Molecular simulation of aging mechanism for HTPB propellants

Abstract

To study the aging mechanism of HTPB (hydroxyl-terminated palybutadiene) propellant, the quantum chemistry method was used to calculate the bond energy of chemical bond of HTPB-TDI (toluene diisocyante) curing system, and transition states of possible four oxidative cross-linking reactions occurring in the aging process of HTPB propellant were investigated. Results show that the bond energy of C-O bond connected with CH2 group is minimum. The energy is determined as 244.95 kJ·mol-1. The rupture of the C-O bond in the aging degradation process easily occurs. The activation energies of possible four oxidation linking reactions are all smaller, and less than the energy needed for HTPB-TDI curing molecular degradation, indicating that oxidation linking reaction is the primary cause of HTPB propellant aging. Among them, the activation energy of ternary-epoxy reaction is minimum and its value is 12.59 kJ·mol-1.