Nanocellulose materials - Preparation, properties, uses

Transcription

1 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 1

2 Pulp & paper industry after year 2000 Paper production Energy costs increase Shortage of wood and all fibre Economy of scale in paper products does not work any more, especially in Europe Capital intensive industry difficult to be flexible Sensitive to economical fluctuation Business environment Shift to more added value paper products is no more competitive approach in Europe and in North America Overcapacity and low prices in Europe Increase in demand and increase in production outside Central Europe: low prices and less export from Europe Conclusion Completely new initiatives are needed 2

3 Present Research on micro / nano fibrillated cellulose (MFC / NFC) and cellulose nano crystals (CNC) has gradually increased since year Today there is on-going all over the world a substantial amount of research on nano cellulose.

4 Nanocellulose research groups SunPap EU-project, (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.

5 European vs. North American approach Europe: Focus on NFC/MFC Long fibrils Amorphous and crystalline parts both in fibrils Mechanical process, or chemimechanical 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

6 The Finnish Centre for Nanocellulosic technologies Est. March 2008 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. 6

7 Nanocellulose New innovations for the forest sector Overall objectives To develop technoeconomically feasible, industrial scale manufacturing techniques for mass production of cellulose nanomaterials To generate new markets for (ligno)cellulosic raw material and renew the potential of existing products Added value from nanocellulose Increased functionality, improved mechanical properties, novel optical and conductivity properties, light weight high performance structures Novel forest based products Breakthroughs 7

8 Vision: Nanocellulose as part of biorefinery Novel products Step change/breakthrough product properties Cellulose nanomaterials Processing Refining Tailoring Biorefining by-products Non-wood crop residues Industrial pulps 8 Industrial pulps

9 From the cellulose molecule to a three a perfect example of selfassembly Fibres Width µm Length 1-3 mm Aalto University School of Science and Technology, Myllytie Pääkkö et al, Biomacromole cules, 8(2007)1934 Fibrils Width 5-30 nm Length over 1 µm Esau, Anatomy of seed plants, 1977, Wiley, NY 9

10 What is nanocellulose? Preparation of nanofibrills Products Esau, Anatomy of seed plants, 1977, Wiley, NY Pääkkö et al, Biomacromolecules, 8(2007)1934 1,7% solid content It is a natural nanomaterial that seems to give a range of opportunities to obtain superior material properties for different end-products WHY? 10

11 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

12 Special properties Pääkkö et al, Biomacromolecules, 8(2007)1934 Semi-crystalline extended chains Cellulose I crystal form 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 to aramid fibers similar to quartz glass 12

13 Manufacturing of NFC: Operation principle of Masuko grinder Operation principle Masuko grinder Grindstone 13

14 Manufacturing of NFC: Operation principle of fluidizer Operation principle Microfluidics fluidizer Cut-away view of an interaction chamber 14

15 Rheological characterization of NFC suspensions/gels => processability Small deformation oscillatory testing stress sweep plate-plate: mm, gap 1 mm 1 pass 4 passes G' max from stress sweep [Pa] plate-plate vane G' max from stress sweep [Pa] vane in cup: vane 28 mm, cup 30 mm passes Number of fluidizer passes 1 pass 4 passes 6 passes Result is geometry dependent! Combination of analytical tools! 15

16 Characterization a challenge Particle size analysis SEM, AFM, (Cryo-) TEM Rheology of suspension On line measurements Combination of analytical tools! AFM imaged fractionated NFC (Ahola, Eronen, Österberg/Aalto University School of Science and Technology) SEM imaged NFC (Pere, Tammelin, Tapper/VTT) 16

17 Transparent gels by homogenization Before fibrillation After fibrillation Concentration 0.8% 17

18 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 18

19 Effect of drying method 20 m Freeze drying Critical point drying m

20 Functionalization of NFC using polymers Methods of functionalization Chemical modification of NFC surface Functionalzation using nanoparticles Nanocellulose Nanocellulose modified with inorganics and surfactants Biochemical modification Enabling drying & redispersing 20

21 Changing the properties of nanocellulose materials by modification Cellulose nanofibres and whiskers Functionalization Hydrophobicity Charge (+/-) Specific interactions Characterization Rheology Charge density Interactions Microscopy Chemical composition Small scale testing Compatibility Strength Application oriented processability of NFC material Ideas for enhanced properties of end products Ideas for novel cellulose based materials Testing of functionalized material in different applications: 1. Composites 2. Nanomaterial Additives 3. Porous cellulose materials 21

22 Surface modification of NFC by silylation Sample O 1s C 1s Si 2p C-C, C-Si DSs (%) (%) (%) (%) NFC ref NFC I ~0.6 NFC II ~1.0 NFC, ref NFC DSs ~0.6 NFC DSs ~1.0 XPS analysis indicate increase in silica content Increase in the relative abundance of C-C and C-Si bonds AFM analysis confirm the successful surface modification Maintain the nanofibrillar structure Tammelin/VTT, Johansson and Österberg/Aalto University School of Science and Technology m height images

23 Water contact angle of the silylated NFC films 180 Silylated NFC films are hydrophobic Nanoscale surface roughness may have effect on the contact angle values Higher value for lower DS Contact angle of water DS=0.6 DS=1 Contact angle of pure NFC is <40 and the age of the water droplet is much lower Time (s) Tammelin/VTT, Johansson and Österberg/Aalto University School of Science and Technology 23

24 Filed patent applications for nanocellulose in different end uses Applications for microfibrilled cellulose NFC applications 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 38 % 8 % 16 % 13 % 3% 18 % 4 % Recent (2009) applications Composite materials (10), Food products (2), Nonwovens (2), Filter materials (2), Paper and board (2), Paper and board coatings (2) 24 Data collected by Dr. Juha Merta, Aalto University School of Science and Technology

25 25 Proposed application areas

26 Potential applications of NFC/MFC/CNC* NFC/CNC/MFC can be used for: Advanced building products Recyclable structural and interior components for transport industry Novel bioplastics Fibre-reinforced composites Switchable optical films Biocomposites for bone-repair Additives for paints, pigments and inks Cosmetic products Iridecent or magnetic films Enhancement of performance of forest products such as building materials, paper, board and packaging. and more. => various functionalization methods and processes are needed *ArboraNano/FPInnovations 26

27 Safety of nanomaterials Occupational safety issues Are 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 comission Official demands are application specific Cellulose nanomaterials are not in REACH, yet Regulations for nanotechnology products in general will be tighter in a near future Best to be proactive and collaborative while the new regulations are being developed 27

28 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. 28

29 29 Thank you for your attention!