Pyrolysis Kinetic Study of Polylactic Acid.

Area of Science:

• Polymer Science
• Chemical Engineering
• Materials Science

Background:

• Polylactic acid (PLA) is a biodegradable polymer with significant applications in textiles and food packaging.
• Understanding the thermal degradation kinetics of PLA is crucial for optimizing its processing and end-of-life management.

Purpose of the Study:

• To investigate the pyrolysis kinetics of polylactic acid (PLA).
• To determine the most suitable kinetic model and reaction mechanism for PLA pyrolysis using thermogravimetric analysis (TGA).

Main Methods:

• Thermogravimetric analysis (TGA) was performed on PLA at various heating rates (5, 10, 20, 30 K/min).
• Four model-free kinetic methods (Friedman, Flynn-Wall-Qzawa (FWO), Kissinger-Akahira-Sunose (KAS), and Starink) were employed.
• Two model-fitting methods (Coats-Redfern and Criado) were utilized to identify the reaction mechanism.

Main Results:

• Model-free methods yielded consistent activation energies for PLA pyrolysis, averaging 97, 109, 104, and 104 kJ/mol for Friedman, FWO, KAS, and Starink, respectively.
• The Criado and Coats-Redfern models were used to evaluate reaction mechanisms.
• The geometrical contraction model (R2) was identified as the best fit for describing the PLA pyrolysis process.

Conclusions:

• The pyrolysis of PLA is well-described by kinetic models, with consistent activation energy values obtained across different model-free methods.
• The geometrical contraction model (R2) accurately represents the primary reaction mechanism during PLA pyrolysis, providing valuable data for material scientists and engineers.