Mechanical properties and deformation behaviors of the hydroxyl-terminated polybutadiene and ammonium perchlorate interface by molecular dynamics simulation

The interfacial structure and deformation behaviors have considerable influences on the structural reliability and durability of the hydroxyl-terminated polybutadiene (HTPB) solid rocket propellant. In this work, an all-atom molecular dynamics (MD) simulation was adopted to investigate mechanical properties and damage behaviors of the HTPB and ammonium perchlorate (AP) interface. The modified polymer consistent force field was implanted to describe intra- and intermolecular interactions. The effects of loading rate, temperature, and moisture content on the interfacial strength and tensile curves were discussed. The simulation results show that the interfacial strength and modulus exhibit an increasing tendency when the loading rate increases. However, increasing the temperature and moisture content will lead to a decrease in the interfacial strength. Two interfacial tensile modes distinguished by the mass density curve were adopted and compared to reveal the internal deformation process. The AP-HTPB interfacial deformation initially occurs inside the HTPB bulk due to its lower mechanical strength than the interface and then gradually expands to the interface region. Furthermore, a linear extrapolation based on phenomenological results was used to reveal the discrepancy in scale between experiments and the MD simulation.