Thermal decomposition of ammonium perchlorate using Monte Carlo methods

One of the most intriguing aspects of ammonium perchlorate (AP) decomposition is its incomplete decomposition at low temperatures, in which the decomposition halts at a level of approximately 30%. Various theories have been proposed to explain this observation based on physical and chemical arguments. Here we consider the notion that geometry itself might contribute to this limiting value. Percolation theory involves the “connectedness” of a geometric lattice, and a network is said to percolate if it is connected continuously end-to-end. It has been demonstrated that in a cubic lattice, percolation occurs at a site density of ~31.1%, remarkably similar to the limiting void fraction in AP. A Monte Carlo (MC) algorithm using simple rules has been developed and applied to particle decomposition. The MC simulations result in porosity evolutions that are reminiscent of actual AP behavior in terms of the overall limiting porosity which is developed, the effect of particle size, and the sigmoidal time response.