanical properties of composite solid propellant, the accelerated aging tests of HTPB (hydroxy-terminated polybutadiene binder)propellant under the interaction of thermal and pre-strain were carried out at 70℃. The aging properties of HTPB propellant at different pre-strain levels were researched through uniaxial tensile tests and scanning electron microscope (SEM) experiments of tensile fracture surfaces. The results show that the oxidative crosslinking reaction of binder matrix is the major aging mechanism of HTPB propellant at researched pre-strain range (≤15%) regardless of different pre-strain levels. At the same aging time, there is a critical pre-strain value that affects the mechanical properties of HTPB propellant. When the aging pre-strain is higher than the critical pre-strain value, the dewetting phenomenon of AP and HTPB matrix bonding interface and the tearing damage phenomenon of binder matrix is evident in tensile fracture surface.