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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 structure rheology 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).
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:
https://www.nist.gov/people/ryan-murphy
Date: 21 August, 2023
Time: 11:00-12:00
Venue: Platinum, B01, ESS, Lund
Coffee/tea and a biscuit will be provided.
If you would like a zoom link, please contact useroffice@ess.eu and this can be provided.
If you are an external visitor to ESS, please arrive between 10:45 and 10:55 to give time to collect your visitor badge and be guided to the event. Please bring your passport or national ID card to identify yourself at security reception.
Judith Houston
Scientific Coordination and User Office