Mechanical, Barrier, Adhesion and Antibacterial Properties of Pullulan / Graphene Bio Nanocomposite Coating on Spray Coated Nanocellulose Film for Food Packaging Applications

In this study, an environmentally friendly and biodegradable pullulan/graphene bio nanocomposite was prepared and coated on the nanocellulose film to improve the surface, mechanical, barrier and antibacterial properties. The nanocellulose films were prepared by using a spray coating of nanocellulose suspension on stainless steel plates. The graphene nanoparticles were prepared by the modified Hummers method. The pullulan/graphene bio nanocomposites were prepared by solvent method with the addition of various wt% (0, 0.05, 0.1, 0.2) of graphene with pullulan. The coating was carried out by the roller coating method. Results showed that the increased graphene nanoparticles in pullulan coating increased the opacity, surface hydrophobicity, tensile strength, oxygen transmission rate and watervapour transmission rate of the coated nanocellulose film. Also, the coated film showed excellent antibacterial properties against both gram-negative E.coli and gram-positive S.aureus. In this research work, it was concluded that the graphene nanoparticles of 0.2 wt% showed efficient results. The exceptional properties of the pullulan/graphene bio nanocomposite coating on the nanocellulose film will give a new pathway to high performance food packaging applications.

The role of MFC and hydrophobically modified ethyl(hydroxyethyl)cellulose in film formation and the barrier properties of methyl nanocellulose film

There is currently a great demand for sustainable and bio-derived coatings for fiber-based packaging materials, which are technically implementable with a high performance. The aim of this work was to investigate the grease resistance of coatings prepared from methyl nanocellulose when applied on paperboard. Co-additives selected from native microfibrillated cellulose (MFC) and hydrophobically modified ethyl(hydroxyethyl)cellulose (EHEC) were used in order to determine their impact on film formation and crack resistance for folds. Small and moderate coat weights were applied in order to determine the critical coat weight for the barrier properties. It was found that high grease resistance can be achieved with methyl nanocellulose and a combination of methyl nanocellulose and MFC coatings. Contact angle determinations for water on uncoated and coated materials showed that EHEC-MFC films have a very high contact angle which is due to both the surface chemistry and roughness. This indicates and confirms that EHEC may facilitate the wetting of oil and greases. Methyl nanocellulose mixed with hydrophobically modified EHEC significantly changed the barrier properties indicating a change in the film formation.