Nanocellulose/natural rubber latex composite film with high barrier and preservation properties

Nanocellulose films have excellent oxygen barrier properties, but their water vapor barrier properties and water resistance are poor. Natural rubber latex (NRL) has been used as a composite material to improve the hydrophobic properties of 2,2,6,6-tetramethylpiperidin-1-oxo (TEMPO) oxidized nanocellulose fibers (TOCNFs) because of its natural core-shell structure that allows for homogeneous mixing with hydrophilic polymers in aqueous solutions. The exposure of the internal hydrophobic isoprene molecular chains of NRL during the drying process allows the composite film to have greatly improved water resistance and excellent water vapor and oxygen barrier properties. The water vapor permeability (WVP) and oxygen permeability (OP) of the film were as low as 6.07 × 10−13 g m/m2·s·Pa and 3.11 × 10−15 cm3 cm/cm2·s·Pa, respectively. The good water resistance of the composite film makes the wet tensile strength of the film up to 15.87 MPa, which reaches 71.69% of the dry tensile strength. In addition, the high ductility of NRL makes the composite film good toughness, and its elongation at break can reach about three times that of most nanocellulose-based films. Strawberry preservation experiments have shown that it can effectively slow down the deterioration of strawberries, extending their shelf life from 2 days to 7 days.