Paper Number
RS34 

Session
Techniques and Methods: Rheometry & Spectroscopy/Microscopy

Title
Simultaneous capillary eheology and neutron scattering on wormlike micelles and rod-like particles

Presentation Date and Time
October 12, 2022 (Wednesday) 5:25

Track / Room
Track 6 / Mayfair

Authors (Click on name to view author profile)

  1. Weigandt, Katie M. (National Institute of Standards and Technology, Center for Neutron Research)
  2. Murphy, Ryan P. (NIST, NCNR)
  3. Kuei, Steve (NIST, Polymers & Complex Fluids)
  4. Salipante, Paul (NIST, Polymers and Complex Fluids)
  5. Hudson, Steven D. (NIST, Polymers & Complex Fluids)

Author and Affiliation Lines (in printed abstract book)
Katie M. Weigandt1, Ryan P. Murphy2, Steve Kuei3, Paul Salipante3 and Steven D. Hudson3
1Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20877; 2NCNR, NIST, Gaithersburg, MD 20899; 3Polymers & Complex Fluids, NIST, Gaithersburg, MD 20899

Speaker / Presenter 
Weigandt, Katie M.

Keywords
experimental methods; colloids; rheometry techniques; suspensions

Text of Abstract
Simultaneous rheology and SANS enable the direct correlation of complex fluid rheology with changes in the nanostructure. For 1D anisotropic particles, we often observe significant rod or wormlike micelle alignment coincident with shear thinning. Traditionally, these simultaneous methods have been limited to maximum shear rates on the order of 1,000 s-1 which is often too low to reach the infinite shear viscosity of the fluid. Recently we have developed tools to enable simultaneous rheology and neutron scattering measurements to investigate complex fluids at high strain rates such that we can approach the infinite shear limit for these materials. Our current suite of tools includes a prototype slit rheometer for relatively low viscosity or shear thinning fluids (?8 < 5 mPa·s) at shear rates up to 100,000 s-1 and a capillary rheoSANS (CR-SANS) instrument capable of simultaneously measuring structure and rheology in excess of 106 s-1. Recently, the new CR-SANS instrument has been used to measure simultaneous structure and rheology of CTAB wormlike micelles, fD virus suspensions, and polymer solutions. In this talk, we will discuss the results from some of these measurements and specifically highlight work with wormlike micelles and rod-like fD virus suspensions. With these new tools we are able to probe structural changes in these fluids at 2-3 orders of magnitude higher shear rate than previously achievable.