## 3 Results and Discussion
### Thermal Stability of Capsule and Their Components  
Moreover, cooking and frying activities involve the oxidation of oils with the consequent loss of unsaturation through bond breaking, additions, substitution, and other well-documented reactions [24]; thus, a significant degradation of the oil is expected after the heating process. Despite this, the FTIR spectra recorded for both VCO and WCO were very similar (see Figure 5a). The disappearance of the -OH stretching characteristic band, at 3350 cm\({}^{-1}\), in the WCO could be related to the absence of mono and diglycerides. Meanwhile, the band found at 725 cm\({}^{-1}\) is typical of -CH\({}_{2}\) rocking, while those at 1100 cm\({}^{-1}\) and 1250 cm\({}^{-1}\) correspond to the C-O stretching vibrations, commonly found in ethers [25]. The vibration of C-H bond in methyl groups is confirmed by the absorption bands at 1370 cm\({}^{-1}\) and 1450 cm\({}^{-1}\), respectively. The strong signal at 1740 cm\({}^{-1}\) is typical  
Figure 4: (**a**) Representation of the creaming evolution over time; (**b**) Results of creaming index measurements over time; (**c–e**) Fluorescence microscopy images showing the droplet size evolution over time (0 h, 3 h, and 30 h, respectively); and (**f–h**) frequency histograms of the droplet diameter fitted to a log-normal distribution at 0 h, 3 h, and 30 h.  
of carbonyl groups (C=O) in saturated aliphatic ethers, while the bands between 2850 and 3015 cm\({}^{-1}\), correspond to symmetrical and nonsymmetrical C-H stretching in methyl (-CH\({}_{3}\)) and methylene (-CH\({}_{3}\)) groups. The similarities in intensity, position and nature of functional groups identified by their characteristic absorption bands in both spectra (VCO and WCO), suggest that WCO is thermally stable, which supports its use as encapsulated rejuvenating agent in asphalt materials usually manufactured at a temperature of 160 \({}^{\circ}\)C.  
Additionally, the thermal stability of the biopolymer (BioPoly) used for the preparation of the WCO capsules was confirmed by the TGA curve in Figure 5b. Indeed, decomposition at 160 \({}^{\circ}\)C -temperature of asphalt mixture preparation-, was nearly 5% for the polymer and remained unchanged when the WCO was encapsulated within the capsules. Two major DTG peaks corresponding to 12% and 32% wt. loss were identified for the BioPoly and, remained similar (with lower intensity) in the WCO Cap. The first peak at 183 \({}^{\circ}\)C is associated with structural dehydration reactions in the alginate, while the second one, at 278 \({}^{\circ}\)C, corresponds to the degradation of CaCO\({}_{3}\). The weight loss below 300 \({}^{\circ}\)C is caused by the loss of hydroxyl groups in the alginate and above this temperature decarboxylation reactions take place forming CO\({}_{2}\) as main product [26]. The relative position of the TGA curve for the WCO capsule indicates a higher thermal stability caused by the presence of the encapsulated WCO. In fact, the first decomposition phase ends at 320 \({}^{\circ}\)C and is associated with the capsule. Above this temperature, the oil decomposes in a two-stage process: the first stage (383 \({}^{\circ}\)C) corresponds to scissoring and breakage of C-H and C-O bonds and, the second (ending at 500 \({}^{\circ}\)C) corresponds to cross-linking and carbonisation. Results of TGA are in line with that found in the FTIR and suggest that encapsulation leads to a thermally stable material. Thus, when capsules are incorporated into a hot asphalt mixture, no significative thermal reaction between alginate matrix and asphalt should be expected, maintaining the integrity of the capsule. In fact, [PERSON] el al. [16] proved that the alginate-based capsules present good thermal and mechanical stability, surviving the mixing and compaction processes showing a strong adhesion to asphalt music by effect of a good interlocking with aggregates. They also concluded that capsule content up to 0.5% wt. of total weight of mixture is adequate to not affect the rheological properties of asphalt.