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Nanocellulose materials- Preparation, properties, uses

The Finnish Centre of Nanocellulosic Technologies

Timo M. Koskinen, UPM-Kymmene Ltd, Pia Qvintus, Anne-Christine Ritschkoff, Tekla Tammelin & Jaakko Pere, VTT Technical Research Centre of Finland

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Pulp & paper industry after year 2000

Paper productionEnergy costs increaseShortage of wood and all fibreEconomy of scale in paper products does not work any more, especially in EuropeCapital intensive industry – difficult to be flexibleSensitive to economical fluctuation

Business environmentShift to more added value paper products is no more competitive approach in Europe and in North AmericaOvercapacity and low prices in EuropeIncrease in demand and increase in production outside Central Europe: low prices and less export from Europe

ConclusionCompletely new initiatives are needed

Present

Research on micro / nano fibrillated cellulose (MFC / NFC) and cellulose nano crystals (CNC) has gradually increased since year 2000.

Today there is on-going all over the world a substantial amount of research on nano cellulose.

Nanocellulose research groups

SunPap – EU-project, 2009-2012 (nanocellulose as a driver)

SustainComp – EU-project (nanocellulose included)

KTH, L Berglund, T Lindström, Sweden

Univ. of Kyoto, Yano & al, Japan

Univ. of Tokyo, Isogai & al, Japan

Univ. of North Carolina & PennState University, U.S.A.

EMPA, Switzerland

ArboraNano, Paprican, Canada

Agenda 2020 (2 parts: biorefinery & nanocellose), U.S.A.

Other groups in Sweden, Germany, Norway, etc.

European vs. North American approach

Europe: Focus on NFC/MFC

Long fibrils

Amorphous and crystallineparts both in fibrils

Mechanical process, or chemi-

mechanical

No self assembly

Strongly shear thinning -rheology depends on the manufacturing process

N.A. - Focus on CNC

Whiskers – short

Crystalline

Chemical process

Acid hydrolysis

Self assembly possible

Defined rheology

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Combines the competencies of Aalto University School of Science and Technology, VTT and UPM:

Profound and cross-disciplinary basic research Multi-technological applied research and high level project administration Product development and techno-economical expertise

Sets up a project portfolio which addresses production technology, physical and chemical modification, characterization and novel applications.

Combines capabilities and resources to create and govern of needed versatile IPR.

Annual volume ca. 40 person years – 5 M€.

The Finnish Centre for Nanocellulosic technologies – Est. March 2008

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Nanocellulose – New innovations for the forest sector

Overall objectivesTo develop technoeconomicallyfeasible, industrial scale manu-facturing techniques for mass production of cellulose nano-materialsTo generate new markets for (ligno)cellulosic raw material and renew the potential of existing products

Added value from nanocelluloseIncreased functionality, improved mechanical properties, novel optical and conductivity properties, light weight high performance structuresNovel forest based products

Breakthroughs

Vision: Nanocellulose as part of biorefinery

ProcessingRefiningTailoring

Industrial pulps

Novel products

Step change/breakthrough product properties

Non-wood crop residues

Cellulose nanomaterials

Industrial pulps

Biorefining by-products

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From the cellulose molecule to a three – a perfect example of self-assembly

Fibres• Width 30-40 µm• Length 1-3 mm

Fibrils• Width 5-30 nm• Length over 1 µm

Esau, Anatomy of seed plants, 1977, Wiley, NY

Aalto University School of

Science and Technology,

Myllytie

Pääkkö et al, Biomacromolecules, 8(2007)1934

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What is nanocellulose?

Preparation of nanofibrills Products

It is a natural nanomaterial that seems to give a range of opportunities to obtain superior material properties for different end-products

Esau, Anatomy of seed plants, 1977, Wiley, NY

Pääkkö et al, Biomacromolecules, 8(2007)1934

1,7% solid content

WHY?

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What is the basis?

How large a fraction of atoms are on the surface of a fiber?

40 m wood fiber, 0.002%4 nm elementary fibril, 19%

The surface atoms specify the properties

Cellulose pulp vs. NFC gel, Pääkkö 2008

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Pääkkö et al, Biomacromolecules, 8(2007)1934

Semi-crystalline extended chains

Young´s modulus 140 GPa(T. Nishino et al. J.Polym.Sci.,Part B,1995)Tensile strength 3 GPa(D.Page, F. El-Hosseiny, J.Pulp Paper Sci. 1983)Coefficient of thermal expansion 0,1 ppm/ºK(H.Yano, Seminar lecture, Otaniemi 2009)

close toaramid fibers

similar toquartz glass

Cellulose Icrystal form

Special properties

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Manufacturing of NFC:Operation principle of Masuko grinder

Masuko grinderGrindstone

Operation principle

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Manufacturing of NFC:Operation principle of fluidizer

Microfluidics fluidizer

Cut-away view of an interaction chamber

Operationprinciple

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Rheological characterization of NFC suspensions/gels => processability

1 pass

4 passes

6 passes

0

1000

2000

3000

4000

5000

6000

7000

1 4 6

Number of fluidizer passes

G' m

ax fr

om s

tress

sw

eep

[Pa]

0

50

100

150

200

250

300

350

G' m

ax fr

om s

tress

sw

eep

[Pa]

plate-platevane

1 pass 4 passes 6 passes

plate-plate:20 mm,

gap 1 mm

vane in cup:

vane 28 mm, cup 30 mm

Result is geometry dependent!

Combination of analytical tools !

Small deformation oscillatory testing – stress sweep

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Characterization – a challenge

Particle size analysis

SEM, AFM, (Cryo-) TEM

Rheology of suspension

On line –measurements

Combination of analytical tools!

SEM imaged NFC (Pere, Tammelin, Tapper/VTT)

AFM imaged fractionated NFC (Ahola, Eronen, Österberg/Aalto University School of Science and

Technology)

Transparent gels by homogenization

Before fibrillation After fibrillation Concentration 0.8%

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Effect of refining and fluidizing on fiber dimensions

NFC after fluidizing: light microscope image (above) and cryo-TEM image (left)

P. Hiekkataipale, Aalto University School of Science and Technology

Effect of drying method

Freeze drying Critical point drying

20 m

20 m19

Methods offunctionalization

Chemical modification of NFC surface

Functionalzation using nanoparticles

Nanocellulose modified with inorganics and

surfactants

Biochemical modification

Enabling drying & redispersing

Nanocellulose

Functionalization of NFC using polymers

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Changing the properties of nanocellulose materials by modification

FunctionalizationHydrophobicityCharge (+/-)

Specific interactions

Cellulose nanofibres and whiskers

CharacterizationRheology

Charge densityInteractionsMicroscopyChemical

composition

Small scale testing

CompatibilityStrength

Testing of functionalized material in different applications:

Application oriented

processability of NFC material

Ideas for enhanced properties of end

products

Ideas for novel cellulose based

materials

1. Composites 2. Nanomaterial Additives

3. Porous cellulose materials

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Surface modification of NFC by silylation

XPS analysis indicateincrease in silica contentIncrease in the relative abundance of C-C and C-Si bonds

AFM analysis confirmthe successful surface modificationMaintain the nano-fibrillar structure

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Sample O 1s (%)

C 1s (%)

Si 2p (%)

C-C, C-Si (%)

DSs

NFC ref 43.8 55.5 0 2.1 NFC I 35.3 60.5 4.3 27.0 ~0.6 NFC II 31.9 62.1 5.9 35.8 ~1.0

Tammelin/VTT, Johansson and Österberg/Aalto University School of Science and Technology

NFC, ref NFC DSs ~0.6 NFC DSs ~1.0

5×5 m height images22

Water contact angle of the silylated NFC films

Silylated NFC films are hydrophobic

Nanoscale surface roughness may have effect on the contact angle values

Higher value for lower DS

Contact angle of pure NFC is <40° and the age of the water droplet is much lower

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020406080

100120140160180

0 50 100 150 200

Time (s)

Con

tact

ang

le o

f wat

er

DS=0.6DS=1

Tammelin/VTT, Johansson and Österberg/Aalto University School of Science and Technology

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Filed patent applications for nanocellulose in different end uses

Composite materials (46, 38%)Nonwovens, adsorbent webs (22, 18%)Paper and board (20, 16%)Food products (15, 13%)Paper and board coatings (10, 8%)Cosmetics and toiletry (4, 3%)Filter materials (5, 4%)Many of the granted patents have expired and many of the applications were not granted

13 %3%

18 %

4 %16 %

8 %

38 %

NFC applications

Recent (2009) applicationsComposite materials (10), Food products (2), Nonwovens (2),Filter materials (2), Paper and board (2), Paper and board coatings (2)

Applications for microfibrilled cellulose

Data collected by Dr. Juha Merta, Aalto University School of Science and Technology24

Proposed application areas

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Potential applications of NFC/MFC/CNC*

NFC/CNC/MFC can be used for:

Advanced building productsRecyclable structural and interior components for transport industryNovel bioplasticsFibre-reinforced compositesSwitchable optical filmsBiocomposites for bone-repairAdditives for paints, pigments and inksCosmetic productsIridecent or magnetic filmsEnhancement of performance of forest products such as building materials, paper, board and packaging….… and more.

=> various functionalization methods and processes are needed

*ArboraNano/FPInnovations

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Safety of nanomaterials

Occupational safety issuesAre there nanomaterials in the work space air?How to protect oneself?The Finnish Institute of Occupational Health has made some initial evaluations

Product safety – EU comissionOfficial demands are application specificCellulose nanomaterials are not in REACH, yetRegulations for nanotechnology products in general will be tighter in a near futureBest to be proactive and collaborative while the new regulations are being developed

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Acknowledgements

Following persons are gratefully acknowledged for their contribution to this presentation

VTT: Unto Tapper, Martina Lille & Sauli Vuoti

Aalto University School of Science and Technology, Department of Forest Products Technology: Tuomas Hänninen, Eero Kontturi, Monika Österberg & Janne Laine

Aalto University School of Science and Technology, Molecular Materials: Panu Hiekkataipale & Olli Ikkala

The Finnish Centre for Nanocellulosic Technologies and UPM-Kymmene Ltd is gratefully acknowledged for the financial support.

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Thank you for your attention!