Variation of the Effective Activation Energy Throughout the Glass Transition

Summary: An advanced isoconversional method has been applied to determine the effective activation energies (E) for the glass transition in polystyrene (PS), poly(ethylene terephthalate) (PET), and boron oxide (B₂O₃). The values of E decrease from 280 to 120 kJ · mol⁻¹ in PS, from 1 270 to 550 kJ mol⁻¹ in PET, and from 290 to 200 kJ mol⁻¹ in B₂O₃. It is suggested that a significant variation in E should be observed for the fragile glasses that typically include polymers.

Variation in the effective activation energy of PS, PET, and B₂O₃ with temperature.