This document summarizes research on developing a spray coating technique to rapidly prepare free-standing nanocellulose films in under a minute. The researchers tested different suspension concentrations and characterized the resulting films. The spray coated films had similar basis weight, thickness, mechanical properties, and barrier properties as films made through vacuum filtration. The spray coating technique provides a fast method for making laboratory-scale nanocellulose films with uniform properties and a smooth glossy surface on one side.

1. Rapid Preparation of Free- standing
Nanocellulose Films using spray coating
Co-authors : Kirubanandan Shanmugam, Prof. Gil Garnier and Dr. Warren
Batchelor
Australian Paper and Pulp Institute, Monash University,
Australia.
Swambabu Varanasi

2. Introduction and Background of the research
Research Objective
Methods
Results
Conclusion
OUTLINE

3. Bio-degradable
Bio-renewable
Bio-compatible
Characteristics
High Specific Strength
Thermal Stability
Hydrophilicity
Chemical
Modification
Hierarchical structure of wood fibers, Network of micro fibrils (Zhu et al., 2014)
INTRODUCTION

4. APPLICATIONS OF NANOCELLULOSE
Solar Cell (Georgia Tech News, 2013) Water and Air Filtration
Touch Screens (Zhu et al., 2014) High performance barrier materials
Images from web

5. NANOCELLULOSE FILMS PREPARATION TECHNIQUES
2. Vacuum filtration
Filtration Separation Drying
1. Casting and Solvent evaporation
Processing Method Processing Time Basis Weight (g/m2)
Casting 3 min 10 to 30
Vacuum Filtration 3 min to 4 hours 60
Sehaqui et. al. Biomacromolecules 2010, 11 (9), pp 2195–2198

6. Processing time –10-27 mins
3. Spray Coating
FREE STANDING FILMS PREPARATION TECHNIQUES
Beneventi, D. et. al. Industrial Crops and Products, 2015. 72: p. 200-205.
Our aim – Developing a spray coating technique to prepare lab scale films with very
minimum processing time ( less than minute)

7. EXPERIMENTAL SETUP
A Professional spray gun for performing spray
coating process
Experimental Conditions :
• Spray distance - 30 cm
• Suspension concentration - 1.0 to 2.0 wt %
• Velocity of conveyor – 0.34 cm/sec
Shanmuagam et. al. Cellulose - DOI: 10.1007/s10570-017-1328-4

8. SUSPENSION CONSISTENCY Vs BASIS WEIGHT & THICKNESS
0
50
100
150
200
250
300
0
50
100
150
200
250
0.8 1 1.2 1.4 1.6 1.8 2 2.2
BasisWeighting/m2
Concentration of nanocellulose in wt%
Basis Weight Vs Suspension Concentration
Thickness Vs Suspension Concentration
Thicknessinµm

9. THICKNESS MAPPING
SprayDirection
Surface exposed to atmosphere - rough
Surface adjacent to plate - Smooth

10. THICKNESS DISTRIBUTION
Spray Coated Film Film made by Vacuum Filtration
1 2 3 4
1
2
3
4
Region
Region
111.0
116.0
121.0
126.0
131.0
136.0
141.0
146.0
151.0
1 2 3 4
1
2
3
4
Region
Region
109.0
111.4
113.8
116.1
118.5
120.9
123.3
125.6
128.0

11. SEM IMAGES OF NANOCELLULOSE SHEET
1µm 10 µm 100 µm
1 µm 10 µm 100 µm
Rough
surface
Smooth
surface

12. SURFACE ROUGHNESS
Rough Smooth
AFM Image of the nano-fibrillated sheet – Rough and Smooth surface at 500 nm

13. Technique used Surface RMS Roughness (nm)
AFM Rough 414.0 nm (10µm
x10µm)
51.4 nm (2µm x
2µm)
Smooth 81.1 nm (10µm
x10µm)
16.7 nm (2µm x
2µm)
Parker Print
Surface
Instrument
Roughness 10.8±0.17µm -
Smoothness 5.5±1.4 µm -
Parker Print
Surface
Instrument
Sheet prepared
via the vacuum
filtration
10.6±0.3 µm
9.9±0.1 µm
-
SURFACE ROUGHNESS

14. OPTICAL PROFILOMETRY
Rough Smooth

15. MECHANICAL AND BARRIER PROPERTIES
Properties Spray Coated Sheet Sheet Prepared by
Vacuum filtration
Tensile Index (Nm/g) 60.2±1.5 62.3±3.4
Tensile stiffness (KN/m) 946±86 941±78
Air permeability
(µm/Pa.s)
<0.003 <0.003
Water Transmission Rate
(g/ m2 day)
35.6±8.5 33.9±3.5

16. CONCLUSION
• A rapid technique to prepare lab scale nanocellulose films
was developed.
• Processing time to prepare lab-scale nano-cellulose films is
less than a minute.
• Spray coated films has similar uniformity, mechanical and
barrier properties compared to films prepared by Vacuum
filtration.
• Spray coated films has one highly smooth and glossy surface.

17. ACKNOWLEDGEMENT
• Kirubandan Shanmugam, Dr. Warren Batchelor and Prof. Gil
Garnier
• Monash Centre for Electron Microscopy, Monash University
• Dr. Natasa, Dr. Rico Tabor for help with AFM
• Dr. Hemayet Uddin, Melbourne Centre for Nanofabrication

18. Thank you
PRESENTED BY
Swambabu Varanasi
Research Fellow
Monash University
Australia