Malvern rheometer helps Oxford scientists unravel secrets of silk

Researchers at Oxford University have published work comparing the rheology of spider and silkworm spinning dope – the liquid material from which solid fibres are spun (Nature Materials, Nov 06).

Critical to the success of this work, which ultimately will contribute to the industrial production of silks, was the new Bohlin Gemini HR nano rheometer from Malvern Instruments. This system is optimized for the control of ultra-low torques and is ideal for probing sensitive material structures and allowing measurement of low volume samples.

Spun fibres, whether natural or man-made, rely on extrusion processes to facilitate molecular orientation and bonding. The purpose of this ongoing work is to gain a better understanding of the flow characteristics of the native spinning feedstock, with a view to applying this knowledge to artificial fibre production.

Prof. Fritz Vollrath who led the research team said: “Silk can outperform most industrial fibres, but spider silk has proved impossible to reproduce. Using the Gemini HR nano we discovered that both of the natural dopes we studied behaved like typical polymer melts, indicating that natural silks can be analyzed using the tools developed for commercial polymers. We hope ultimately that this will help make possible the industrial production of silks using nature’s own way.”

The Bohlin Gemini HR nano enables the measurement and control of nano-torque levels. At the same time it retains a continuous working torque range to 200 mNm allowing complete rheological characterization. Allied to the most sensitive normal force measurement available, the Gemini HR nano offers the ultimate in instrument capabilities for weakly-structured and low viscosity systems.