Effect of combining cellulose nanocrystals and graphene nanoplatelets on the properties of poly(lactic acid) based films

In the present work, cellulose nanocrystals (CNC) and graphene nanoplatelets (GR) were combined in two different ratios and incorporated into polylactic acid (PLA) by melt blending technique, at a total loading level of 1 wt%. The obtained PLA-CNC/GR nanocomposites were further processed by hot pressing for manufacturing films. For comparison purposes, PLA-CNC, PLA-GR and PLA-T (PLA blended with the organic surfactant Triton X-100) compositions were also prepared following the same procedure. The produced materials were characterized by several techniques, including Field-Emission Scanning Electron Microscopy (FE-SEM). The mechanical properties assessment showed an increase of 8 and 11% in the Young's modulus and tensile strength respectively for PLA-CNC/GR (ratio 50/50) film compared to PLA-T. The thermal properties were also positively influenced by the incorporation of both nanofillers. Similarly, the gas barrier properties were improved by 23% in Oxygen Transmission Rate (OTR) for films containing simultaneously CNC and GR. Finally, the antifungal properties were evaluated against Aspergillus Niger finding a superior antifungal activity in the CNC/GR hybrid films. The incorporation of CNC and GR in PLA showed a favourable impact in the overall properties of the obtained materials with only 1 wt% of nanofiller content. These results suggest that CNC/GR hybrid nanocomposites have a considerable potential in agricultural films or in food packaging trays applications.