What type of materials possess a glass transition temperatur

What type of materials possess a glass transition temperature (T_g)? How do the material properties differ below and above the glass transition temperature (T_g)? What type materials possess a melting temperature only and no T_g?

Solution

6a) Amorphous Polymers.

The glass transition temperature (Tg) is the temperature where cooling a non-crystalline polymer (Amorphous polymers) transforms from a super cooled liquid to a rigid glass. This transition is unique to polymer materials.

6b) when polymer is cooled below Tg, it becomes hard and brittle like glass. If polymer is heated above Tg, it becomes ductile and flexible.

6c) crystalline polymers do not have a Tg, instead they have only melting point.