Study of the α-Mechanical Relaxation in Molecular Glass-Forming Liquids

A procedure yielding to the determination of the low-frequency dynamical behavior of glass-forming systems with low glass transition temperature is presented in this paper. The liquids are injected in an inorganic porous medium and the mechanical response of the heterogeneous composite samples is studied. It is shown that the dynamic behavior of the liquid is poorly affected by the presence of the substrate. This enables to build the long-time relaxation diagram for maltitol, sorbitol and LiCl, 6H 2 O. The mechanical measurements are interpreted in the framework of a model based on the assumptions of localized disorder (defects) and hierarchically constrained dynamics in the glass transition region.