CDR for Engineers Australia Chemical Engineering

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Career Episode 1
Introduction
CE1.1. This report reveals my experience through an industry-oriented project on “Spray coating
process for the development of nanocellulose and their composites films”. I worked as a process
engineer for the development of experimental setup in spraying at laboratory, bench and pilot-scale
to produce nanocellulose and nanocomposite films as packaging material. This project started on
26th Nov 2015 at Department of Chemical Engineering, Monash University, Clayton, Australia and
completed on 27th May 2019.
Background
Engineering works
CE1.2. I assigned to develop a flexible process to produce a layer on the base sheet to enhance its
barrier performance. I also produced free-standing nanocellulose film and nanocellulose based
composites via spray coating for packaging applications. This project was supported by Bioprocess
Advanced Manufacturing Initiative, Monash University, Australia. I utilized suggestions from many
industry professionals from various paper and pulp industries and academics from Monash
University. Based on the literature review, spraying nanocellulose for forming a film on the base
surface consumes very minimal time. This method allowed preparing the film with high basis weight
and thickness in a rapid manner. Spraying is an alternative for vacuum filtration and solvent casting,
considerable laboratory method for nanocellulose film preparation. In vacuum filtration, filtration
time increased due to solids content in the nanocellulose suspension. As a result, it consumes a
long time for forming the films/sheets and then odd to peel the formed sheet from the filter surface.
My task was design and construction of an experimental set up on spraying nanocellulose with
desired solid content on the polished impermeable surface to form the films/sheets and allowing for
drying and enhancing smooth peeling from the surface.
Objectives of the work
CE1.3. I split this industry-supported project into the following stages:
1. Developing a process of spraying nanocellulose on the base sheets to form a barrier layer.
This layer can lower air permeance of the coated paper for food packaging applications.
2. Developing the same spraying process on the polished impermeable surface to produce a
free-standing film for many functional applications.
3. Developing spraying nanocellulose suspension with inorganics on the polished
impermeable surface to produce free-standing composites.
4. Analysing of recyclability potential of spray-coated nanocellulose film and a potential
alternative to synthetic packaging materials.
5. Engineering the surface roughness and smoothness of the nanocellulose films via spray
coating.

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Engineering Tasks in this Project
CE1.4. I constructed and developed a full-fledged spray coating experimental set up for developing
nanocellulose films and nanocomposites. I chose the right professional spray system that integrated
with a conveyor. The speed of the conveyor can be varied. The experimental setup was used for
the processing of smooth films from pure nanocellulose suspension and nanocomposites from clay
and suspension. I analysed the film’s properties with the droplets of nanocellulose suspension from
the spray nozzle and selected a right nozzle for these studies based on spray distance and size of
the droplets. I performed tuning roughness of the film and tailoring the basis weight, the thickness
of the films.
Roles and Responsibilities
CE1.5. My responsibilities were,
• Development of a rapid process for spraying nanocellulose on the smooth polished metal
surface.
• Construction of a prototype concept into a flexible process to produce multiple
nanocellulose films and composites.
• Evaluation of the flow properties of nanocellulose and the effect of fibres content on the
viscosity of the suspension and finding a sprayable concentration of nanocellulose.
• Optimization of the parameters in spray coating for good film formation and suitable
applications.
• Preparation of the nanocellulose films and its composites with inorganics for packaging
applications.
• Tailoring the properties of nanocellulose film and nanocomposites via spraying different
concentration of nanocellulose with or without inorganics.
• Investigating the mechanical, bulk and surface properties of nanocellulose films and its
composites.
• Troubleshooting the issues in the spray coating setup for preparing the well-uniformed
sheets.
• Evaluating of the barrier potential of spray-coated nanocellulose films and composites.
• Performing recycling of spray coating nanocellulose films into the secondary fibres
nanocellulose films produced via vacuum filtration and investigating the barrier
performance of the film from recycled nanofibers.
• Spraying nanocellulose virgin fibres on the packaging paper to increase its barrier
potential.

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Organization Structure
CE1.6. I played as an Engineer and Research Scholar in this project and communicated with various
researchers and industrial professionals. I reported the progress on various stages of the project.
Director & Industrial R& D
Professor Commercial Expectations
Supervisor
Market Potential
Scope Post-Doctoral
Fellow
Structure
Methods
Kirubanandan – Engineer in Training
Personal Engineering Activity:
Design Considerations and Requirements:
CE1.7. Based on the first discussion with my supervisors, I gathered the requirements of film formation
via spraying of nanocellulose on both impermeable (Polished stainless steel) and permeable
surface (packaging paper). I found that the film formation should take minimal time and should be
quite easy to peel the NC film from the surface without any destruction when compared to the
peeling the film from the filter surface in the vacuum filtration process. The nanocellulose film
roughness was also tuned by spraying on different surfaces and tailored simply by adjusting
cellulose fibrils content in the suspension and optimizing the process parameters in the
experimental setup.
Development of Spray Coating of Nanocellulose
CE1.8. I reviewed the advantages of spraying method through an enormous literature review and
observed their advantages such as contactless and contour coating with the base surface without
influencing surface topography during the coating process. I developed a spray coating method for
a range of achievable basis weight of film higher than that of the NC film via filtration. I proved this
rapid method of performing with the spraying a higher suspension consistency compared to vacuum

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filtration and reduced the quantity of water in the spray coated wet film. I confirmed the efficacy of
spray coating through good and comparable uniformity and mapping of the thickness of NC film
with the film via vacuum filtration.
Change of Configuration of Experimental Set up
CE1.9. I configured and commissioned the spray coating experimental setup and optimized numerous
parameters for spraying of nanocellulose on the stainless-steel plate on the moving conveyor which
could have varying velocity. When altered to the full flexible spray coating process, I investigated
the effects of conveyor velocity, cellulose nanofibrils solid concentration and experimental setup
configuration such as the positioning of the spray gun and use of various spray nozzles, etc. I
investigated these effects on the uniformity of the film and their properties. I used scanning electron
microscopy (SEM) for evaluating surface topography and morphology of nanofibrils on spray-
coated film with the support of Image J software. I fixed the nanocellulose waste collection system
in the experimental setup by positioning a metal plate at the bottom of the belt of the conveyor to
remove/collect the excess nanocellulose on the belt in the conveyor.
Figure 1 – An experimental setup of spray coating for the production of nanocellulose films.

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Figure 2 – Liquid Scaraping system in the experimental set up.
This novel rearrangement provided to minimise waste of nanocellulose when spraying on the
stainless plates.
CE1.10.
Developing a correlation between process variables:
I derived a correlation between the process variable and the properties of films. This correlation
would be an application for scaling up the spraying process. The developed correlation was based
on the film width, suspension consistency, and the conveyor velocity to evaluate the basis weight
of the film to be achieved in the spraying process.
Characterization of Spray Coated Nanocellulose films
CE1.11. I performed the characterization of the bulk properties such as basis weight and
thickness of the spray-coated films and compared with the film via vacuum filtration. The bulk
properties of NC film were tailored by suspension consistency and velocity of the conveyor. I used
many international standards such as ASTM E96, AS/NZ 208, 448, 437 and TAPPI T411& T 460
for characterization of NC films. The uniformity of spray-coated NC film was considered as a quality
control marker. The effect of process parameters such as spray droplets from the spray nozzle,
suspension consistency and modifying configuration of spray pattern was engineered to control the
uniformity of the film. I resolved the formation of ripples on the film by increasing the suspension
consistency and adding few alterations in spray coating experimental set up such as change of
nozzle, optimizing spray distance and spray pressure. By this way I imporved the uniformity of the
film. The mechanical strength of spray-coated NC films was investigated and reported as
comparable strength with the film via vacuum filtration.

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Barrier Performance of Spray Coated Film:
CE1.12. I evaluated the air permeance and water vapour permeability of nanocellulose film as
per AS/NZ Std T 460 and ASTM E96/E96M-05 and compared them with the barrier potential of
vacuum filtered NC film confirming that the spray-coated NC film would be a potential packaging
material and compared with commercial synthetic polymers. I proved that spraying nanocellulose
on the polished metal surface produced a compact structure of nanocellulose film which produced
good resistance against air and water vapour.
Producing Unique Surface of Spray Coated Film
CE1.13. I produced the two unique surfaces of nanocellulose film via spraying and measuring
its surface roughness via numerous instruments like AFM and Profilometry. The spray-coated NC
film has two distinct surfaces namely a smooth one which has a roughness of 330 nm and the rough
side which has a roughness of 2440 nm. I used a few software such as Olympus Analysis (OLS
5000) and Gwyddion 2.49 for processing of profilometry images to confirm the surface roughness.
The smooth surface can play a major role in the development of many functional materials such as
flexible electronics and Optoelectronics devices.
Recycling of Spray Coated Nanocellulose Film
CE1.14. I investigated recycling and reprocessing of spray-coated nanocellulose film to show
the sustainable platform. I dispersed pieces of NC film and suspended in water according to TAPPI
standard T205 SP-02 for recycling fibres. I disintegrated the soaked pieces of NC film for 75,000
revolutions at 3000 rpm in a laboratory-scale disintegrator. I developed NC film from the recycled
NC suspension through the vacuum filtration method TAPPI T205 sp-95. I investigated the effect
of recycling on the recycled film from recycled fibres and their properties compared with virgin film.
Developing Sustainable Pathway
CE1.15. Once completed recycling and reprocessing nanocellulose films, I evaluated the film’s
barrier performance before and after recycling and compared the results with synthetic polymers in
the literature and engineering handbooks. The air permeance and water vapour permeability of the
recycled NC film are almost in agreement with the results generated from commercial packaging
material such as polyolefin film and nylon material. The recycling process that I developed is an
eco- friendly and chemical-free sustainable process and is upscalable with spray coating.
Developing Nanocellulose –Inorganics Composites
CE1.16. I developed nanocellulose- inorganics composites via spray coating process which
proved to be high-performance barrier material. The engineering challenge I faced in this work was
the preparation of nanocomposites in a rapid manner with less time consumption in comparison
with vacuum filtration and incorporation of nano-clay into the layers of nanocellulose fibrils after
homogenization of raw nanocellulose. This resulted in high performing barrier materials. I
investigated the mechanical and barrier properties of nanocomposites, the effects of inorganics on
nanocellulose and structure of composite with X-Ray Diffraction.

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Developing nanocellulose barrier layers on the base sheet
CE1.17. I developed NC barrier layers on the packaging paper and evaluated its barrier
performance with mechanical properties. I performed spraying of cellulose nanofibre suspension
from 0.5 to 1.5 wt. % on the packaging paper. I achieved coat weight from 2.9±0.7 to 29.3±6.9 g/m2
and air permeability of spray coated substrate varied from 0.78±0.17 to <0.0030 µm/Pa.S at a
sprayable concentration from 0.5 to 1.5 wt.% of suspension. I performed the scanning electron
microscopy investigation on spray-coated nanocellulose barrier layers on the paper to evaluate
barrier layers and interpreted the surface pores on the paper substrates filled with sprayed
nanocellulose fibres and formed a continuous fibrous film on the surface of the packaging paper
that induces a drop in the air permeability of the paper substrate and increases its tensile strength
of spray-coated paper from 109.7±7 to 131.1±13.4 N. I concluded spray coating, a rapid process
for producing barrier nanocellulose layer on the paper substrates.
Tuning the surface smoothness and roughness of the nanocellulose film
CE1.18. I engineered the surface roughness of film via spraying on various substrates having
high to low roughness. I investigated RMS roughness of the two surfaces with Optical Profilometry.
I achieved the roughness of film around 389 nm on the spray-coated side and 2087 nm on the free
side. The spray-coated NC film has ultra-high smoothness on the side exposed to the polished
stainless-steel surface. I sprayed nanocellulose on different surfaces such as ordinary stainless
steel, super mirror stainless steel, and silicon wafers for tuning roughness of the film. I investigated
the factors such as the diameter and length of cellulose fibrils and surface smoothness of
contact/base surface controlling the roughness/smoothness of the film. The surface smoothness
requirements for NC substrate applications play an important factor in fabricating materials such as
printed electronics and opto-photonics devices.
Project Management and Communication
CE1.19. I conducted the main part of the spray coating experiments on the preparation of
nanocellulose films and nanocomposites. Analysing the surface and topography of spray-coated
surface was performed by my fellow research scholar under my direction. I published these works
namely “Rapid method and flexible process” in cellulose journal and “recyclability of NC film” in
sustainable material and technologies journal. Currently, I prepared two new research articles for
my PhD thesis. I drafted the progress reports and presentation on my project and used endnote
citation software for referencing and MINITAB, ORIGIN for data processing. I performed various
hazard analysis and risk assessment of spraying process of NC and NC-Clay suspension on the
surface and drafted safe work instructions and risk assessment documents for the operation of a
spray coating experimental set up for any users. I trained few fellow PhD students to how to spray
coatings for their applications and demonstrated this feasible method to visitors from other
universities and Industries.

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CE.1.20: Summary
Through this project, I had a platform for developing nanocellulose films and nanocomposites
via spray coating and I gained engineering practice and skills through
designing/constructing/commissioning of the spray coating set up. I engineered the properties of
nanocellulose films and nanocomposites and the smoothness/roughness of the film via a flexible spray
coating process. I proved a sustainable pathway on recycling of nanocellulose films and its suitability
to be used as packaging materials. Spray coating is a rapid method and upscalable process for the
production of nanocellulose films and nanocomposite. I used ASTM, AS/NZ and TAPPI standards for
evaluating properties of NC film and its composites. I referred many standard handbooks on
nanocellulose, composite and paper and paper boards for deriving the conclusion of NC film properties
and spraying performance. I implemented a few software such as advanced MS-EXCEL, ORIGIN and
MINITAB for data analysis on spraying notably thickness mapping of spray-coated NC film.