## 4 Conclusions  
The possibilities of reprocessing polylactide (PLA)-based bionanocomposites with nanofibrilated cellulose (NFC) and plasticized with poly(ethylene glycol) (PEG) were demonstrated, assuming relevant polymer degradation and encouraging their use for downgraded applications after reprocessing. Plasticizing PLA with PEG promoted more significant degradation during the first and second processing stages. Low-molar mass PEG slightly accentuated thermo-mechanical degradation during compounding, while non-relevant differences between PEG-400 and PEG-1500 were found after injection molding and thermo-compression. In terms of crystalline morphology, the plasticizing effect of PEG and accentuated chain scission enhanced the mobility of the PLA to form crystalline domains, emphasized for compositions with PEG with lower molar mass. The technological limitation must also be considered due to the thermo-oxidative decomposition of PEG at temperatures much lower than that of PLA. The presence of NFC in the bionanocomposites was not critical for the chain scission of PLA during processing. Complementarily, the NFC acted as a nucleating agent favoring crystallization with a limited concentration for the nucleating function in the range from 1 to 3 wt% of NFC. The evaluation of the thermal properties, especially after reprocessing, pointed out the necessity of controlling the cooling stage, as it may determine the final crystalline structure and, therefore, the specimens' performance. The mechanical validation of the injection-molded dog-bone specimens for a first service life demonstrated the contribution of PEG as a plasticizer to increase ductility and reduce tensile strength and tensile modulus. It was more relevant the lower the molar mass of PEG, especially at a low concentration of NFC. The addition of NFC reduced the drop in the stiffness caused by PEG, still offering higher elongation at break than pure PLA. The increasing porosity and an uneven fracture surface for high NFC contents (5 wt%) may be related to the agglomeration of the nanoparticles during processing. The exploration of reprocessed compression-molded films for a second service life during water immersion revealed the contribution of high temperatures to the absorption of water, diffusivity, solubility, and permeability. PEG and NFC increased the absorbed water and the solubility coefficient. The integrity of the plasticized films was compromised due to the release of PEG domains during immersion in the rubbery state at high temperatures (58 and 70 \({}^{\circ}\)C), especially for the PEG with lower molar mass. The role of NFC was demonstrated to modulate diffusivity in all of the compositions, but only small percentages of nanoparticles (1 and 3 wt%) were able to moderate permeability. Altogether, although reprocessing can cause significant degradation, these bionanocomposites showed promise to be sustainable candidates for food packaging or agricultural applications where modulated mechanical or water contact behaviors are required. Their renewable origin, functionality, and material valorization possibilities will open new possibilities for spreading the use of these green composites.