## 3 Results and Discussion  
### Thermogravimetric Analysis  
Figure 3, below, illustrates the TG thermograms for the carbonization of chitin and chitosan at heating rates ranging from 5 to 40 \({}^{\circ}\)C/min. The key thermal parameters, including characteristic temperatures corresponding to the primary carbonization stages of each feedstock and differential TG (dTG), are also summarized in Table 1.  
Chitosan generally exhibits a lower onset temperature (Ti) for the main carbonization stage compared with chitin at the same heating rates. This difference is primarily attributed to the deacetylation process in chitosan, which reduces the presence of acetyl (-COCH\({}_{3}\)) groups and leads to a more amorphous structure with fewer intermolecular hydrogen bonds. Unlike chitin, which adopts a highly crystalline arrangement due to its acetyl content, chitosan's amorphous nature enhances polymer chain mobility and increases accessibility to thermal energy, making it more susceptible to thermal degradation. The partial deacetylation of chitosan results in a higher concentration of amino groups (-NH\({}_{2}\)) along the polymer chain, facilitating the disruption of both intermolecular and intramolecular hydrogen bonds. Compared with chitin, chitosan exhibits weaker intermolecular interactions, such as hydrogen bonding and van der Waals forces, due to its higher amino group content. These weaker interactions reduce the structural stability of the polymer, making the chains more prone to thermal decomposition at lower temperatures. Overall, the combination of partial deacetylation, an amorphous structure, and weaker intermolecular interactions in chitosan, relative to chitin, contributes to its lower onset temperature for the active degradation stage, as can be seen in the numerical results. Additionally, chitosan, which is \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & **Heating Rate** & **Ti \({}^{*}\) (\({}^{\circ}\)C)** & **dTGmax \({}^{**}\)** & **Tf \({}^{***}\) (\({}^{\circ}\)C)** \\ \hline \multirow{4}{*}{Chitosan} & 5 & 218.7 & 287.8 & 366.2 \\  & 10 & 226.5 & 299.4 & 401.5 \\  & 20 & 238.1 & 310.5 & 504.3 \\  & 40 & 243.8 & 320.5 & 543.6 \\ \hline \multirow{4}{*}{Chitin} & 5 & 233.7 & 392.4 & 434.8 \\  & 10 & 237.9 & 406.5 & 443.1 \\ \cline{1-1}  & 20 & 241.2 & 423.9 & 529.1 \\ \cline{1-1}  & 40 & 249.8 & 443.5 & 559.7 \\ \hline \hline \end{tabular} \({}^{*}\)Ti is the initial temperature of the main carbonization zone. \({}^{**}\) dTGmax is the maximum temperature from the dTG curves. \({}^{***}\)Tf is the final temperature of the main carbonization zone.  
\end{table} 
Table 1: Characteristic temperatures for the carbonization of chitin and chitosan. Figure 3: TG curves of chitosan and chitin. partially deacetylated compared with chitin, generally exhibits a lower final temperature (Tf) for its main carbonization zone. During non-isothermal degradation under an inert atmosphere, the lower final temperature of active carbonization in chitosan is associated with deacetylation, increased amorphous structure, and a higher presence of reactive amino groups, all of which contribute to enhanced chain mobility. As the heating rate increased from 5 to 40 \({}^{\circ}\)C/min, distinct shifts of the thermograms of both chitin and chitosan toward higher temperature regions were observed, demonstrating a well-defined and predictable thermal hysteresis. This phenomenon is primarily attributed to the relatively low thermal conductivities of materials degraded in thermogravimetry. To put it in other words, the temperature gradient between the surface and the interior of the feedstock particles was reduced, enabling more uniform heating and facilitating decomposition due to an extended residence time at lower heating rate values. Furthermore, the peak temperatures obtained from dTG profiles exhibited an increase in peak intensities together with increasing peak temperatures particularly in the maximum weight loss rates at each stage, where the variations were most pronounced.