This document summarizes research on developing barrier films from nanocellulose using spray coating. Spray coating nanocellulose suspensions allows the density and barrier properties of resulting films to be tailored by adjusting the solid content. Films produced through spray coating at 1.0-2.0% nanocellulose content had an air permeance below 0.003 μm/Pa*s, indicating they could serve as effective packaging materials. Water vapor permeability of spray coated films ranged from 6.99-4.19×10-11 g/m*Pa*s depending on basis weight and decreased further at higher solid contents, demonstrating potential as an alternative to synthetic plastics for packaging applications.

1. Barrier Performance of Spray Coated
Nanocellulose Film
Kirubanandan Shanmugam, Swambabu Varanasi, Gil Garnier, Warren Batchelor.
Department of Chemical Engineering, Bioresource Processing Research Institute of
Australia (BioPRIA), Monash University, Melbourne, Vic 3800, Australia.
*Presenting Author, E-mail: kirubanandan.shanmugam@monash.edu
Nanocellulose (NC) is one of the predominant cellulose nanofiber
substrates developing high-performance barrier material that is
renewable, recyclable and biodegradable. The film developed from
nanocellulose have very low oxygen permeability, however, their water
vapour permeability is significantly higher than conventional packaging
plastics, such as Low-Density Poly-ethylene (LDPE).
Water vapour permeability (WVP) of the NC film has been decreased by
forming the film via various methods.The method of preparation of film is
one of the criteria for promoting their barrier performance. Vacuum
filtration is commonlyused to form NC film. However, it has poordrainage
time and exponentially increasing with solid content in the suspensionfor
forming the film.The method forspray-coating nanocellulose is developed
to form a compactfilm which two unique surfaces namely smooth on the
base side and rough on free side1,2
.The density of the film can be tailored
via simply adjusting solid content in the NC suspension. Spraying
improves both the ease of preparation of the film and reduces the water
vapour permeability via tailoring the density of the film.
The air permeance of the spray coated film prepared spraying of NC from
1.0 wt. % to 2.0 wt. % NC suspension is less than 0.003 µm /Pa.S
confirming that be an impermeable film confirming a good packaging
material. The effectof suspensionconsistency onthe barrier performance
of the film is also investigated. For NC films prepared via spraying with
basis weight between 86.26±13.61 to 155.85±18.01 g/m2
, WVP ranged
from 6.99±1.17 x 10-11
to 4.19±1.45 x 10-11
g/ m Pa S. In comparison,100
g/m2
NC film prepared via vacuum filtration which had WVP of 5.50±0.84
x 10-11
g/ m Pa S, spray-coated film (of 96.6 g/m2
) show similar
permeability at around 5.34±0.603X 10-11
g/ m Pa S.
The water vapour permeability of the spray coated film from 1.75 wt. %
and 2.00 wt. % NC could be reduced below that achieved with vacuum

2. filtration. The best performance achieved with the spraying of 2.0 wt. %
NC was a water vapour permeability of 3.91 X 10-11
g/m.s.pa. This value
shows an impermeable film for packaging applications. Considering the
barrier performance of the film, spray-coated nanocellulose film can
perform as an effective barrier material and a potential alternative to
synthetic plastics.
Graphical Abstract
Reference
1
Shanmugam, K., Doosthosseini, H., Varanasi, S., Garnier, G., & Batchelor, W. (2018).
Flexible spray coating process for smooth nanocellulose film production. Cellulose, 25(3),
1725–1741. doi: 10.1007/s10570-018-1677-7.
2
Shanmugam, K., Varanasi, S., Garnier, G., & Batchelor, W. (2017). Rapid preparation of
smooth nanocellulose films using spray coating. Cellulose, 24(7), 2669–2676. doi:
10.1007/s10570-017-1328-4.