Rheology in the southern hemisphere
Written by: Adrian Hill
My role as Product Technical Specialist for the range of rheology products at Malvern takes me all across the globe supporting our customers, and I’ve just come to the end of a ‘rheology tour’ of all the states in Australia… it’s definitely a big country! I’d particularly like thank all the representatives from our local distributor, ATA Scientific, for helping out at each of the seminars.
Part of our seminars down under were focused on promoting the advantages of rheology, and judging by the number of viscometer users attending our talks, hopefully we’ve been able to get them interested in the benefits a rheometer can provide. We start by giving an overview of rheology; describing with everyday practical examples what rheology measures…. simulating conditions to measure how a materials resistance to flow – its viscosity – changes under different processes. And then expanding on the deformation type testing which classifies sample type to allow behavior to be predicted, highlighting the additional information that a rheometer gives over a viscometer.
No matter if you have never heard of the term rheology…. we are all rheologists really as we use it everyday, from squeezing toothpaste from the tube (overcoming yield stress), to knowing that shower gel will only pour slowly from a bottle unless you squeeze it to produce a much faster flow (inducing shear thinning). In simple terms, a rheometer can put numbers, and science, to material behavior that we know. One of the benefits of Malvern’s latest rheometer platform – Kinexus – is aimed at making rheology testing easier and more robust with its unique Standard Operating Procedure (SOP)-driven rSpace software interface.
With a firm basic understanding of rheology, the seminars then explored how we can go further and start to control, even change the rheology of a material by understanding what goes into it. Rheology is a very descriptive bulk material property, and as with any material property, the properties arise from the constituents of the material. At Malvern, with our combination of rheological and particle and molecular characterization instruments (for size, shape and charge), we can help our users understand how these properties all link together. Take dispersions as an example – bulk rheological properties are significantly affected by changing (micro-scale) particle properties – see for example our White Paper ‘10 ways to… Control rheology by changing particle properties (Size, Zeta potential and Shape).’
The final part of my down under trip was to visit some of our customers – all of who have been well looked after by our local support. This leads to my final end note from Australia, and I have to disclose my one slight disappointment…….on checking in the hotel sink that the water did flow down the plug hole clockwise, unlike back home in the UK…. I found that the Kinexus rheometer installed at the University of Newcastle, Australia, still shears the material to simulate flow conditions the same way as they do in the northern hemisphere. I guess that our development engineers gave the Kinexus more control than the coriolis effect!
Let the debate about the coriolis effect commence….