Professor Ole Hassager and his research team have shown that liquid substances can break under circumstances of high strain rates at sufficient speed. This discovery challenges some fundamental preconceptions of the nature of fluids and has attracted international attention.
If you have ever grappled with a surfboard some time in your life, you might be familiar with the problem of catching just the right moment when the big wave “breaks”. In this context, the breaking of the water is a metaphor. However in reality, as a new surprising research result shows, polymer liquids can break in a more literal sense too.
Under the right conditions, Ole Hassager, professor from DTU Chemical Engineering – in collaboration with Researcher Qian Huang (in the photo), Postdoctoral Fellow Nicolas J. Alvarez and PhD Aamir Shabbir – found that liquid substances can actually break like brittle glass. By stretching fluids composed of polymer at sufficiently high strain rates, the researchers found that as long as the strain rate was fast enough, fracture of the fluid followed.
The project found its end in June and has since attracted international attention – for instance, the American Physical Society published a feature about the new finding. They write:
“The idea of soft materials has challenged our classic notions of fluid and solid materials. Experiments such as these manifestly demonstrate that processes such as brittle fracture that are innately related to solids can indeed take place in fluid-like materials (…) It will be interesting to see how properties that characterize the fracture process (for example, the fracture energy) can be quantitatively related to both the viscous and elastic properties of soft materials, and how these might be used to manipulate material strengths and macroscopic properties such as material elasticity.“
Read the article ‘Multiple Cracks Propagate Simultaneously in Polymer Liquids in Tension’ (where a video recording of the process is also available) or the mention in APS.