Effect of recycling on the properties of nanocellulose-barrier and mechanical properties

Plastic based packaging causes significant problems in the environment. They are neither renewable nor biodegradable and plastics are accumulating in the environment, damaging the eco-system. Recycling also remains problematic. Sustainable, recyclable materials with outstanding barrier performance are required to replace these synthetic plastics. Nanocellulose is a potential candidate to replace synthetic polymers as packaging barrier layers. Nanocellulose films have low oxygen permeability and reasonable water vapour permeability. However, the effect on the fibres and material of recycling such films has not been widely investigated. In the work reported here, we made nanocellulose films via spray coating and then recycled them using disintegration, before forming into films with vacuum filtration. The formed films were compared virgin films also formed with vacuum filtration. The recycled films retained 70 % of the strength of the virgin films. The water vapour permeability (WVP) approximately doubled, increasing to 1.2 x 10^-10g.m^-1.s^-1Pa^-1. Investigations across a range of length scales pinpointed that the likely difference was due to bundles of the cellulose nanofibers that had not fully separated in recycling.