## 3 Results and Discussion
### Characterization of Starch/MCC Films
#### 3.2.2 Chemical Composition and Interactions  
Figure 4 illustrates the FTIR spectra of MCC, cassava starch film, and cassava starch films augmented with various contents of MCC (1%, 3%, and 5%). In the FTIR spectrum of MCC, peaks within the range of 3600-3000 cm\({}^{-1}\) are attributed to the stretching of -OH. Additionally, the peaks observed at 1204 cm\({}^{-1}\) and 1318 cm\({}^{-1}\) are assigned to OH-deformation and CH\({}_{2}\) wag, respectively, representing structural components of cellulose ([PERSON], 2018; [PERSON] et al., 2023). The FTIR spectrum of the pure cassava starch film shows many absorption peaks. The stretching vibration of the O-H bond of intra- and intermolecular bonded -OH groups in starch is shown by the peak at about 3286 cm\({}^{-1}\)([PERSON] et al., 2018). The stretching vibration of the C-H bond in aliphatic methyl (-CH\({}_{3}\)) or methylene (-CH\({}_{2}\)) groups is indicated by the band at about 2922 cm\({}^{-1}\). Moreover, the carbonyl group's (C = O) vibrational stretching is responsible for the prominent signal at 1645 cm\({}^{-1}\). The findings resemble the research conducted by [PERSON], [PERSON] et al. (2022) [PERSON] et al. (2022). However, some studies have suggested that this sharp band may be due to the O-H bending of absorbed water molecules in the starch films ([PERSON] et al., 2020). The vibration of C-OH bending and -CH\({}_{2}\) bending in the plane are represented by peaks at 1414 cm\({}^{-1}\) and 1318 cm\({}^{-1}\), respectively. The peak at 1150 cm\({}^{-1}\) is attributed to the C-O-C ant symmetric bridge stretching, while the peaks at 1078 cm\({}^{-1}\) and 997 cm\({}^{-1}\) can be attributed to the C-O-H and C-O stretching vibration in the respective functional groups C-O-C ([PERSON], 2018). The peak at 928 cm\({}^{-1}\) represents asymmetric C-O stretching vibration from the glycosidic linkage, and the peak at 860 cm\({}^{-1}\) indicates symmetrical CH and CH\({}_{2}\) deformation in starch ([PERSON] et al., 2018). The FTIR spectra of the pure cassava starch film and the MCC reinforced films exhibit similarities, indicating a similar chemical structure containing the same functional groups. Different amounts of MCC incorporated into the cassava starch-based films in the FTIR spectra do not demonstrate significant differences in functional groups. Notably, peaks at 1318 cm\({}^{-1}\) and 1204 cm\({}^{-1}\), associated with distinct cellulose peaks, are evident in all starch/MCC films. Strong interactions between MCC and cassava starch molecules are confirmed by the remarkable drop in peak intensity at 3286 cm\({}^{-1}\) corresponding to the -OH group with increasing MCC content ([PERSON] et al., 2020). The amount of -OH groups decreases as a result of this interaction, which causes polymer chains to lose hydroxyl groups in the form of water molecules ([PERSON] et al., 2020).  
\begin{table}
\begin{tabular}{l c} \hline \hline
**Formulations** & **Thickness (\(\upmu\)m)** \\ \hline Starch & 127 \(\pm\) 8 \\ Starch/1\%MCC & 127 \(\pm\) 6 \\ Starch/3\%MCC & 139 \(\pm\) 6 \\ Starch/5\%MCC & 144 \(\pm\) 9 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Thickness of films (n = 6).