Barrier Performance of Spray Coated Cellulose Nanofibre Film

Abstract

Cellulose nanofibre (CNF) is the sustainable nanomaterial used for developing high-performance barrier materials that are renewable, recyclable, and biodegradable. The CNF film has very low oxygen permeability; however, its water vapor permeability is significantly higher than that of conventional packaging plastics. The fabrication method influences their barrier properties of the film. A spray-coating CNF on a stainless-steel plate was developed to form a compact film with two unique surfaces, namely a smooth layer on the base side and rough layer on the free side. It improves both the ease of preparation of the film and reduces the water vapour permeability via tailoring the basis weight and thickness of the film through simple adjusting CNF content in the suspension. The air permanence of the film from 1.0 wt.% to 2.0 wt.% CNF suspension is less than 0.003 µm/Pa·S confirming that is an impermeable film and proves a good packaging material. SEM, optical profilometry, and AFM revealed that the spray-coated surface was smooth and glossy. For sprayed CNF films with basis weight between 86.26 ± 13.61 and 155.85 ± 18.01 g/m2, WVP were ranged from 6.99 ± 1.17 × 10−11 to 4.19 ± 1.45 × 10−11 g/m·Pa·S. In comparison, the WVP of 100 g/m2 vacuum filtered CNF film was 5.50 ± 0.84 × 10−11 g/m·Pa·S, spray-coated film (of 96.6 g/m2) also show similar permeability at around 5.34 ± 0.603 × 10−11 g/m·Pa·S. The best performance was achieved with spraying of 2.0 wt.% CNF and a water vapour permeability of 3.91 × 10−11 g/m·s·Pa. Spray coated CNF film is impermeable against air and water vapour and a potential alternative to synthetic plastics.