Are you using a rheometer?

This equipment can clarify material properties based on the molecular structure of polymers.
Recently, there is an increasing need for detailed analysis of the change process of material structure for advanced control of viscoelasticity.
In this newsletter, we will introduce a “structural analysis method using polarization imaging” that combines a rheometer and a polarization high-speed camera to meet these needs.

Polarization high-speed camera for viscoelasticity evaluation

Polarization high-speed camera and rheometer

*The rheometer is a product of Anton Paar
https://www.photonic-lattice.com/en/products/crysta-pi-5wp/

Feature

The polarization high-speed camera can quantify the polarization state in a single shot, and can track instantaneous changes in viscoelasticity due to its high-speed imaging performance.

Capturing instantaneous orientation changes of polymer fluids

Measurement example – Dynamic structural change of cellulose nanofiber (CNF)

CNF has a three-dimensional network structure, but as shown in the viscosity curve below, it exhibits shear-thinning behavior in which viscosity decreases with shear rate. However, there is a viscosity plateau (green area) around ~10 sec-1.

Viscosity curve of CNF

What kind of structural changes occurred in this plateau?

Looking at the scattering image of SALS in the figure below, the shape changes from a circle to an ellipse as the shear rate increases. This corresponds to aggregates of fibers oriented in the direction of flow.
According to the orientation of the principal axis of the polarization image, the orientation of the fibers was spatially random before 10 sec-1, but after 10 sec-1 they suddenly oriented in the direction of flow, making them uniform in the radial direction within the channel. This confirms that it changed to a smooth state continuously.

Usually, if the viscosity curve is different from what we expected, we often suspect that foreign matter is mixed in or that the equipment itself is out of order. In this study, we were able to gain a deeper understanding of the viscoelastic characteristics of CNFs by capturing instantaneous changes in the orientation of polymer fluids in combination with polarization imaging.

Contact Us

You can install polarization high-speed camera to Anton Paar’s MCR302. The first demo is free of charge, so please feel free to contact us. For other models, we will conduct a preliminary inspection of the actual machine and confirm whether or not it can be installed.

Please also refer to a link below for more technical introduction.
https://www.photonic-lattice.com/en/technology/