Measuring complex fluids under extreme flow conditions

Utilizing the unique focusing optics, flexible sample space, and SAXS capabilities at the FMB-beamline, a group of researchers from the National Institute of Standards and Technology measured the rheology and structure of complex fluids subjected to extreme flow velocities while confined within micrometer-sized capillaries.

What did the scientists do?

A capillary rheometer capable of producing high shear rates at the wall, previously developed for neutron scattering, was modified to expand the accessible shear rates up to 107 s-1 when using a high-flux x-ray source with small spot sizes, such as the FMB-beamline at CHESS. Using the new setup optimized for x-ray scattering, the structure and rheology of worm-like micelle solutions were measured at high shear rates to better understand the microstructural alignment, breakdown, and shear thinning rheology of these widely utilized surfactants.

Why is this important?

Worm-like micelle surfactant systems have numerous applications ranging from pharmaceutical formulations to enhanced oil recovery. The simultaneous rheology and x-ray scattering measurements will help link the changes in macroscopic rheological properties to the changes in nanoscale fluid structure such as micelle orientation and length distribution. These measurements are also important to improve rheological models, which currently fail to accurately predict the viscosity of complex fluids at high shear rates.

Read more on the CHESS website

Image: SAXS measurements at the FMB-beamline showed distinct changes in the worm-like micelle structure under flow