The highly transparent and flexible films prepared using NFCs exhibited a dras­tic improvement mechanical properties, with a maximum enhancement in Young’s modulus of 78% and 150% for high molecular weight chitosan and water-soluble high molecular weight chitosan (WSHCH), respectively with 20 wt.% of NFC load­ing; and of 200% and 320% for low molecular weight chitosan and water-soluble low molecular weight chitosan, respectively with 60 wt.% of NFC loading. The tensile strength values were in closer agreement with the trend of modulus values. As it can be assumed from a classical reinforcement effect, the values for elongation at break were reduced.39 Similar trends was also observed using bacterial cellulose.44