## 3 Results and Discussion
### Films Characterization
#### 3.1.6 Thermal Characterization  
TGA and DSC tests were carried out to study the influence of ASE addition and the extrusion process on the thermal stability and crystallinity of PCL-based films. All samples presented a characteristic DSC curve showing exothermic crystallization and endothermic melting transitions around 30 and 55 \({}^{\circ}\)C, respectively (Figure 3A). Moreover, the Tg was obtained around \(-60\)\({}^{\circ}\)C [33]. Regarding TGA (Figure 3B), film samples showed one degradation step with initial and maximum temperatures around 385 and 415 \({}^{\circ}\)C, respectively. This thermal degradation took place, in inert atmosphere, through the rupture of the polyester chains via ester pyrolysis reaction with the release of CO\({}_{2}\), H\({}_{2}\)O and carboxylic acids [17]. On the other hand, the DTGA curve obtained for ASE showed one overlapping degradation step with T\({}_{\text{ini}}\) at \(139\pm 5\)\({}^{\circ}\)C and T\({}_{\text{f}}\) at \(534\pm 5\)\({}^{\circ}\)C. ASE T\({}_{\text{max}}\) was obtained at \(339\)\({}^{\circ}\)C \(\pm\) 4 \({}^{\circ}\)C and it was assigned to the degradation of antioxidant compounds with a weight loss of 88% of the total mass. Finally, \(3.8\pm 0.2\%\) of residual mass was obtained (Figure S3).  
These results are in accordance with the degradation temperatures reported for different antioxidant compounds and extracts. In a previous study, active antioxidant food packaging films were produced by the incorporation of ascorbic acid, ferulic acid, quercetin, and green tea extract into an ethylene vinyl alcohol (EVOH) copolymer. TGA results of films confirmed the presence of degradation peaks at \(232\)\({}^{\circ}\)C for ferulic acid and \(249\)\({}^{\circ}\)C for ascorbic acid which were related to the degradation of antioxidant compounds present in the matrix since the TGA analysis of the pure compounds confirmed the same degradation peaks [58]. A similar thermal stability than that of ASE was reported for curcumin with three degradation steps between \(224\)-\(239\)\({}^{\circ}\)C, \(439\)-\(444\)\({}^{\circ}\)C and around \(570\)\({}^{\circ}\)C [59]. Recently,  
Figure 3: (**A**) DSC curves obtained for neat PCL, PCL3, and PCL6 during the second heating scan in nitrogen atmosphere (\(10\)\({}^{\circ}\)C min\({}^{-1}\)); (**B**) DTGA curves for neat PCL, PCL3, PCL6 and ASE in inert atmosphere (\(10\)\({}^{\circ}\)C min\({}^{-1}\)).  
[PERSON], [PERSON] and [PERSON] [60] reported that plant compounds are thermally degraded in three main regions, according to the results obtained for _Punica granatum_ peel ethanolic extracts obtained by ultrasonic-assisted extraction. The first region (up to 200 \({}^{\circ}\)C) was attributed to moisture loss and evaporation of volatile matters. The second one, up to 400 \({}^{\circ}\)C, was mainly due to de-carboxylation and the release of CO\({}_{2}\) during higher temperatures and, the last one up to hardly 600 \({}^{\circ}\)C represented the oxidation of crucial carbon residue.  
In this work, no significant differences (\(p>0.05\)) were obtained in DSC and TGA parameters among the studied composites containing ASE compared to the neat PCL film (Table 2). These results imply that the addition of ASE did not significantly alter the thermal stability of PCL-based films. Additionally, from Figure 3B, it was concluded that no residual solvent was present in films, since any evaporation of the residual solvent mixture was not observed in the DTGA curves.