Can redispersible low-charged nanofibrillated cellulose be produced by the addition of carboxymethyl cellulose prior to its drying?

Transcription

1 Can redispersible low-charged nanofibrillated cellulose be produced by the addition of carboxymethyl cellulose prior to its drying? Ali Naderi, Tom Lindström, Jonas Sundström, Göran Flodberg

2 Outline Innventia: company presentation Background Aim Investigations Conclusions

3 Innventia (Boosting business with science) Research institute 210 employees A no dividend organization Commissioned research Exploratory research Cluster research programs with several partners multi-client Bilateral single client projects In close collaboration with Other institutes Universities EU funded projects

4 Innventia Nanocellulose and speciality cellulose Biobased composites, barriers and new functions Mechanical pulping Kraft pulping Lignin and carbon fibres Product performance and identity Production and application of Hemicelluloses Printing solutions and functionality Packaging development Materials for packaging Paper mechanics and modelling Biorefinery processes Bioenergy and biofuels Recovery and process modelling Testing & analysis Sustainable solutions Papermaking and Paper Chemistry Fibre and stock preparation

5 Nanofibrillated cellulose Nanofibrillated cellulose (NFC, microfibrillated cellulose, MFC, cellulose nanofibrils, CNF): Length: micrometres Width: < 100 nm Source: Plant-based fibres from e.g. wood

6 NFC production 1. Chemo-mechanical pre-treatment 2. Mechanical delamination

7 NFCs based on different pre-treatment processes : Enzymatic hydrolysis Carboxymethylation TEMPO CMC * -grafting Cationization Phosphorylation * Carboxymethyl cellulose

8 Mechanical delamination: high pressure homogenization

9 Great potential for a variety of applications Paper and board Dry strength agent Reduction of dusting and linting Coating Nanobarriers New materials Filaments and threads Nanocomposites Nanostructured foams and gels Nanopaper NFC-filament Other areas of application Electronics Food Cosmetics Pharmaceutical

10 Problem NFC is produced at low dry contents (<< 10% (w/w)) Negative impact on the environment High transportation-cost Low flow-through Industrial applications require 10% (w/w) Coating Composites

11 Need Concentrated/dried NFC systems Readily redispersible Simple processes (using existing machinery) Low energy cost Regain their original (never-dried) properties

12 Solution? Carboxymethyl cellulose (CMC) as redispersion aid Herrick FW (1983) Redispersible microfibrillated cellulose. US Pat. 4,481,076 Cantiani et al. (1998) Treatment of essentially amorphous cellulose nanofibrils with carboxylcellulose with a high degree of substitution. WO A1 Lowys et al. (2001) Rheological characterization of cellulosic microfibril suspensions. Role of polymeric additives. Food Hydrocoll 15:25-32 Note! High addition levels of CMC 30% (w/w) High amount of shearing (energy cost) Recovery of the never-dried properties?

13 Solution? Butchosa N, Zhou Q (2014) Water redispersible cellulose nanofibrils adsorbed with carboxymethyl cellulose. Cellulose 21 (6): Claim! Note! Easy redispersion: 2% (w/w) CMC Sever shearing (high energy consumption) was employed Analysis Tensile strength measurements: NFC films were produced by severe shearing of NFC in the dilution process prior to film production Rheological studies: cone-plate geometry with smooth surfaces wall slip effects

14 Aim Redispersion with the aid of CMC: Addition of CMC before drying Redispersion Analysis

15 Can redispersible low-charged nanofibrillated cellulose be produced by the addition of carboxymethyl cellulose? Naderi et al. (2015) Nordic Pulp & Paper Research Journal 30(4) CMC Molecular weight ( kg/mol) Charge density (D.S ) Added amount (1-10% (w/w) based on the amount of NFC) Mixing protocol Redispersion of concentrated NFC-CMC systems Selected results!

16 Material Pulp: Bleached never-dried sulphite pulp (Nymölla mill, Sweden) Tap water CMC: Cekol (CpKelco) D.S. = mpa.s

17 Enzymatically pre-treated NFC Pulp First refining (125 kwh/tonne) Charge density 60 ( eq/g) Enzymatic treatment Second refining (100 kwh/tonne) High pressure homogenization GEA Homogenizer 3% (w/w), 1200 bar

18 Preparation of NFC-CMC suspensions 0.5% (w/w) CMC CMC was added to NFC (produced at 3% (w/w)) Total dry content (NFC + CMC): 1% (w/w) CMC/NFC = 0.01 (w/w) Mixing Propeller mixer: 2000 rpm/2 minutes Rotor-stator homogenizer: rpm/30 seconds

19 Drying and redispersion Oven drying: 105 C/ 18 hours Redispersion protocol*: 1% (w/w) Soaking in water (24 hours) Propeller mixing: 2000 rpm/2 minutes Rotor-stator homogenizer: rpm/30 seconds * Naderi et al. (2015): Microfluidized carboxymethyl cellulose modified pulp: a nanofibrillated cellulose system with some attractive properties, Cellulose 22(2),

20 Redispersion Apparent redispersion Unsucessful redispersion

21 Analysis Rheological properties Tensile strength properties of NFC films

22 Rheological studies Bob & cup geometry Serrated surfaces Minimizing wall sleep effects Pre-shearing* before measurements To even out the sample * Naderi, A. and Lindström, T. (2015): Rheological measurements on nanofibrillated cellulose systems: A science in progress Monda, H. I. (ed.), Cellulose and cellulose derivatives: synthesis, modification and applications, Nova Science Publishers, Inc., New York, pp

23 Tensile strength measurements on NFC films 0.1% (w/w), dilution with magnetic stirring overnight Drying at 50 C/7 hours

24 Results

25 Results Pure NFC was not redispersible CMC-addition (1-10% (w/w)) lead to apparent redispersion

26 Rheological studies Total dry content: 1% (w/w), CMC/NFC = 0.01 (w/w) Viscosity (Pa.s) 1 G'(Pa) 1 0,1 Never-dried NFC CMC 0.01 Redispersed NFC CMC 0.01 Never-dried NFC CMC 0 0,01 0, Never-dried NFC CMC 0.01 Redispersed NFC CMC 0.01 Never-dried NFC 1.0 -CMC 0 0,1 0,01 0,1 1 Shear rate (s -1 ) Strain (%) Lower viscosity and G for the redispersed NFC-CMC system

27 Tensile strength of NFC films Grammage: 30 g/m 2 TSI (knm/kg) TEA index (knm/kg) Strain (%) Never-dried NFC CMC Redispersed NFC CMC Inferior properties for the redispersed systems

28 Conclusions Apparent redispersion by CMC-addition (1% (w/w)) Full recovery of the original properties was not achievable

29 Acknowledgements Stora Enso Sweden Thank you for your attention!