By Lea Falcoz Vigne, Centre Technique du Papier (CTP). This was presented during the New Ideas for the Paper Industry: Young Researchers' Presentations session, organised as part of European Paper Week 2015. More at http://www.cepi.org/epw

1. Interaction of hemicelluloses and cellulose and
their influence on the cellulose microfibrillation
process
EUROPEAN FIBRE AND PAPER RESEARCH ORGANISATIONS
17th - 19th November 2015 in Brussels
L. Falcoz-Vigne
L. Heux, K. Mazeau, Y. Nishiyama
V. Meyer, M. Petit-Conil

2. Outline
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Context and objective
1- Xylan extraction
1.1 Protocol of xylan extraction from MFC
1.2 Characterization of extracted xylan
1.3 Characterization of MFC after xylan extraction
2- Xylan re-adsorption experiment
3- Cellulose-xylan interaction
Conclusion

3. CONTEXT: MFC production
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 MFC production: process in 2 steps
1- Pre-treatment
Enzyme + Refining
2- Homogenisation at high pressure
1 pass at 1000 bar + 4 passes at 1500 bar
MFCPre-treated fibresKraft/sulfite pulps
200µm
 Homogenizer
Pre-treated
fibers
MFC
Microfibrillation
Valve
Impact ring
 High energy consumption (10 MWh/t)
 Enzymatic treatments are effective but quite
empirical

4. CONTEXT: Objective and programm
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Objective: to acquire a fundamental knowledge of the interactions between
the polysaccharides of the fibre wall
 To optimise the fibres pre-treatment
 To decrease the energy consumption of the MFC production by at
least 20% (1 pass into the homogenizer)

5. Solid state NMR (400 MHz) presentation
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 NMR spectra are sensitive to local environment and conformation
(conformation around glycosidic linkage, hydroxymethyl conformation)
1
23
4 5
6
cellulose
 The spectra are dependent on hemicelluloses concentration in MFC
 The hemicelluloses contribution to MFC signal will be validated after xylan
extraction from MFC from birch Kraft and NMR analysis
A.Teleman, P.T.Larsson and T.Iversen, Cellulose, 2001, 8, 209-215
Wet MFC from birch Kraft:
rich in hemicelluloses (23.5%)
Wet MFC from M. pine sulfite:
poor in hemicelluloses (2.5%)
5060708090100110120
Chemical shift (ppm)
C6C4 crystalline
C1
C2, C3 and C5
C4 disordered
Crystalline
core
Disordered
surface

6. 1- Xylan extraction
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1- Exchange of solvent water/tert-buthyl alcohol (TBA) and MFC freeze-drying in TBA
Fumagalli,M., Ouhab, D., Boisseau M., S., Heux, L., Biomacromolecules, 2013, 14, 3246-3255
Increase the
MFC
accessible
surfaces
MFC freeze-dried in water (Sspe = 13 m²/g) MFC freeze-dried in TBA (Sspe = 158 m²/g)
3- Separation and purification: Centrifugation, dialysis, freeze drying
2- Xylan extraction: MFC is redispersed in DMSO - 5% LiCl (24 h, 25°C)
Hägglund E., Lindberg B., McPherson J., Acta chemica Scandinavica, 1956, 10, 1160-1164
Yield of xylan extraction: 65% +/- 4.5%

7. 1- Xylan characterisation
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 Xy – wood: is branched with glucuronic acid
 Xy – MFC: homopolymer of xylose
Habibi Y. and Vignon M.R., Carbohydrate Polymers, 2005, 340, 1431-1436
The extracted xylan Xy – MFC is compared with a xylan extracted from wood chips
with 10% NaOH Xy – wood:

8. 1- Comparison of NMR spectrum before and after
xylan extraction
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 The solid state NMR MFC signal is
influenced by xylan extraction (especially
on C4 and C6 area)
 A ≠ B + C
 The xylan conformation is modified
when it is adsorbed onto the cellulose
surface
A = MFC before extraction
B = MFC after extraction
C = Xylan at 97% of relative humidity
B + C
A = MFC before extraction
B = MFC after extraction
C4
C6

9. 2- Xylan conformation change by re-adsorption
experiment
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 Two model were reconstructed with:
 Xylan conformation change when it is adsorbed onto the cellulose
surface is validated in re-constructed model.
 Adsorbed xylan: 13.5% on MFC from birch Kraft, 9% on MFC from pine sulfite
“MFC after extraction” + extracted xylan
in DMSO then dialysis
20%
13.5%
Residual non
adsorbed
xylan
MFC after extraction
MFC before extraction
MFC + 13.5% of xylan
MFC + 20% of xylan
Wet samples

10. 2- Theoretical estimation of the xylan surface
covering area
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 Specific surface of MFC measured with BET (Sspe):
• 158.0 m²/g for MFC from birch Kraft
• 119.4 m²/g for MFC from pine sulfite
 Molecular modelling predicts a monolayer
adsorption with: 1 xylose per 0.25 nm²
Mazeau K. and Charlier L., Cellulose, 2012, 19, 337-349
 A monolayer of xylan is adsorbed onto the MFC surface
 Re-adsorbed xylan content is controlled by the MFC accessible surface
MFC from birch Kraft
0.14 g of xylan /
g of cellulose
Sspe x 0.25 10-18
x (Na / Mxylose)
0.10 g of xylan /
g of cellulose
MFC from pine sulfite
NMR results 0.135 g of adsorbed xylan/
g of cellulose
0.09 g of adsorbed xylan/
g of cellulose
Covering surface
area
115% 95%

11. 3- Interaction cellulose/xylan
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 The sandwiches formation protocol was established
Xylan
Cellulose
Cellulose
 First traction tests were performed
with dried sandwiches: the cellulose
films broke before peeling
Peeling tests will be performed at different conditions of humidity to soften
the structure and be closer to the condition onto the homogenizer
 Sandwiches were made with extracted xylan or labelled
with fluorescein isothiocyante FITC (DS = 0,04%)
 Cross sections were observed in microscopy
Films of MFC
Film of xylan
20 µm

12. Conclusion
« InTechFibres’ property – do not divulgate » - EFPRO 2015 - LFV 12
 65% of xylan could be extracted from MFC birch Kraft
 The extracted xylan is a homopolymer of xylose
XylanCellulose
Xylan extraction
 The adsorbed xylan content observed in NMR is
correlated to the specific surface of cellulose
measured in BET.
 NMR analysis on re-adsorption confirmed xylan
conformation change when it is adsorbed onto
cellulose
Xylan conformation
 The xylan is adsorbed at the cellulose surface on
a mono-layer
 On dried sandwiches the interaction cellulose /xylan
are stronger than MFC cohesion
Interaction cellulose/xylan

13. Acknowledgements
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Laurent Heux
Karim Mazeau
Yoshiharu Nishiyama
Sonia Molina Boisseau
Marie-France Métral
Valérie Meyer
Michel Petit-Conil
Matthieu Schelcher
François Cottin
Arthur Janodet
The Ph.D program is supported by:
the Agence Nationale pour la
recherche et la Technologie.
the Institut Carnot
PolyNat
the Centre Technique
du Papier.
www.webCTP.com www.polynat.eu www.anrt.asso.fr