Different degree of fibrillation: strategy to reduce permeability in nanocellulose-starch films

The motivation of this study was the need to decrease the permeability without compromising the others properties of nanocellulose-starch films. For this, we produced films with untreated cassava starch and hydroxypropylated cassava starch in combination with nanocellulose submitted to four fibrillation levels and compared with the films made with the same starches and cellulose. The films were submitted to physical, morphological, mechanical and thermal tests. All films are low permeability to air regardless of starch type and level of nanocellulose fibrillation. Films produced using nanocellulose with a higher degree of fibrillation absorbed more water, had the higher contact angles for glycerol and lower contact angles for water. The apparent density was not affected by starch type and level of nanocellulose fibrillation, with an average density of 0.98 g m(-3). Films produced using more fibrillated nanocellulose had smaller crystallinity. The best mechanical properties were obtained with films made with untreated cassava starch. The greatest increase in the mechanical properties of cassava starch films was 146% for the burst index using nanocellulose N300, and 244% for the tensile index using nanocellulose N540. Thermal stability increased with increasing crystallinity.