## 3 Results and Discussion
### Validation of the Bionanocomposites
#### 3.2.1 First Service Life: Mechanical Performance and Fracture Surface of Dog-Bone Specimens
Finally, observing the macroscopic appearance of the fracture region in the dog-bone specimens, it was easy to detect a whitish area formed due to necking during the tensile tests, in which strain-induced crystallization could be visually identified. This behavior was corroborated by analyzing the crystallinity of the close-to-fracture section. The obtained degree of crystallinity of the fracture region (\(X_{c\_frac{\text{{fac}}}{\text{{fac}}}}\)) is also presented in Table 3.  
In general, unless for pure PLA, a significant increase in the crystallinity degree in the fracture region was found for the plasticized PLA and bionanocomposites. As suggested in previous sections, using PEG may allow the PLA macromolecular chains to flow and rearrange, forming tensile-induced crystalline domains. Moreover, moderated percentages of NFC (1 and 3 wt%) enhanced the crystallization due to its nucleating performance. At the same time, higher amounts of NFC (5 wt%) promoted the lowest variation in the degree of crystallinity after mechanical fracture, probably due to the already mentioned nanofiller agglomeration. Figure 7: Microscopic appearance of cryofracture surfaces (left) and tensile fracture surfaces (right) of the dog-bone specimens of PLA, plasticized PLA-PEG, and PLA/PEG/NFC bionanocomposites. 2.2 Downgraded Second Service Life: Diffusion, Sorption, and Permeation of Water in Film Reprocessed Specimens  
The thermo-compressed reprocessed films were validated by assessing their water absorption behavior during immersion at 8, 23, 58, and 70 \({}^{\circ}\)C. The water absorption profiles as a function of time are plotted in Figure 8, where the early absorption after immersion and the virtual saturation could be perceived. The absorption profiles for neat PLA in the initial immersion stage looked similar for all of the temperatures. First, the percentage of absorbed water (\(M_{t}\)) increased fast and almost linearly, followed by a less intense non-linear growth until the curve reached saturation, involving a classic Fickian performance [96; 97; 98; 99; 100; 101]. The mass of the PLA increased by \(\sim\)0.75% through the immersion in water at 8 and 23 \({}^{\circ}\)C, while at 58 and 70 \({}^{\circ}\)C, the mass augmented up to \(\sim\)1.5% at saturation. Therefore, as expected, higher temperatures increased the water uptake of the PLA. The curves of the plasticized PLA-400 and PLA-1500 showed a more relevant increase in mass compared to neat PLA due to the hydrophilic nature of PEG, with  
Figure 8: Absorbed percentage of water (\(M_{t}\)) during immersion for the PLA, plasticized PLA-PEG, and PLA-PEG-NFC nanocomposite films at 8, 23, 58, and 70 \({}^{\circ}\)C. \begin{table}
\begin{tabular}{c c c} \hline  & \(\mathbf{X_{c0}}\) & \(\mathbf{X_{c\_frac}}\) \\  & **(\%)** & **(\%)** \\ \hline PLA & 15.3 (\(\pm\)2.6) & 15.0 (\(\pm\)4.0) \\ PLA-400 & 18.5 (\(\pm\)0.8) & 42.0 (\(\pm\)2.2) \\ PLA-400-NFC1 & 19.1 (\(\pm\)0.1) & 39.8 (\(\pm\)0.2) \\ PLA-400-NFC3 & 15.9 (\(\pm\)0.5) & 37.0 (\(\pm\)4.9) \\ PLA-400-NFC5 & 16.6 (\(\pm\)1.1) & 32.6 (\(\pm\)3.8) \\ PLA-1500 & 20.8 (\(\pm\)1.4) & 40.8 (\(\pm\)0.6) \\ PLA-1500-NFC1 & 25.7 (\(\pm\)2.6) & 42.6 (\(\pm\)0.8) \\ PLA-1500-NFC3 & 20.5 (\(\pm\)0.2) & 36.4 (\(\pm\)3.5) \\ PLA-1500-NFC5 & 20.6 (\(\pm\)0.3) & 34.2 (\(\pm\)3.8) \\ \hline \end{tabular}
\end{table} 
Table 3: Degree of crystallinity of dog-bone specimens after processing (\(X_{c0}\)) and in the fracture region after the tensile test (\(X_{c\_frac}\)). multiple hydroxyl groups in its structure. The higher molar mass of the PEG involved more water absorption. The more cohesive and entangled the system, the more PLA-1500 can swell and increase the water uptake ability. For the bionanocomposites, a trend towards even higher water uptakes was observed when the NFC content increased, especially at the lowest temperatures. Although the NFC in this study was acetylated for improving dispersion and may result in a hydrophobic behavior, it can still have hydroxyl groups available to attract water to its surface.