Abstract: A series of PET films with different crystallinity (X_é) have been made through annealing at 110℃. The α-peak of short-circuit thermally stimulated current (corresponding to T_g) shifted to the higher temperature region when Xe increased. With the rise of X_é, the activation energy of dipolar thermal relaxation for main chain segmental motion in amorphous phase decreased linearly and the time constant of dipolar thermal relaxation increased exponentially.Crystallization by annealing leads to the increase of the trap depth, but the ability to trap charge carriers showed a maximum when X_é was 22%.

Key words: poly(ethylene terephthalate), crystallization, thermally stimulated current, molecular motion, trap