Understanding How Glasses 'Relax' Provides Some Relief for Manufacturers

From NIST Tech Beat: April 26, 2011
Contact: Chad Boutin
301-975-4261

Researchers at the National Institute of Standards and Technology (NIST) and Wesleyan University have used computer simulations to gain basic insights into a fundamental problem in material science related to glass-forming materials, offering a precise mathematical and physical description* of the way temperature affects the rate of flow in this broad class of materials—a long-standing goal.
Manufacturers who design new materials often struggle to understand viscous liquids at a molecular scale. Many substances including polymers and biological materials change upon cooling from a watery state at elevated temperatures to a tar-like consistency at intermediate temperatures, then become a solid "glass" similar to hard candy at lower temperatures. Scientists have long sought a molecular-level description of this theoretically mysterious, yet common, "glass transition" process as an alternative to expensive and time-consuming trial-and-error material discovery methods. Such a description might permit the better design of plastics and containers that could lengthen the shelf life of food and drugs.
A fundamental question is why many materials behave differently when temperature changes.

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