Chitosan-based films reinforced with cellulose nanofibrils isolated from Euterpe oleraceae MART

The use of local raw materials for the production of biodegradable films can simultaneously contribute to the development of the Amazon and global sustainability. This work aimed to evaluate the physical and mechanical performance of chitosan-based bionanocomposite films reinforced with different loads of cellulose nanofibrils obtained from açaí (Euterpe oleraceae Mart.) under two nanofibrillation degrees. Nanofibrils were obtained by 3 and 21 passages in a grinder defibrillator. The films were produced by casting with nanofibril reinforcement at 5 wt.%, 10 wt.%, 15 wt.%, and 20 wt.%. The increase in the nanofibril level and nanofibrillation degree reduced water vapor absorption (75.20% to 51.93%), water solubility (28.33% to 17.91%), and density (0.87 g.cm−3 to 0.61 g.cm−3). The water vapor permeability decreased with higher nanofibril loads for both 3-pass (47.30% to 43.61%) and 21-pass (49.82% to 44.48%) reinforced films, but not with nanofibrillation degree. The increase in 3-pass nanofibril level decreased tensile strength (8.18 MPa to 7.88 MPa), modulus of elasticity (867.62 MPa to 670.02 MPa) and elongation at break (0.02 mm.mm−1 to 0.01 mm.mm−1). However, the opposite effect happened to 21-pass nanofibrils, with increases from 9.16 MPa to 9.73 MPa and from 502.00 MPa to 1119.62 MPa for tensile strength and modulus of elasticity, respectively. Meanwhile, the maximum elongation at rupture did not vary. It was concluded that chitosan-based bionanocomposite films reinforced with 20 wt.% of 21-pass nanofibril were more resistant, except for water vapor permeability. Adding coarser nanofibrils enhanced this property. The 3-pass nanofibrils reinforcement enables water solubility, which benefits other packaging applications.