Studies of the mechanical behavior of ammonium perchlorate particles, a glass-bead filled polyurethane binder, and a typical continuum binder

Experimental studies were carried out on a continuum Neoprene binder, a glass bead-filled-polyurethane binder, and unbound micro-pulverized ammonium perchlorate particles. As a result of stress relaxation and creep experiments, it is concluded that the large deformation behavior of the filled binder can be described in part in terms of the large deformation behavior of the continuum binder. The time scale of relaxation of stress in the filled binder is much longer than that of the unfilled binder. It is determined by frictional processes between the filler and binder and also among the filler particles. As a result of relaxation and creep studies on ammonium perchlorate particles, it is found that the time scale of relaxation is of the same order of magnitude as that of the filled binder. In addition, it is believed that the static indeterminacy of the unbound particles helps to explain much of the strain variation at given stress level that is observed in tensile experiments of composite propellants