## 3 Results
### FT-IR Analysis  
As shown in Figure 1, starches from cassava, potato, wheat, corn, pea, and rice are suitable raw materials for the production of biodegradable films. Each of these starches possesses unique molecular, chemical, and physical properties, which serve as both advantages and limitations in developing eco-friendly films.  
Figure 1: FTIR spectra of starch analysis (CSN—cassava native starch samples, CSM—cassava modified starch samples, PSN—potato native starch samples, PSM—potato modified starch samples, WSN—wheat native starch samples, WSM—wheat modified starch samples, CoSN—corn native starch samples, CoSM—corn modified starch samples, PeSN—pea native starch samples, PeSM—pea modified starch samples, RSN—rice native starch samples, RSM—rice modified starch samples.).  
Cassava starch, with its high amylopectin content, contributes to the production of elastic and durable films. However, its high hydrophilicity results in significant water absorption under humid conditions, potentially compromising the film's longevity. To address this limitation, additional additives or thermal modification may be required to enhance the stability of cassava starch-based films in high-moisture environments [37].  
Potato starch demonstrates excellent water-binding capacity and chemical stability, making it suitable for strong and mechanically stable films. Thermal modification further improves its resistance to moisture and enhances its structural integrity, making it particularly useful for applications requiring long-term durability in humid conditions [38].  
Wheat and rice starches, characterized by low molecular weight and low OH absorption, exhibit high biodegradability, making them ideal for short-term applications such as disposable or single-use products. Thermal modification improves their molecular stability while retaining rapid biodegradation, ensuring their suitability for environmentally safe, short-term usage [39].  
Pea starch, with high OH absorption, provides excellent water retention properties, making it suitable for flexible films designed for use in humid environments. Thermal modification enhances its moisture resistance and stability, enabling its application in films requiring prolonged durability [40].  
The FTIR data also highlight that thermal modification universally improves the structural stability of starches, reducing OH absorption, optimizing molecular distribution, and enhancing chemical stability, consistent with the research findings of [PERSON] et al. [41]. These improvements expand the range of applications for thermally modified starches in biodegradable films.  
In conclusion, the choice of starch type and the need for thermal modification depend on the intended application. Starches with high molecular weight, such as cassava and potato, are preferred for long-term use, while wheat and rice starches are more suitable for short-term applications due to their rapid biodegradability. Pea starch offers a balance of flexibility and durability for use in moist environments. Each starch type can be optimized through thermal modification or additives to better meet specific functional requirements in biodegradable film production.