Processing of PLA nanocomposites with cellulose nanocrystals extracted from Posidonia oceanica waste: Innovative reuse of coastal plant

• Cellulose nanocrystals (CNC) were isolated from Posidonia oceanica waste.
• The surface of nanocrystals was also modified using a commercial surfactant (s-CNC).
• Poly(lactic acid) (PLA) nanocomposites reinforced with CNC and s-CNC were developed.
• The surfactant favours the CNC dispersion in the polymer supporting their effect on PLA properties.
• PLA/cellulose systems can be used as new bio-nanocomposites in industrial applications.

Poly(lactic acid) (PLA) nanocomposite films, reinforced with cellulose nanocrystals (CNC) extracted from Posidonia oceanica plant waste, were produced by solvent casting and their morphological, mechanical, thermal, optical and migration properties were studied. Cellulose nanocrystals were successfully extracted through an optimized chemical treatment, followed by sulphuric acid hydrolysis. The nanocrystals were added to the neat polymer at two different weight percentages (1 and 3%wt) using a commercial surfactant to increase the dispersion of CNC in the biodegradable matrix. All the nanocomposites kept the optical transparency of the PLA matrix, while morphological investigations underlined the rougher fracture surfaces of the CNC based systems and a more porous structure of the PLA matrix, induced by the addition of surfactant modified s-CNC. The surfactant favours the cellulose nanocrystal dispersion in the polymer matrix, remarkably enhancing the nucleation effect for matrix crystallization and producing its plasticization. The migration levels for all the studied nanocomposites were well below the legislative limits required for their use as food packaging materials. The successful production of biodegradable nanocomposites incorporating cellulosic sources from biomass waste suggests the possibility of using these new bio-nanocomposites in industrial applications.

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