Define what a glass transition is and what happens to a polymer because of it

The glass transition occur when the given temperature gets drop below the temperature of the glass transition for the polymers. During the creases of the long range of the given motion, the polymer start changing from the state of hard into the form of brittle.

The range of the glass transition temperature are between the 0 to - 150°C. The basic use of the polymer is basically depend upon the main properties of the polymer.