Details

Autor(en) / Beteiligte

• Ojovan, Michael I

Titel

On Viscous Flow in Glass-Forming Organic Liquids

Ist Teil von

• Molecules (Basel, Switzerland), 2020-09, Vol.25 (17), p.4029

Ort / Verlag

Switzerland: MDPI AG

Erscheinungsjahr

2020

Link zum Volltext

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• The two-exponential Sheffield equation of viscosity η(T) = A ·T·[1 + A ·exp(H /RT)]·[1 + C·exp(H /RT)], where A , A , H , C, and H are material-specific constants, is used to analyze the viscous flows of two glass-forming organic materials-salol and α-phenyl- -cresol. It is demonstrated that the viscosity equation can be simplified to a four-parameter version: η(T) = A·T·exp(H /RT)]·[1 + C·exp(H /RT)]. The Sheffield model gives a correct description of viscosity, with two exact Arrhenius-type asymptotes below and above the glass transition temperature, whereas near the T it gives practically the same results as well-known and widely used viscosity equations. It is revealed that the constants of the Sheffield equation are not universal for all temperature ranges and may need to be updated for very high temperatures, where changes occur in melt properties leading to modifications of A and H for both salol and α-phenyl- -cresol.