On the relaxation nature of the glass transition of amorphous polymers and low-molecular amorphous materials

Abstract

The relative temperature range (δTg/Tg) characterizing the liquid-to-glass transition is a single-valued function of the fluctuation volume fraction fg frozen at the glass transition temperature Tg. The fluctuation volume ΔVe of the amorphous material is determined by delocalization of active (excited)) atoms, i.e., their thermal displacements from equilibrium positions. The fluctuation volume fraction f = ΔVe/V controls the molecular mobility that is characteristic of delocalized atoms in the liquid-glass transition region. It is shown that δTg for the majority of amorphous materials is only 0.7% of the glass transition temperature Tg. The narrow temperature range δTg is consistent with the classical Simon concept on the insignificant temperature range in which the structure is frozen.