expanding the processability and applications of cellulose and chitin nanomaterials · 2020. 12....
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Expanding the Processability and
Applications of Cellulose and Chitin
Nanomaterials
Carson Meredith
School of Chemical & Biomolecular
Engineering
Renewable Bioproducts Institute
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Solid
Particles in composites, adhesives and films
Solid
Cellulose Nanofillers for
Polymers and CoatingsChitin-based Barrier
Materials
Engineering of Particles and Particle Interfaces
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Nanomaterials from Cellulose
4
Acid Digestion
Cellulose
Nanocrystals (CNCs)
J. Mater. Chem., 2012, 22, 20105; Wood Handbook, 2010
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Nanomaterials from Chitin
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Nanomaterials from Chitin
Chitin Nanofibers Chitin Nanocrystals
1 µm
Acid Hydrolysis
Zeng et al. (2012)
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Stiffness & Density Comparison
CNC on Par w/ Kevlar
MP
a
g/cm3
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Objectives
Develop approaches to increase processability and utilization
of pilot/industrial-scale cellulose nanocrystals (CNCs) or chitin
nanofibers (ChNFs)
1) CNCs in polyurethane and acrylics
2) Spray coating of CNCs
USDA Forest Products Laboratory
CNC Pilot Production Facility
3) Process monitoring for optimization
of ChNF production
4) Spray-coated ChNF barrier
materials
ChNF Lab Production Facility
Georgia Tech
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Chemical Modification of CNC Surface
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Di-isocyanate Modification
+
IPDI Modified Cellulose (m-CNC)Cellulose (um-CNC)
60 °C
Catalyst
2 NCO: dibutyltin dilaurate (DBTDL)
2
1
Onset of degradation
increases by 20 °C for 5 wt.%
m-CNC composite
200
210
220
230
240
250
260
270
280
290
300
Onse
t o
f d
eg
rad
atio
n (C
)
0%
1% um-CNC
5% um-CNC
1% m-CNC
5% m-CNC
ACS Applied Materials & Interfaces, 2016
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Mechanical Properties of poly(urethane)
nanocomposites
1 wt.% m-CNC 5 wt.% m-CNC
1 wt.% um-CNC 5 wt.% um-CNC
0 wt.% CNC
200 um
0
0.2
0.4
0.6
0.8
1
1.2
1.4
To
ug
hne
ss [J
/cm
3̂]
0%
1% um-CNC
1% m-CNC
5% um-CNC
5% m-CNC
257 %
0
2
4
6
8
10
12
14
16
Te
nsile
Str
eng
th [M
pa]
0%
1% um-CNC
1% m-CNC
5% um-CNC
5% m-CNC
226 %
5 wt.% m-CNC0 wt.% CNC 5 wt.% um-CNC
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NCO chemistry as route to other
polymers
+ =
IEM
2-isocyanatoethylmethacrylate
CNC IEM/CNC
In-situ polymerization
+ =
MMA IEM/CNC IEM/CNC_PMMA
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13
CNC Dispersion in Acrylic Polymers
IEM/CNC_PMMA
2.0 wt.%
CNC_PMMA
2.0 wt.%
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Spray coating CNC-filled epoxy
Spray coating chitin
He
ate
d S
urf
ace
Ba
se
Po
lym
er
Nitrogen
Supply
Ch
itin
Su
sp
en
sio
nSu
bstr
ate
Water-
borne
CNC-
Epoxy
Prior work on CNC-waterborne
epoxy formulations
Xu,Girouard,Schueneman,Shofner Meredith Polymer 2013
Girouard,Xu,Schueneman,Shofner Meredith Polymer 2015
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Neat 15% CNC
100 um
Spray coated epoxy – CNC composites
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pH tracking
Reactors11 Nos.
Blocked
end
High Pressure
Orifice0.005”(Z5), 0.008”(Z8)
Cavitation & Shear Shear & Collisions
Lowered Pressure
Outlet
22 LPH (max)30,000 psi (max)
ChNF Production via Homogenization
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ChNF Production via Homogenization
NH
HC=ONH2
Monitoring of surface area during processing via pH
+n m
++
+ +
++
+
+
+ +
+
++
+ +
+ ++ +
pH
Cycles
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Low (8,600 psi), Mixed (15,000 & 22,000 psi) & High (25,000 psi)
0.5 wt. % pure chitin suspension in acetic acid (pH 3)
pH tracking
Use of pH to monitor chitin defibrillation
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5 cycles 15 cycles
20 cycles 30 cycles
ChNF Morphology during processing
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Spray coating chitin nanofibers
Spray coating chitin
He
ate
d S
urf
ace
Ba
se
Po
lym
er
Nitrogen
Supply
Ch
itin
Su
sp
en
sio
n
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Barrier properties of chitin coated-PLA
0.000
0.005
0.010
0.015
0.020
0.025
0.030
0.035
0.040
0.045
0.00 0.10 0.20
Oxygen
Tra
nsm
issi
on B
arri
er @
50
% R
H (
bar
rer)
Loading (g-coat/g-PLA)
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Water vapor transmission
0
20
40
60
80
100
120
140
160
180
200
0 10 20 30 40 50 60 70 80 90 100
Wat
er V
apor
Tra
nsm
issi
on R
ate
(g-W
ater
/m2/d
ay)
Relative Humidity (%)
Coated Film 0.21 g-coat/g-
PLA loading
Control Film
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Conclusions
CNCs
• Modification of CNC with IPDI was successful with improved
dispersion, thermal, and mechanical property compared to the
neat polyurethane
• NCO a practical route to other functional groups and polymers
• Spray-coating up to 15 wt% CNC in waterborne formulations
ChNFs
• pH a simple and useful measure of defibrillation
• Spray coating of ChNF aqueous dispersions
• Upgrading barrier properties of base films
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Acknowledgements
Coauthors:
• Dr. Meisha Shofner, Georgia Tech MSE Faculty
• Dr. Greg Schueneman, USDA Forest Products Laboratory
• Dr. Shanhong Xu, GW University (former postdoc)
• Dr. Natalie Girouard, PolyOne (former PhD student)
Funding:
• USDA Forest Products Lab
• Georgia Tech Renewable Bioproducts Institute
PSE Fellowships & Equipment Grants