Calorimetry based on energy absorbed from time-dependent fields

Abstract

The energy that a supercooled liquid absorbs from a time dependent field is used to determine the time scales involved in the dynamic heat capacities of the slow degrees of freedom. The time resolved changes in fictive temperatures are obtained from dielectric relaxation data derived from the same field that provides the energy input. For a generic molecular glass-former, it is found that dielectric and thermal time scales are locally correlated and agree within 15%. For a monohydroxy alcohol and an ionic liquid, however, such an identity between dielectric and calorimetric time scales is not observed. It is demonstrated that only the field induced change of the fundamental susceptibility, χ( ω), can be exploited for this dynamic calorimetry, whereas χ 3( ω) is not sensitive to these effects.