MECHANICAL BEHAVIOR OF ENERGETIC POLYMERIC MATERIALS

Abstract

Understanding the mechanical behavior of energetic materials under the strain rate, temperature, and dormant storage environments of military applications is necessary for predicting their performance and safety tolerances and their useful life. This work focuses on the mechanical integrity of nitrocellulose base gun propellants and the correlation of brittleness with abnormal energetic performance. Compressive mechanical properties at a strain rate of 1000 percent-of-length per second as a function of temperatures descending to −60°C, and the failure appearances of the tested samples, are used to identify ductile-brittle transition temperatures and relate to propellant functioning. Preliminary data of mechanical property changes with time indicate that embrittlement takes place in these materials with age, shifting the ductile-brittle transition to higher temperatures or less severe loading conditions; glass transition temperatures, determined using thermo-mechanical and calorimetric methods, are suggested as promising materials parameters for indexing such time dependent changes.