Question

Is increasing the glass transition temperature will increase or decrease toughness?

Answer 1

Tansition temperature:

If the glassy material is heated, the chains reach a temperature at which they can move.This temperature is called the glass transition temperature.

Above this temperature the polymer is flexible.Since the physical properties of a polymer are strongly dependent on the size or length of the polymer chain. Long chains get tangled up in each other and stick together far more than short chains.So increasing chain length furthermore tends to decrease chain mobility, increase strength and toughness, and increase the glass transition temperature shorter molecules can pass over each other more easily so materials made of these molecules are softer.