CHRNS:Rheometers

Timestamp capabilities and upgrades

SECoPS-compatible Python Libraries with ADARA timestamp packet emission to be compatible with the CHRNS Initiative.  Code is available here: Rheosansverse (SECoP/ADARA rheometer control): https://gitlab.nist.gov/gitlab/jkrzywon/rheosansverse

Rheometer ARES G2
The ARES G2 rheometer provides strain-controlled rheological measurements (meaning the strain input is decoupled from the stress output), which enables more advanced techniques such as orthogonal superposition rheometry. With the dielectric cell mounted, this rheometer can also be used to simultaneously measure the sample impedance spectroscopy, rheology, and SANS microstructure [1].

CHRNS has upgraded the forced-convection oven design to improve SANS measurements. The new oven design enables easier access to samples and geometry when positioned on the neutron beamline, reduces background scattering by implementing double-paned quartz windows, and increases the maximum achievable scattering angle. The forced-air convection design enables rapid temperature changes (approximately 1 °C/s) over the tested range of -100 °C to 200 °C.
 

1-2 Shear Cell
The 1-2 shear cell allows users to probe the microstructure of viscoelastic materials under shear flow in the 1-2 plane (velocity-gradient), a flow plane that cannot be directly measured with other Couette-type geometries and rheometers. There is a strong coupling between the bulk rheology and microstructural features in the 1-2 plane of shear. For example, flow instabilities such as shear banding can be studied by scanning the aperture across the gap in the 1-2 plane.

CHRNS has upgraded the motor and controller to provide improved control of shear modes and a better user interface. The new motor and controller also provide better integration with the SANS instrument.

[1] “Dielectric RheoSANS — Simultaneous Interrogation of Impedance, Rheology and Small Angle Neutron Scattering of Complex Fluids”, J. Vis. Exp, 122, e55318, DOI: 10.3791/55318 (2017).
https://www.nist.gov/ncnr/sample-environment/sans-equipment/shear-and-rheology