Some insights into fragility as a function of thermodynamic parameters: From orientational to structural glass transitions

The work in this Letter is aimed at propossing some ideas on the definition of the fragility as a function of thermodynamic parameters for a reduced set of OG-formers: cycloheptanol, cyclooctanol and their binary mixtures. Previous possible proposals such as ΔCp or ( Δ T gl / T gl A ) are now reexamined. Among other proposals, (ΔCp/Cp,gl) can correlate with ( Δ T gl / T gl A ) such that a link between the thermodynamic (ΔCp/Cp,gl) relation and kinetic (F1/2)-parameters can be outlined. Data either from the literature or measured by us of certain glass-forming materials have been used to extend this link to a more general approach. In addition, an alternative proposal in which the volume is considered as a thermodynamic variable is also discussed.