Nanocellulose films as air and water vapour barriers: A recyclable and biodegradable alternative to polyolefin packaging

Synthetic polymer packaging is neither reprocessable, renewable nor biodegradable and is difficult to recycle into useful barrier materials. Cellulose fibre based packaging is renewable, easily reprocessable, recyclable and biodegradable, however, it is a poor barrier material both before and alter recycling, especially against air and water vapour. Nanocellulose (NC), formed by breaking down cellulose fibres into nanoscale diameter fibres, is a renewable alternative to synthetic polymer packaging barrier layers. This research investigates the recyclability of virgin NC films. Nanocellulose films were recycled and prepared into films, using standard dispersion-based laboratory papermaking techniques through mixing and vacuum filtration of the resultant suspension. The recycled films retained (similar to)70% of the strength of the virgin films. Although the water vapour permeability (WVP) approximately doubled, increasing to 1.29 x 10(-10) g.m(-1).s(-1) Pa-1, it is still comparable to synthetic polymer packaging materials such as Polyethylene(PE), Plasticized PVC, Oriented Nylon 6 and Polystyrene (PS). SEM micrographs reveal no fibre agglomeration and no damage to the fibres during the recycling process. The optical uniformity measurements of recycled NC film confirms a drop in uniformity of the film at smaller length scales and an increase in uniformity at larger length scales, compared with virgin NC film. The retained strength and barrier properties combined with easy reprocessability of the product promises a sustainable and recyclable alternative to conventional polyolefin packaging, providing a very attractive alternative for the packaging industry. (C) 2019 Elsevier B.V. All rights reserved.