Examining the entropy theory's application to viscosity data and the inference for a thermodynamic transition in an equilibrium liquid

Abstract The belief that the configurational entropy theory had demonstrated the validity of the Kauzmann entropy extrapolation to a temperature Tk, and had led to the inference that an Ehrenfest-type transition occurs at T2, has been examined. It is found that the theory neither supports the Kauzmann extrapolation nor suggests an abrupt decrease in Cp of an equilibrium liquid at Tk or T2. It is found that the inference of a thermodynamic transition was a result of two approximations: (i) the Cp of a liquid remains constant with changing temperature and (ii) the configurational entropy, Sconf, at Tg is equal to the residual entropy of a glass. Both were needed to correlate the viscosity data with the Sconf formalism. Without these, the theory seems consistent with the interpolation of an equilibrium liquid's Cp along a stretched sigmoid shape curve from 0 K to its measured value [J. Chem. Phys. 113 (2000) 751]. The known temperature dependence of a liquid's transport properties can be reconciled with its configurational entropy, Sconf, change without invoking an underlying thermodynamic transition. This puts into questions the validity of models, which had assumed that a thermodynamic transformation occurs at Tk or at T2.