Glassy state, of materials

The glassy state of materials refers to a nonequilibrium, solid state, such as is typical of inorganic glasses, synthetic noncrystalline polymers and food components. Characteristics of the glassy state include transparency, solid appearance and brittleness (White and Cakebread 1966 Sperling 1992). In such systems, molecules have no ordered structure and the volume of the system is larger than that of crystalline systems with the same composition. These systems are often referred to as amorphous (i.e., disordered) solids (e.g., glass) or supercooled liquids (e.g., rubber, leather, syrup) (Slade and Levine 1991 Roos 1995 Slade and Levine 1995). 

The glassy state of materials prepared under normal conditions is in a non-equilibrium state, in which an excess volume and enthalpy exist. When such a non-equlibrium glassy state is held at temperatures a few degrees lower than T, the excess thermodynamic properties decrease to those of an ideally equilibrium state. At the same time, the mechanical properties of the materials change (lOj. 

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