Study of the High-Temperature Decomposition of AP and PMMA by the Linear Pyrolysis Method

Abstract

Experimental results from studying the kinetics of the high-temperature decomposition of ammonium perchlorate (AP) and polymethylmethacrylate (PMMA) using a radically improved method of linear pyrolysis are presented. The method used allowed kinetic data corresponding to high temperatures and reaction rates to be obtained (which cannot be done using classical isothermal methods). Patterns of the high-temperature decomposition of AP and PMMA that do not manifest themselves at low temperatures are characterized. The macrokinetics of the high-temperature decomposition of AP are shown to be strongly affected by dissociative sublimation at thermodynamic equilibrium, which yields ammonia and perchloric acid vapor. The activation energies of the high-temperature decomposition of PMMA and some other polymers were found to significantly exceed those of the limiting stages of their low-temperature decomposition. As the temperature grows, the kinetic mechanism of polymer decomposition changes. Because of this, the burning of polymers occurs in the “third mode,” characterized by an almost constant pyrolysis surface temperature over a wide range of polymer burning rates. Original data on the pyrolysis of solid propellant components obtained using the chemical arc (in which the stationary high-temperature decomposition of polymer and oxidizer occurs under the influence of the flat flame of interaction between the gaseous products of their linear pyrolysis) are presented. The effects of Fe₂O₃ and CuO (solid propellant combustion catalysts) on the rates of AP and PMMA linear pyrolysis are considered.