A comparison of rheology, dielectric response, and calorimetry within indane-based glass-formers

We report dynamics data on a family of indane glass-forming liquids. Although structural variations make the glass transition vary over a 77 K range, the fragility and width of the relaxation time distribution from oscillatory shear measurements are quite similar for all 14 indanes studied. In contrast, the measured width of the primary relaxation time distribution from dielectric measurements varies considerably for different indanes. The temperature dependence of relaxation time can be described using either Vogel-Fulcher or dynamic scaling, but only the latter allows both mechanical and dielectric data sets to have the same divergence temperature. The consequences of this observation for the thermodynamic significance of such a divergence temperature are discussed.