Effect of cellulose nanocrystals on the properties of pea starch–poly(vinyl alcohol) blend films

Incorporation of cellulose nanocrystals (CNCs) to pea starch–poly(vinyl alcohol) (PVA) (1:2 ratio) blend films was carried out in order to improve their mechanical and barrier properties and film stability throughout storage, thus overcoming some drawbacks of starch based films. Different ratios (1, 3 and 5 %) of CNC were used and structural, thermal and physical (barrier, mechanical and optical) properties were analysed in comparison to the control film without CNC. Incorporation of CNC enhanced phase separation of polymers in two layers. The upper PVA-rich phase contained lumps of starch which emerged from the film surface, thus reducing the film gloss. CNCs were dispersed in both polymeric phases as aggregates, whose size increased with the CNC ratio rise. CNC addition did not implied changes in water vapour barrier of the films, but they became slightly stiffer and more stretchable, while crystallization of PVA was partially inhibited.