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. 2022 Dec 20;15(1):12.
doi: 10.3390/polym15010012.

Pyrolysis Kinetic Study of Polylactic Acid

Zaid Alhulaybi  1 , Ibrahim Dubdub  1 , Mohammed Al-Yaari  1 , Abdulrahman Almithn  1 , Abdullah F Al-Naim  2 , Haidar Aljanubi  3
Affiliations

Pyrolysis Kinetic Study of Polylactic Acid

Zaid Alhulaybi et al. Polymers (Basel). .

Abstract

Polylactic acid (PLA) is a biodegradable polymer and is mainly used in the textile and food packaging fields. The aim of this work is to build knowledge on the kinetics of the pyrolysis of PLA with the help of thermogravimetric analysis (TGA) using four model-free methods, namely Friedman, Flynn-Wall-Qzawa (FWO), Kissinger-Akahira-Sunose (KAS), and Starink. Additionally, two model-fitting methods (the Coats-Redfern and Criado methods) were applied. TGA data at 5, 10, 20, and 30 K/min heating rates were collected. The obtained activation energies of the pyrolysis of PLA at different conversions by the model-free models were in good agreement and the average values were 97, 109, 104, and 104 kJ/mol for Friedman, FWO, KAS, and Starink, respectively. The Criado model was used together with the Coats-Redfern model to identify the most appropriate reaction mechanism. As per this work, the best controlling reaction mechanism of the PLA pyrolysis can be expressed by the geometrical contraction model (R2).

Keywords: PLA; activation energy; biodegradable polymer; kinetics; pyrolysis; recycling; thermogravimetric analyzer (TGA).

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Thermogravimetric analysis (TGA) and Derivative thermogravimetric (DTG) curves for pyrolytic cracking of PLA at different heating rates.
Figure 2
Figure 2
Regression lines of the experimental data of the PLA pyrolysis by: (a) Friedman, (b) FWO, (c) KAS, and (d) Starink models.
Figure 3
Figure 3
Activation energies for (Friedman, FWO, KAS, and Starink) of PLA pyrolysis.
Figure 4
Figure 4
Criado model master plots of the PLA pyrolysis at different heating rates: (a) 5 K/min (b) 10 K/min, (c) 20 K/min, and (d) 30 K/min.
See this image and copyright information in PMC

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