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
Outline Innventia: company presentation Background Aim Investigations Conclusions www.innventia.com 2016 2
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 www.innventia.com 2016 3
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 www.innventia.com 2016 4
Nanofibrillated cellulose Nanofibrillated cellulose (NFC, microfibrillated cellulose, MFC, cellulose nanofibrils, CNF): Length: micrometres Width: < 100 nm Source: Plant-based fibres from e.g. wood www.innventia.com 2016 5
NFC production 1. Chemo-mechanical pre-treatment 2. Mechanical delamination www.innventia.com 2016 6
NFCs based on different pre-treatment processes : Enzymatic hydrolysis Carboxymethylation TEMPO CMC * -grafting Cationization Phosphorylation * Carboxymethyl cellulose www.innventia.com 2016 7
Mechanical delamination: high pressure homogenization www.innventia.com 2016 8
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 www.innventia.com 2016 9
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 www.innventia.com 2016 10
Need Concentrated/dried NFC systems Readily redispersible Simple processes (using existing machinery) Low energy cost Regain their original (never-dried) properties www.innventia.com 2016 11
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. WO9802487A1 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? www.innventia.com 2016 12
Solution? Butchosa N, Zhou Q (2014) Water redispersible cellulose nanofibrils adsorbed with carboxymethyl cellulose. Cellulose 21 (6):4349-4358 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 www.innventia.com 2016 13
Aim Redispersion with the aid of CMC: Addition of CMC before drying Redispersion Analysis www.innventia.com 2016 14
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) 568-577 CMC Molecular weight ( 70-1000 kg/mol) Charge density (D.S. 0.4-0.9) Added amount (1-10% (w/w) based on the amount of NFC) Mixing protocol Redispersion of concentrated NFC-CMC systems Selected results! www.innventia.com 2016 15
Material Pulp: Bleached never-dried sulphite pulp (Nymölla mill, Sweden) Tap water CMC: Cekol 50000 (CpKelco) D.S. = 0.8-0.9 4500-7500 mpa.s www.innventia.com 2016 16
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 www.innventia.com 2016 17
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: 20000 rpm/30 seconds www.innventia.com 2016 18
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: 20000 rpm/30 seconds * Naderi et al. (2015): Microfluidized carboxymethyl cellulose modified pulp: a nanofibrillated cellulose system with some attractive properties, Cellulose 22(2), 1159-1173 www.innventia.com 2016 19
Redispersion Apparent redispersion Unsucessful redispersion www.innventia.com 2016 20
Analysis Rheological properties Tensile strength properties of NFC films www.innventia.com 2016 21
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. 187-202. www.innventia.com 2016 22
Tensile strength measurements on NFC films 0.1% (w/w), dilution with magnetic stirring overnight Drying at 50 C/7 hours www.innventia.com 2016 23
Results www.innventia.com 2016 24
Results Pure NFC was not redispersible CMC-addition (1-10% (w/w)) lead to apparent redispersion www.innventia.com 2016 25
Rheological studies Total dry content: 1% (w/w), CMC/NFC = 0.01 (w/w) 100 100 10 10 Viscosity (Pa.s) 1 G'(Pa) 1 0,1 Never-dried NFC 0.99 -CMC 0.01 Redispersed NFC 0.99 -CMC 0.01 Never-dried NFC 0.99 -CMC 0 0,01 0,1 1 10 Never-dried NFC 0.99 -CMC 0.01 Redispersed NFC 0.99 -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 www.innventia.com 2016 26
Tensile strength of NFC films Grammage: 30 g/m 2 TSI (knm/kg) TEA index (knm/kg) Strain (%) Never-dried NFC 0.99 -CMC 0.01 107 6 3.4 1.9 4.2 2.3 Redispersed NFC 0.99 -CMC 0.01 85 7 1.4 0.4 2.2 0.4 Inferior properties for the redispersed systems www.innventia.com 2016 27
Conclusions Apparent redispersion by CMC-addition (1% (w/w)) Full recovery of the original properties was not achievable www.innventia.com 2016 28
Acknowledgements Stora Enso Sweden Thank you for your attention! www.innventia.com 2016 29