On Crossover Temperatures of Viscous Flow Related to Structural Rearrangements in Liquids

Area of Science:

• Physical Chemistry
• Materials Science
• Fluid Dynamics

Background:

• Liquid viscosity typically exhibits non-Arrhenius behavior at lower temperatures and transitions to Arrhenius behavior at higher temperatures.
• A known crossover temperature marks the transition from non-Arrhenius to Arrhenius behavior, associated with minimum viscosity (ηmin).

Purpose of the Study:

• To investigate the existence of an additional crossover in viscous flow at temperatures above the established non-Arrhenius to Arrhenius crossover.
• To propose explicit equations for calculating this new crossover temperature (T) and the minimum possible viscosity (ηmin).

Main Methods:

• Theoretical analysis of viscous flow in liquids.
• Development of explicit equations for T and ηmin.
• Numerical estimations and comparison with experimental data.

Main Results:

• An additional crossover temperature (T) for viscous flow was identified at temperatures significantly above the known crossover.
• Proposed equations for T and ηmin accurately predict experimentally measured data.
• Numerical estimations indicate T is practically unattainable, but its influence is observable near this temperature.

Conclusions:

• The study reveals a previously unrecognized high-temperature crossover in liquid viscous flow.
• The proposed equations offer a valuable tool for predicting liquid behavior under extreme thermal conditions.
• Understanding this non-activated flow regime contributes to the broader knowledge of fluid dynamics.