Unveiling the Origin of a Nonequilibrium Dynamic Process Detected by X-Ray Photon Correlation Spectroscopy via a Finite Element Analysis Approach
Li Ma, Fan Zhang, Andrew J. Allen, Lyle E. Levine
It is a scientific and engineering challenge to characterize materials under nonequilibrium conditions. In recent years, X-ray photon correlation spectroscopy (XPCS), a synchrotron based coherent X-ray scattering technique, has been found useful in -determining the time scales associated with various nonequilibrium processes, with detailed descriptions of the underlying processes lacking. Here, Both static ultra-small angle X-ray scattering (USAXS) and dynamic USAXS based XPCS were used to investigate a transient structural change (a nonequlibrium process) associated with an isothermal anneal in a glass polymer composite system. While the bulk USAXS technique lacked the required sensitivity to detect the change in the microstructures, the local structural reorganization was apparent in the XPCS study. The structural changes were modeled using a three dimensional finite element analysis approach and used wave-propagation theory to simulate the resulting reciprocal-space coherent scattering intensity. There was qualitative agreement between the modeling and experimental results, which demonstrates that stress relaxation in the viscous polymer matrix was responsible for the observed changes. This analysis demonstrates that multi-physics modeling of complex systems can be used to interpret XPCS measurements of nonequilibrium processes.
, Zhang, F.
, Allen, A.
and Levine, L.
Unveiling the Origin of a Nonequilibrium Dynamic Process Detected by X-Ray Photon Correlation Spectroscopy via a Finite Element Analysis Approach, ACTA Crystallographica Section A, [online], https://doi.org/10.1107/S205327331400686X
(Accessed July 31, 2021)