THE SCALING OF THE DIELECTRIC ALPHA-RELAXATION AND BETA-RELAXATION OF AMORPHOUS POLYETHYLENETEREPHTHALATE

Broadband dielectric spectroscopy (10(-2)Hz-10(9)Hz) has been employed to study the scaling of the alpha- and beta-relaxation in amorphous polyethyleneterephthalate (PET). The experimental results are compared with the predictions of the mode coupling theory (MCT). No agreement is found in contrast to an analysis of Gotze and Sjogren, which was based on experimental data limited to frequencies < 10(6) Hz. It is suggested that low frequency beta-relaxations (omega less-than-or-equal-to 10(9) Hz) cannot be interpreted in the framework of the idealised MCT.