New closure could prevent jams in cosmetics packaging

Voigtmann, a researcher at the Institute for Material Physics in Space, told CosmeticsDesign-Europe.com, “I work on the theory that ‘jammed’ configurations might be unlocked via external flow or forces​.”

“The research could be helpful to understand how to process complex materials, such as pastes or suspensions. For example, it might be important in an industrial application to tailor material properties (such as its resistance to flow, or how easily a material can be spread​),” he added.

Three classes of materials ​

According to the German scientist, “Many every-day materials are soft matter. In the cosmetics industry most creams, lipsticks etc. are composed of soft matter​.”

Until now, studies have been carried out by using models for three classes of materials: soft matter (toothpaste), metallic liquids, or granular materials (like sand) which Voigtmann says does not do a great job of accurately describing these materials. ​

New model​

In light of this, ​he has devised two models that take into account the common properties between the three material classes.

His team re-analyzed simulation results on different glass-form jamming systems driven by hard-sphere-like excluded-volume interactions, by fitting a simple schematic mode-coupling theory model for the rheology of dense systems under prescribed shear flow.

“Here the goal was to determine whether their yield stress is either continuous; for example it gets smaller with the flow rate, or discontinuous where it remains at a constant value regardless of the flow rate at a decreasing flow rate​,” explains Voigtmann.

In regards to the cosmetic industry, he concluded, “We might at some point in the future be able to explain generic trends (for example, will adding smaller or bigger components to a suspension make it flow more easily or not​).”