Ships At Winter

Vitrification
Certain materials, such as glass or glycerol, may harden without crystallizing; these are called amorphous solids. Amorphous materials as well as some polymers do not have a true freezing point as there is no abrupt phase change at any specific temperature. Instead, there is a gradual change in their viscoelastic properties over a range temperatures. Such materials are characterized by a glass transition which occurs at a glass transition temperature which may be roughly defined as the "knee" point the material's density vs. temperature graph.