Multiscale rheology experiments can support the development of new materials
Rheology experiments hold a lot potential for new scientific insights according to Roland Kádár.
Multiscale rheology experiments can produce data not just on how matter deform and flow, but also how it behaves at different length scales. This knowledge is essential to develop new and optimised materials for energy production and storage, electronics, photonics and healthcare. A recent workshop at LINXS back in May aimed to build knowledge on how to write a rheo-beamline proposal, what kinds of experiments are currently available, and what is involved in preparing and performing multiscale rheology experiments.
Developed rheology experiments at MAX IV
Roland Kadar, theme leader of the RheoMAXESS theme, has during recent years, developed specific rheology experiments at MAX IV to retrieve information on how sof matter at different length scales behave under stress. Utilising both X-rays and polarised light techniques simultaneously with rheological experiments, this approach is completely novel as these experiments can produce simultaneous data on how matter react at length scales from the micrometre scale, down to the nanometre scale: all within the same sample. Previously, this data could only be retrieved with separate experiments, a process which cannot always be trusted, as the data was not measured simultaneously.
– We are now in a position to also measure for example how the orientation propagates across the lengthscales of matter when subjected to a simple shear flow or deformation with both humidity and temperature controlled environments. This is particularly important for so-called hierarchical materials, often inspired by nature (biomimetic), says Roland Kádár, Professor of Rheology at Chalmers University of Technology.
He emphasises how this approach allows for the retrieval of information about samples to a level that was not possible before. Hierarchical materials are complex materials organised into multiple levels of structure, from the molecular level, and nanoscale structures formed therewith, into fiber or platelet like structures, up to large visible structures. Such materials can be made to exhibit for example mechanical and optical properties in ways that considerably exceeds their non-hierarchical counterparts.
– From a broad perspective, an important direction in materials science has been to mimic the capabilities of natural materials. Wood, for example, spans length scales from cellulose molecules to porous cellular structures, while bone likewise exhibits hierarchical organisation across nano- and microscales adapted for load-bearing, says Roland Kádár.
– A considerable success of synthetic plastic materials, has been the ability to attain certain hierarchical structures induced during processing. By processing we essentially mean flow and temperature gradients. Exploring the possibilities of forming new hierarchical structures from natural building blocks using similar methods could ensure their performance and ease of forming.
Th potential for scientific insights with rheology experiments is yet untapped
The workshop gathered about 20 researchers, mainly first timers who had never before performed rheology experiments. The aim was to present the potential with these techniques and to analyse specific science cases. Roland Kádár, Marko Bek, also from Chalmers, and Ann Terry, Group leader and beamline manager at MAX IV, led the workshop and were on hand to respond to specific questions.
– Rheology experiments can be difficult to perform and interpret; and combining several techniques for multiscale experiments makes it even more challenging. However, the potential for new scientific insights is very well worth it, in my view, says Roland Kádár.