Hydrophobic-modified nano-cellulose fiber/PLA biodegradable composites for lowering water vapor transmission rate (WVTR) of paper

•Nano-scale cellulose fiber (NCF) was hydrophobic modified via free radical polymerization.•Biodegradable composites were made by incorporating modified NCF into PLA matrix.•The WVTR of paper decreased dramatically after being coated with the composites. New biodegradable nanocomposites have been successfully prepared by incorporating modified nano-cellulose fibers (NCF) in a biodegradable polylactic acid (PLA) matrix in this work. The hydrophobic-modified NCF was obtained by grafting hydrophobic monomers on NCF to improve the compatibility between NCF and PLA during blending. The resulting NCF/PLA composites were then applied on paper surface via a cast-coating process in an attempt to reduce the water vapor transmission rate (WVTR) of paper. The WVTR tests, conducted under various testing conditions and with different coating weights, demonstrated that the modified NCF/PLA composites coating played a critical role in lowering WVTR of paper. The lowest WVTR value was 34g/m2/d, which was obtained with an addition of 1% of modified NCF to PLA and the composites coating weight at 40g/m2 and substantially lower than the control value at 1315g/m2/d. The paper coated with the modified biodegradable composite is promising as green-based packaging materials.