By Cameron Chai
A team at the National Institute of Standards and Technology (NIST) working with Wesleyan University researchers has utilized computer graphics to study glass-forming materials, delivering a mathematical and physical description of temperature impacts on the rate of flow in these materials.
Most manufacturers are unable to understand viscous liquids at the nano-scale. Polymers and biological materials altered when cooled from a liquid to a tar-like thickness at mid-level temperatures, and turn into solid glass at low temperatures.
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In some delicate glass-forming materials, a small temperature change can alter the material from fluid to extremely viscous. In strong fluids this viscosity change is slower. This affects the time needed to work with a cooling material.
According to NIST scientist, Jack Douglas, it is necessary to understand the underlying physical procedures involved in order to develop a customized material.
The viscosity of glass-forming liquids depends on molecules moving around other atoms in long strings almost frozen in one place. The snake-like structures result in enhanced viscosity of the liquid. The team discovered that the growth rate of the involuntary snake-like strings corresponds to the fluid fragility.
Douglas and Francis Starr of Wesleyan University achieved diverse fluid fragility using a computer model that simulated a polymer fluid with nano-particles. Adding different quantities of nano-particles and altering their interaction with the polymers allowed them to understand how temperature changes altered the fluidity and how the cluster movement corresponded to the fluid's property alterations. Douglas says this research could enable material designing.