Abstract
We show that on cooling towards glass transition configurational entropy exhibits more significant changes than predicted by classic relation. A universal formula according to Kauzmann temperature {T}_{K} is given: S={S}_{0}{t}^{n}, where t=left(T-{T}_{K}right)/T. The exponent n is hypothetically linked to dominated local symmetry. Such a behaviour is coupled to previtreous evolution of heat capacity Delta {C}_{P}^{config.}left(Tright)=left(nC/Tright){left(1-{T}_{K}/Tright)}^{n-1} associated with finite temperature singularity. These lead to generalised VFT relation, for which the basic equation is retrieved. For many glass-formers, basic VFT equation may have only an effective meaning. A universal-like reliability of the Stickel operator analysis for detecting dynamic crossover phenomenon is also questioned. Notably, distortions-sensitive and derivative-based analysis focused on previtreous changes of configurational entropy and heat capacity for glycerol, ethanol and liquid crystal is applied.
Highlights
We show that on cooling towards glass transition configurational entropy exhibits more significant changes than predicted by classic relation
In Ref.[50] the analysis for 42 low-molecular-weight glass formers led to the conclusion: ‘...there is no compelling evidence for the Vogel–Fulcher–Tammann (VFT) prediction that the relaxation time diverges at a finite temperature
Configurational entropy SC(T) may be characterised by the critical-like behaviour, what gives corrected values of the Kauzmann temperature. Both are realised by the n parameter values similar to those calculated from dielectric data in the Dyre-Olsen energy index[51,52,53]
Summary
We show that on cooling towards glass transition configurational entropy exhibits more significant changes than predicted by classic relation. Distortionssensitive and derivative-based analysis focused on previtreous changes of configurational entropy and heat capacity for glycerol, ethanol and liquid crystal is applied. It bases mainly on a comparison between experimental data and their scaling via VFT and other model relations.
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