Technological watch

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 lead 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 bionanocomposite 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 (mNFC) demonstrated an improved barrier performance than the unmodified nanofibrillated cellulose (NFC). Oxygen transmission rate (OTR) and water vapour transmission rate (WVTR) of the coated pulps were in the range of 60?300 cm3 m?2 day?1 and 10?30 g m?2 day?1, respectively, comparable to those of conventional food packaging materials. Surface resistance of the coated pulps were also greatly improved, indicated by water contact angle (WCA), oil contact angle (OCA), Kit test, and oil adsorption 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 a great potential in converting paper?based materials to high barrier and sustainable food packaging.This article is protected by copyright. All rights reserved.