Affinity and its derivatives in the glass transition process.

Area of Science:

• Thermodynamics
• Materials Science
• Physical Chemistry

Background:

• The thermodynamic treatment of the glass transition is a complex and debated topic.
• Previous studies have utilized non-equilibrium thermodynamics and lattice-hole theory to explore this phenomenon.
• Existing models have not fully accounted for the influence of pressure on structural degrees of freedom.

Purpose of the Study:

• To provide new insights into the thermodynamic treatment of the glass transition.
• To incorporate pressure as a variable to account for the freezing-in of structural degrees of freedom.
• To demonstrate the importance of previously neglected terms in the affinity-driving force.

Main Methods:

• Employing a thermodynamic approach based on the lattice-hole theory of liquids.
• Including pressure as an additional variable in the theoretical framework.
• Utilizing macroscopic non-equilibrium thermodynamics to derive coefficients like C(p), κ(T), and α(p).

Main Results:

• Identified and incorporated crucial, previously neglected terms related to the derivatives of the affinity-driving force.
• Calculated thermodynamic coefficients as a function of pressure and temperature.
• Revealed classical aspects of vitrification and structural recovery processes.

Conclusions:

• A minimalist model, such as the lattice-hole theory, rigorously applied with macroscopic non-equilibrium thermodynamics, can explain key features of glass transition phenomenology.
• The inclusion of pressure is vital for accurately describing the freezing-in of structural degrees of freedom.
• This approach serves as a valuable pedagogical tool for understanding the thermodynamics of the glass transition.