Scientific Analysis: Measuring Bulk Rheology with Non-Contact Techniques

jul 19 2018

Viscoelasticity refers to the unique deformation characteristics of a material that exhibits both viscosity and elasticity, displaying time-dependent strain to applied forces. Scientific analysis of viscosity is typically concerned with the flow behavior of materials when subjected to mechanical agitation such as torque or pressure over a defined period. This rheological method presents complications for the accurate scientific analysis of complex viscoelastic formulations, as it provides insufficient information about the physiochemical structure of the product.

Non-contact bulk rheology is used to measure the macroscopic viscoelasticity of a solution at rest, providing more precise and robust scientific analysis of gels and emulsions. This is preferable over conventional bulk rheology methods that acquire the shear viscosity of a solution as a measure of its resistance to shearing flows, because mechanical strain can perturb the network of complex viscoelastic formulations and provide non-representative, inaccurate scientific analysis of a product or solution.

This article will explore the use of non-contact scientific analysis for measuring bulk rheology in further detail:

How Does Non-Contact Rheological Scientific Analysis Work?

Bulk rheological scientific analysis of soft media at rest and over time requires a novel approach for characterizing weak fluidic substances such as gels and emulsions. Multi-speckle diffusing wave spectroscopy (MS-DWS) is a unique optical analysis method for determining the structural properties of a fragile sample non-invasively, enabling analysis of complex solutions over time and temperature without mechanical stress.

The Rheolaser MASTER has been developed for non-contact bulk rheological scientific analysis, with six integrated sample chambers for glass containers between 4 – 20mL. Complex solutions can be assessed within the equipment at temperature conditions of up to 90°C, with available structural analyses including gel point determination, sol-gel transitions, gel strength, and more.

This product uses MS-DWS to monitor particle mobility within a solution using an incident laser beam. The presence of multiple entities causes interferences in scattered light and create speckle patterns. Fluctuations of this pattern are the result of Brownian motion that depends upon the viscoelastic structure of the product and determines the speed of motion and distance that particles within a fluid are free to travel.

Scientific analysis of this mobility provides non-invasive information about the rheological properties of the structure. For example, in a strong gel (viscoelastic media) particle mobility tends to be limited by the solution’s network structure while simple viscous media will have a much more linear mean square displacement (MSD) value.

Bulk rheology scientific analysis of viscoelastic fluids  enables accurate rheological monitoring of product stability or gelling processes with no mechanical agitation with correlation of time or temperature

Scientific Analysis with Formulaction

Formulaction was founded in 1994 with the simple goal of providing smart scientific analysis for as broad a range of industries as possible. In the years since, we have become a world-leader in concentrated dispersion analysis and have forged a reputation for innovative analytical techniques and products.

If you would like any more information about performing bulk rheology measurements with Formulaction products, please do not hesitate to contact us.

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