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When: 21 August 2023, 11:00–12:00
Where: Platinum, ESS, Lund, Sweden
Speaker: Ryan Murphy (NIST)
Title: Combining high-shear capillary rheometry and small-angle scattering methods
Organiser: ESS Science Seminars; Judith Houston, Scientific Coordination and User Office
Abstract
Processing methods such as spraying, coating, and jetting can produce extreme flow velocities within confined geometries. High shear rates and stresses near the wall can induce reversible or irreversible changes within the complex fluid microstructure. To quantify these flow-induced changes, a capillary rheometer was developed to measure the viscosity of complex fluids at high shear rates and to measure the microstructure simultaneously using small-angle scattering. Originally developed for small-angle neutron scattering [1], the same capillary setup and methodology was expanded recently for x-ray scattering, which enables significantly lower count times, improved sample and shear rate throughput, higher shear rates up to 10,000,000 s-1, and extremely confined flows within capillaries down to 500 nm. This work will highlight and discuss the rheometer design criteria, recent rheometer upgrades, the advantages and limitations when using either neutron or x-ray sources, and software control improvements. The structurerheology relationships of different model systems will be discussed, including worm-like micelles, lipid vesicles, polymers, proteins, silica nanoparticles, and larger colloidal crystals. By combining and expanding the measurement capabilities of capillary rheometry and scattering methods, new fundamental insights can be used to produce pharmaceuticals, coatings, lubricants, and fuel additives with improved flow-stability and rheological behavior.
[1] R. P. Murphy, et al., Soft Matter. 16, 6285-6293 (2020)
Biography
Ryan Murphy is from the National Institute of Standards and Technology, NIST Center for Neutron Research, Gaithersburg, Maryland, USA. His recent publications can be found on the NIST website: