Temperature-Volume Entropic Model for Viscosities and Structural Relaxation Times of Glass Formers

Area of Science:

• Materials Science
• Chemical Physics
• Thermodynamics

Background:

• The temperature dependence of viscosity in glass-forming materials is crucial for understanding their dynamics.
• Previous entropic models have successfully described temperature-dependent viscosity but lacked volume dependence.
• Glass transition phenomena involve complex interplay between temperature, volume, and molecular dynamics.

Purpose of the Study:

• To generalize an existing entropic model to incorporate both temperature and volume effects on viscosity and structural relaxation times.
• To evaluate the performance of the extended model in describing supercooled liquids near the glass transition.
• To discuss the findings in relation to the thermodynamic scaling law for viscous systems.

Main Methods:

• Generalization of a previously formulated entropic model.
• Application of the extended model to temperature-volume data of viscosities and structural relaxation times.
• Analysis of structural dielectric relaxation times (τα(T,V)) for supercooled van der Waals liquids.

Main Results:

• The generalized entropic model successfully describes the temperature-volume dependence of viscosities and relaxation times.
• The extended model demonstrates improved accuracy compared to its temperature-only precursor.
• The model accurately captures the structural dielectric relaxation times of supercooled van der Waals liquids.

Conclusions:

• The generalized entropic model provides a robust framework for understanding the dynamics of glass-forming materials under varying temperature and volume conditions.
• The study highlights the importance of considering both temperature and volume in entropic models for viscosity and relaxation.
• The findings support the applicability of thermodynamic scaling laws to molecular dynamics in viscous systems.