Multifunctional bionanocomposite films of poly(lactic acid), cellulose nanocrystals and silver nanoparticles

Nanocomposite films were prepared by the addition of cellulose nanocrystals (CNCs) eventually surfactant
modified (s-CNC) and silver (Ag) nanoparticles in the polylactic acid (PLA) matrix using melt extrusion
followed by a film formation process. Multifunctional composite materials were investigated in terms
of morphological, mechanical, thermal and antibacterial response. The nanocomposite films maintained
the transparency properties of the PLA matrix. Thermal analysis showed increased values of crystallinity
in the nanocomposites, more evident in the s-CNC based formulations that had the highest tensile Young
modulus. The presence of surfactant favoured the dispersion of cellulose nanocrystals in the polymer
matrix and the nucleation effect was remarkably enhanced. Moreover, an antibacterial activity against
Staphylococcus aureus and Escherichia coli cells was detected for ternary systems, suggesting that these
novel nanocomposites may offer good perspectives for food packaging applications which require an
antibacterial effect constant over time