This Liquid Snapped Instead of Flowing and Scientists Were Shocked

By Drexel U., April 3, 2026

https://scitechdaily.com/this-liquid-snapped-instead-of-flowing-and-scientists-were-shocked/

Research from Drexel University suggests that if pulled apart with enough force per area, a simple liquid — a liquid that flows into the shape of its container — will break like a solid object. 

Credit: Drexel University

Researchers discovered that liquids can suddenly snap like solids when stretched hard enough. This unexpected behavior challenges basic physics and could lead to new technological applications.

In a discovery that could reshape how scientists think about fluids, researchers at Drexel University have found that under certain conditions, a simple liquid can break apart like a solid. The study, published in Physical Review Letters, shows that viscous liquids can suddenly fracture when stretched with enough force.

This unexpected behavior points to viscosity, or a liquid’s resistance to flowing, as a key factor in how liquids respond to stress. It also suggests new ways liquids could be controlled in technologies ranging from hydraulics and 3D printing to biological systems like blood flow.

“Our findings show that if pulled apart with enough force per area, a simple liquid — a liquid that flows — will reach what we call a point of ‘critical stress,’ when it will actually fracture like a solid. And this is likely true for all simple liquids, including common examples, such as water and oil,” said Thamires Lima, PhD, an assistant research professor in Drexel’s College of Engineering, who helped to lead the research. “This fundamentally changes our understanding of fluid dynamics.”

New research from Drexel University shows how simple liquids, like the hydrocarbon liquid shown here, can actually fracture like a solid object if stretched with enough force.

 Credit: Drexel University



Unexpected Liquid Fracture During Testing

The discovery happened by chance while Lima and her team were studying the properties of two simple liquids as part of a project with ExxonMobil Technology & Engineering Company. During an extensional rheology test — which measures how much force is needed to stretch a liquid — the researchers noticed something unusual. Instead of thinning out gradually like honey, the tar-like liquids suddenly snapped apart.

“What we observed was so unexpected that we needed to repeat the experiments a few more times to make sure it was real,” said Nicolas Alvarez, PhD, a professor in the College of Engineering whose lab led the research. “Once we confirmed the phenomenon, the research became an entirely different scientific endeavor.”

Using a high-speed camera, the team captured a process typically seen in solid materials. When solids are stretched, they elongate until they reach a critical stress point, then abruptly break. This type of failure is known as brittle fracture, and according to the researchers, it had never before been observed in a simple liquid.

“This was an incredibly surprising thing to behold,” Lima said. “The fracture caused a very loud snapping noise that actually startled me. I thought at first the machine had broken, but soon realized that the noise came from the stretching fluid.”

Critical Stress and the Role of Viscosity

The first liquids to show this behavior were tar-like hydrocarbon blends. These materials fractured at a critical stress of 2 megaPascals — roughly comparable to the tension you might feel if a laundry bag filled with 10 bricks caught on your fingernail while falling.

To better understand what was happening, the researchers repeated the experiments with a different simple liquid, styrene oligomer, that had the same viscosity as the hydrocarbon blends. It fractured under the same conditions, pointing to viscosity as the key factor behind the solid-like breaking behavior. This result suggests that many simple liquids may share a similar breaking threshold.

The team then varied the temperature to change viscosity. At each level, they identified a specific stretching rate that triggered fracture, always tied to the same 2 megaPascal “critical stress” point. At lower viscosities, the liquids could not be broken because the equipment could not stretch them fast enough.

Challenging Traditional Views of Liquids

Until now, fracture has been understood as a property linked to elasticity, which is a material’s ability to store and withstand stress. Simple liquids do not typically store stress in this way. Instead, they flow when force is applied, rather than bending or breaking.

In most cases, elasticity only becomes important when a liquid is cooled below its “glass transition,” the temperature at which it begins to behave more like a solid. Observing fracture in liquids that are still fully in their liquid state shows that breaking is not limited to elastic materials.

“Although viscoelastic and polymer liquids — things like Oobleck or homemade slime — have demonstrated solid-like fracture behavior, simple liquids have always been thought to exhibit continuous deformation at temperatures above their glass transition and therefore would not fracture,” Lima said. “Showing that viscous effects are enough to promote solid-like fracture behavior opens a world of new questions to explore in this area of scientific inquiry.”

A Broad and Possibly Universal Effect

The researchers also compared a simple liquid, oligomer styrene liquid, with its polymer counterpart. Both materials fractured at the same critical stress level, suggesting that elasticity is not responsible for the behavior in simple liquids.

“This suggests that many other elastic liquids might also break at a relatively similar critical stress point,” Lima said. “This points to a phenomenon that is relatively chemistry independent and possibly generalizable to a wide range of liquids.”

What Causes Liquids to Break

The team plans to continue studying this phenomenon to understand the underlying physics. Early evidence suggests it may be related to cavitation — a process in which tiny vapor bubbles form and collapse rapidly, sending shockwaves through the liquid.

“Now that we have reported this unanticipated behavior, the work of fully understanding why it happens and how the behavior manifests in other liquids is an important next step,” Lima said. “It will also be interesting to see how this finding may be applied to assist fiber spinning and other applications that use viscous liquids.”

The Life of Earth

https://chuckincardinal.blogspot.com/