Beyond the Arrhenius rate law in simulating the shock-driven decomposition of polyimide

Building off of previous work simulating the shock-driven decomposition of polysulfone, we present simulations of the shock-driven decomposition of polyimide. In agreement with the previous work, we find that the Arrhenius rate equation is insufficient for quantitatively reproducing the experimental wave profiles, and we also find that the Arrhenius rate equation cannot reproduce many of the qualitative features of the wave. In light of these results, we examined both an empirical Eyring rate equation as well as the Shock Reactive Flux Method (SRFM) as presented by Valone and found neither to be able to fully capture the quantitative behavior of the measured wave. More specifically, we found that the Eyring equation was only marginally better than an Arrhenius rate law in achieving the very fast reaction rates required to reproduce data at high particle velocities. While the SRFM offered two additional parameters for fitting reaction behavior, we found that the rate law was only able to reproduce the data over a limited range of particle velocities while not being able to reproduce measured shock velocities.