Reaction Rate Analysis by Thermal Analysis

Significance of the Topic

The kinetics of chemical reactions such as polymer degradation, resin curing and hydrate dehydration play a crucial role in material stability, shelf-life prediction and process optimization. Rapid determination of activation energy and reaction rates through thermal analysis enables reliable predictions of long-term behavior under storage or processing conditions.

Objectives and Study Overview

This study demonstrates how reaction rate analysis combined with thermogravimetric (TG-DTA) and differential scanning calorimetry (DSC) measurements can be used to:

• Determine activation energies of various reactions.
• Perform isothermal predictions of reaction progress at target temperatures.
• Optimize storage and processing parameters for polymeric and crystalline materials.

Methodology

TG and DSC experiments were carried out at multiple linear heating rates to generate conversion-temperature profiles. Reaction rate analysis software applied model-free kinetics to extract activation energies and pre-exponential factors. Isothermal analyses then simulated reaction times required to reach specific conversion levels at lower, industrially relevant temperatures.

Used Instrumentation

The following Shimadzu instrumentation and software were employed:

• TG-DTA analyzer with LabSolutions TA reaction rate analysis module.
• DSC calorimeter for endothermic and exothermic transitions.
• Data acquisition at heating rates ranging from 1 to 20 °C/min.

Main Results and Discussion

Three case studies illustrate the approach:

• Polyethylene Terephthalate (PET) Decomposition: Activation energy ≈197 kJ/mol. Isothermal prediction shows 70 % mass loss in 2.7 h at 360 °C versus 138 h at 300 °C.
• Epoxy Resin Curing: Activation energy ≈62.2 kJ/mol. To achieve 90 % curing requires ~197 h at 20 °C, enabling optimization of cure schedules in industrial applications.
• Copper Sulfate Pentahydrate Dehydration: Three distinct dehydration stages with activation energies of ~127.4, 178.6 and 115.8 kJ/mol, reflecting different water‐binding strengths.

Benefits and Practical Applications

Reaction rate analysis by thermal methods provides:

• Rapid assessment of long-term stability without extended low-temperature experiments.
• Quantitative activation energies for mechanistic insight.
• Data-driven optimization of storage, curing and processing conditions in polymer and chemical industries.

Future Trends and Opportunities

Advances in thermal analysis and kinetic modeling are expected to:

• Integrate real-time predictive algorithms into manufacturing control systems.
• Extend model-free methods to complex multiphase reactions.
• Combine thermal data with spectroscopic or imaging techniques for deeper mechanistic understanding.

Conclusion

Thermal reaction rate analysis using TG and DSC provides a robust framework for determining activation energies and predicting reaction progress under target conditions. The approach accelerates stability studies and process development for polymers, adhesives and crystalline hydrates.

References

No specific literature citations were provided in the original text.