New generation of composite films of cellulose nanofibrils with mineral particles as high strength materials with gas barrier properties

Cellulose nanofibrils (CNF) is a type of renewable and biodegradable material comprising fibres with nanosized diameters obtained from wood pulp or non-woody resources. Their inherent properties, such as high specific surface area and mechanical strength, make them of high potential interest for several applications.

One area of interest concerns the production of high-strength CNF-based films possessing gas barrier properties, to be used as substrate for electronic displays or as barrier material for food packaging. Films of only CNF typically have high strength and transparency and can show reasonable gas (oxygen and water vapour) barrier properties under conditions of low humidity.

However, under more extreme conditions, the barrier properties are strongly diminished due to the CNF hydrophilicity. One possibility to improve the barrier properties of CNF can be based on the production of CNF-based composites with other components such as clayey minerals acting themselves as good barriers for the gas passage.

Thus, a synergy between the high strength and transparency of the CNF matrix and the high barrier property of the filler would be possible.