Determination of the Structural Relaxation Enthalpy Using a Mathematical Approach

Area of Science:

• Materials Science
• Physical Chemistry
• Solid-State Physics

Background:

• Structural relaxation is a key phenomenon in amorphous materials, influencing molecular mobility and properties like dissolution rate.
• Existing quantification methods using differential scanning calorimetry (DSC) have notable disadvantages.
• Understanding and accurately measuring structural relaxation is crucial for materials development.

Purpose of the Study:

• To develop and validate a novel mathematical model for analyzing structural relaxation enthalpy.
• To overcome the limitations of current DSC-based quantification methods.
• To provide a robust tool for assessing structural relaxation in amorphous solid dispersions.

Main Methods:

• A new mathematical model was developed and fitted to calorimetric data.
• The model separates the structural relaxation peak from the glass transition.
• Validation involved parameter sensitivity analysis and comparison with existing methods on differently stressed amorphous samples.

Main Results:

• The proposed model accurately quantifies structural relaxation enthalpy.
• It demonstrates high robustness and accuracy, surpassing established methods.
• The heating rate dependence of the calculated enthalpy aligns with theoretical expectations.

Conclusions:

• The developed mathematical model offers a superior method for quantifying structural relaxation.
• This tool is valuable for future research on the impact of structural relaxation on material properties.
• The method enhances the understanding and application of amorphous materials.