Comparing physico-mechanical and thermal properties of alginate nanocomposite films reinforced with organic and/or inorganic nanofillers

Montmorillonite (MMT) and cellulose nanoparticles (CNP) were added to alginate biopolymer to compare the properties of bionanocomposites reinforced with different organic and inorganic nanofillers in various loading contents (1, 3, and 5 wt%). Both MMT and CNP decreased the water solubility (WS) of the films. However, at all filler contents the WS of the alginate/MMT (84–61%) nanocomposites was significantly (P < 0.05) lower than that of alginate/CNP films (95–77%). Surface hydrophobicity of the nanocomposites showed a great improvement (83%) with crystalline hydrophobic CNP addition, while MMT made filmsʹ surface more hydrophilic. The addition of both nanoreinforcements similarly caused a reduction in the water vapor permeability of the alginate-based nanocomposites. Due to the similar polysaccharide structures and good interfacial interactions, the TS and E of the nanocomposite films improved with an increase in CNP content and reached a maximum at the highest loading level (5 wt%). However, when the content of MMT went beyond 1 wt% nanocomposites, a decrease in the TS was observed. Finally, these results propose that organic CNP more than ability to make a fully renewable and natural nanocomposites may also introduce some other advantages compared to inorganic nanoclay fillers when added to carbohydrate biopolymers.