impact of micro/nanofibrillated cellulose preparation on … · impact of micro/nanofibrillated...

IMPACT OF MICRO/NANOFIBRILLATED CELLULOSE PREPARATION ON THE REINFORCEMENT PROPERTIES OF PAPER AND COMPOSITES FILMS.

Denilson DA SILVA PEREZa,* Sandra TAPIN-LINGUAa, Anne LAVALETTE a,c, Thiago BARBOSAa,c,d, Israel GONZALEZb, Gilberto SIQUEIRAb, Julien BRASb, Alain DUFRESNEb. a) Institut Technologique FCBA, New Materials Division, Grenoble, France. b) INP Grenoble PAGORA, Grenoble, France. c) ESB - Ecole Supérieure du Bois, Nantes, France. d) UFPR - Universidade Federal do Parana, Curitiba, Brazil. * E-mail : [email protected]

Introduction Micro- and nano-fibrillated cellulose (M/NFC) seem to be one of the ways of better exploiting the potential of cellulosic fibres than the usual paper-based application (1-6). Depending on the fibrous raw materials, pre-treatment and fibrillation conditions, different types of micro/nanofibrillated cellulose can be obtained in terms of microfibrilles individualisation, dimensions, crystallinity, etc. Moreover, the chemical modification of micro- and nano-fibres surfaces can not only impart different functionalities but also be used as pre-treatment for their production. In particular TEMPO-mediated oxidation allow selectively creating carboxyl groups on C6 carbon of cellulosic fibres, which can be used for further grafting of specific moieties either by amidation or esterification (5-8). The work described here aims at understanding the impact of M/NFC preparation on the properties of these materials and consequently on their reinforcement capabilities for paper and composites applications.

Materials and Methods Bleached kraft pulps from hardwoods or softwoods were used as raw materials for the production of M/NFC. The pulps were firstly highly refined then enzymatically treated (Celluclast-Novozymes, 5% pulp consistency, 10 mL enzyme for 100 g–dry pulp, 50°C, 2 hours.). Different M/NFC grades were produced by homogenization using laboratory-scale equipment Microfluidizer M110EH at 2 % concentration equipped with different interaction chambers (Z-shaped, internal diameter of 100, 200, and 400 µm) allowoing microfibrils individualisation by high pressure shearing (up to 2200 bars) of the cellulosic suspensions. Three contrasted types of M/NFC were produced and used as reinforcement agents for paper and latex composites films. Moreover, these M/NFC were chemically modified in surface by TEMPO-oxidation and amidation of the carboxyl groups to graft polyethyleneglycol (PEG) or aromatic groups based on the protocol of the work described earlier for fibres (9).

Results and discussions

1) M/NFC preparation Different optical and electronic microscopy devices were used to follow the conversion of pulp fibres into nanofibrillated cellulose (Figure 1).

Figure 1 – A :Light micrographyexamination of MFC obtained using 400 µm chamber; B : SEM examination of M/NFC obtained using 200 µm chamber; C : TEM examination of NFC obtained using 100 µm chamber.

The cellulosic material obtained after 3 passes in 400 µm chamber is essentially composed of short cut fibres and some microfibrils (MFC). After 5 passes in a 200 µm chamber NFC is obtained, but important non-destructured material is still present. Finally, 5 passes in a 100 µm chamber allow obtaining a homogenous material constituted essentially of cellulose nanofibres.

A B

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2) Paper reinforcement The different M/NFC were applied as reinforcement agent at 1, 5 and 20 % in weight on refined hardwoods and softwoods pulps aiming at improving the physical properties (bulk and tensile, tear, burst indexes). Figure 2 clearly demonstrates that the smaller and more homogeneous the M/NFC, the higher the reinforcement effects. Thus, the addition of 20 % of M/NFC produced after 5 passes on 100 µm chamber allows improving simultaneously the tensile and tear indexes higher than 90 %. For the M/NFC produced using 400 µm and 200 µm chambers which are less homogenous, the improvements are respectively 38 % and 56 % for the tensile index and 37 % and 80 % for the tear index. TEMPO-oxidation of M/NFC allows further gains in physical properties (+ 10-25 %).

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Figure 2: Effect of the addition of hardwood and softwood MFC on the pulp mechanical properties (HW-R-26:

hardwood bleach Kraft pulp refined at 26 °SR; SW-R-25: softwood bleach Kraft pulp refined at 25 °SR / SW_100-5: MFC from softwood pulps; HW_100-5: MFC from hardwood pulps)

3) Composites films An important reinforcement was obtained when using M/NFC (Table 1). At 3 % of M/NFC, the Young’s modulus compared to latex is multiplied by 6 and the tensile strength is by 2. At 12 % of non-modified M/NFC, the Young’s modulus can reach 60-fold the latex one. If TEMPO-oxidized M/NFC are used, values up to 100-fold the modulus of latex were obtained, while the tensile strength is multiplied by 12. Moreover, these composites films preserve certain elasticity, measured by the strain at break values, contrarily to the non-modified M/NFC. Finally, the grafting of PEG or aromatic chains by amidation generated films with high tensile strength and strain at break, but considerably lower Young’s modulus.

Table 1 – Mechanical properties of composites films reinforced with different MFC/NFC. Type and characteristics of the reinforcement E (MPa) ƐR (%) δR (MPa)

Latex alone 0.77 409 0.65

(3%) 4.47±2.05 230±88.05 1.18±0.2 Natural

(12%) 47.64±5.25 76±15.55 2.35±0.04

(3%) 5.32±0.49 307±50.91 1.75±0.25 TEMPO Oxidised (12%) 75.75±19.61 191±62.93 7.82±0.53

(3%) 8.51±2.85 377±96.43 1.77±0.04 Amided aniline

(12%) 17.82±3.31 51±9.19 7.07±0.91 (3%) 6.22±1.34 349±0 2.01±0.33

Microfibrils

Amided PEG (12%) 12.11±0.45 16.5±0.7 7.45±0.55

Acknowledgments The authors thank ADEME (contract AGRICE 06.01C.0039)/CTPi members for the financial support. References 1) Herrick FW et al. (1983). J Appl Polym Sci: Appl Polym Symp 37:797-813. 2) Turbak AF et al. (1983). J Appl Polym Sci: Appl Polym Symp 37:815 - 827. 3) Henriksson M. et al. (2007). Europ Polym J 43:3434-3441. 4) Paakko M. et al. (2007). Biomacromolecules 8:1934-1941. 5) Saito T. et al. (2006). Biomacromolecules 7:1687-1691. 6) Saito T. et al (2007). Biomacromolecules 8:2485-2491. 7) da Silva Perez, D. et al. (2003) Biomacromolecules, 4, 1417-1425 (2003).

9) da Silva Perez, D. Guillemain, A., Petit-Conil, M., Strategies for surface fibre functionalisation using TEMPO-mediated oxydation. 11th European Workshop on Lignocellulosics and Pulps, Hamburg, Germany (2010) Proceedings, pp 377-380.

Impact of micro/nanofibrillated cellulose preparation on the reinforcement

properties of paper and composites films

Sandra Tapin-Lingua, Denilson Da Silva Perez

Tappi Nano2010 - 28/09/2010 - STL - 2

• Chemical pre-treatmentsControlled acid hydrolysis Alkaline swelling and/or

hydrolysisSurface cellulose chemical

modifications

• Enzymatic pre-treatmentsCellulasesHemicellulases

• Mechanical treatmentsFibers refining/beating/grinding

“Homogenizers”

Micro/nanofibrillated cellulose

Introduction

Pääkkö et al., Biomacromolecules, 2007, 8, 1934-1941

Tappi Nano2010 - 28/09/2010 - STL - 3

OBJECTIVES

• Produce micro/nanofibrillated cellulose from bleached chemical pulps

• Develop analytical techniques for the characterization of M/NFC

• Evaluate the potential as reinforcement agents for papermaking and composites films applications

• Contribute to the emergence of new products and markets for the pulp and paper industry

Tappi Nano2010 - 28/09/2010 - STL - 4

Materiels and methods to M/NFC production

Pulp pre-treatment

Strong refining– Enhance fibre accessibility and treatment

efficiencyEnzymatic pre-treatment with cellulases

– Weaken the fibres and enhance microfibrillation

– Facilitate fibres transit into the vessel of the Microfluidizer

Bleached Kraft Pulp

Refined BKP

Refined and enzymaticalytreated BKP

Mechanical refining

Cellulase treatment50 °C, 2h

Tappi Nano2010 - 28/09/2010 - STL - 5

Materiels and methods to M/NFC production

NFC Oxidation with TEMPOCOOH rate: 1.0 mmol/g

Mechanical refining

Bleached Kraft Pulp

Refined BKP

Refined and enzymaticalytreated BKP

Cellulase treatment 50 °C, 2h

Homogenizing:3 times through 400 µm

+ 5 *: 200 µm

MFC

+ 5 *: 200 µm+ 5 *: 100 µm

NFC

NFC ox

Mechanical treatment processed by high-pressure homogenizer: Microfluidizer M-110EH

At constant liquid flow Pressure applied depends on the internal diameter of the fluidization chambers

– 100 bars for the 400 µm chamber,– 1500 bars for the 200 µm chamber– 2200 bars for the 100 µm chamber

Concentrations of the suspensions: 2 %

TEMPOOxidation

Tappi Nano2010 - 28/09/2010 - STL - 6

• Evaluation of the micro-/ nanofibres sizeMorFi analysis

Detection limit: ≈ 7 µmOptical microscopy analysisTEM analysisSEM examinations

• Determination the suspension viscosity• Evaluation of the impact of M/NFC on pulp properties

depending:Pulp origin used to produce M/NFCM/NFC suspension quality (size and heterogeneity)

M/NFC Characterization

Tappi Nano2010 - 28/09/2010 - STL - 7

• Light microscopy observationsEffect of the different passages through the homogenizer

400-3400-1

200-1

100-1


200-5 MFC

100-5 NFC

Reduction of cellulosic particles sizeIncrease in homogeneity

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• SEM examinationSamples directly observed

Reduction of cellulosic particles sizeIncrease in homogeneity

Run 200-5 100-5MFC NFC

Tappi Nano2010 - 28/09/2010 - STL - 9

• TEM examinationSamples directly observed without/with Uranyl acetate staining

100-9

17nm

200-5

N/MFC Characterization

Run

Average MFC Diameter

MFC

100-5

20nm

NFC

Tappi Nano2010 - 28/09/2010 - STL - 10

Effect of M/NFC on pulp properties

• Introduction of M/NFC in pulp to evaluate their impact on paper properties:

2 pulp origins: Softwood (SW) and hardwood (HW)

3 different M/NFC qualities3 concentrations introduced

1%, 5% or 20 % weight

•M/NFC retention controlled by gravimetric measurement

M/NFC SW or HW

Pulp26 °SR BKPSW or HW

Tappi Nano2010 - 28/09/2010 - STL - 11

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On tensile indexin M/NFC

concentration: tensile index enhancementPulp properties : NFC > MFC

Not effect of the pulp origin of the NFC


• Impact of M/NFC addition in pulp

SW NFC

HW NFC

HW MFC

Tappi Nano2010 - 28/09/2010 - STL - 12


• Impact of M/NFC addition in pulpOn tensile index

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+ 20 % MFC mechanical properties x2

Increase of tensile and tear index but bulk remained stable

Tappi Nano2010 - 28/09/2010 - STL - 13

water evaporation (T>Tg) → particle coalescence

Effect of M/NFC on composite films

Nanocomposite film

NFC HW Polymer

Matrix = aqueous dispersed polymer (latex)Reinforcements

Cellulosic Fibres unmodified and modified (TEMPO oxidized)NFC unmodified and modified3 and 12 % weight

or Fibres

• Introduction of M/NFC in polymer matix to evaluate their impact on composite properties:

Tappi Nano2010 - 28/09/2010 - STL - 14

Effect of fibre introduction on composite films

Latex (NR)

HWF 3%

HWF 12%

Reference E (MPa) ƐR (%)Natural Latex 0.77 409

HWF 3% 2.2 ± 0.6 213 ± 9.2HWF 12% 9.4 ± 0.6 66 ± 3.5

HWF-Ox 3%

HWF-0x 12%

Latex (NR)

• Unmodified fibresPhases

separation: no reinforcement

• TEMPO-oxidized fibres

Homogenous film

With fibres addition:Young modulus: Elongation: HWF-Ox 3% 2.9 ± 0.3 302 ± 82.0

HWF-Ox 12% 34.5 ± 9.2 275 ± 44.5

Tappi Nano2010 - 28/09/2010 - STL - 15

Latex (NR)NFC 3%

NFC 12%

Reference E Mpa ƐR (%) δR (MPa)Natural Rubber 0.7 409 0.65 NFC 3% 4.5 ± 2.0 230 ± 88.0 1.2 ± 0.2NFC 12% 47.6 ± 5.3 76 ± 15.5 2.4 ± 0.04

Effect of M/NFC on composite films

Latex (NR)NFC-ox 3%

NFC-ox 12%

• Unmodified NFC • TEMPO-oxidized NFCHomogenous films

NFC-Ox 3% 5.3 ± 0.5 307 ± 50.9 1.7 ± 0.2NFC-Ox 12% 75.7 ± 19.6 191 ± 62.9 7.8 ± 0.5

NFC-OX 12%: Tensile strengthStrain at break

Tappi Nano2010 - 28/09/2010 - STL - 16

CONCLUSION

• MFC ProductionDevelopment of a M/NFC production protocolCharacterisation of M/NFC

• M/NFC induced properties on pulp strengthMechanical properties: x 2 with NFC additionImpact of NFC characteristics on pulp properties the smaller and more homogenous give the best results

• M/NFC induced properties on composites filmsMechanical properties

Young modulus:» x 62 with 12 % NFC »x 98 with 12 % Oxidized NFC

Tensile strength:» x 12 with 12 % oxidized NFC

Oxidation of fibres/MFC improves the strength properties of composites

Tappi Nano2010 - 28/09/2010 - STL - 17

ACKNOWLEDGEMENTS

Co-autors: Anne Lavalette, Thiago Brabosa, IsraelGonzalez, Gilberto Siqueira, Julien Bras and Alain Dufresne

Partial financial support from French energy agency-ADEME

Industrial partners

Laboratory and R&D InstitutesPAGORACERMAV-CNRS

impact of micro/nanofibrillated cellulose preparation on … · impact of micro/nanofibrillated...

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