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Unravelling the secrets of the web with rheology

25 April 2012 One Comment

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Customer contact is always something that is maintained here at Malvern – with our Customer Support and Technical and Application teams available to ensure our users are able to get the most out of their instruments. Since many of our users are in universities, one particularly interesting aspect for me is being able to keep up to date with the latest research developments that Malvern systems are being used for.

It was a pleasure to be able to catch up again recently with members of the Oxford Silk Group, to hear about further progress with their fascinating work on rheological characterization of spider silk dope and the spun fibre. Dr Chris Holland and Maxime Boulet-Audet gave absorbing insight into aspects of hand-rearing their precious spider colony, how the mechanical properties of their webs are such that they can even ensnare a flying bird (thankfully released safely!), and the intricate working techniques the group have developed to be able to ‘haul-off’ various types of silk threads from their spiders. Amazing stuff!

What really is amazing though is how nature has rheologically-optimized a fibre extrusion process to provide materials, methods and performance properties that are so far in advance of current industrial fibre production techniques. The spider silk feedstock is aqueous-based, it is extruded at room temperature with relatively low energy requirements, and undergoes a shear-induced phase transition to spontaneously self-assemble and produce a fibre with ultimate tensile properties that are way beyond those of artificial fibres.

It was nice to hear from Chris that the sensitivity of the Malvern rheometer had been able to answer a question regarding yield stress or zero shear viscosity characteristics of the spider feedstock, which is only available in tiny quantities for them to work with. It was also very useful for us to appreciate exactly how Max is combining the rheometer with spectroscopic techniques to gain an understanding of chemical and microstructural changes in the phase transition.

Ultimately it is maintaining contact with our users, at all levels, that helps Malvern to continue to develop and produce instruments to meet real measurement needs.

As a closing thought……..when you next see the intricacy of a spiders web fully revealed by the presence of early morning dew droplets, not only is it a beautiful image in itself, but nature’s grasp of rheology to allow its creation is really a thing of beauty too…….