High tenacity cellulosic fibers can be produced via ionic liquid processing. Researchers at Aalto University have been exploring this technique as an alternative to the conventional Lyocell (NMMO) process which has some limitations. In their work, they have: 1) Successfully dissolved and spun cellulosic fibers from various ionic liquids such as ILHU, showing superior spinning properties compared to NMMO and other ionic liquids tested. 2) Produced fibers from ILHU with tensile strengths up to 50 cN/tex, outperforming commercial viscose and modal fibers. 3) Continued research aims to further optimize the ionic liquids used and fiber properties through modification techniques, with

1. High tenacity cellulosic fibres
via ionic liquid processing
Michael Hummel, Anne Michud, Shirin Asaadi,
Marjaana Tanttu, and Herbert Sixta
FUBIO seminar
Paasitorni
27.8.2013

2. Outline
• Background
• Spinning at Aalto
• Results
2

3. 3
2012
0
2
4
26
28
30
32
Paper
MCC
Nitrocellulose
Film, casings
Ether
Viscose
Amount,t/a
Cotton
Lyocell
Acetate
Global textile market
- Cotton stagnant at 26-28 Mio t/a
- High cotton prices
- 33-37% minimum share of
cellulosics in textiles
- GAP of 15 Mio t/a of cellulosic
fibers in 2030
Growth rates
- Viscose, Lyocell > 9%/a
- Acetate 1.5%/a
- Ethers 3.5%/a
- Others 0-5%/a
Brice, R., High purity cellulose through 2020, in The Cellulose
Gap 2012: Monte Carlo
Haemmerle, F.M., The cellulose gap. Lenzinger Berichte, 2011.
89: p. 12-21
Background

4. Textile chain
4
http://www.lenzing.com/en/fibers/tencel/botanic-
fiber.html

5. Viscose
CS2/NaOH
Carbamate
NaOH/urea in o-
xylene *
BioCelsol
Enzyme/NaOH/ZnO
(urea/thiourea)
BoCell
Superphosphoric acid
Air gap / acetone regen
Michelin
Formate/air
gap/saponified
DuPont
Acetate in
TFA/HCOOH/steamdr
awn/saponified
Fortisan
Acetate/acetone
spun, saponified
Cupro
[Cu(NH3)4](OH)2
LYOCELL
(a) NMMO.MH
(b) Ionic liquids
*CarbaCell®
WATER
Supercritical
conditions
Commercial, now or in former times
Non-commercial

6. Viscose
CS2/NaOH
LYOCELL
(a) NMMO.MH
(b) Ionic liquids
Commercial, now or in former times
Non-commercial
Global production 2012
0.15 Mio t (3 sites)
(2014: 0.22 Mio t, 4 sites)
3.7 Mio t
(Global capacity: 5.0 Mio t)

7. Viscose vs. Lyocell
7
Andrzej Ziabicki, Fundamentals of fiber spinning,
John Wiley & Sons Ltd, (ISBN: 0-471-98220-2).
Viscose Lyocell
NaOH / CS2
wet spinning dry-jet wet spinning
derivatization direct dissolution
wood pulp or IL

8. Viscose process
8
PULP
Caustic Soda Dissolving Lye
Solving Water
Carbon Disulfide
Steeping
Lye
Removal Ageing
Cooling
Xanthogenation
Dissolving
Filtration
Ripening
Baling Press
Cutting
Drying
and
Opening
Aftertreatment
Spinning
Stretching
Deaeration
Shredding
VISCOSE
FIBRES

9. Dissolution Filtration
Water
Pulp
(Cellulose)
Spinning
Regeneration
Washing
NMMO recycling
NMMO,
Stabilizer
Waste
Water
Bleaching
Finishing
Drying
Lyocell-
Fiber
Lyocell Process

10. Lyocell process
10
Extrusion
velocity Take-up velocity
Air gap
Filtering and spinning
Liquid filaments enter
coagulation bath via air gap

11. Structure formation
Crystallites
Laminas
Irregular molecules
arrangement
Draw
11
Fourné, Synthetic Fibers; Carl Hanser Verlag, Munich 1999.
Extrusion
Shear stress
Extensional stress
Diffusion controlled
regeneration of
cellulose

12. Fiber properties
12
Viscose Lyocell [bmim] Cl [emim] OAc
Titre
[dtex]
1.4 1.3 1.7 1.8
Tenacity cond.
[cN/dtex]
23.9 40.2 43.0 44.7
Elongation cond.
[%]
20.1 13.0 9.6 10.4
Tenacity wet
[cN/dtex]
12.5 37.5 35.9 38.1
Elongation wet
[%]
22.0 18.4 11.6 11.9
Hermans’
orientation factor
ca.0.40 ca.0.70 n/a n/a
Röder et al. Lenzinger Berichte, 2009, 87, 98-105;
Gindl et al. Polymer, 2008, 49, 792-799.

13. Problems with NMMO
13
redox-active moiety
(instable) cyclic ether
• Limited compatibility with
redox-active substances (for
in-situ modification)
• Stabilizers required to avoid
cellulose degradation and
thermal run away reactions
• High energy demand for
solvent recycling.

14. Ionic liquid (IL)
• …is a salt in its liquid state
• …liquid that consists
exclusively of ions
25 °C
100 °C
conventional salt melt
(> 100 °C)
Ionic Liquid (IL)
(< 100 °C)
Subclass: Room Temperature
Ionic Liquid (RTIL)
(< 25 °C)

15. Fiber spinning with ILs
15
YEAR IL Dope conc Temp h0
* Titer DR
Fiber-
Tenacity
Author REF
wt% °C Pas dtex [-]
cN/tex
(cond)
2002 [C4mim]Cl 10 100 R.D.Rogers JACS, 124, 4974
2005 [AMIM]Cl 10 80 1.3 10.5 36.8 G.Laus Lenz Ber, 84, 71
2005 [BMIM]Cl 10 105 1.0 13.7 37.9 G.Laus Lenz Ber, 84, 71
2006 [BMIM]Cl 10.4 1.6 10.9 44.7 C. Michels Lenz. Ber., 86, 144
2008 [C2mim]Cl 3.8 70 25.0 R.D.Rogers J.Mater.Chem,18,283
2008 [C4mim][OAc] 13.2 90 9690 1.7 7.3 44.1 B.Kosan Cellulose,15,59
2010 [C4mim]Cl 8 85 1350 12.1 2.4 26.4 T.Cai Appl.Polym.Sci, 115, 1047
2012 [C4mim]Cl 5 90 50? 2.2 5.0 38.8 G. Jiang Cellulose,19,1075
2012 [C2mim][OAc] 10 20 18000 4.1 2.3 24.6 D.Ingildeev Appl. Polym.Sci,
2012 [[C2mim][DEP] 10 60 18000 4.9 2.3 26.4 D.Ingildeev Appl. Polym.Sci,

16. Spinning at Aalto

17. Pulp
dissolution
Dope
characterization
Fiber
spinning
Fiber analysis
Pulp
dissolution
Dope
characterization
Fiber
spinning
Fiber analysis
17
pre-mixing kneading/dissolution filtration

18. 18
Pulp
dissolution
Dope
characterization
Fiber
spinning
Fiber analysis
shear-rheological characterization
(to determine spinnability)
0.01 0.1 1 10 100
10
100
25 °C
50 °C
70 °C
80 °C
100 °C
complexviscosity/Pa•s
 / s
-1
extensional-rheological characterization
(to determine filament stability in air gap)
0 400 800 1200 1600 2000
0.01
0.1
1
Dmid
/mm
Time /s

19. 19
Pulp
dissolution
Dope
characterization
Fiber
spinning
Fiber analysis

20. Pulp
dissolution
Dope
characterization
Fiber
spinning
Fiber analysis
20
Standard fiber
analysis
• Titer (linear density)
• Tenacity
• Elongation at break
• Modulus
Polarized light
microscope
• Birefringence
• orientation
SEM
• Morphology
• Structure-
property relations
Mechanical stress
• Fibrillation
tendency

21. • Pre-hydrolysis eucalyptus kraft pulp (PHK-Euca)
• Intrinsic viscosity 424 g/ml (DP 1009)
• Mw 196.4 kDa
• PDI 3.1
Dope preparation
21
N-methylmorpholine N-oxide (NMMO) / water mixture (1:1, mol:mol)
1-ethyl-3-methylimidazolium acetate ([emim]OAc)
NMMO
ILHU
[emim]OAc
PHK-Euca
NMMO/H2O/PHK-Euca
ILHU/PHK-Euca
[emim]OAc/PHK-Euca

22. Rheological characterization
22
• Spinning temperature
chosen according to the
visco-elastic properties of
NMMO solution at 100ºC
• ILHU and NMMO solutions
both solid at room
temperature
• Due to the cold coagulation
bath, the filament structure
is fixed instantaneously
T
[°C]
η0*
[Pa.s]
ω
[s-1]
G
[Pa]
ILHU13 wt-% 80 21 306 1.5 4 100
NMMO 13 wt-% 100 20 000 3.0 4 955
[EMIM]OAc 20 wt-% 95 20 262 1.9 5 000
0.01 0.1 1 10 100
10
100
1000
10000
ILHU
/Bahia 13 wt-%, 80o
C
[EMIM]OAc 20 wt-%, 95o
C
NMMO/Bahia 13 wt-%, 100o
CDynamicmoduli[Pa]
Angular Frequency [1/s]
0.01 0.1 1 10 100
10
100
1000
10000
ILHU
/Bahia 13 wt-%, 80o
C
[EMIM]OAc 20 wt-%, 95o
C
NMMO/Bahia 13 wt-%, 100o
CDynamicmoduli[Pa]
Angular Frequency [1/s]
0.01 0.1 1 10 100
10
100
1000
10000
ILHU
/Bahia 13 wt-%, 80o
C
[EMIM]OAc 20 wt-%, 95o
C
NMMO/Bahia 13 wt-%, 100o
CDynamicmoduli[Pa]
Angular Frequency [1/s]

23. [EMIM]OAc/PHK-Euca 20 wt-%
• Textr. = 95ºC
• Vextr. = 0.8 cm3/min
ILHU/PHK-Euca 13 wt-%
• Textr. = 80ºC
• Vextr. = 0.8 cm3/min
NMMO/H2O/PHK-Euca 13 wt-%
• Textr. = 100ºC
• Vextr. = 0.8 cm3/min
BREAK-UP in
the spinning
bath when
stretched
UNSTRETCHED STRETCHED
Fiber spinning
23

24. Video
24
Video

25. 25
Results

26. • Unstable spinning
• Draw ratio > 2 impossible  Breaks
• Titer > 8 dtex
• Tenacity < 17 cN/tex and no clear
trend noticeable
Spinning of NMMO and [emim]OAc
26

27. Spinning of ILHU
27
0 2 4 6 8 10 12 14 16 18 20
0
2
4
6
8
10
12
14
16
Draw ratio
Titer[dtex]
15
20
25
30
35
40
45
50
55
Tenacitycond
[cN/tex]

28. Comparison of Fibers
28
Viscose Modal
NMMO
(Tencel®)
ILHU
Titre [dtex] 1.4 1.3 1.3 1.2
Tenacity cond. [cN/dtex] 23.9 33.1 40.2 50.5
Elongation cond. [%] 20.1 13.5 13.0 8.5
Tenacity wet [cN/dtex] 12.5 18.4 37.5 46.4
Elongation wet [%] 22.0 14.1 18.4 9.6
TencelPolynosic Cupro CV CMD[DBNH]OAcNMMO
0
10
20
30
40
50
Tenacity[cN/tex]
Cond. wet
ILHU
NMMO
Commercial fibers Aalto
0
2
4
6
8
10
Titer[dtex]
0 5 10 15 20 25
0
5
10
15
20
25
30
35
40
45
Tenacitycond
[cN/tex]
Elongationcond
[%]
CMD ILHU
CV NMMO
Cupro

29. Current research activities
• Screening of different ionic liquids
• Implementation of different pulps of various
grade
• Fiber modification
– Cross-linking
– Additives
– Polymer blends
• Study of structure formation
29

30. Summary
30
? !
Lyocell process for high
performance textile fibers
Projected increased
demand in cellulosic
fibers
Ionic liquid as powerful solvents for
cellulosic material
Intrinsic problems with
NMMO MH as solvent
system
Production of high tenacity fibers
New ILHU shows superior
spinning properties
0 2 4 6 8 10 12 14 16 18 20
0
2
4
6
8
10
12
14
16
Draw ratio
Titer[dtex]
15
20
25
30
35
40
45
50
55
Tenacitycond
[cN/tex]
Determine full potential of ILs for
cellulose processing
Further testing of new ILs

31. 31
Acknowledgments

32. Acknowledgments
PhD candidates
• Anne Michud
• Lauri K.J. Hauru
Master students
• Mikko Heinämäki
• Joni Saastamoinen
• Benoît Arnoul-Jarriault
• Eeva Hartikainen
• Prof. Ilkka Kilpeläinen
• Dr. Alistair King
• Arno Parviainen
• Prof. Jukka Seppälä
• Dr. Sami Lipponen
• Tapio Saarinen
• Dr. Frank Hermanutz
• Dr. Denis Ingildeev
• Dr. Frank Meister
• Dr. Birgit Kosan
• Dipl.-Ing. Philipp Schuster
32