Standardization of micro- and nanocelluloses

Transcription

1 Standardization of micro- and nanocelluloses Workshop on International Standards for Nanocellulose June 9 th, 2011 Ulla Forsström and Erkki Hellén VTT Technical Research Centre of Finland 1

2 Formulating the Finnish view with

3 Main national research activities 3

4 Nanocelluloses A Class of Nanomaterials Examples of Raw Materials: Wood Pulp Bacteria Straw Sugar Beet Banana Potato Examples of Production Methods: Grinding, Homogenizer, Intensification, Hydrolysis / Electrospinning, Ionic liquids Top-Down / Bottom-Up 4

5 Wide variety of micro- and nanofibrillar celluloses Novel products Step change/breakthrough product properties Cellulose nanomaterials Industrial sidestreams, wastes Processing Refining Tailoring Biorefining by-products Industrial pulps Non-wood crop residues Industrial pulps Wood, harvesting residues

6 leading to a wide range of applications

7 Important aspects for standardization International standardization of micro- and nanocelluloses needed to support commercialization Open international standard development No national standards First need to agree on terminology and start to standardize measurement methods No need to standardize products: different micro- or nanocelluloses Important to check already standardized measurement methods, some of which can be applied also to micro- and nanocelluloses 7

8 Wide variety of cellulosic fibers another view Length Wood pulp fiber TEMPO Innventia II gen Yano Interest area: Microfibrillated cellulose Daicel Celish KY-100G Rettenmeier MFC Rettenmeier UFC 100 FTech MCC Fibrillatio on degree e increaes NCC Chemically modified grades Width

9 Wide variety of different celluloses suggestion for classification Size/Dimensions/Branching Bacterial cellulose Scale bar: 20 μm Chain or rod-like structure All dimensions in nanoscale Nanowhiskers vvv v v v v Nanofibres Nanofibrillated Microfibrillated Interest area 20 Ribbon-like structure Overall dimensions in macroscale, fine structure in nanoscale Branched structure Overall dimensions in macroscale, fine structure in nanoscale 0 15 Image area 1x1 μm Image area 2x2 μm Charge/mass Image area 2x2 μm Colloidal l dispersion i Polyelectrolyte-like Interest area Woodfibre like Decreasing surface charge 9

10 Suitable characterization methods depend on fibril type Size/Dimensions/Branching Bacterial cellulose Scale bar: 20 μm Chain or rod-like structure All dimensions in nanoscale Nanowhiskers Nanofibres vvv v v v Set 3 v Set 4, Nanofibrillated Set 2 20 Microfibrillated Set 1 Ribbon-like structure Overall dimensions in macroscale, fine structure in nanoscale Branched structure Overall dimensions in macroscale, fine structure in nanoscale 0 15 Image area 1x1 μm Image area 2x2 μm Charge/mass Image area 2x2 μm Colloidal l dispersion i Polyelectrolyte-like Woodfibre like Decreasing surface charge 10

11 Starting gpoints for standardization Fibrillated, mechanically manufactured micro- and nanocelluloses form a specific subgroup of celluloses Distinct from crystalline grades Terminology should agree with existing standards and help in defining relevant groups of cellulose fibers Branched/ribbon-like Micro/nano Crystalline/including amorphous parts Rigid/flexible Chemically modified/unmodified Different characterization methods required for different types of cellulose materials 11

12 Characterization methods used for in-organic and synthetic nanomaterials are not directly applicable to fibrillar celluloses The main population of fibrillated celluloses consists of particles longer than 1 µm => Challenging! For example: In NanoSight system the longest fibres cover signals from smaller particles. However after removing the longest fibres, the NanoSight can measure shorter NFC particles. 12

13 Characterization methods working well for micro- and nanofibrillated celluloses Standards exist Dry matter content ph Brightness Low shear viscosity Transmittance Brookfield RVDV-I Prime viscometer with vane shape spindles Microscopic methods (OM/LM, SEM, TEM, AFM) X-ray scattering/diffraction (WAXS, SAXS, XRD) Development work needed Centrifugation Amount of nanomaterial 13

14 Basic characteristics given by combination of viscosity, transmittance and microscopy Sneck A., 2011 TAPPI Int. Conference on Nanotechnology for Renewable Materials 14

15 Basic characterization - Important physical and chemical properties of fibrillated celluloses Appearance, dimensions, aspect ratio, branching degree by microscopy Amount of nanomaterial 10 (nano/non-nano, %) 0 Average particle size, particle size distribution of the nano fraction Specific surface area Crystallinity (rigidity, flexibility) Surface charge, chemistry % 60 Masscolloider Fluidizer 50 Carboxymethylation TEMPO oxidation Dry fibril width, nm Manual analysis of FE-SEM images: dry fibril width Pöhler,T. et. al. Int. Conf. Nanotech Dissolved (colloidal) substance (amount, quality) Date 15

16 Testing for environmental, health and safety aspect of fibrillated celluloses, examples of standards/guidelines Cytotoxicity tests: Acute cytotoxicity assays (HTD- and TPC-tests) according to ISO RNA-synthesis inhibition tests EN Determination of Cytotoxicity Genotoxicity tests: Ames test, OECD guideline (OECD 471, 1997) OECD guidelines for in vitro micronucleus tests (e.g. OECD 487, 2010) Immunotoxicity tests: No official standards for immunotoxicological tests Ecotoxicity tests: ISO 6341(1996) and ISO/DIS (2009) Date 16

17 Published safety testing data of micro- and nanocelluloses Pitkänen et al., Int. Conf. Nanotech Cytotoxicological analysis: No indications of toxicity it found Sample Whiskertype UFC Fibrillar NFC HTD Hepa-1 No changes in cells morphology No changes in cells morphology Cytotoxicity HTD HaCaT No changes in cells morphology No changes in cells morphology HTD HeLa229 Not tested No changes in cells morphology Sublethal effects RNA synthesis inhibition assay Not tested Did not reduce mrna synthesis in HeLa229 cells Cell de eath rate (% %) CTR µg/ml MFC MCC Vartiainen et al, Cellulose (2011) 18: Immunotoxicological analysis: No indications dcato of toxicity cty found 17

18 Material specifications to support commercialization Basically similarly to wood fibers cf. TC-6 paper, board and pulps Some development work needed Property Characterization i method Apparatus Satus of the method Dry matter content According to standard Ready for standardization ph According to standard Ready for standardization Brightness According to standard Development needed on sample preparation Size range Light scattering Fiber analysator Nanosight, N5 FiberLab Development needed Rheology Low shear viscosity, yield stress Brookfield Ready for standardization Chemical purity, Fiber analytical methods GC, MS Ready for use composition 18

19 Conclusions Important to identify the needs for standardization Companies, global view People from Finnish companies and research institutes are willing to participate in international standardization of micro- and nano-celluloses Information for standardization already available Several research projects producing more info for standardization on-going, some projects close to demonstration/scale-up phase 19

20 Why to standardize? Important benefits: Suitability of products and processes for their intended purpose Prevention of barriers to trade Facilitation of technological cooperation Active discussion about best characterization and safety testing ti methods and international ti networking needed d Next collection date 30 September 2011 Please contact: t ulla.forsstrom@vtt.fi tt fi 20

21 COST Action FA0904 Eco-sustainable food packaging g based on polymer nanomaterials International Workshop Novel nanostructured polymeric materials for food packaging and beyond September (Thursday-Friday), 2011 at VTT, Espoo, Finland The main objective of the Cost Action FA0904 is to constitute an international scientific and technology network on issues related to eco-sustainable Polymer Nanocomposites Food Packaging for the preservation, conservation and distribution of high quality and safe food. Action FA0904 Food and Agriculture Date 21