Correlation between non-Debye behavior and<i>Q</i>behavior of the α relaxation in glass-forming polymeric systems

Abstract

By means of quasielastic neutron scattering we have shown that the dynamics of the \ensuremath{\alpha} relaxation on three different polymeric glasses shows a clear non-Debye behavior on a mesoscopic time scale. The spectral shape is found to be independent of temperature and momentum transfer (Q). The characteristic relaxation time follows a power-law Q dependence, \ensuremath{\tau}(Q)\ensuremath{\propto}${\mathit{Q}}^{\mathrm{\ensuremath{-}}\mathit{n}}$ (n&gt;2), n beong dependent on the system. We found that the Q behavior and the non-Debye behavior are directly correlated. These results have important implications concerning the physical mechanisms behind the dynamics of the \ensuremath{\alpha} relaxation.