## 3 Results and Discussion
### Kinetics
The average experimental activation energies for the carbonization of chitosan, as determined using the Friedman, FWO, KAS, and Starink methods, were 152.2 kJ/mol, 131.1 kJ/mol, 128.1 kJ/mol, and 128.6 kJ/mol, respectively. While the average experimental activation energies in chitin carbonization for the Friedman, FWO, KAS, and Starink methods were 160.0, 159.9, 157.3, and 157.8. The higher degree of acetylation in chitin, characterized by a greater proportion of N-acetylglucosamine units, enhances intermolecular interactions, leading to increased structural stability and a higher activation energy requirement for carbonization. In contrast, chitosan undergoes partial deacetylation, resulting in a reduced number of acetyl groups. This reduction weakens hydrogen bonding and van der Waals interactions compared with chitin, thereby lowering the activation energy needed for carbonization. Consequently, chitosan exhibits a lower average activation energy for carbonization than chitin, indicating that it undergoes thermal degradation more readily at lower temperatures. In addition, fluctuations in activation with respect to the conversion degree for both chitosan and chitin were observed. This suggests that the carbonization of chitosan and chitin is not governed by a single uniform reaction but involves a sequence of complex, temperature-dependent transformations. Different functional groups in the structure may degrade at different temperatures, leading to shifts in activation energy, while processes such as aromatization, dehydrogenation, or intermediate char formation can further introduce fluctuations in the apparent activation energy for the carbonization of chitosan and chitin. In the final stage of the primary thermal decomposition zone, the activation energy of chitosan exhibited a decreasing trend, whereas for chitin, it showed an increasing tendency. The divergence in activation energy trends during the final stage of the primary thermal decomposition zone can be attributed to differences in their chemical structures and thermal degradation pathways. In the final stage, chitosan undergoes extensive char formation and depolymerization, with residual polymer breakdown occurring at lower energy barriers. Figure 5: Activation energy distribution with respect to conversion degree and the average activation energy values calculated by different kinetic models. The presence of amino groups facilitates fragmentation, reducing activation energy, while secondary reactions, such as volatile release and char rearrangement, further contribute to this decline. On the other hand, the increasing activation energy in the final stage indicates dominant cross-linking and intermolecular interactions for chitin. Residual acetyl groups in chitin enhance char stabilization and aromatization, strengthening bonds and requiring higher energy for degradation. Additionally, condensed carbonaceous structures may introduce diffusion limitations, further raising activation energy for carbonization of chitin at the last stages of thermal degradation. The activation energy results also indicate that the activation energy trends closely align with predictions obtained using artificial neural networks. Furthermore, the findings demonstrate that artificial neural networks can accurately predict the average activation energy value. The percentage error between the experimental and predicted average activation energy values ranged from 0.11% to 2.88%, confirming the reliability of the predictive model. The lowest error is observed for the prediction of the chitosan carbonization using the KAS (0.20%) and FWO (0.11%) models, suggesting that these models provide the most accurate predictions for chitosan. Similarly, for chitin, the KAS model (0.12%) demonstrates the smallest deviation, indicating high reliability in prediction. The average predicted activation energies for the carbonization of chitosan, as determined using the Friedman, FWO, KAS, and Starink methods, were 156.5 kJ/mol, 131.3 kJ/mol, 128.4 kJ/mol, and 128.8 kJ/mol, respectively.