Bionanocomposites of chitosan/montmorillonite incorporated with Rosmarinus officinalis essential oil: Development and physical characterization

The aim of this work was to evaluate the physical properties of bionanocomposites based on chitosan (Ch) reinforced with different commercial nanoclays and further incorporated with rosemary essential oil (REO). Cloisite®Na+, Cloisite®Ca++ and Cloisite®20 were evaluated through mechanical and X-ray diffraction (XRD) analyses. Incorporation of montmorillonites (MMT´s) improved the mechanical properties, with natural MMT's providing greater reinforcement. Cloisite®Na+ was chosen to be casted incorporated with different concentrations of REO (0; 0.5; 1; 2%), due to its higher hydrophilic character. Rosemary essential oil reduced the tensile strength (33% at 2% of REO) and films turned opaque, more saturated in colour, and UV light block was improved (between 25-75% at 400 nm for 0.5-2% of REO). Superficial hydrophilicity and water solubility increased with the addition of REO while swelling index decreased. Bionanocomposites showed greater potential than pure chitosan for being used as packaging for food industry.