Research on microscopic structure–activity relationship of AP particle–matrix interface in HTPB propellant

The matrix and particle interface of hydroxyl-terminated polybutadiene (HTPB) propellant is the weakest part of its mechanical properties, making it prone to dewetting damage and destroying the structural integrity of the propellant. This article uses nano-indentation, gas cluster ion beam etching, and X-ray photoelectron spectroscopy experimental analyses to study the physicochemical properties of the interface and subsequently construct a microscopic model for the HTPB matrix and ammonium perchlorate particle interface. The model fully considers the existing forms of curing agent toluene diisocyanate, bonding agent Tris (2-methyl-aziridine) phosphine oxide (MAPO), and the aging products of the propellant in the interface structure. Meanwhile, the physicochemical properties, mechanical properties, and adhesive properties of the interface under different tensile loading conditions were analyzed. The results indicate that the bonding agent MAPO significantly enhances the mechanical and adhesive properties of the interface. The interface is sensitive to changes in temperature and tensile rate, and the aged interface is more fragile.