Abstract
A model of the fast relaxation process in amorphous polymers is presented based on the damping of the boson peak vibrations by the free-volume fluctuations. Comparison of the fast relaxation in polycarbonate as is seen in the low-frequency Raman spectra with the positron annihilation lifetime spectroscopy data for the fractional free volume in a broad temperature interval 50–450 K shows an apparent correlation between the relaxation strength and the free volume, in good agreement with the predictions of the model.