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    4000 Roskilde

    Denmark

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Organization profile

Organisation profile

The goal of the Glass and Time Research Centre is to enhance understanding of the physical properties of viscous liquids

Glass is formed from a liquid that becomes more and more viscous as it cools. All liquids can form a glass if they cool quickly enough to avoid crystallization. The research conducted by Glass and Time is purely basic research that focuses on acquiring an increased understanding of the properties of viscous liquids before they solidify into glass. In this way, the Centre’s research can also secure a better understanding of the properties of various glasses, as we already know that these properties are inherited from the liquid.

The liquids we have studied are not glass as we know it from windows or drinking glasses – they are simple organic liquids such as glycerine, which, when abruptly cooled to far below room temperature, acquire a glass form. By studying such model systems, it is hoped that the Glass and Time Research Centre will be able to uncover general laws of nature that apply to all liquids and glasses.

The research conducted at the Glass and Time Research Centre is therefore more about viscous liquids than about glass. On the basis of studies of simple organic liquids, and using new measurement methods, we have put forward theories for the dynamics of viscous liquids. A common characteristic is the idea that the physics of viscous liquids may be simpler than was previously thought.

The primary purpose of the Research Centre is to investigate the validity of these theories for new classes of viscous liquids – including under high pressure. An absolutely central aspect of the Centre’s research is to perform comprehensive simulations of so-called computer fluids. A secondary purpose is to develop measurement methods that will for the first time make it possible to measure a complete set of so-called thermo-viscoelastic response functions. A more recent perspective is to be able to describe in general how and why the physical properties of materials change over the years. Through this research, we aim to provide a better basis for understanding how all materials age over time. Just think of how plastic rulers contract slightly over the years!

Examples of viscous liquids are polymer melts, silicates, ion melts, highly cooled organic liquids such as alcohol and glycerine, and certain subcooled metal alloys or sugar solutions. Despite their chemical diversity, these liquids exhibit a number of common characteristics. The central concept here is relaxation time – the time it takes for a fluid to return to equilibrium following an external disturbance. For water and ordinary liquids the relaxation time is around 1 picosecond, but for viscous liquids it can easily be a month or more. The relaxation time increases enormously upon cooling; it can often rise by a factor of ten when the temperature is reduced by 1%.

Potential applications of the research range from fibre optics and insulation materials to advanced materials used for a variety of biomedical purposes, such as in sensors and batteries. The food industry has also expressed great interest in acquiring a greater understanding of solidification processes.

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