Sustainable nanocomposite coating for moulded pulp with enhanced barrier properties for food packaging applications

Due to poor barrier properties and high sensitivity to moisture, the applications of paper-based food packaging remain limited. While gaining high barrier performance and surface durability, laminating papers with binders and other materials often leads to reduced recyclability and sustainability. Herein, we present a promising approach to improve the barrier properties and surface oil resistance of bagasse moulded pulp while preserving its green profile. A bio-nanocomposite layer, combining nanocellulose and shellac (natural polyester), was coated on the surface of moulded pulp. This nanocomposite coating layer provides excellent gas barrier and water barrier performance simultaneously, thanks to the ester modification of nanocellulose to improve its hydrophobicity. With a good compatibility and dispersion in the shellac matrix phase, the modified nanofibrillated cellulose demonstrated an improved barrier performance compared with the unmodified nanofibrillated cellulose. Oxygen transmission rate and water vapour transmission rate of the coated pulps were in the range 60-300 cm(3) m(-2) day(-1) and 10-30 g m(-2) day(-1), respectively, comparable to those of conventional food packaging materials. The surface resistance of the coated pulps was also greatly improved, indicated by the water contact angle, oil contact angle, Kit test and oil resistance test in a bowl model. The nanocomposite was able to enhance the tensile strength of the moulded pulp by 23%. In summary, the current sustainable nanocomposite coating layer demonstrated great potential in converting paper-based materials to high barrier and sustainable food packaging. (c) 2022 Society of Industrial Chemistry.

Automated summary

A bio-nanocomposite coating layer, consisting of nanocellulose and shellac, was coated on the surface of bagasse moulded pulp to improve barrier properties and surface oil resistance. The coated pulps demonstrated excellent gas barrier and water barrier performance, as well as improved tensile strength.