Cellulose Fibers From
Nanometers to Millimeter
New Applications and Opportunities
Arthur J. Ragauskas
Institute of Paper Science and Technology
Georgia Institute of Technology
Current Nanotechnologies in Modern Pulp Mill
Printing speeds continue to increase
Consumer demands more/sharper colors
• Silica nanoparticles for highperformance retention/drainage providing
better formation
-Silica sol 1st generation 1980s
-350 paper machines/25 countries
• Silica nanoparticles yielding a favorable
open sheet structure for select bag
applications
Current Generation of Nanotechnologies in Modern Pulp Mill
New nano-sizing technologies to
improve surface sizing
Nanoparticles
– Improved coating hold out
– Improved print quality
EKA Chemicals Inc.
Nano-Enhanced Paper
New Product Platform Applications
Nano-Enhanced Paper: Product Platform Studies
Fiber-Fiber Bonding Improvement
• Common method: Refining is one of the
common methods for improving fiber-fiber
bonding in papers
• Our approach: Bond nano/micro-fibrils onto
fiber surface to enhance the fiber-fiber
bonding.
Nano-Enhanced Paper: Product
Platform Studies
SEM of Unmodified Fiber
Surfaces are relatively smooth
Fibrils was generated by refining
Nano-Enhanced Paper
~70 nm
0.5 micrometer
5%
Precipitated
cellulose
~200 nm
SEM of Nano-fibril and Microfibril Fibers
Nano-Enhanced Paper:
Tensile Strength Improvement
45
Tensile Index (KN/m)
40
35
30
25
20
15
10
5
0
Control
Nano fibril
Nano-Enhanced Paper:
Folding Strength Improvement
2
Folding Index (times*cm /g)
4
3.5
3
2.5
2
1.5
1
0.5
0
Control
Nano fibril
3.5 time increases in the folding strength
Nano-Enhanced Paper:
ZDT Strength Improvement
100
90
80
ZDT (PSI)
70
60
50
40
30
20
10
0
Control
Nano fibril
33% increase in ZDT
Nano-Enhanced Paper: Coatings
Application of Polyelectrolyte
Coating Technologies
Layer-by-Layer Self-Assembly
General Considerations:
• Assembly via electrostatic and H-bond interactions
• Aqueous Processing
• Process Parameters:
• pH; salt concentration
• Polymer charge/DP
• Wide range of materials can be employed
Nano-Enhanced Paper: Coatings
Current Studies
PAH
n
n
NH3+ Cl-
++++++
N Cl+
_____
Montmorrilonite K10
Kaolin InFilm 9
PDDA
Nano-Enhanced Paper: Coatings
Current Studies
PAH
n
n
NH3+ Cl-
++++++
N Cl+
_____
Montmorrilonite
Kaolin
PDDA
Nano-Enhanced Paper: Coatings
n
n
NH3+ ClPAH
Montmorrilonite
Kaolin
+
PDDA
8 Bilayers of PDDA/
Kaolin
1.00
Number of bilayers
0.90
8
7
6
5
4
3
2
1
0.80
0.70
Absorbance
8 Bilayers PDDA/
Montmorrilonite
N Cl-
0.60
0.50
0.40
0.30
0.20
0.10
0.00
250
350
450
550
Wavelength (nm)
650
750
850
Nano-Enhanced Paper: Coatings
n
n
NH3+ ClPAH
N Cl+
PDDA
Kaolin
Nano-Enhanced Paper: Coatings
Current Studies
n
n
NH3+ Cl-
Initial Fibers
N Cl+
8 Bilayers of PAH
Kaolin
Nano-Enhanced Paper: Coatings
Current Studies
n
n
NH3+ Cl-
N Cl+
Nano-Enhanced Paper: Coatings
Current Studies
n
n
NH3+ Cl-
N Cl+
Bilayers of PAH/Kaolin
Ongoing Studies
• Enhance hydrophobic effect
• Utilize select nanoclays
• Examine optical properties
• Alternative barrier properties
Nano/Self Assembly Program
Clay
Charge
Charge
Charge
Polymer
Polymer
Polymer
Control
Coated clay
36
34
Tensile Index
32
30
28
26
5%
10%
15%
Percentage clay
20%
9 layer
Nano Clays for Barriers/Coatings
• Numerous patents/
differing materials
• Impact of differing
alkylammonium nanoclays as
fillers/coatings
• Barrier
• Printability
The thickness of nanoclay in the
composite is about 1nm.
Polymer-Nanoclay Composites
The thickness of
nanoclay in the
composite is about
1nm.
Barrier coating for
food containers and
paper packages
• Water and vapor
resistance
• Fatty and oil
resistance
• Paper-board
strength
3.0
0.4
2.0
0.3
1.5
0.2
1.0
0.1
0.5
0.0
0.0
0
1
2
3
4
5
2
2.5
COBB Test (g/100 in. 2 h per unit loading)
0.5
2
2
WVTR x 10 (g/100 in 24 h per unit loading)
Polymer-Nanoclay Composites
Paper Application
Nanoclay Content (wt %)
Relationship between barrier properties (WVTR and
COBB) of waxed liner paper and nanoclay content.
Wax used: Paraffin wax.
• 3% nanoclay in wax can increase water-barrier by 50%, and gas
barrier by 100%, target for wax-coated paper container
Nano-Enhanced Paper and Board
Composites
Nanocellulose Additives for Innovative Composites
1. Disperse Plastic Resin
2. Heat Press - Resin Coat Fiber
Resins: PLA, Starch, PMMA
Micron
Resin
Nano
Resin
Heat Press
Heat Press
Enhanced Fiber Coverage
Less Resin Needed
Nano-Enhanced Paper and Board
Composites
Nanocellulose Additives for Innovative Composites
1. Disperse Plastic Resin
Fiber
2. Heat Press – PMMA
Polymethyl methacrylate
Micro-sized PMMA
Nano-sized PMMA
Contact Angle (degrees)
70
65
60
60 nm PMMA
5-100 micron PMMA
55
50
45
40
35
30
0% PMMA
30%
PMMA
ECF SW Kraft
80
75
10%
PMMA
10% PMMA
30% PMMA
Contact Angle
80.0
70.0
Contact Angle (degree)
micro
60.0
nano
50.0
40.0
30.0
20.0
10.0
0.0
pure fiber
10% PMMA
30% PMMA
SEM
ECF Pulp Fines
SEM
Course PMMA, 10%
Nano PMMA, 10%
Polystyrene-ECF Kraft Composite
Nano-polystyrene sheets being characterized
Anticipate Benefits According to nano PMMA
NanoCellulosic Structures
m
mm
100 μm
1 μm
OH
OH
O
OH
HO
O
O
O
OH
OH
OH
OH
O
OH
O
O
O
O
O
HO
O-Cellulose
OH
OH
OH
HO
O
O
HO
O
OH
HO
O
HO
OH
HO
O-Cellulose
O
HO
OH
OH
O
OH
10 nm
10 μm
1 nm
Surface Area m2/g
140
Stiffness
Specific Stiffness
120
E-Glass Fibers
Paper Fibers
100
80
60
40
approx.1
4
Graphite
25 - 300
Fumed Silica
100 - 400
Si
sa
l
Ju
te
Fl
ax
H
em
p
EG
la
ss
0
N
C
an
oi
r
oc
el
lu Co
lo
se tton
W
hi
sk
er
D
s
ou
g
Po
la
s
nd
Fi
er
r
os
a
Pi
ne
20
Fully Exfoliated Clay
Nanocellulose Whiskers
Carbon Nanotubes
approx. 500
400 - 700
approx. 100
Nano-Enhanced Cellulosics
•
Acid Hydrolysis Technique
¾
¾
¾
¾
¾
¾
¾
Bleached softwood kraft pulp
Strong Acid
Stirred at 45 C, 45 min ~ 1 hour
Dilute with water
Centrifuged, wash and neutralize
Allowed to stand over a mixed bed resin for 48 h
The mixture was centrifuged and the supernatant was filter through
filter paper. The filtrate was colloidal nanowhisker suspension
Over +50% of yield could be achieved by this method.
Nano-Enhanced Cellulosics
¾ Nanocellulose Whisker:Polystyrene Composite Film
Physical Properties
¾
Polystyrene /whisker
film
TEA*,
J/m2
Elongation,
%
Modulus
(MPa)
Polystyrene
8.9
1.3
46.5
Polystyrene/
NC whisker
+70%
+ 11%
+ 23%
*: Tensile energy absorption.
¾
¾
Mechanical tests were carried out on an Instron 4400R
4.5 inch length * 15 mm width
Nano-Enhanced Composites:
¾ Nanocellulose Whisker
¾ Acrylic Acid Composite Film
Experimental Method
• Dow acrylic latex, solids 50%
• Add cellulose whiskers or hardwood bleached
kraft pulp
• Mixture cured at RT
• Initial film dried 50 ˚C for 2 days.
Nanocellulose Whisker:Acrylic Acid Composite Film
14
Tensile
strength, MPa
12
TEA, J/m2
4000
Whisker
10
Pulp Fiber
3000
Whisker
8
Pulp Fiber
2000
6
4
1000
2
0
0
5
10
Cellulose, %
15
20
0
5
10
Filler, %
350
300
250
Strain, %
0
200
Whisker
150
Pulp Fiber
100
50
0
0
5
10
Filler,%
15
20
15
20
Nanocellulose Whisker:Acrylic Acid Composite Film
Latex Film
20% Cellulose Whiskers:Latex Film
5% Cellulose Whiskers:Latex Film
40
Contact angle
35
30
25
20
0
5
10
15
Whisker content, %
20
25
Nanocellulose Balls
•
•
•
•
•
•
•
SW ECF bleached kraft pulp
Refined to 20-mesh
Swell fibers with 5M NaOH followed by DMSO
Sonicate cellulose with HCl – H2SO4 75 oC
Wash with water, purify by centrafugation
Sonicate cellulose with HCl – H2SO4 75 oC
Wash with water, purify by centrafugation
Nanocellulose Balls
Nanocellulose Balls
500
450
400
Size (nm)
350
300
250
200
150
100
50
0
2
4
6
Time (hour)
8
10
12
Size (nm)
0
180
160
140
120
100
80
60
40
20
0
0
1
2
3
4
Time (hour)
First nanocellulose procedure able to provide practical control of particle sphere dimensions!!
5
Nanocellulose Balls – 76 nm
AFM Images
Nanocellulose Balls
180 nm balls
76 nm balls
S-800 FE SEM
Nanocellulose Crystallinity Results
13C-CP/MAS NMR Analysis
C-2, 3, 5
C-1
C-4
C-6
Crystallinity index
Original pulp – Cellulose 1
0.61
300 – 500 nm Nanocellulose Balls
Cellulose II
0.65
50 – 100 nm Nanocellulose Balls
Cellulose II
0.70
NanoCellulosic Structures
Nanocellulose Whisker-Balls:Acrylic Acid Composite Film
5% Cellulose Whiskers:Latex Film
Latex Film
TEA
5% Cellulose Balls:Latex Film
1400
1200
1000
800
600
400
200
0
Latex
nanoball whisker
acacia
Pathforward
• Nanocellulose balls
–
–
–
–
Derivatives to be used for superabsorbers – viscosity modifiers
Artificial blood/drug delivery
Cosmetics
Template for Nanospheres
• Nanocellulose whiskers
– Composites with plastics
– Composites with natural polymers
– In-situ polymerization
Cellulose Superabsorbents
Tying Cellulose Together
+
PEG
PMA
135 °C
+
H OH
H
H
H O
H
H
H O
H
H O
OH
H
H
H
n
Cellulose
US Patent 5049235
H O
OH
H
OH
OH
O
HO
H
H
HO
O
OH
H
H
OH
HO
O
HO
H OH
H
OH
SW Kraft Pulp
Water Absorbed
Water Retained
200
140
g water/ g dry material
175
g water/ g dry material
Milled Pine Water Retained
Milled Pine Thermal
Pine Pulp Thermal
150
125
100
75
50
120
Pine Water Retained
100
80
60
40
20
25
0
0
0
10
20
30
40
50
60
70
0
% PMVEMA
Tea bag method, 0.1 g in water for 8 h
ECF Pine Kraft Fibers
• 2.499 mm
• 0.455 mm
10
20
30
40
50
60
% PMVEMA
Centrifuge for 10 min at 770 rpm
70
Crosslinked Pulps – ECF Pine Kraft
Water absorption and retention value (g/g)
240
210
Water absorption and retention value (WAARV) of SW
Uncrosslinked
189.2
Crosslinked
190
137.9
150
120
WAARV (g/g)
WAARV (g/g)
180
86.5
90
60
30
4.97
4.72
3.82
160
130
100
0
2.406
0.974
Fiber length (m m )
0.499
70
0
0.5
1
1.5
2
Fiber length (mm, LW)
2.5
3
Crosslinked Whisker Sample
Preparation
• Whiskers + PMVEMA + PEG Æ film
– Vary percentage (weight) of whiskers
• 0, 25%, 50%, 75% 100% whisker films
– Air dry in oven
• Cure at 135°C for 6.5 min
• Stored in humidity controlled desiccators for
further testing
– 2%, 54%, 92% relative humidity
Crosslinked CelluloseWhisker Films
0CNW
25CNW 50CNW
75CNW
Behavior of Crosslinked
Materials in Water
• Crosslinked pulp fibers Æ dry, then wetted…
0.5 g SA Pulp +
8.5 ml
21.5 ml
136.5 ml
• Crosslinked whisker films Æ dry, then wetted…
Mechanical Properties
of Crosslinked Whiskers
Tensile (Stress-Strain)
– Measured with 500 N
Load Cell, on Instron 4411
– A rectangular shaped strip
(60 mm long x 8 mm
wide) with a 25 mm
distance between the two
heads, with a 5 mm/min
load rate
2% RH
9
50%
CNW
Film
54% RH
8
92% RH
Stress, MPa
7
6
5
4
3
2
54% Relative Humidity
1
0
PMA-PEG/CNW100
5
0
PMA-PEG/CNW75
3
2
1
0
0
50
100
150
Strain, %
200
250
50
100
150
Strain, %
PMA-PEG/CNW50
PMA-PEG/CNW25
4
Stress, MPa
•
10
300
200
250
300
Water Sorption of Crosslinked
Whiskers
• Timed absorption
Water uptake (g/g,%)
1000
800
PMA-PEG/CNW25
PMA-PEG/CNW50
PMA-PEG/CNW75
600
400
200
0
0
2000
4000
Time(min)
6000
Surface Morphology
25% CNW Film – Cut
25% CNW Film – Tensile Test Fractured
25CNW
Surface Morphology
After Water Absorption
50CNW
75CNW
Conclusions
• First example of crosslinked cellulose
whisker films that exhibit unique hydrogel
properties
– Tailorable physical properties
• Future applications for managing
water/humidity in packaging and for
medical devices
Nanotechnology at IPST@GT
• Georgia Tech to be Part of 13-University National
Nanotechnology Infrastructure Network Funded by National
Science Foundation
• National and International Investigators
• Current Nano forest product studies include:
–
–
–
–
–
–
Nanoclay coatings/barriers
Nanoclays for UF composite wood products
Nanocellulose super absorbers
Nanocellulose self-assembly
Nanolignocellulosic composites
Cationic Polymeric Nanoparticle Retention Systems
Fiber - Challenge
Innovative Products
Billion Packages
120
1990
2000
2005
100
80
60
40
20
2005
2000
0
Metal
Petroleum Costs
Plastic
1990
Glass
Paper
Sustainability
Acknowledgements
L. Allison, R. Chandra, T. Dyer, Y. Feng, D.H. Kim,
K. Knutson, Y. Pu, L. A. Retzlaff, L. Vander Wielen
Drs. Y. Deng and Z.L. Wang/GA Tech
IPST Member Companies
DOE, NSF, USDA, GA TIP3
arthur.ragauskas@ipst.gatech.edu