Strength and barrier enhancements of composites and packaging boards by nanocelluloses - A literature review

This presentation reviews the recent research on new nanocellulose-based materials relevant to food packaging. The following materials are included: i) composites having nano-sized cellulosic additive or reinforcement filler and the following matrix materials: poly(lactic acid) (PLA), cellulose derivatives, or cellulose in so-called all-cellulose composites, and ii) packaging boards. Nano-sized celluloses (nanocelluloses) comprise micro- and nanofibrillar celluloses, nanocrystalline celluloses and whiskers. Sufficient mechanical and barrier properties are essential for a food packaging material. This potential of the cellulose-based materials is thus examined from the viewpoint of their tensile properties, and moisture and oxygen barrier properties, and compared to those of petro-based materials. In the discussion, an evaluation is made on the improvements achieved by usig nano-sized celluloses either as reinforcement filler or functional additive. The materials containing nanocelluloses either as a coating or additive have great potential to exceed the oxygen barrier properties of petro-plastics, provided that the mechanical properties of the composite, mainly ductility, is sufficient. Water vapor barrier properties of cellulose-based materials are still far from those of LDPE, even with nanocellulose additive. Relatively little research has been done on mineral-filled nanocellulose containing composites. Enhanced moisture barrier coatings may be found among those materials.