Shock experiments reveal the behavior of polymers transitioning into their reactants

Polysulfone is a polymer material with applications ranging from medicine to space due to its specific properties in extreme conditions. To better understand its properties in these conditions, Huber et al. studied its structural transition into higher density products from shock compression.

Previous studies of polysulfone’s response to shock compression did not allow for the observation of two-wave velocimetry profiles to calculate the separate reactants and products states. By accessing pressures between 14.6 and 26.2 GPa, the authors were able to observe a two-wave structure, indicating the chemical decomposition of the material dependent on both the temperature and pressure of the system.

“It is obvious that the kinetics that drive the reactants to products transition are very important,” said author Rachel Huber. “These particle velocity profiles do not show a separate distinct reactants and products particle velocity profile, it is a mixture of the two, dependent on where you are within the transition region.”

The group used two separate shock experiments to study the transition at different pressures. One experiment directly measured velocity flows in the material using an electro-magnetic embedded velocity gauge. The other determined the shock transmission through careful placement of photonic Doppler velocimetry at the interfaces of the polysulfone to capture both shock velocity and particle velocity.

Additional work remains to be done to push the model into more realistic pressure and temperature regions for applications in extreme conditions.

“High pressure, high temperature shock experiments such as these, where the two-wave particle velocity profiles allow for careful calculation of both the reactant and product states, are still needed for numerous polymers to understand the physics and chemistry that drives the transition region,” Huber said.

Source: “Polysulfone shock compressed above the decomposition threshold: Velocimetry and modeling of two-wave structures,” by R. C. Huber, J. Peterson, Joshua D. Coe, D. M. Dattelbaum, L. L. Gibson, R. L. Gustavsen, J. M. Lang, and S. A. Sheffield, Journal of Applied Physics (2020). The article can be accessed at https://doi.org/10.1063/1.5124252 .