Theoretical study on the pyrolysis of chitosan used as the sustainable fresh fruit packaging material: Mechanism and kinetics

Abstract

Pyrolysis and incineration have emerged as an ideal waste management approach in the paper packaging sector. As a promising candidate for coated paper packaging, the pyrolysis behavior of chitosan has garnered increasing attention. This investigation systematically explored the molecular-level pyrolysis pathways of chitosan-derived model compounds, representative of natural polymer polysaccharides, through density functional theory (DFT) calculations. The computational simulations identified eight distinct initiation pathways for thermal decomposition, including glycoside bond cleavage, side chain breakage, and ring-opening reactions. The principal end-products derived from chitosan pyrolysis have been conclusively identified as small-molecule volatiles and aromatic heterocycles. Kinetic analysis quantified pyrolysis rate constants and demonstrated chitosan’s unique thermal lability, that is, the initial reaction rate constants show positive temperature dependence in the temperature range of 500–950 K. This work provides a reference for study of the synergistic effect of chitosan with other components in the actual pyrolysis process and the process design of fresh fruit packaging materials based on polymer polysaccharides, further advancing the sustainable design of chitosan-based packaging aligned with circular economy principles.