Pentaerythritol tetranitrate (PETN) is a secondary energetic material generally used in initiators for industrial and government applications. Changes in the morphology and surface area of aging powders have been observed during aging, which can modify the initiability and performance. Here work is presented using two different techniques to determine kinetic and thermodynamic parameters of single crystal PETN. Atomic force microscopy is used for low-temperature analysis, while thermogravimetric analysis is used at higher temperatures. A mechanism is proposed to expand the understanding of coarsening observed in real world PETN.